Capacitance-voltage characteristic measuring method and capacitance-voltage characteristic measuring device

Abstract

To provide a capacitance-voltage characteristic measurement method and a capacitance-voltage characteristic measurement device that can easily measure CV characteristics of a capacitor structure including an insulator after light irradiation.SOLUTION: A laminate containing an insulator layer and a semiconductor layer is irradiated with light from the insulator layer side. Charges are generated in the insulator by photoexcitation. Measured is capacitance-voltage characteristics of a capacitor structure after light irradiation that includes a first electrode that contacts the laminate from the insulator layer side, a second electrode that contacts the laminate from the semiconductor layer side, and the laminate after light irradiation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a capacitance-voltage characteristic measuring method and a capacitance-voltage characteristic measuring device. [Background technology]

[0002] Insulators are used as materials in the circuits and displays of electronic devices. For example, when an insulator is used as a substrate, semiconductor elements and wiring are provided on a substrate made of the insulator, thereby forming a circuit of the electronic device or display. Such an insulator as a substrate insulates the semiconductor elements from each other, the wiring from each other, and the semiconductor elements and wiring from each other, so as to prevent unintended short circuits from occurring in the circuit.

[0003] As described above, insulators used as materials for substrates, etc., may generate electric charges during long-term operation of electronic devices and displays. In this case, the electric charges accumulated in the insulator may affect the operation of semiconductor elements, which may cause a decrease in the reliability of the electronic devices and displays.

[0004] In particular, in an insulator constituting a display substrate (e.g., a flexible substrate), light is irradiated from light-emitting elements and the like when the display is driven, and as a result, charges are generated and accumulated in the insulator due to photoexcitation. The charges thus accumulated in the insulator change the operation of semiconductor elements, such as thin film transistors (TFTs), provided on the display substrate, and cause a decrease in the reliability (operational stability) of the display. Specifically, the influence of the charges in the insulator causes a change in the driving voltage (threshold voltage) of the TFT, which causes the emission luminance of the light-emitting element to change over time, or the light-emitting element to unintentionally continue to emit weak light even when the power is turned off, thereby impairing normal operation of the display.

[0005] As a conventional technique for evaluating the charge of an object, for example, there is a technique in which a capacitor is formed by contacting a semiconductor wafer to be measured with a conductivity measuring probe, the capacitance of the capacitor is measured after irradiating the semiconductor wafer with light, and the charge carrier lifetime of the semiconductor wafer is measured based on the change in capacitance over time (see Patent Document 1). There is also a technique in which a voltage is applied to a MOS diode to evaluate the amount of charge trapped at the interface between the semiconductor (Si) and the oxide film (SiO2) in the MOS diode (see Non-Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2004-146831 A [Non-patent literature]

[0007] [Non-Patent Document 1] SM Gee, "Semiconductor Devices (2nd Edition) - Basic Theory and Process Technology -", Sangyo Tosho Co., Ltd., March 30, 2015, pp.161-166 Summary of the Invention [Problem to be solved by the invention]

[0008] Incidentally, as an insulating material for a substrate or the like used in a circuit or display of an electronic device, it is preferable to select an insulator that generates (accumulates) a smaller amount of charge due to photoexcitation. It is important to evaluate the amount of charge generated in the insulator due to photoexcitation and select such an insulator based on the evaluation results. In addition, in order to evaluate the amount of charge, it is essential to irradiate the insulator to be evaluated with light and measure the capacitance-voltage characteristics (hereinafter referred to as CV characteristics) of the capacitor structure including the insulator after the light irradiation. However, the above-mentioned conventional technology does not disclose any method for measuring the CV characteristics of the capacitor structure including the insulator after the light irradiation, and therefore it is difficult to measure the CV characteristics that are essential for evaluating the amount of charge in the insulator due to photoexcitation.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a capacitance-voltage characteristics measuring method and a capacitance-voltage characteristics measuring apparatus that can easily measure the CV characteristics of a capacitor structure including an insulator after light irradiation. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems and achieve the object, the capacitance-voltage characteristic measuring method of the present invention is characterized by including a light irradiation step of irradiating a laminate including an insulator layer and a semiconductor layer with light from the insulator layer side to generate charges in the insulator by photoexcitation, and a measurement step of measuring the capacitance-voltage characteristics of a capacitor structure after light irradiation, the capacitor structure including a first electrode contacting the laminate from the insulator layer side, a second electrode contacting the laminate from the semiconductor layer side, and the laminate after light irradiation.

[0011] In addition, the capacitance-voltage characteristics measuring method of the present invention is characterized in that, in the above invention, a charge blocking layer having a higher electrical resistance than the insulator is interposed between the insulator layer and the semiconductor layer in the laminate.

[0012] In addition, the capacitance-voltage characteristic measuring method of the present invention is characterized in that, in the above invention, the first electrode is a transparent electrode that is transparent to the light irradiated to the laminate, and the light irradiation process irradiates the laminate of a capacitor structure before light illumination formed by the first electrode, the second electrode, and the laminate before light irradiation with the light from the insulator layer side via the first electrode.

[0013] Furthermore, the capacitance-voltage characteristic measuring method of the present invention is characterized in that, in the above invention, the first electrode is a movable electrode that is in contact with the laminate and can be separated from it, the light irradiation process separates the first electrode from the laminate and irradiates the laminate with the light from the insulator layer side, and the measurement process forms the capacitor structure after light irradiation using the first electrode, the second electrode, and the laminate after light irradiation, and measures the capacitance-voltage characteristics of the capacitor structure after light irradiation.

[0014] Moreover, in the capacitance-voltage characteristics measuring method according to the present invention, in the above invention, the movable electrode is a mercury probe.

[0015] Furthermore, the capacitance-voltage characteristic measuring device according to the present invention is characterized in that it comprises: a first electrode that contacts a laminate including an insulator layer and a semiconductor layer from the insulator layer side; a second electrode that contacts the laminate from the semiconductor layer side; a light source that irradiates light to the laminate from the insulator layer side; a DC power supply that applies a DC bias voltage to a capacitor structure after light irradiation including the first electrode, the second electrode, and the laminate after light irradiation; an AC power supply that applies an AC voltage to the capacitor structure after light irradiation; a measuring unit that measures the capacitance-voltage characteristics of the capacitor structure after light irradiation; and a housing that forms a darkroom in which at least the light source, the laminate, the first electrode, and the second electrode are contained.

[0016] In addition, the capacitance-voltage characteristics measuring device of the present invention is characterized in that, in the above invention, the laminate further includes a charge blocking layer interposed between the insulator layer and the semiconductor layer and having a higher electrical resistance than the insulator.

[0017] In addition, the capacitance-voltage characteristic measuring device of the present invention is characterized in that, in the above invention, the first electrode is a transparent electrode that is transparent to the light from the light source, and the light source irradiates the light from the insulator layer side through the first electrode to the laminate of a pre-light-irradiation capacitor structure formed by the first electrode, the second electrode, and the laminate before light irradiation.

[0018] In addition, the capacitance-voltage characteristics measuring device of the present invention is characterized in that, in the above invention, the first electrode is a movable electrode that is in contact with and can be separated from the laminate, and the movable electrode moves away from the laminate when the light source irradiates the laminate with light, and comes into contact with the laminate after light irradiation.

