Measurement apparatus, measurement method, and ion-sensitive semiconductor device

Abstract

To provide a measuring device with which it is possible to avoid additional measurements in each characteristic value measurement.SOLUTION: The measuring device comprises: a first ion sensitive semiconductor element, a second ion sensitive semiconductor element and a reference electrode that are contactably arranged in a medium the characteristic value of which is to be measured; a signal input unit for receiving a first signal from the first ion sensitive semiconductor element and a second signal from the second ion sensitive semiconductor element and generating a sensor signal; a signal processing unit for processing the sensor signal; and a memory for storing first data that pertains to the chronological change of the first and second ion sensitive semiconductor elements and mutually communicably connected to the signal processing unit. The signal processing unit processes the sensor signal using the integral power-on time of the first and second ion sensitive semiconductor elements and the first data, and generates an output signal for the characteristic value of the medium. The first ion sensitive semiconductor element includes a first sensitive membrane and the second ion sensitive semiconductor element includes a second sensitive membrane that is different from the first sensitive membrane.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a measurement apparatus, a measurement method, and an ionic semiconductor device. [Background technology]

[0002] Patent Document 1 discloses an electrochemical sensor. The electrochemical sensor includes a sensor unit equipped with a field effect transistor. The electrochemical sensor includes a comparison circuit that compares a characteristic value measured by the sensor unit with a target value for the characteristic value of the sensor unit, a circuit that calculates voltage conditions for injecting charges into a charge storage film from the comparison result, and a control circuit that controls the application of a voltage under the conditions calculated by this circuit to the sensor unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-180711 A Summary of the Invention [Problem to be solved by the invention]

[0004] In an ion-sensitive semiconductor element, for example the ion-sensitive field effect transistor of Patent Document 1, when the sensitive membrane is immersed in an aqueous solution for pH measurement, the output voltage of the ion-sensitive semiconductor element fluctuates.

[0005] Specifically, the ion-sensitive semiconductor element may be used continuously for a long time for constant monitoring of a medium such as soil or an aqueous solution. In this case, a drift appears in the output of the ion-sensitive semiconductor element, specifically, the pH sensor. This drift reduces the measurement accuracy of the pH sensor.

[0006] The output drift of a pH sensor can also be eliminated or reduced by performing an additional calibration measurement after each measurement of the property value of the medium, but this additional measurement requires additional measurement time in addition to the time required to measure the property value, and this additional time accumulates according to the number of measurements of the property value.

[0007] An object of the present invention is to provide a measuring apparatus, a measuring method, and an ion-sensitive semiconductor device that can avoid additional measurements for each measurement of a characteristic value. [Means for solving the problem]

[0008] A measuring device according to a first aspect of the present invention includes a first ion-sensitive semiconductor element arranged so as to be in contact with a medium whose characteristic value is to be measured, a second ion-sensitive semiconductor element arranged so as to be in contact with the medium, a reference electrode arranged so as to be in contact with the medium and with the medium located between the first ion-sensitive semiconductor element and the second ion-sensitive semiconductor element, a signal input unit that receives a first signal from the first ion-sensitive semiconductor element and a second signal from the second ion-sensitive semiconductor element and generates a sensor signal, and a signal processing unit that is coupled to the signal input unit and processes the sensor signal. and a memory that stores first data relating to temporal fluctuations of the first ion sensitive semiconductor element and the second ion sensitive semiconductor element and is communicatively coupled to the signal processing unit, wherein the signal processing unit processes the sensor signal using the accumulated current flow time of the first ion sensitive semiconductor element and the second ion sensitive semiconductor element and the first data to generate an output signal for the characteristic value of the medium, wherein a first sensitive film of the first ion sensitive semiconductor element includes a first material, and a second sensitive film of the second ion sensitive semiconductor element includes a second material, and the first material is different from the second material.

[0009] According to this measuring device, the first ion-sensitive semiconductor element having the first sensitive film and the second ion-sensitive semiconductor element having the second sensitive film show different changes over time. Based on the first data representing the difference in the changes over time, the signal processor processes the sensor signals from the first ion-sensitive semiconductor element and the second ion-sensitive semiconductor element. Through this processing, the signal processor can generate an output signal for a characteristic value (e.g., pH) related to the ions of the medium. By using the first data, the first ion-sensitive semiconductor element, and the second ion-sensitive semiconductor element, the influence of the changes over time of the first ion-sensitive semiconductor element and the second ion-sensitive semiconductor element is reduced in the output signal. Furthermore, the measuring device can avoid performing a measurement every time the characteristic value of the medium is measured to compensate for the changes over time.

[0010] The measuring device according to the first aspect of the present invention further includes a timer that measures the time during which current is passed through the first ion-sensitive semiconductor element and the second ion-sensitive semiconductor element, the signal processing unit updates the accumulated current passing time based on the current passing time, and the memory stores the updated accumulated current passing time from the signal processing unit.

[0011] According to this measuring device, the current-flow time of the timer in the measuring device is updated, for example, every time the current-flow of the first ion sensitive semiconductor element and the second ion sensitive semiconductor element is terminated. The memory stores the updated integrated current-flow time.

[0012] The measuring device according to the first aspect of the present invention further includes a temperature sensor for monitoring the temperatures of the first ion-sensitive semiconductor element and the second ion-sensitive semiconductor element, the temperature sensor generating a temperature signal indicating the temperature, the memory storing second data relating to changes in the temporal fluctuations of the first ion-sensitive semiconductor element and the second ion-sensitive semiconductor element relative to temperature, and the signal processing unit processing the sensor signal using the second data and the temperature signal to generate the output signal.

[0013] According to this measuring device, the fluctuation over time of the first ion-sensitive semiconductor element of the first sensitive film and the second ion-sensitive semiconductor element of the second sensitive film exhibits temperature dependency. Based on the second data representing this temperature dependency, the signal processor processes the sensor signal. This processing enables the signal processor to generate an output signal for a characteristic value of the medium, and the effect of the fluctuation over time with respect to temperature is reduced in the output signal.

[0014] In the measuring device according to the first aspect of the present invention, the characteristic value includes a hydrogen ion concentration (pH) of the medium, the first sensitive film of the first ion sensitive semiconductor element includes at least one of silicon oxide, silicon nitride, aluminum oxide, and tantalum oxide, and the second sensitive film of the second ion sensitive semiconductor element includes at least one of silicon oxide, silicon nitride, aluminum oxide, and tantalum oxide, different from the first sensitive film.