[0019] In addition, in the capacitance-voltage characteristics measuring device according to the present invention, the movable electrode is a mercury probe.

[0020] In addition, in the above-mentioned invention, the capacitance-voltage characteristics measuring device according to the present invention is characterized in that it further comprises a wavelength changing unit that changes a wavelength of the light from the light source.

[0021] In addition, in the capacitance-voltage characteristics measuring device according to the present invention, the semiconductor layer is provided on the second electrode. Effect of the Invention

[0022] The present invention has an effect of easily measuring the CV characteristics of a capacitor structure including an insulator after light irradiation. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of a CV characteristic measuring device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing an example of the CV characteristics of a capacitor structure measured in the first embodiment of the present invention. [Diagram 3] FIG. 3 is a flow chart showing an example of a photoexcited charge quantity measuring method to which the CV characteristic measuring method according to the first embodiment of the present invention is applied. [Figure 4] FIG. 4 is a schematic diagram showing an example of the configuration of a CV characteristic measuring device according to the second embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic diagram showing an example of the configuration of a CV characteristics measuring device according to the third embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing an example of the configuration of a CV characteristic measuring device according to the fourth embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing an example of a measurement result of the CV characteristic in the first embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing an example of a measurement result of the CV characteristic in Example 2 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, the embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be carried out by modifying them in various ways according to the purpose and application. It should be noted that the drawings are schematic, and the dimensional relationship of each element, the ratio of each element, and the like may differ from the actual ones. The drawings may also include parts whose dimensional relationship and ratio differ from each other. In addition, the same components are given the same symbols in each drawing.

[0025] <Embodiment 1> (CV characteristic measuring device) First, a CV characteristic measuring device according to a first embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing an example of a configuration of the CV characteristic measuring device according to the first embodiment of the present invention. The CV characteristic measuring device 1 according to the first embodiment is an example of a device (capacitance-voltage characteristic measuring device) that measures CV characteristics to evaluate the amount of charge caused by photoexcitation in a target insulator. As shown in FIG. 1, the CV characteristic measuring device 1 includes a transparent electrode 2a, a supporting electrode 2b, a light source 3, a DC bias power supply 4, an AC power supply 5, a capacitance measuring device 6 and a voltmeter 7 that constitute a measuring unit 8, and a housing 9.

[0026] The transparent electrode 2a and the support electrode 2b are an example of a pair of electrodes for forming a capacitor structure 10, which is the object of measurement of CV characteristics in the present embodiment 1. In the present embodiment 1, as shown in FIG. 1, a laminate 15 is sandwiched between the transparent electrode 2a and the support electrode 2b in the layer thickness direction to form the capacitor structure 10. The laminate 15 is an example of a laminate including at least a layer of an insulator 11 to be the object of evaluation of the charge amount by photoexcitation, and a layer of a semiconductor 12 to enable quantitative measurement of the CV characteristics. Specifically, in the present embodiment 1, the laminate 15 is composed of a layer of an insulator 11 and a layer of a semiconductor 12, as shown in FIG. 1. For example, the laminate 15 is formed by stacking a layer of an insulator 11 on a layer of a semiconductor 12.

[0027] Examples of the semiconductor material constituting the layer of the semiconductor 12 include inorganic semiconductors such as elemental semiconductors and compound semiconductors, and organic semiconductors. Examples of elemental semiconductors include silicon and germanium. Examples of compound semiconductors include zinc selenide, zinc oxide, gallium arsenide, gallium nitride, silicon carbide, and silicon germanium. Among these, inorganic semiconductors are preferable as the semiconductor material, and silicon, which can easily form a thermal oxide film, is particularly preferable.

[0028] The transparent electrode 2a is an example of a first electrode that contacts the laminate 15 including the layer of the insulator 11 and the layer of the semiconductor 12 from the layer side of the insulator 11. In the present embodiment 1, as shown in FIG. 1, the transparent electrode 2a is arranged so as to be in surface contact with the upper surface of the insulator 11 in the laminate 15 (the upper surface in the layer thickness direction of the insulator 11). The transparent electrode 2a is also electrically connected to a DC bias power supply 4, an AC power supply 5, and a measuring unit 8 (a capacitance measuring device 6 and a voltmeter 7 in the present embodiment 1) via wiring or the like. The transparent electrode 2a is an electrode that is transparent to the light 3a emitted from the light source 3, and is formed of a transparent conductive film such as indium tin oxide (ITO).

[0029] The support electrode 2b is an example of a second electrode that contacts the laminate 15 including the layer of the insulator 11 and the layer of the semiconductor 12 from the layer side of the semiconductor 12. In this embodiment 1, as shown in FIG. 1, the support electrode 2b is arranged so as to be in surface contact with the lower surface of the semiconductor 12 in the laminate 15 (the surface on the lower side in the layer thickness direction of the semiconductor 12). Although not shown in FIG. 1, the support electrode 2b is provided on a support such as a mounting table (stage) and is configured to support the laminate 15 from below. In addition, the support electrode 2b is electrically connected to the DC bias power supply 4, the AC power supply 5, and the voltmeter 7 of the measurement unit 8 via wiring or the like. The support electrode 2b is made of a conductive metal film such as copper, and faces the transparent electrode 2a in the direction perpendicular to its surface (the layer thickness direction of the laminate 15). In this embodiment 1, the layer of the semiconductor 12 in the laminate 15 is placed on the upper surface of the support electrode 2b. On the other hand, a layer of semiconductor 12 may be provided in advance on the upper surface of support electrode 2b, and laminate 15 may be formed by stacking (placing) a layer of insulator 11 on the layer of semiconductor 12 provided on support electrode 2b.

[0030] The light source 3 is an example of a light source for generating charges in the insulator 11 by photoexcitation. As shown in FIG. 1, the light source 3 irradiates the laminate 15 with light 3a from the layer side of the insulator 11. In the present embodiment 1, the light source 3 irradiates the laminate 15 of the capacitor structure 10 before light irradiation with light 3a from the layer side of the insulator 11 through the transparent electrode 2a. The capacitor structure 10 before light irradiation is a capacitor structure formed by the transparent electrode 2a, the support electrode 2b, and the laminate 15 before light irradiation. The light source 3 irradiates the insulator 11 of the laminate 15 with the light 3a by irradiating the laminate 15 as described above with the light 3a, thereby generating charges in the insulator 11 by photoexcitation. The charges generated by photoexcitation in this way are mainly accumulated in the insulator 11.

[0031] As the light source 3, for example, a light source that emits light including a plurality of wavelength bands, such as a xenon light source, a halogen light source, a krypton light source, a deuterium tungsten light source, a tungsten halogen light source, an argon light source, or a single-wavelength light source that emits light of a single wavelength band, such as an LED light, may be used. Among these, a single-wavelength light source is preferable as the light source 3. In addition, the intensity of the light 3a from the light source 3 is preferably such that a change in the amount of charge of the insulator 11 before and after irradiation of the light can be confirmed, and the insulator 11 is not damaged.