[0015] According to this measuring device, the first ion sensitive semiconductor element has a first sensitive film containing at least one of silicon oxide, silicon nitride, aluminum oxide, and tantalum oxide. The second ion sensitive semiconductor element has a second sensitive film different from the first sensitive film and containing at least one of silicon oxide, silicon nitride, aluminum oxide, and tantalum oxide. The combination of these materials causes a clear difference in the temporal fluctuation between the first ion sensitive semiconductor element and the second ion sensitive semiconductor element.

[0016] A measurement method for measuring characteristics of a medium according to a second aspect of the present invention includes: bringing an ion-sensitive semiconductor device including a first ion-sensitive semiconductor element having a first sensitive film made of a first material, and a second ion-sensitive semiconductor element having a second sensitive film made of a second material different from the first material, into contact with a medium whose characteristic value is to be measured; passing a current through a reference electrode in contact with the medium so that the medium is located between the ion-sensitive semiconductor device and the reference electrode; obtaining sensor signals related to the medium from the first ion-sensitive semiconductor element and the second ion-sensitive semiconductor element after passing a current through the reference electrode and bringing the ion-sensitive semiconductor device into contact with the medium; and processing the sensor signals based on first data related to fluctuations over time of the first ion-sensitive semiconductor element and the second ion-sensitive semiconductor element and an accumulated current-passing time of the ion-sensitive semiconductor device to generate an output signal for the characteristic value.

[0017] According to this measurement method, the first ion-sensitive semiconductor element of the first sensitive membrane and the second ion-sensitive semiconductor element of the second sensitive membrane exhibit different variations over time. Based on first data representing the difference in the variations over time, the sensor signals from the first ion-sensitive semiconductor element and the second ion-sensitive semiconductor element are processed to generate an output signal related to a characteristic value of the medium (e.g., pH). This processing allows a signal for the characteristic value of the medium to be generated, in which the influence of the variations over time can be reduced. Furthermore, the measurement method makes it possible to avoid performing measurements every time the characteristic value of the medium is measured to compensate for the changes over time.

[0018] The method according to the second aspect of the present invention further includes measuring a current flow time of the first ion sensitive semiconductor element and the second ion sensitive semiconductor element, updating the accumulated current flow time using the current flow time, and storing the accumulated current flow time in a memory.

[0019] According to this measurement method, the integrated value of the measured current-flow time of the ion-sensitive semiconductor device is updated, for example, every time the current-flow of the first ion-sensitive semiconductor element and the second ion-sensitive semiconductor element is completed.

[0020] The method according to a second aspect of the present invention further comprises sensing a temperature of the ion sensitive semiconductor device to generate a temperature signal, and obtaining a sensor signal comprises processing the sensor signal further using second data relating to temperature change in the temporal variation and the temperature signal to generate the output signal.

[0021] According to this measurement method, the temporal variation of the first ion-sensitive semiconductor element of the first sensitive membrane and the second ion-sensitive semiconductor element of the second sensitive membrane exhibits temperature dependency. Second data exhibiting this temperature dependency is additionally used to process the sensor signal to generate an output signal for a characteristic value of the medium. This processing allows a signal for the characteristic value of the medium (e.g. pH) to be generated, in which the influence of the temperature dependency on the temporal variation can be reduced.

[0022] An ion-sensitive semiconductor device according to a third aspect of the present invention has a substrate having a semiconductor region of a first conductivity type, a first sensor window and a second sensor window, and further comprises an insulating film provided on the substrate, a first sensitive film provided between a first portion of the semiconductor region and the first sensor window and including a first material, a first source region of a second conductivity type different from the first conductivity type provided in the semiconductor region, a first drain region of the second conductivity type provided in the semiconductor region, and a second sensitive film provided between a second portion of the semiconductor region and the second sensor window and including a second material. a second source region of the second conductivity type provided in the semiconductor region, and a second drain region of the second conductivity type provided in the semiconductor region, wherein the first sensor window reaches the first sensitive film, the second sensor window reaches the second sensitive film, the first portion of the semiconductor region is between the first source region and the first drain region, the second portion of the semiconductor region is between the second source region and the second drain region, and the first material of the first sensitive film is different from the second material of the second sensitive film.

[0023] According to this ion-sensitive semiconductor device, at least two field-effect ion-sensitive semiconductor elements are provided on the same substrate. These ion-sensitive semiconductor elements differ from each other in terms of the material of the sensitive film, but have almost the same other characteristics. This makes it possible to highlight the difference in the change over time caused by the difference in the sensitive film. Effect of the Invention

[0024] According to the present invention, it is possible to provide a measuring apparatus, a measuring method, and an ion-sensitive semiconductor device that can avoid additional measurements for each characteristic value measurement. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a measurement device according to the present embodiment. [Diagram 2] FIG. 2 is a diagram showing a schematic diagram of an ion-sensitive semiconductor device according to the present embodiment. [Diagram 3] FIG. 3 is a schematic cross-sectional view taken along line III-III shown in FIG. [Figure 4] FIG. 4 is a diagram illustrating exemplary steps of a measurement method according to the present embodiment. [Diagram 5] FIG. 5 is a graph showing the change over time of the ion-sensitive semiconductor element. [Figure 6] FIG. 6 is a graph showing the temperature dependence of the change over time of the ion-sensitive semiconductor element. [Figure 7] FIG. 7 is a graph showing an Aurhenius plot of the temperature characteristics of FIG. [Figure 8] FIG. 8 is a diagram illustrating an example of a hardware configuration of the processing unit illustrated in FIG. [Figure 9] FIG. 9 is a diagram showing a schematic diagram of an ion-sensitive semiconductor device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or similar parts are denoted by the same or similar reference numerals, and redundant explanations will be omitted.

[0027] FIG. 1 is a diagram that illustrates an example of a measurement device according to the present embodiment.

[0028] The measuring device 11 includes an ion-sensitive semiconductor device 13 , a reference electrode 15 , a signal input unit 17 , a signal processing unit 19 , and a memory 21 .

[0029] The ion-sensitive semiconductor device 13 includes a first ion-sensitive semiconductor element 25 and a second ion-sensitive semiconductor element 27. Specifically, each of the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27 has a field-effect structure. The ion-sensitive semiconductor device 13, specifically the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27, are arranged so as to be in contact with a medium 100 whose characteristic value is to be measured. The characteristic value may be the hydrogen ion concentration (pH) of the medium 100. The first ion-sensitive semiconductor element 25 has a first sensitive film 25a containing a first material, and the second ion-sensitive semiconductor element 27 has a second sensitive film 27a containing a second material. The first material is different from the second material.