[0032] The DC bias power supply 4 is an example of a DC power supply that applies a DC bias voltage to a measurement target of CV characteristics. In the present embodiment 1, as shown in FIG. 1, the DC bias power supply 4 is configured by an output variable DC power supply that can change the output of the DC bias voltage within a predetermined range, and is configured as a circuit so as to apply the DC bias voltage to a capacitor structure 10 that is a measurement target of CV characteristics. Before the light source 3 irradiates the insulator 11 with light 3a, the DC bias power supply 4 applies a DC bias voltage to the capacitor structure 10 before light irradiation, which includes the transparent electrode 2a, the supporting electrode 2b, and the laminate 15 before light irradiation. After the light source 3 irradiates the insulator 11 with light 3a, the DC bias power supply 4 applies a DC bias voltage to the capacitor structure 10 after light irradiation, which includes the transparent electrode 2a, the supporting electrode 2b, and the laminate 15 after light irradiation. In either case, the DC bias power supply 4 applies a DC bias voltage to the capacitor structure 10 while continuously or intermittently changing the output of the DC bias voltage within a preset voltage range.

[0033] The AC power source 5 is an example of an AC power source that applies an AC voltage to a measurement target of CV characteristics. In the present embodiment 1, as shown in FIG. 1, the AC power source 5 is configured as a circuit so as to apply an AC voltage to a capacitor structure 10, which is a measurement target of CV characteristics. Before the light source 3 irradiates the insulator 11 with light 3a, the AC power source 5 applies an AC voltage to the capacitor structure 10 before light irradiation, which includes the transparent electrode 2a, the supporting electrode 2b, and the laminate 15 before light irradiation. After the light source 3 irradiates the insulator 11 with light 3a, the AC power source 5 applies an AC voltage to the capacitor structure 10 after light irradiation, which includes the transparent electrode 2a, the supporting electrode 2b, and the laminate 15 after light irradiation.

[0034] The measurement unit 8 measures the CV characteristics of the capacitor structure 10 before the light source 3 irradiates the insulator 11 with light 3a, and measures the CV characteristics of the capacitor structure 10 after the light irradiation when the light source 3 has irradiated the insulator 11 with light 3a. In the present embodiment 1, as shown in FIG. 1, the measurement unit 8 is composed of a capacitance measuring device 6 and a voltmeter 7.

[0035] The capacitance measuring device 6 is a device for measuring the capacitance C in the CV characteristic of the capacitor structure 10. In detail, the capacitance measuring device 6 is configured by an LCR meter or the like, and is configured as a circuit so as to read an AC signal and measure the capacitance C of the capacitor structure 10 as shown in FIG. 1. The capacitance measuring device 6 measures the capacitance C of the capacitor structure 10 in which charges are accumulated in the laminate 15 by application of a DC bias voltage from the DC bias power supply 4 and application of an AC voltage from the AC power supply 5 before the light source 3 irradiates the insulator 11 with light 3a. In addition, the capacitance measuring device 6 measures the capacitance C of the capacitor structure 10 in which charges are accumulated in the laminate 15 by application of a DC bias voltage from the DC bias power supply 4, application of an AC voltage from the AC power supply 5, and irradiation of the light 3a from the light source 3 after the light source 3 irradiates the insulator 11 with light 3a. In either case, the capacitance measuring device 6 measures the capacitance C of the capacitor structure 10 corresponding to each value of the DC bias voltage applied to the capacitor structure 10 while changing it within a predetermined voltage range. The capacitance measuring device 6 also displays the measured capacitance C.

[0036] The voltmeter 7 is a device for measuring the applied voltage V in the CV characteristic of the capacitor structure 10. In detail, as shown in Fig. 1, the voltmeter 7 is connected in parallel to a pair of electrodes (the transparent electrode 2a and the supporting electrode 2b in the first embodiment) constituting the capacitor structure 10 via wiring, and measures the voltage (applied voltage V) applied to the capacitor structure 10. For example, the voltmeter 7 measures the DC bias voltage applied to the capacitor structure 10 by the DC bias power supply 4 as the applied voltage V of the capacitor structure 10. The voltmeter 7 also displays the measured applied voltage V.

[0037] The housing 9 is an example of a housing forming a darkroom in which at least the light source 3, the laminate of the capacitor structure to be irradiated with light by the light source 3, the first electrode, and the second electrode are housed. In the present embodiment 1, as described above, the capacitor structure to be irradiated with light by the light source 3 is the capacitor structure 10 shown in FIG. 1, and the laminate, the first electrode, and the second electrode of the capacitor structure 10 are the laminate 15, the transparent electrode 2a, and the support electrode 2b, respectively. That is, the housing 9 in the present embodiment 1 forms a darkroom in which at least the light source 3, the laminate 15, the transparent electrode 2a, and the support electrode 2b are housed. More specifically, the housing 9 is a hollow structure that forms a darkroom that can block light other than the light 3a from the light source 3 (hereinafter, appropriately referred to as external light). As shown in FIG. 1, the darkroom formed by the housing 9 houses the light source 3, the transparent electrode 2a, the support electrode 2b, the laminate 15, the DC bias power supply 4, the AC power supply 5, the capacitance measuring device 6, and the voltmeter 7. Of these, the laminate 15 is housed removably in the darkroom of the housing 9. When a layer of the semiconductor 12 is provided in advance on the supporting electrode 2b, the insulator 11 of the laminate 15 is housed removably in the darkroom of the housing 9. By housing the light source 3, the laminate 15, the transparent electrode 2a, the supporting electrode 2b, etc. in the darkroom, the housing 9 can block external light from these housed items. As a result, the light 3a from the light source 3 can be appropriately irradiated onto the laminate 15 (particularly the insulator 11) of the capacitor structure 10, which is the object of measurement of CV characteristics.

[0038] (CV characteristics of capacitor structure) Next, a description will be given of the CV characteristics of the capacitor structure 10 measured by the CV characteristic measuring device 1 according to the present embodiment 1. Fig. 2 is a diagram showing an example of the CV characteristics of the capacitor structure measured in the present embodiment 1 of the present invention. As shown in Fig. 2, the CV characteristics of the capacitor structure 10 in the present embodiment 1 are represented by the correlation between the capacitance C and the applied voltage V of the capacitor structure 10.

[0039] In detail, the capacitance C of the capacitor structure 10 is measured by the capacitance measuring device 6 in response to the applied voltage V of the capacitor structure 10 before and after the light irradiation of the capacitor structure 10 by the light source 3. The applied voltage V of the capacitor structure 10 is measured by the voltmeter 7 in conjunction with the measurement of the capacitance C by the capacitance measuring device 6 before and after the light irradiation of the capacitor structure 10 by the light source 3. The CV characteristic of the capacitor structure 10 before the light irradiation is represented by the correlation between the capacitance C of the capacitor structure 10 before the light irradiation measured by the capacitance measuring device 6 and the applied voltage V of the capacitor structure 10 before the light irradiation measured by the voltmeter 7. The CV characteristic of the capacitor structure 10 after the light irradiation is represented by the correlation between the capacitance C of the capacitor structure 10 after the light irradiation measured by the capacitance measuring device 6 and the applied voltage V of the capacitor structure 10 after the light irradiation measured by the voltmeter 7.

[0040] For example, as shown in FIG. 2, the CV characteristic of the capacitor structure 10 before light irradiation is represented by a correlation line Y1 (solid line in FIG. 2) showing the correlation between the capacitance C of the capacitor structure 10 before light irradiation and the applied voltage V. The CV characteristic of the capacitor structure 10 after light irradiation is represented by a correlation line Y2 (dashed line in FIG. 2) showing the correlation between the capacitance C of the capacitor structure 10 after light irradiation and the applied voltage V. As shown by the correlation lines Y1 and Y2, whether the capacitor structure 10 is before or after light irradiation, the capacitance C of the capacitor structure 10 shows a correlation of being a high value including a maximum value, a correlation of being sharply decreased from the high value, and a correlation of being gradually increased or decreased or being a constant value after the sharp decrease, for the applied voltage V that changes (increases) sequentially within a predetermined voltage range.

[0041] Here, in the CV characteristic of the capacitor structure 10 after light irradiation, the applied voltage V when the capacitance C drops sharply increases compared to the CV characteristic of the capacitor structure 10 before light irradiation, as is clear from a comparison between the correlation lines Y1 and Y2 shown in Fig. 2. That is, the correlation line Y2 representing the CV characteristic of the capacitor structure 10 after light irradiation is shifted in the increasing direction of the applied voltage V (to the right in the drawing of Fig. 2) by the increase in the applied voltage V when the capacitance C drops sharply, compared to the correlation line Y1 representing the CV characteristic of the capacitor structure 10 before light irradiation. This shift phenomenon of the correlation line Y2 relative to the correlation line Y1 occurs due to the fact that the light 3a from the light source 3 is irradiated onto the insulator 11 of the capacitor structure 10, and charges are generated and accumulated in the insulator 11 due to photoexcitation.

[0042] By using the above-mentioned CV characteristics of the capacitor structure 10 before and after light irradiation, it is possible to obtain parameters such as the flat band voltage and the capacitance in the charge storage state of the capacitor structure 10 (hereinafter, appropriately referred to as the capacitance in the charge storage state) required to derive the amount of charge excited in the insulator 11 by irradiation with the light 3a from the light source 3 (hereinafter, appropriately referred to as the amount of photoexcited charge). Specifically, as shown in FIG. 2, the flat band voltage V FB The flat band voltage V of the capacitor structure 10 after light irradiation can be derived from the applied voltage V when the capacitance C drops sharply in the CV characteristic (see correlation line Y1) of the capacitor structure 10 before light irradiation. FB The capacitance C2 can be derived from the applied voltage V when the capacitance C drops sharply in the CV characteristic (see correlation line Y2) of the capacitor structure 10 after light irradiation. I is, for example, the capacitance in a state where charges are stored in the layer of the semiconductor 12 included in the capacitor structure 10 before light irradiation. The capacitance C I corresponds to the capacitance of the insulating region of the capacitor structure 10 (the layer of insulator 11 in this embodiment 1), and can be derived from the capacitance C at which the capacitance becomes maximum in response to the applied voltage V in the CV characteristics of the capacitor structure 10 before light irradiation.

[0043] The photoexcited charge Q of the insulator 11 can be calculated based on the parameters obtained from the CV characteristics of the capacitor structure 10 as described above, using the following formulas (1) and (2). In detail, the flat band voltage V of the capacitor structure 10 before light irradiation is FB 1 and the flat band voltage V of the capacitor structure 10 after light irradiation. FB 2 and the flat band voltage V based on equation (1) FB 1 and the flat band voltage V FB 2, the flat band voltage difference ΔV of the capacitor structure 10 before and after light irradiation is calculated. FB Based on the formula (2), the flat band voltage difference ΔV FB and the capacitance C of the charge storage state I By multiplying this by , the amount of photoexcited charge Q of the insulator 11 is derived. ΔV FB =|V FB 2-V FB 1| (1) Q=C I ×ΔV FB (2)

[0044] (Method of measuring CV characteristics of capacitor structure) Next, a CV characteristic measuring method according to the first embodiment of the present invention will be described. Fig. 3 is a flow chart showing an example of a photoexcited charge measuring method to which the CV characteristic measuring method according to the first embodiment of the present invention is applied. This photoexcited charge measuring method is a method for measuring the charge amount (i.e., photoexcited charge amount Q) due to photoexcitation accumulated in a target insulator 11, and is realized, for example, by sequentially performing each of steps S101 to S106 shown in Fig. 3. The CV characteristic measuring method according to the first embodiment is a method for measuring the CV characteristics of a capacitor structure 10 required for measuring the photoexcited charge amount Q of the insulator 11, and is realized, for example, by performing at least each of steps S103 and S104 shown in Fig. 3 using the above-mentioned CV characteristic measuring device 1 (see Fig. 1).

[0045] In detail, as shown in FIG. 3, in the CV characteristic measuring method according to the present embodiment 1, first, a first CV characteristic measuring step is performed (step S101). This first CV characteristic measuring step is a step of measuring the CV characteristic of the capacitor structure 10 before light irradiation. In the present embodiment 1, the capacitor structure 10 before light irradiation is a capacitor structure including a transparent electrode 2a contacting the laminate 15 from the layer side of the insulator 11, a support electrode 2b contacting the laminate 15 from the layer side of the semiconductor 12, and the laminate 15 before light irradiation. For example, in step S101, the laminate 15 before light irradiation is disposed between the transparent electrode 2a and the support electrode 2b of the CV characteristic measuring device 1, thereby forming the capacitor structure 10 before light irradiation. The laminate 15 may be formed in advance by stacking a layer of the insulator 11 on a layer of the semiconductor 12 in a stage before step S101, or may be formed by stacking a layer of the insulator 11 on a layer of the semiconductor 12 during the process of step S101.

[0046] In step S101, the CV characteristic measuring device 1 measures the CV characteristic of the capacitor structure 10 before light irradiation using the capacitance measuring device 6 and the voltmeter 7. At this time, the capacitance measuring device 6 measures the capacitance C of the capacitor structure 10 in a state in which charge is accumulated in the laminate 15 by application of a DC bias voltage from the DC bias power supply 4 and an AC voltage from the AC power supply 5, corresponding to each value of the DC bias voltage applied to the capacitor structure 10 while changing within a predetermined voltage range. The voltmeter 7 measures the DC bias voltage applied to the capacitor structure 10 before light irradiation by the DC bias power supply 4 as the applied voltage V of the capacitor structure 10 before light irradiation. The CV characteristic of the capacitor structure 10 before light irradiation is represented by a correlation line Y1 (see FIG. 2) showing the correlation between the capacitance C of the capacitor structure 10 before light irradiation measured by the capacitance measuring device 6 and the applied voltage V of the capacitor structure 10 before light irradiation measured by the voltmeter 7. The correlation line Y1 is displayed on, for example, a display unit (not shown) provided in the capacitance measuring instrument 6 or the CV characteristic measuring device 1 as a measurement result of the CV characteristic of the capacitor structure 10 before light irradiation.