[0030] A reference electrode 15 is provided for the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. The reference electrode 15 is also arranged so as to be in contact with the medium 100.

[0031] The signal input unit 17 receives a first signal S1 from the first ion sensitive semiconductor element 25 and a second signal S2 from the second ion sensitive semiconductor element 27, and also outputs a sensor signal S SEN The signal processing unit 19 is coupled to the signal input unit 17 and generates a sensor signal S SEN The memory 21 is communicably coupled to the signal processing unit 19. The memory 21 stores first data 21a relating to the temporal fluctuations of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27.

[0032] The signal processing unit 19 calculates a sensor signal S using the first data 21a and the integrated current application time 21b of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. SEN to obtain an output signal S for the characteristic value of the medium 100. OUT to output 46.

[0033] According to the measurement device 11, the first ion-sensitive semiconductor element 25 having the first sensitive film 25a and the second ion-sensitive semiconductor element 27 having the second sensitive film 27a exhibit different changes over time. Based on the first data 21a representing the difference in the changes over time, the signal processing unit 19 calculates the sensor signals S from the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27. SEN By this processing, the signal processing unit 19 outputs an output signal S for a characteristic value (e.g., pH) related to the ions of the medium 100. OUT By using the first data 21a, the first ion-sensitive semiconductor element 25, and the second ion-sensitive semiconductor element 27, the influence of the change over time of the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27 can be generated. OUT In addition, the measurement device 11 can avoid a calibration measurement to compensate for changes over time every time the characteristic value of the medium 100 is measured. Furthermore, the measurement device 11 can obtain the characteristic value of the medium 100 for a long period of time without calibration.

[0034] The signal input unit 17 is connected to one terminal S of each of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. Specifically, the signal input unit 17 may include current sources 45a, 45b, which are connected between one terminal S of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 and a ground line, respectively. The current sources 45a, 45b provide bias currents to the ion sensitive semiconductor elements (25, 27). The signal input unit 17 may also include a conversion unit 47, which processes each of the first signal S1 and the second signal S2 to generate a sensor signal S. SENThe conversion unit 47 may include one or more A / D converters. By way of example and not limitation, the conversion unit 47 includes A / D converters 47a, 47b. The first signal S1 and the second signal S2 may be processed by the respective A / D converters 47a, 47b. In this embodiment, the signal processing unit 19 and the memory 21 are included in the processing unit 33. The memory 21 also has respective areas for storing values ​​(data) of the first data 21a and the integrated energization time 21b.

[0035] The measuring device 11 may further include a timer 31. The timer 31 may measure, for example, a time during which current is passed through the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. The signal processing unit 19 may update the integrated current passing time 21b based on the current passing time, and the memory 21 may store the updated integrated current passing time 21b from the signal processing unit 19.

[0036] According to this measuring device 11, the current flow time measured by the timer 31 in the processing unit 33 is updated, for example, every time current flow ends for the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. The memory 21 stores the updated integrated current flow time 21b.

[0037] Specifically, the measurement device 11 may include a first power source 43 and a second power source 44. The first power source 43 may be connected to the other terminals D of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 via a first switch 50a. The first switch 50a switches the other terminals D of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 to a ground line or the first power source 44 in response to a signal from the control unit 41. The second power source 44 provides a reference voltage Vr and may be connected to the reference electrode 15 via a second switch 50b. The second switch 50b may have a similar structure to the first switch 50a.

[0038] The timer 31 can determine the period from closing to opening of the first switch 50a in response to, for example, a signal that controls the opening and closing of the first switch 50a (a signal that the control unit 41 provides to the first switch 50a). In this embodiment, the opening and closing of the second switch 50b is synchronized with the opening and closing of the first switch 50a.

[0039] The characteristics of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 vary in response to changes in the environmental temperature. For temperature compensation, the measurement device 11 may further include a temperature sensor 29, such as a thermistor, a thermocouple, or a semiconductor PN diode. The temperature sensor 29 is provided to monitor the temperatures of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. For this purpose, the temperature sensor 29 may be disposed in the vicinity of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. The temperature sensor 29 generates a temperature signal S indicative of the temperature based on the temperature monitor for the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. TEMP Generates a temperature signal S TEMP is provided to the processing unit 33.

[0040] The memory 21 stores the second data 21c, and the second data 21c includes a value related to a correction (temperature correction) for the change in the temporal fluctuation of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 relative to temperature.

[0041] The signal processing unit 19 receives the second data 21c and the temperature signal S TEMP Using the sensor signal S SEN to produce a temperature compensated output signal S OUT to output 46.

[0042] According to the measurement device 11, the temporal fluctuation of the first ion-sensitive semiconductor element 25 of the first sensitive film 25a and the second ion-sensitive semiconductor element 27 of the second sensitive film 27a shows temperature dependency. Based on the second data 21c representing this temperature dependency, the signal processing unit 19 calculates the sensor signal S SEN By this processing, the signal processing unit 19 outputs an output signal S for the characteristic value of the medium 100.OUT and this output signal S OUT In this case, the influence of environmental temperature on temporal fluctuation is reduced.

[0043] Fig. 2 is a diagram showing a schematic cross section of an ion-sensitive semiconductor device according to the present embodiment taken along line III-III in Fig. 2.

[0044] 2, the ion sensitive semiconductor device 13 is provided in the form of a semiconductor chip, which includes a first ion sensitive semiconductor element 25 and a second ion sensitive semiconductor element 27. By way of example and not limitation, the semiconductor chip may include a temperature sensor 29, e.g., a resistor, integrated together with the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. By way of example and not limitation, in the ion sensitive semiconductor device 13, the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 are arranged in parallel in the same direction.

[0045] The first material of the first sensitive film 25a of the first ion sensitive semiconductor element 25 may include at least one of silicon oxide (e.g., SiO2), silicon nitride (e.g., Si3N4), aluminum oxide (e.g., Al2O3), and tantalum oxide (e.g., Ta2O5). The second material of the second sensitive film 27a of the second ion sensitive semiconductor element 27 may include at least one of silicon oxide (e.g., SiO2), silicon nitride (e.g., Si3N4), aluminum oxide (e.g., Al2O3), and tantalum oxide (e.g., Ta2O5) to be different from the first sensitive film 25a. By way of example and not limitation, the first sensitive film 25a may be silicon nitride (e.g., Si3N4), and the second sensitive film 27a may be tantalum oxide (e.g., Ta2O5).