[0047] After the above-mentioned step S101 is performed, a first flat band voltage deriving step is performed (step S102) as shown in FIG. 3. This first flat band voltage deriving step is a step of deriving a flat band voltage V FB This is the process of deriving 1.

[0048] In step S102, the flat band voltage V FB 1 is derived based on the CV characteristics of the capacitor structure 10 before light irradiation measured in the above-mentioned step S101. In detail, the applied voltage V when the capacitance C drops sharply in the above-mentioned correlation line Y1, which is the measurement result of the CV characteristics of the capacitor structure 10 before light irradiation, is the flat band voltage V FB 1. This flat band voltage V FB The derivation process of 1 can be executed by, for example, an arithmetic processing unit (not shown) included in the capacitance measuring device 6 or the CV characteristic measuring device 1.

[0049] After the above-mentioned step S102 is performed, a light irradiation step is performed (step S103) as shown in Fig. 3. This light irradiation step is a step in which light is irradiated from the insulator 11 layer side to the laminate 15 including the insulator 11 layer and the semiconductor 12 layer, and charges are generated in the insulator 11 by photoexcitation.

[0050] In the present embodiment 1, as shown in FIG. 1, the first electrode that contacts the laminate 15 from the layer side of the insulator 11 is a transparent electrode 2a that is transparent to the light 3a irradiated to the laminate 15 by the light source 3. In step S103, the light source 3 of the CV characteristic measuring device 1 irradiates the laminate 15 of the capacitor structure 10 before light irradiation with the light 3a from the layer side of the insulator 11 through the transparent electrode 2a. In detail, the light source 3 irradiates the capacitor structure 10 before light irradiation that has already been formed in the CV characteristic measuring device 1 in the above-mentioned step S101 with the light 3a from the transparent electrode 2a side. The light 3a emitted from the light source 3 passes through the transparent electrode 2a and reaches the insulator 11 of the laminate 15. In this way, the light source 3 irradiates the light 3a to the insulator 11 through the transparent electrode 2a. In the insulator 11 irradiated with the light 3a from the light source 3, charges are generated due to photoexcitation. The charges due to this photoexcitation are mainly accumulated in the insulator 11.

[0051] After performing the above-mentioned step S103, a second CV characteristic measuring step is performed as shown in FIG. 3 (step S104). This second CV characteristic measuring step is a step of measuring the CV characteristic of the capacitor structure 10 after light irradiation. In the present embodiment 1, the capacitor structure 10 after light irradiation is a capacitor structure including a transparent electrode 2a contacting the laminate 15 from the layer side of the insulator 11, a support electrode 2b contacting the laminate 15 from the layer side of the semiconductor 12, and the laminate 15 after light irradiation. The capacitor structure 10 after light irradiation in step S104 is obtained by irradiating the above-mentioned capacitor structure 10 before light irradiation with light 3a from the light source 3.

[0052] In step S104, the CV characteristic measuring device 1 measures the CV characteristic of the capacitor structure 10 after light irradiation using the capacitance measuring device 6 and the voltmeter 7. At this time, the capacitance measuring device 6 measures the capacitance C of the capacitor structure 10 in a state in which charges are accumulated in the laminate 15 by application of a DC bias voltage from the DC bias power supply 4, application of an AC voltage from the AC power supply 5, and irradiation with light 3a from the light source 3, corresponding to each value of the DC bias voltage under the same conditions as in step S101 described above. The voltmeter 7 measures the DC bias voltage applied to the capacitor structure 10 after light irradiation by the DC bias power supply 4 under the same conditions as in step S101 described above as the applied voltage V of the capacitor structure 10 after light irradiation. The CV characteristic of the capacitor structure 10 after light irradiation is represented by a correlation line Y2 (see FIG. 2) showing the correlation between the capacitance C of the capacitor structure 10 after light irradiation measured by the capacitance measuring device 6 and the applied voltage V of the capacitor structure 10 after light irradiation measured by the voltmeter 7. The correlation line Y2 is displayed on, for example, a display unit (not shown) provided in the capacitance measuring instrument 6 or the CV characteristic measuring device 1 as a measurement result of the CV characteristic of the capacitor structure 10 after light irradiation.

[0053] After the above-mentioned step S104 is performed, a second flat band voltage deriving step is performed (step S105) as shown in FIG. 3. In this second flat band voltage deriving step, the flat band voltage V FB This is the process of deriving 2.

[0054] In step S105, the flat band voltage V FB 2 is derived based on the CV characteristics of the capacitor structure 10 after light irradiation measured in step S104 described above. In detail, the applied voltage V when the capacitance C drops sharply on the correlation line Y2, which is the measurement result of the CV characteristics of the capacitor structure 10 after light irradiation, is the flat band voltage V FB 2. This flat band voltage V FB The derivation process of 2 can be executed by, for example, an arithmetic processing unit (not shown) included in the capacitance measuring device 6 or the CV characteristic measuring device 1.

[0055] The CV characteristic measuring method according to the present embodiment 1 includes each of the steps S101 to S105 described above. After each of the steps of this CV characteristic measuring method is performed, that is, after the above-mentioned step S105 is performed, a photoexcited charge amount deriving step is performed (step S106) as shown in Fig. 3, and the photoexcited charge amount measuring method according to the present embodiment 1 is terminated. This photoexcited charge amount deriving step is a step of deriving the amount of charge excited in the insulator 11 by irradiation with light 3a from the light source 3, that is, the photoexcited charge amount Q of the insulator 11.

[0056] In step S106, the photoexcited charge Q of the insulator 11 is calculated based on the flat band voltage V FB 1 and the flat band voltage V FB 2 and the capacitance C of the charge storage state I For example, in step S106, the maximum value of the capacitance C in the CV characteristics of the capacitor structure 10 before light irradiation measured in the above-mentioned step S101 is calculated based on the capacitance C in the charge storage state. I In addition, these flat band voltages V FB 1. V FB 2, a calculation process is performed based on the above-mentioned formula (1), and the flat band voltage difference ΔV of the capacitor structure 10 before and after light irradiation is calculated. FB is calculated. Next, the flat band voltage difference ΔV FB and the above capacitance C I and the photoexcited charge Q of the insulator 11 is calculated by performing arithmetic processing based on the above-mentioned formula (2). The arithmetic processing in step S106 can be derived, for example, by a arithmetic processing unit of a photoexcited charge amount measuring device applied to the photoexcited charge amount measuring method or a arithmetic processing unit of the above-mentioned CV characteristics measuring device (neither of which are shown).

[0057] The photoexcited charge amount Q derived in this way can be used to evaluate the photoexcited charge amount of the target insulator 11. For example, the photoexcited charge amount Q of the insulator 11 is compared with a preset threshold (upper limit) of the charge amount, and based on the comparison result, the insulator 11 with a smaller amount of charge accumulated due to photoexcitation (i.e., the insulator 11 with excellent light resistance) can be selected. Specifically, when the photoexcited charge amount Q is larger than the threshold, it can be determined that the insulator 11 has insufficient light resistance, and when the photoexcited charge amount Q is equal to or less than the threshold, it can be determined that the insulator 11 has good light resistance. The insulator 11 with good light resistance is expected to be adopted as an insulating material constituting a substrate of a TFT mounted on an organic EL display or the like, for example. In addition, in evaluating the amount of photoexcited charge of insulator 11, the amount of photoexcited charge Q is divided by the volume of insulator 11 to calculate the amount of photoexcited charge per unit volume of insulator 11, and this calculated value is compared with a preset upper limit threshold value, and the light resistance of insulator 11 can be evaluated based on the comparison result.

[0058] In the above-mentioned first CV characteristic measurement step (step S101), the laminate 15 formed by laminating the semiconductor 12 layer and the insulator 11 layer is interposed between the transparent electrode 2a and the support electrode 2b of the CV characteristic measurement device 1 to form the capacitor structure 10, but the CV characteristic measurement method according to the present embodiment 1 is not limited to this. For example, in the CV characteristic measurement method according to the present embodiment 1, the layer of the semiconductor 12 may be fixedly disposed on the support electrode 2b in advance, and the insulator 11 before light irradiation may be interposed between the layer of the semiconductor 12 on the support electrode 2b and the transparent electrode 2a to form the capacitor structure 10 before light irradiation. With this method, it is sufficient to prepare a single layer of the insulator 11 as the measurement sample, and the effort of preparing the laminate 15 can be saved, and the measurement sample can be easily prepared. In addition, even if the capacitor structure 10 is reformed by sequentially switching the multiple insulators 11 every time the measurement of the CV characteristic of the capacitor structure 10 after light irradiation is completed, the characteristic difference of the semiconductor 12 between the multiple capacitor structures 10 whose CV characteristics are measured can be eliminated. This makes it possible to reduce measurement errors in the CV characteristics, so that the CV characteristics of the capacitor structure 10 can be measured with high accuracy, and as a result, the amount of photoexcited charge Q of the insulator 11 can be derived with high accuracy.

[0059] As described above, in embodiment 1 of the present invention, light 3a from light source 3 is irradiated onto laminate 15 including a layer of insulator 11 and a layer of semiconductor 12 from the layer side of insulator 11, and this light irradiation generates charges in insulator 11 due to photoexcitation, and the CV characteristics of capacitor structure 10 after light irradiation are measured, which includes a first electrode (transparent electrode 2a in this embodiment 1) contacting laminate 15 from the layer side of insulator 11, a second electrode (support electrode 2b in this embodiment 1) contacting laminate 15 from the layer side of semiconductor 12, and laminate 15 after light irradiation.

[0060] Therefore, it is possible to easily measure the CV characteristics of the capacitor structure 10 that is affected by the charge generated in the insulator 11 by photoexcitation, i.e., the CV characteristics of the capacitor structure 10 including the insulator 11 after light irradiation. By using such CV characteristics of the capacitor structure 10 after light irradiation and the CV characteristics of the capacitor structure 10 before light irradiation, it is possible to easily measure the parameters essential for evaluating the amount of charge in the insulator 11 due to photoexcitation (specifically, the above-mentioned flat band voltage V FB 1. Flat band voltage V FB 2. Flat band voltage difference ΔV FB and the capacitance of the charge storage state, C I ) can be easily derived. As a result, the amount of photoexcited charge Q of the insulator 11 can be easily derived.

[0061] In the first embodiment of the present invention, a transparent electrode 2a is used as a first electrode that contacts the laminate 15 from the layer side of the insulator 11, and the laminate 15 of the capacitor structure 10 before light illumination is irradiated with light 3a from the light source 3 from the layer side of the insulator 11 via the transparent electrode 2a. Therefore, compared with the conventional case where a probe electrode is brought into contact with the laminate 15 from the layer side of the insulator 11, the light irradiation area of ​​the insulator 11 can be made wider, and the probe electrode can be prevented from scratching the target surface of the insulator 11 that is irradiated with light. As a result, the CV characteristics of the capacitor structure 10 including the insulator 11 after light illumination can be measured more easily and stably.

[0062] <Embodiment 2> (CV characteristic measuring device) Next, a CV characteristic measuring device according to the second embodiment of the present invention will be described. FIG. 4 is a schematic diagram showing one configuration example of the CV characteristic measuring device according to the second embodiment of the present invention. As shown in FIG. 4, the CV characteristic measuring device 21 according to the second embodiment has a laminate 25 interposed between the transparent electrode 2a and the supporting electrode 2b instead of the laminate 15 of the CV characteristic measuring device 1 according to the first embodiment. That is, in the second embodiment, the CV characteristic measuring device 21 has a capacitor structure 20 including the transparent electrode 2a, the supporting electrode 2b, and the laminate 25 instead of the capacitor structure 10 in the first embodiment as a measurement target of CV characteristics. In addition, the laminate 25 in the second embodiment further includes a charge blocking layer 23 between the layer of the insulator 11 and the layer of the semiconductor 12. The other configurations are the same as those of the first embodiment, and the same components are given the same reference numerals.

[0063] 4, the capacitor structure 20 is formed by sandwiching the laminate 25 between the transparent electrode 2a and the supporting electrode 2b in the layer thickness direction. In the present embodiment 2, the capacitor structure 20 before irradiation with light from the light source 3 is formed by the transparent electrode 2a, the supporting electrode 2b, and the laminate 25 before irradiation with light. The capacitor structure 20 after irradiation with light from the light source 3 is formed by the transparent electrode 2a, the supporting electrode 2b, and the laminate 25 after irradiation with light.

[0064] The laminate 25 is an example of a laminate including at least the above-mentioned layer of the insulator 11 and the layer of the semiconductor 12. In the present embodiment 2, as shown in FIG. 4, the laminate 25 includes the same layer of the insulator 11 and the layer of the semiconductor 12 as in the embodiment 1, and further includes a charge blocking layer 23. The charge blocking layer 23 is a layer for blocking the movement of charges from the layer of the insulator 11 to the layer of the semiconductor 12. The charge blocking layer 23 is made of an insulator having a higher electric resistance than the insulator 11, and is interposed between the layer of the insulator 11 and the layer of the semiconductor 12. The laminate 25 is formed by stacking the charge blocking layer 23 on the layer of the semiconductor 12, and stacking the layer of the insulator 11 on the charge blocking layer 23.

[0065] The insulator constituting the charge blocking layer 23 may be either an organic insulator or an inorganic insulator, but is preferably an inorganic insulator, more preferably an oxide insulator, and particularly preferably an oxide insulator formed by thermal oxidation (hereinafter referred to as a thermal oxide film). In addition, the thickness of the charge blocking layer 23 is preferably thinner than the thickness of the insulator 11 as the measurement sample, but is not particularly limited thereto.

[0066] In the second embodiment, a layer of semiconductor 12 in laminate 25 is placed on the upper surface of support electrode 2b. On the other hand, a layer of semiconductor 12 may be provided in advance on the upper surface of support electrode 2b, and laminate 25 in the second embodiment may be formed by placing a laminate consisting of charge blocking layer 23 and layer of insulator 11 on the layer of semiconductor 12 provided on support electrode 2b. Alternatively, charge blocking layer 23 may be laminated on the layer of semiconductor 12 provided on support electrode 2b, and layer of insulator 11 may be laminated on charge blocking layer 23, thereby forming laminate 25.