[0046] According to this measuring device 11 and the combination of these materials, a clear difference in the fluctuation over time appears between the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27.

[0047] Referring to Figure 3, there is shown a semiconductor device structure for the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 shown in Figure 2. Since the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 have the same structure, in the following description, the first ion sensitive semiconductor element 25 will be described, and the reference numeral for the second ion sensitive semiconductor element 27 will be given in parentheses.

[0048] The ion sensitive semiconductor device 13 includes a common substrate 51 for the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. The substrate 51 has a semiconductor region of a first conductivity type (e.g., p-type) and can be, for example, a p-type silicon substrate. The substrate 51 includes a first portion 51a for the channel CH of the first ion sensitive semiconductor element 25 (a second portion 51b for the channel CH of the second ion sensitive semiconductor element 27). The ion sensitive semiconductor device 13 further includes an insulating film 53, a first sensitive film 25a (a second sensitive film 27a), a first source region 55a (a second source region 57a), and a first drain region 55b (a second drain region 57b). The first source region 55a (the second source region 57a) is indicated by "S" in FIG. 1, and the first drain region 55b (the second drain region 57b) is indicated by "D" in FIG. 1.

[0049] The insulating film 53 covers the substrate 51 and has a first sensor window 53a for the first ion sensitive semiconductor element 25 (a second sensor window 53b for the second ion sensitive semiconductor element 27). The first sensor window 53a (second sensor window 53b) is provided on the first portion 51a (second portion 51b) of the substrate 51. The first sensor window 53a (second sensor window 53b) is provided in the insulating film 53 and reaches the first sensitive film 25a (second sensitive film 27a). The first sensitive film 25a (second sensitive film 27a) is provided between the first portion 51a (second portion 51b) of the semiconductor region of the substrate 51 and the first sensor window 53a (second sensor window 53b). The insulating film 53 includes, for example, silicon oxide or silicon nitride.

[0050] The first source region 55a (second source region 57a) includes a second conductive type semiconductor (e.g., an n-type semiconductor) provided in the substrate 51, and the first drain region 55b (second drain region 57b) includes a second conductive type semiconductor provided in the substrate 51. The first portion 51a (second portion 51b) of the semiconductor region is located between the first source region 55a (second source region 57a) and the first drain region 55b (second drain region 57b).

[0051] According to the ion-sensitive semiconductor device 13, at least two field-effect ion-sensitive semiconductor elements 25, 27 are provided on the same substrate 51. Meanwhile, these ion-sensitive semiconductor elements 25, 27 in the ion-sensitive semiconductor device 13 differ from each other in terms of the materials of the sensitive films (25a, 27a), but have other characteristics that are almost the same. This makes it possible to highlight the difference in changes over time caused by the difference in the sensitive films (25a, 27a).

[0052] By way of example and not limitation, the first sensor window 53 a and the second sensor window 53 b extend in the same direction within the insulating film 53 on the substrate 51 .

[0053] The first sensor window 53a and the second sensor window 53b each include a through-hole penetrating the insulating film 53, and are used to control the channel CH in the first portion 51a of the semiconductor region of the substrate 51. Specifically, the medium 100 shown in FIG. 1 enters the through-hole and makes contact with the first sensitive film 25a (second sensitive film 27a).

[0054] A channel CH is formed directly below the first sensor window 53a (second sensor window 53b) depending on the potential of the reference electrode 15 and the electrical characteristics of the medium 100. The channel CH directly below the first sensor window 53a (second sensor window 53b) can connect the first source region 55a (second source region 57a) and the first drain region 55b (second drain region 57b) to each other.

[0055] By way of example and not limitation, the first sensor window 53a (second sensor window 53b) is separated from the semiconductor region of the substrate 51 by a gate insulating film. In this embodiment, in order to obtain a good channel CH, the gate insulating film of the first ion sensitive semiconductor element 25 (27) includes a first sensitive film 25a (27a) and a silicon oxide film 59 (e.g., a thermal oxide film), and the silicon oxide film 59 forms an interface with the semiconductor region of the substrate 51.

[0056] The ion-sensitive semiconductor device 13 can be manufactured, for example, as follows: A p-type silicon wafer is prepared. An element isolation silicon oxide region for isolating a plurality of ion-sensitive semiconductor elements is formed on the p-type silicon wafer. The element isolation silicon oxide region defines the element area of ​​each of the ion-sensitive semiconductor elements (25, 27). A gate oxide film is formed in the element area of ​​the p-type silicon wafer by thermal oxidation. A first sensitive film (e.g., a silicon nitride film) is formed on the gate oxide film in one element area by deposition, photolithography, and etching. A second sensitive film (e.g., a tantalum oxide film) is formed on the gate oxide film in another element area by deposition, photolithography, and etching. After these formations, dopants for the n-type source region and the n-type drain region are introduced into both element areas by photolithography and ion implantation. After this introduction, an insulating film is deposited on the entire surface of the silicon wafer. A sensor window is formed in this insulating film by photolithography and etching. After the sensor window is formed, metallization is performed to form electrodes.

[0057] By way of example and not limitation, the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 may be provided on different semiconductor substrates.

[0058] 4 is a diagram showing exemplary steps of a measurement method according to the present embodiment. As an example of the measurement method, a method of measuring the characteristics of a medium 100 will be described. In the following description, for ease of understanding, the reference numerals used in FIGS. 1 to 3 will be used where possible.

[0059] In step S11, a first ion-sensitive semiconductor element 25 having a first sensitive film 25a and a second ion-sensitive semiconductor element 27 having a second sensitive film 27a are prepared. The preparation of these ion-sensitive semiconductor elements 25, 27 includes fabricating the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27, or obtaining the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27 by a method other than fabrication. By way of example and not limitation, the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27 are provided in the ion-sensitive semiconductor device 13.

[0060] In step S12, the reference electrode 15, the first ion-sensitive semiconductor element 25, and the second ion-sensitive semiconductor element 27 are brought into contact with the medium 100 whose characteristics are to be measured. For example, the medium 100, e.g., a liquid, is poured into a container with the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27 arranged at a distance from the reference electrode 15. Alternatively, the container with the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27 arranged at a distance from the reference electrode 15 is inserted into the medium 100, e.g., soil.

[0061] In step S13, electricity is applied to the ion-sensitive semiconductor device 13 and the reference electrode 15. For example, in the measurement apparatus 11 shown in FIG.

[0062] In step S14, in response to the energization, measurement of the energization time of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 is started. For this measurement, the timer 31 of the measurement device 11 can be used, for example.

[0063] In step S15, after the medium 100 is contacted and the above-mentioned current is applied, a sensor signal S relating to the medium 100 is generated from the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. SEN get.

[0064] Specifically, a channel CH is generated in each of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 according to the characteristics of the medium 100. The first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 provide a first signal S1 and a second signal S2 according to the generated channel CH. The first signal S1 and the second signal S2 are generated by a series circuit of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 and the respective current sources 45a, 45b. In the A / D conversion unit 47, the first signal S1 and the second signal S2 can be serially converted into digital values ​​by, for example, a single A / D converter, or can be parallelly converted into digital values ​​by the A / D converters 47a, 47b. The digital value generated in this manner is the sensor signal S SEN Provided as.

[0065] In step S16, if necessary, the sensor signal S SEN Prior to or after the acquisition, the temperature of the ion sensitive semiconductor device 13 is detected to obtain a temperature signal S TEMP can be generated.

[0066] In step S17, the first data 21a relating to the time-dependent changes of the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27 and the integrated current-carrying time 21b of the ion-sensitive semiconductor device 13 are read from the memory 21. Based on the read first data 21a and the integrated current-carrying time 21b, the sensor signal S SEN to obtain an output signal S for the characteristic value of the medium 100. OUT Generate.

[0067] As already explained, the detection characteristics of the ion-sensitive semiconductor device 13 inevitably change depending on the time of use (i.e., change over time). The amount of change over time can be identified using the first data 21a from the difference between the first signal S1 and the second signal S2 from the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27.

[0068] If necessary, the sensor signal S SENIn processing the temperature signal S TEMP can be used for temperature compensation. In addition to the first data 21a, the second data 21c and the temperature signal S TEMP The sensor signal S SEN The temperature compensated output signal S OUT may be generated.

[0069] According to this measurement method, the temporal fluctuation of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 shows temperature dependency. Based on the second data 21c showing this temperature dependency, a temperature compensated output signal S for the characteristic value of the medium 100 is obtained. OUT to provide a sensor signal S SEN This treatment can reduce the influence of the time-dependent fluctuations of the ion-sensitive semiconductor elements 25 and 27 and the temperature dependency of the fluctuations on the measured value of, for example, the pH of the medium 100.

[0070] In step S18, the measurement can be repeated if necessary.

[0071] In step S19, when the measurement is completed, the current is cut off to the ion-sensitive semiconductor device 13 and the reference electrode 15. For example, in the measurement apparatus 11 shown in FIG.

[0072] In step S20, in response to the end of energization, the timer 31 that was started in step S14 reads the elapsed time. The measured energization time is used to update the integrated energization time 21b. The updated integrated energization time 21b is stored in the memory 21. According to this measurement method, the integrated value of the measured energization time of the ion-sensitive semiconductor device 13 is updated, for example, every time energization of the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27 is ended.

[0073] Specifically, according to this measurement method, the first ion-sensitive semiconductor element 25 and the second ion-sensitive semiconductor element 27 exhibit different variations over time. Based on the first data 21a that indicates the difference in the variations over time, the sensor signal S SEN is an output signal S relating to the characteristic value of the medium 100. OUT This processing allows for the generation of an output signal indicative of the property value (e.g., pH) that is less susceptible to variations over time. The measurement method also allows for the avoidance of repeated measurements of the property value of the medium 100 to compensate for variations over time. Furthermore, the property value of the medium 100 can be obtained without calibration over an extended period of time.

[0074] The measurement device 11 can include a calibration measurement mode and a field measurement mode different from the calibration measurement mode. Switching between these modes is realized by the control unit 41 in response to an input from the outside, for example.

[0075] The field measurement mode enables the measuring device 11 to measure the medium 100. The calibration measurement mode enables the measuring device 11 to measure for the first data 21a and the second data 21c, while the measuring device 11 measures the measurement values ​​related to the characteristic values ​​of the standard medium, e.g. the signal S SEN This allows the output of the

[0076] Data for the first data 21a and the second data 21c can be created from the output measurement values. The first data 21a and the second data 21c created in this manner are stored in the memory 21. In the calibration measurement mode, the measurement device 11 selectively makes the first area (21a) in the memory 21 writable to save the first data 21a. According to this measurement device 11, in modes other than the calibration measurement mode, the first area (21a) in the memory 21 can be protected from unintentional writing.

[0077] In the calibration measurement mode, the measurement device 11 selectively makes the second area (21c) in the memory 21 writable to store the second data 21c. According to this measurement device 11, in modes other than the calibration measurement mode, the second area (21c) in the memory 21 can be protected from unintentional writing.

[0078] In the field measurement mode, the measuring device 11 makes the third area in the memory 21 writable to store the data of the accumulated current-flow time. According to this measuring device 11, the data of the accumulated current-flow time can be protected in modes other than the field measurement mode.

[0079] 5 is a graph showing the change over time of the ion-sensitive semiconductor element. An ion-sensitive semiconductor element having a silicon nitride (Si3N4) sensitive film is prepared as the first ion-sensitive semiconductor element 25. Also, an ion-sensitive semiconductor element having a tantalum oxide (Ta2O5) sensitive film is prepared as the second ion-sensitive semiconductor element 27.

[0080] In Fig. 5, the vertical axis indicates the fluctuation rate of the output of the ion-sensitive semiconductor element (change from the initial value) as a voltage value, and the horizontal axis indicates the current-flow time. In the measurement, each ion-sensitive semiconductor element having a different type of sensitive film is immersed in a standard medium (e.g., 40 degrees Celsius, pH 6.86). The drain voltage is, for example, 1.0 to 2.5 volts, and the voltage of the reference electrode is, for example, about 0 to 3 volts.

[0081] Fig. 6 is a graph showing the temperature dependency of the rate of change over time of the output value of the ion-sensitive semiconductor element. The horizontal axis shows the temperature of the standard medium, and the vertical axis shows the rate of change of the output value of the ion-sensitive semiconductor element. Fig. 7 is a graph showing an Aurhenius plot of the temperature characteristics of Fig. 6. In Fig. 6, the vertical axis shows the rate of change on a logarithmic scale, and the horizontal axis shows the reciprocal of the temperature of the standard medium.

[0082] 5, two characteristic lines GT1 and GT2 are plotted. The characteristic line GT1 shows the characteristics of an ion-sensitive semiconductor element with a silicon nitride sensitive film, and the characteristic line GT2 shows the characteristics of an ion-sensitive semiconductor element with a tantalum oxide sensitive film.