[0067] (Method of measuring CV characteristics of capacitor structure) Next, a CV characteristic measuring method according to the second embodiment of the present invention will be described. The CV characteristic measuring method according to the second embodiment is the same as the above-mentioned first embodiment, except that the measurement target is replaced from the capacitor structure 10 of the first embodiment to the capacitor structure 20 of the second embodiment. That is, the photoexcited charge amount measuring method to which the CV characteristic measuring method according to the second embodiment is applied is realized by sequentially performing each process of steps S101 to S106 shown in FIG. 3 with the capacitor structure 20 of the second embodiment as the measurement target of CV characteristics. The CV characteristic measuring method according to the second embodiment is a method for measuring the CV characteristics of the capacitor structure 20 required for measuring the photoexcited charge amount Q of the insulator 11, and is realized by performing, for example, at least each process of steps S103 and S104 shown in FIG. 3 using the above-mentioned CV characteristic measuring device 21 (see FIG. 4).

[0068] Specifically, in the first CV characteristic measurement step (step S101) in the present embodiment 2, the pre-light-irradiated laminate 25 is disposed between the transparent electrode 2a and the support electrode 2b of the CV characteristic measurement device 21, thereby forming the pre-light-irradiated capacitor structure 20. The laminate 25 may be formed in advance by sequentially laminating the charge blocking layer 23 and the layer of the insulator 11 on the layer of the semiconductor 12 in a stage prior to step S101, or may be formed by sequentially laminating the charge blocking layer 23 and the layer of the insulator 11 on the layer of the semiconductor 12 during the process of step S101.

[0069] In step S101, the CV characteristic measuring device 21 measures the CV characteristics of the capacitor structure 20 before light irradiation using the capacitance measuring device 6 and the voltmeter 7. The measurement of the CV characteristics by the CV characteristic measuring device 21 in step S101 is the same as that of the above-mentioned embodiment 1, except that the CV characteristics to be measured are the capacitor structure 20 before light irradiation. That is, in step S101, the capacitance C of the capacitor structure 20 before light irradiation is measured by the capacitance measuring device 6, and the applied voltage V of the capacitor structure 20 before light irradiation is measured by the voltmeter 7. The CV characteristics of the capacitor structure 20 before light irradiation are represented by a correlation line Y1 (see FIG. 2) indicating the correlation between the capacitance C of the capacitor structure 20 before light irradiation measured by the capacitance measuring device 6 and the applied voltage V of the capacitor structure 20 before light irradiation measured by the voltmeter 7.

[0070] Next, in the first flat band voltage derivation step (step S102) in the second embodiment, the flat band voltage V FB 1 is derived. This flat band voltage V FB The derivation process of 1 is the same as that of the above-described embodiment 1, except that the CV characteristics of the capacitor structure 20 before light irradiation are used.

[0071] Next, in the light irradiation step (step S103) in the present embodiment 2, the light source 3 of the CV characteristic measuring device 21 irradiates the laminate 25 of the capacitor structure 20 before light irradiation with light 3a from the layer side of the insulator 11 through the transparent electrode 2a. In detail, the light source 3 irradiates the capacitor structure 20 before light irradiation, which has already been formed in the CV characteristic measuring device 21 in the above-mentioned step S101, with light 3a from the transparent electrode 2a side. The light 3a emitted from the light source 3 penetrates the transparent electrode 2a and reaches the insulator 11 of the laminate 25. In this way, the light source 3 irradiates the light 3a to the insulator 11 through the transparent electrode 2a. In the insulator 11 irradiated with the light 3a from the light source 3, charges are generated due to photoexcitation.

[0072] 4, a charge blocking layer 23 having a higher electrical resistance than the insulator 11 is interposed between the layer of the insulator 11 and the layer of the semiconductor 12 in the laminate 25. The charge blocking layer 23 can prevent the charge generated in the insulator 11 by photoexcitation from moving to the layer of the semiconductor 12. As a result, the charge generated by photoexcitation in the insulator 11 is accumulated in the insulator 11 without escaping to the layer of the semiconductor 12.

[0073] Next, in the second CV characteristic measurement step (step S104) in the present embodiment 2, the capacitor structure 20 before light irradiation is irradiated with light 3a from the light source 3 to obtain the capacitor structure 20 after light irradiation. In step S104, the CV characteristic measurement device 21 measures the CV characteristics of the capacitor structure 20 after light irradiation using the capacitance measurement device 6 and the voltmeter 7. The measurement of the CV characteristics by the CV characteristic measurement device 21 in step S104 is the same as that of the above-mentioned embodiment 1, except that the CV characteristics are measured for the capacitor structure 20 after light irradiation. That is, in this step S104, the capacitance C of the capacitor structure 20 after light irradiation is measured by the capacitance measurement device 6, and the applied voltage V of the capacitor structure 20 after light irradiation is measured by the voltmeter 7. The CV characteristics of the capacitor structure 20 after light irradiation are represented by a correlation line Y2 (see FIG. 2) showing the correlation between the capacitance C of the capacitor structure 20 after light irradiation measured by the capacitance measurement device 6 and the applied voltage V of the capacitor structure 20 after light irradiation measured by the voltmeter 7.

[0074] Next, in the second flat band voltage derivation step (step S105) in the second embodiment, the flat band voltage V FB 2 is derived. This flat band voltage V FB The derivation process of 2 is the same as that of the above-described embodiment 1, except that the CV characteristics of the capacitor structure 20 after light irradiation are used.

[0075] The CV characteristics measurement method according to the present embodiment 2 includes each of steps S101 to S105 in the present embodiment 2. After each step of the CV characteristics measurement method is performed, the photoexcited charge amount deriving step S106 is performed as in the above-described embodiment 1, and the photoexcited charge amount measurement method according to the present embodiment 2 is completed.

[0076] The photoexcited charge amount derivation step (step S106) of the second embodiment is the flat band voltage V FB1 and the flat band voltage V FB 2 is used, the present embodiment is the same as the above-mentioned embodiment 1. That is, in step S106, the photoexcited charge Q of the insulator 11 in the capacitor structure 20 of the present embodiment 2 is increased to the flat band voltage V FB 1. V FB 2. Capacitance C in the charge storage state I and is derived based on equations (1) and (2). In the second embodiment, the capacitance C I is, for example, the capacitance in a state where charges are stored in the layer of the semiconductor 12 included in the capacitor structure 20 before light irradiation. The capacitance C I corresponds to the capacitance of the insulating region of the capacitor structure 20 (in this embodiment 2, the region of the insulator 11 layer and the charge blocking layer 23), and can be derived from the capacitance C at which the capacitance becomes maximum according to the applied voltage V in the CV characteristics of the capacitor structure 20 before light irradiation.