[0083] The characteristics of an ion sensitive semiconductor device according to an embodiment can be approximated as a polynomial in time t, for example and not for limitation.

[0084] For example, a first order approximation is: Characteristic 1: Vsa(t)=Vsa0+[pH]×Sa+t×Dsa...(1) Characteristic 2: Vsb(t)=Vsb0+[pH]×Sb+t×Dsb...(2) Vsa and Vsb: values ​​obtained in the measurement. t: Cumulative power supply time. [pH]: Hydrogen ion concentration. Ss and Sb: Coefficients related to hydrogen ion concentration. Dsa and Dsb: Coefficient of temporal variation per hour. Vsa0 and Vsb0: Terms independent of time and hydrogen ion concentration (constant terms).

[0085] Initial value of characteristic 1: Vsa(t=0)=Vsa0+[pH]×Sa Initial value of characteristic 2: Vsb(t=0)=Vsb0+[pH]×Sb

[0086] In the graph of FIG. 5, the characteristic lines GT1 and GT2 are expressed by the coefficients related to time in the following equation. Characteristic line GT1:△Vsa(t)=Vsa(t)-Vsa(t=0)=t×Dsa Characteristic line GT2:△Vsb(t)=Vsb(t)-Vsb(t=0)=t×Dsb

[0087] Since [pH] is known at the time of calibration, the coefficients Ss and Sb for hydrogen ion concentration, the coefficients Dsa and Dsb for time-dependent variation, and the constant terms Vsa0 and Vsb0 can be determined based on the time-dependent variations of the measured values ​​Vsa and Vsb. The main part of the temperature dependence is in the coefficients Dsa and Dsb for time-dependent variation.

[0088] The voltage difference ΔV(t) of the time-dependent variation, i.e., the rate of variation with respect to time, represents the difference between characteristic line GT1 and characteristic line GT2. Here, without loss of generality, it can be assumed that ΔVsa(t)>ΔVsb(t).

[0089] △V(t)=△Vsa(t)-△Vsb(t) = t × (Dsa - Dsb) 1, in the measurement device 11, the signal input unit 17 receives signals S1 and S2 that can be approximated by the equations (1) and (2) that represent the time-dependent variations. Specifically, at the time t, the measured values ​​S1 and S2 are expressed as follows: Measurement value 1: S1(t) = Vsa0 + [pH] × Sa + t × Dsa Measurement value 2: S2(t) = Vsb0 + [pH] × Sb + t × Dsb (S1(t)-S2(t))=(Vsa0-Vsb0) + [pH] × (Sa-Sb) +t×(Dsa-Dsb)

[0090] The hydrogen ion concentration [pH] is expressed by the following formula: [pH]=((S1-S2)-(Vsa0-Vsb0)-t×(Dsa-Dsb)) / (Sa-Sb)...(3)

[0091] (Example 1 of the first data 21a) By way of example and not limitation, the memory 21 may store first data 21a including coefficients for hydrogen ion concentration (Ss and Sb), coefficients of variation over time (Dsa and Dsb), and constant terms (Vsa0 and Vsb0).

[0092] The signal processing unit 19 can calculate the characteristic value (eg, pH) according to the approximation formula (3) using the first data 21a and the integrated current application time 21b.

[0093] (Example 2 of the first data 21a) By way of example and not limitation, the memory 21 may store first data 21a including a coefficient for hydrogen ion concentration (Sa-Sb), a coefficient of variation over time (Dsa-Dsb), and a constant term (Vsa0-Vsb0).

[0094] The signal processing unit 19 calculates a characteristic value (eg, pH) according to the approximation formula (3) using the first data 21a and the integrated current application time 21b.

[0095] (Example 3 of the first data 21a) By way of example and not limitation, the memory 21 may store a table including a number of times (t1, t2, ... tn) and values ​​associated with those times (ΔV(t1), ΔV(t2), ... ΔV(tn)), and a constant term (Vsa0-Vsb0).

[0096] The signal processing unit 19 identifies the time closest to the accumulated current flow time 21b in the measurement from the times (t1, t2, ... tn) in the table, and calculates a characteristic value (e.g., pH) according to approximation formula (3) using the measurement values ​​(Vsa and Vsb) at the closest time and the constant term (Vsa0-Vsb0).

[0097] The first data 21a is not limited to the above examples, and may include any numerical values ​​that represent the trends shown by the characteristic lines GT1 and GT2 (or the characteristics 1 and 2). For example, the first data 21a does not exclude a table of raw measurement values ​​used to specify the approximation equations for the characteristics 1 and 2.

[0098] The approximation of the characteristic of the ion sensitive semiconductor element is not limited to a polynomial in time, but may include, for example, a transcendental function of time t, or may include both a polynomial in time t and a transcendental function of time t.

[0099] The second data 21c may include values ​​for the activation energies of the characteristics 1 and 2 according to the Aurhenius plot. The signal processor 19 receives the second data 21c and the temperature signal S TEMP Using the sensor signal S SEN The sensor signal S SEN Temperature compensation is performed.

[0100] The second data 21c is not limited to the above examples, and may include any numerical values ​​that indicate the temperature-related tendency indicated by the characteristic lines GT1 and GT2 (or the characteristics 1 and 2). Furthermore, the second data 21c does not exclude a table of raw measured values ​​of the temperature dependence indicated by the characteristic lines GT1 and GT2 (or the characteristics 1 and 2).

[0101] FIG. 8 is a diagram showing an example of the hardware configuration of the processing unit shown in FIG. The processing unit 33 is configured by, for example, a microcomputer, and includes a processor (Central Processing Unit: CPU) 401, a main storage device 402 as a temporary storage area, a non-volatile auxiliary storage device 403, an interface unit (I / F unit) 404 that receives signals from the outside, and an output unit 405 that outputs control signals. The CPU 401, the main storage device 402, the auxiliary storage device 403, the interface unit 404, and the output unit 405 are each connected to a bus 406. The auxiliary storage device 403 stores a measurement program 407 that describes the procedure of the measurement process in the measurement device 11. The processing unit 33 enables, for example, the CPU 401 to provide a calibration measurement mode by executing a first program 407a, and the CPU 401 to provide a field measurement mode by executing a second program 407b. The main operations of the processor 401 are shown below.

[0102] The processor 401 can be configured to control the opening and closing of the switches 50 a and 50 b for energizing the ion sensitive semiconductor device 13 and the reference electrode 15 .

[0103] The processor 401 can be configured to start measuring the energization time of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27 using the timer 31 in response to the control of energization.

[0104] After contacting the medium 100 and applying current, the processor 401 detects a sensor signal S related to the medium 100 from the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27. SEN The signal may be configured to receive:

[0105] The processor 401 receives the sensor signal S SEN Prior to, after, or simultaneously with the acquisition of the temperature signal S, a temperature sensor is used to detect the temperature of the ion sensitive semiconductor device 13. TEMP The signal may be configured to receive:

[0106] The processor 401 can be configured to read out the first data 21a relating to the temporal fluctuations of the first ion sensitive semiconductor element 25 and the second ion sensitive semiconductor element 27, and the integrated current-carrying time 21b of the ion sensitive semiconductor device 13 from the memory 21. The processor 401 also uses the read out first data 21a and the integrated current-carrying time 21b to calculate the sensor signal S SEN to obtain an output signal S for the characteristic value of the medium 100. OUT The signal may be configured to generate:

[0107] The processor 401 receives the second data 21c relating to the temperature change over time and the temperature signal S TEMP is further used to obtain the sensor signal S SEN to produce a temperature compensated output signal S OUT The signal may be configured to generate:

[0108] The processor 401 measures (sensor signal S SEN and receiving a sensor signal S SEN to process the output signal S OUT The method may be configured to repeat the steps of:

[0109] The processor 401 can be configured to repeat the steps of: opening the switch 50 a and the switch 50 b to cut off the current flow to the ion sensitive semiconductor device 13 and the reference electrode 15 .

[0110] The processor 401 can be configured to read the timer 31 in response to the end of the energization and to update the accumulated energization time 21b using the measured energization time. The processor 401 can also be configured to store the updated accumulated energization time 21b in the memory 21.

[0111] FIG. 9 is a schematic diagram showing an ion-sensitive semiconductor device integrated circuit according to another embodiment of the present invention.

[0112] The ion-sensitive semiconductor device integrated circuit 14 may include a plurality of ion-sensitive semiconductor devices 13. In this embodiment, the plurality of ion-sensitive semiconductor devices 13 are referred to as a first ion-sensitive semiconductor device 61, a second ion-sensitive semiconductor device 62, a third ion-sensitive semiconductor device 63, and a fourth ion-sensitive semiconductor device 64. The ion-sensitive semiconductor device integrated circuit 14 includes a substrate 51 and an insulating film 53. The first ion-sensitive semiconductor device 61, the second ion-sensitive semiconductor device 62, the third ion-sensitive semiconductor device 63, and the fourth ion-sensitive semiconductor device 64 are integrated on a common substrate 51 having a semiconductor region of a first conductivity type. As shown in FIG. 3, an insulating film 53 is provided on the substrate 51.

[0113] The first ion-sensitive semiconductor device 61 includes a first ion-sensitive semiconductor element 61a and a second ion-sensitive semiconductor element 61b arranged in parallel and adjacent to each other. The second ion-sensitive semiconductor device 62 includes a third ion-sensitive semiconductor element 62a and a fourth ion-sensitive semiconductor element 62b arranged in parallel and adjacent to each other. The third ion-sensitive semiconductor device 63 includes a fifth ion-sensitive semiconductor element 63a and a sixth ion-sensitive semiconductor element 63b arranged in parallel and adjacent to each other. The fourth ion-sensitive semiconductor device 64 includes a seventh ion-sensitive semiconductor element 64a and an eighth ion-sensitive semiconductor element 64b arranged in parallel and adjacent to each other.

[0114] As shown in FIG. 3, a first sensitive film 25a for each of the first ion-sensitive semiconductor element 61a, the third ion-sensitive semiconductor element 62a, the fifth ion-sensitive semiconductor element 63a, and the seventh ion-sensitive semiconductor element 64a is provided on a first portion 51a of the semiconductor region of the substrate 51. Furthermore, these ion-sensitive semiconductor elements 61a to 64a include a first sensitive film 25a and a first sensor window 53a provided in the insulating film 53 so as to reach the first sensitive film 25a. Furthermore, each of the ion-sensitive semiconductor elements 61a to 64a includes a first source region 55a and a first drain region 55b of a second conductive type semiconductor provided on the substrate 51. The first portion 51a is provided between the first source region 55a and the first drain region 55b.

[0115] As shown in FIG. 3, the second sensitive film 27a for each of the second ion-sensitive semiconductor element 61b, the fourth ion-sensitive semiconductor element 62b, the sixth ion-sensitive semiconductor element 63b, and the eighth ion-sensitive semiconductor element 64b is provided on the second portion 51b of the semiconductor region of the substrate 51. Moreover, these ion-sensitive semiconductor elements 61b to 64b include a second sensor window 53b provided in the insulating film 53 so as to reach the second sensitive film 27a. Furthermore, each of the ion-sensitive semiconductor elements 61b to 64b includes a second source region 57a ​​and a second drain region 57b of a second conductive type semiconductor provided on the substrate 51. The second portion 51b is provided between the second source region 57a ​​and the second drain region 57b. The first material of the first sensitive film 25a is different from the second material of the second sensitive film 27a.

[0116] The ion sensitive semiconductor device integrated circuit 14 includes a switch 65 for selecting one of a first ion sensitive semiconductor device 61, a second ion sensitive semiconductor device 62, a third ion sensitive semiconductor device 63, and a fourth ion sensitive semiconductor device 64.

[0117] For example, the switch 65 can connect any one of the first ion sensitive semiconductor device 61 , the second ion sensitive semiconductor device 62 , the third ion sensitive semiconductor device 63 , and the fourth ion sensitive semiconductor device 64 to the signal input section 17 .

[0118] The signal input unit 17 receives signals from the first ion-sensitive semiconductor device 61, the second ion-sensitive semiconductor device 62, the third ion-sensitive semiconductor device 63, and the fourth ion-sensitive semiconductor device 64, and outputs a sensor signal S SEN The signal processing unit 19 is coupled to the signal input unit 17 and generates a sensor signal S SEN Process.

[0119] By way of example and not limitation, the ion sensitive semiconductor device integrated circuit 14 can measure the medium 100 using at least two devices selected from the ion sensitive semiconductor devices 61, 62, 63, 64 to obtain a plurality of characteristic values ​​(e.g., a plurality of pH values). The signal processor 19 processes these characteristic values, for example by arithmetic averaging, to generate an output signal S OUT can be generated.

[0120] Alternatively, according to the ion-sensitive semiconductor device integrated circuit 14, a single characteristic value can be obtained by measuring the medium using a single device selected in order from the ion-sensitive semiconductor devices 61, 62, 63, and 64. Such a measurement can reduce the cumulative current-carrying time of each device.

[0121] Alternatively, the memory 21 can store the first data 21a and the second data 21c for each of the ion sensitive semiconductor devices 61, 62, 63, and 64, which are based on mutually different approximation formulas.

[0122] Alternatively, one of the ion-sensitive semiconductor devices 61, 62, 63, 64 can be selected depending on the type of medium 100 to be measured.

[0123] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the present invention, all of which are included in the technical concept of the present invention. [Explanation of symbols]

[0124] REFERENCE SIGNS LIST 11 measuring device, 13 ion-sensitive semiconductor device, 14 ion-sensitive semiconductor device integrated circuit, 15 reference electrode, 17 signal input section, 19 signal processing section, 21 memory, 21a first data, 21b accumulated current application time, 21c second data, 25 first ion-sensitive semiconductor element, 25a first sensitive film, 27 second ion-sensitive semiconductor element a second sensitive film, a temperature sensor, a first portion, a second portion, a second portion, a first ... first portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second portion, a second 3b...sensor window, 55a, 57a...source region, 55b, 57b...drain region, 59...silicon oxide film, 61...ion-sensitive semiconductor device, 61a, 61b...ion-sensitive semiconductor element, 62...ion-sensitive semiconductor device, 62a, 62b...ion-sensitive semiconductor element, 63...ion-sensitive semiconductor device, 63a, 63b...ion-sensitive semiconductor element, 64 ion-sensitive semiconductor device, 64a, 64b ion-sensitive semiconductor element, 65 switch, 100 medium, 401 processor, 402 main memory device, 403 auxiliary memory device, 404 interface section, 405 output section, 406 bus, 407 measurement program, 407a, 407b program, S one terminal, D other terminal

Claims

1. a first ion sensitive semiconductor element arranged so as to be in contact with a medium whose characteristic value is to be measured; A second ion sensitive semiconductor element arranged so as to be in contact with the medium; the medium is located between the first ion sensitive semiconductor element and the second ion sensitive semiconductor element, and a reference electrode is arranged so as to be in contact with the medium; a signal input unit that receives a first signal from the first ion sensitive semiconductor element and a second signal from the second ion sensitive semiconductor element and generates a sensor signal; a signal processor coupled to the signal input for processing the sensor signal; a memory that stores first data related to the time-dependent changes of the first ion sensitive semiconductor element and the second ion sensitive semiconductor element and is communicatively coupled to the signal processing unit; Including, the signal processing unit processes the sensor signal using an integrated current-flow time of the first ion sensitive semiconductor element and the second ion sensitive semiconductor element and the first data to generate an output signal for the characteristic value of the medium; a first sensitive film of the first ion sensitive semiconductor element includes a first material; a second sensitive film of the second ion sensitive semiconductor element includes a second material; the first material is different from the second material; Measuring equipment.

2. The device further includes a timer for measuring a time during which the first ion sensitive semiconductor element and the second ion sensitive semiconductor element are energized, The signal processing unit updates the integrated current application time based on the current application time, The memory stores the updated integrated current application time from the signal processing unit.

2. The measuring device of claim 1.

3. a temperature sensor for monitoring temperatures of the first ion sensitive semiconductor element and the second ion sensitive semiconductor element; the temperature sensor generating a temperature signal indicative of the temperature; the memory stores second data relating to changes in the temporal fluctuations of the first ion sensitive semiconductor element and the second ion sensitive semiconductor element with respect to temperature; the signal processor processes the sensor signal using the second data and the temperature signal to generate the output signal. The measuring device according to claim 1 or 2.

4. the characteristic value includes a hydrogen ion concentration of the medium; the first sensitive film of the first ion sensitive semiconductor element includes at least one of silicon oxide, silicon nitride, aluminum oxide, and tantalum oxide; The second sensitive film of the second ion sensitive semiconductor element is different from the first sensitive film and contains at least one of silicon oxide, silicon nitride, aluminum oxide, and tantalum oxide. The measuring device according to any one of claims 1 to 3.

5. 1. A method for measuring a characteristic of a medium, comprising: contacting an ion-sensitive semiconductor device, the ion-sensitive semiconductor device including a first ion-sensitive semiconductor element having a first sensitive film made of a first material and a second ion-sensitive semiconductor element having a second sensitive film made of a second material different from the first material, with a medium whose characteristic value is to be measured; applying an electric current to a reference electrode in contact with the medium such that the medium is located between the reference electrode and the ion-sensitive semiconductor device; obtaining a sensor signal related to the medium from the first ion sensitive semiconductor element and the second ion sensitive semiconductor element after energizing the reference electrode and contacting the ion sensitive semiconductor device with the medium; processing the sensor signal based on first data relating to time-dependent variations of the first ion sensitive semiconductor element and the second ion sensitive semiconductor element and an integrated current-carrying time of the ion sensitive semiconductor device to generate an output signal for the characteristic value; A measurement method including:

6. measuring a current-flow time of the first ion sensitive semiconductor element and the second ion sensitive semiconductor element, and updating the integrated current-flow time using the current-flow time; storing the integrated current application time in a memory; Further comprising: The measurement method according to claim 5.

7. sensing a temperature of the ion sensitive semiconductor device to generate a temperature signal; Further comprising: obtaining the sensor signal includes processing the sensor signal further using second data related to temperature changes over time and the temperature signal to generate the output signal. The measurement method according to claim 5 or 6.

8. a substrate having a semiconductor region of a first conductivity type; an insulating film provided on the substrate, the insulating film having a first sensor window and a second sensor window; a first sensitive film provided between a first portion of the semiconductor region and the first sensor window and including a first material; a first source region of a second conductivity type different from the first conductivity type provided in the semiconductor region; a first drain region of the second conductivity type provided in the semiconductor region; a second sensitive film provided between a second portion of the semiconductor region and the second sensor window and including a second material; a second source region of the second conductivity type provided in the semiconductor region; a second drain region of the second conductivity type provided in the semiconductor region; Including, the first sensor window reaches the first sensitive film; the second sensor window reaches the second sensitive film; the first portion of the semiconductor region is between the first source region and the first drain region; the second portion of the semiconductor region is between the second source region and the second drain region; the first material of the first sensitive film is different from the second material of the second sensitive film; Ion-sensitive semiconductor device.

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