[0077] In the first CV characteristic measurement step (step S101) in the present embodiment 2, the laminate 25 formed by laminating the semiconductor 12 layer, the charge blocking layer 23, and the insulator 11 layer is interposed between the transparent electrode 2a and the support electrode 2b of the CV characteristic measurement device 21, thereby forming the capacitor structure 20, but the CV characteristic measurement method according to the present embodiment 2 is not limited to this. For example, in the CV characteristic measurement method according to the present embodiment 2, the layer of the semiconductor 12 may be fixedly disposed on the support electrode 2b in advance, and a laminate of the insulator 11 and the charge blocking layer 23 before light irradiation may be interposed between the layer of the semiconductor 12 on the support electrode 2b and the transparent electrode 2a, thereby forming the capacitor structure 20 before light irradiation. Alternatively, a laminate of the semiconductor 12 layer and the charge blocking layer 23 may be fixedly disposed on the support electrode 2b in advance, and the insulator 11 before light irradiation may be interposed between the charge blocking layer 23 in the laminate on the support electrode 2b and the transparent electrode 2a, thereby forming the capacitor structure 20 before light irradiation.

[0078] The above method can reduce the time and effort required to prepare the laminate 25, and can easily prepare a measurement sample. In addition, even if the capacitor structure 20 is re-formed by sequentially switching the multiple insulators 11 every time the measurement of the CV characteristics of the capacitor structure 20 after light irradiation is completed, the characteristic difference of the semiconductor 12 can be eliminated between the multiple capacitor structures 20 whose CV characteristics are measured. This can reduce the measurement error of the CV characteristics, so that the CV characteristics of the capacitor structure 20 can be accurately measured, and thus the photoexcited charge amount Q of the insulator 11 can be accurately derived.

[0079] As described above, in the second embodiment of the present invention, a charge blocking layer 23 having a higher electrical resistance than the insulator 11 is interposed between the layer of the insulator 11 and the layer of the semiconductor 12 in the laminate 25 for forming the capacitor structure 20 whose CV characteristics are to be measured, and the rest of the configuration is the same as that of the first embodiment. Therefore, the same effects as those of the first embodiment can be obtained, and the charge generated in the insulator 11 by photoexcitation can be prevented from escaping to the layer of the semiconductor 12, thereby suppressing the variation in the measured value of the capacitance C when measuring the CV characteristics of the capacitor structure 20 after light irradiation. As a result, the amount of shift in the CV characteristics after light irradiation from the CV characteristics before light irradiation due to the influence of light irradiation (i.e., the flat band voltage difference ΔV FB ) can be derived with high accuracy, and as a result, the amount of photoexcited charge Q of the insulator 11 can be derived with high accuracy.

[0080] <Embodiment 3> (CV characteristic measuring device) Next, a CV characteristics measuring device according to a third embodiment of the present invention will be described. Fig. 5 is a schematic diagram showing an example of the configuration of a CV characteristics measuring device according to the third embodiment of the present invention. As shown in Fig. 5, a CV characteristics measuring device 31 according to the third embodiment further includes a wavelength changing unit 33 for varying the wavelength of light 3a emitted from the light source 3, in addition to the configuration of the CV characteristics measuring device 21 according to the second embodiment described above. The other configuration is the same as that of the second embodiment, and the same components are denoted by the same reference numerals.

[0081] The wavelength changer 33 changes the wavelength of the light 3a emitted from the light source 3. In detail, the wavelength changer 33 is configured by a spectrometer such as a prism or a diffraction grating, and is provided on the light emitting unit side of the light source 3 as shown in FIG. 5. The wavelength changer 33 receives light from the light source 3 and separates the received light into light 3a of a plurality of continuous wavelength bands. The wavelength changer 33 sequentially outputs the light 3a of the plurality of wavelength bands thus separated by wavelength band in a predetermined order. That is, the light 3a output from the light source 3 through the wavelength changer 33 is irradiated onto the insulator 11 of the laminate 25 while continuously changing the wavelength in a predetermined order. The wavelength changer 33 may sequentially output the light 3a while continuously changing the wavelength from the short wavelength side to the long wavelength side, or may sequentially output the light 3a while continuously changing the wavelength from the long wavelength side to the short wavelength side.

[0082] (Method of measuring CV characteristics of capacitor structure) Next, a CV characteristic measuring method according to the third embodiment of the present invention will be described. The CV characteristic measuring method according to the third embodiment is similar to the above-mentioned second embodiment, except that the insulator 11 is irradiated with the light 3a whose wavelength is continuously changed by the wavelength changing unit 33, in order for each wavelength band. That is, in the photoexcited charge quantity measuring method to which the CV characteristic measuring method according to the third embodiment is applied, each process of steps S101 to S106 shown in FIG. 3 is sequentially repeated for each wavelength band of the light 3a that is continuously changed by the wavelength changing unit 33. In the CV characteristic measuring method according to the third embodiment, at least each process of steps S103 and S104 is repeatedly performed for each wavelength band of the light 3a that is continuously changed by the wavelength changing unit 33.

[0083] For example, when the insulator 11 is irradiated with light of a first wavelength band among the light 3a of a plurality of wavelength bands emitted from the light source 3 and dispersed by the wavelength changing unit 33, the above-mentioned steps S101 to S106 are performed for the light of the first wavelength band. Then, when the insulator 11 is irradiated with light of a second wavelength band continuous from the first wavelength band among the light 3a of the plurality of wavelength bands, the above-mentioned steps S101 to S106 are performed again for the light of the second wavelength band. In this manner, the steps S101 to S106 are repeatedly performed until the wavelength changing unit 33 finishes changing the wavelength of the light 3a. As a result, in the third embodiment, the CV characteristics of the capacitor structure 20 before and after light irradiation and the flat band voltage V FB 1. V FB 2 and the flat band voltage difference ΔV FB and the capacitance of the charge storage state, C I and the amount of photoexcited charge Q of the insulator 11 is obtained.

[0084] As described above, in the third embodiment of the present invention, the wavelength of the light 3a emitted from the light source 3 is changed by the wavelength changer 33, the light 3a in a plurality of wavelength bands is sequentially irradiated to the insulator 11 for each wavelength band, and each step of the photoexcited charge quantity measuring method (including each step of the CV characteristic measuring method) is repeatedly performed for each wavelength band of the light 3a irradiated to the insulator 11, and the rest is configured in the same manner as in the second embodiment. Therefore, while enjoying the same effects as in the second embodiment described above, physical data such as the CV characteristic required for deriving the photoexcited charge quantity Q of the insulator 11 can be obtained for each of the plurality of wavelength bands of the light 3a irradiated to the insulator 11, and therefore it becomes possible to evaluate the dependency of the photoexcited charge quantity Q of the insulator 11 on the wavelength of the irradiated light.

[0085] <Embodiment 4> (CV characteristic measuring device) Next, a CV characteristic measuring device according to a fourth embodiment of the present invention will be described. FIG. 6 is a schematic diagram showing one configuration example of a CV characteristic measuring device according to the fourth embodiment of the present invention. As shown in FIG. 6, a CV characteristic measuring device 41 according to the fourth embodiment includes a movable electrode (e.g., a mercury probe 42a) instead of the transparent electrode 2a of the CV characteristic measuring device 21 according to the second embodiment. That is, in the fourth embodiment, a capacitor structure 40 including a mercury probe 42a, a supporting electrode 2b, and a laminate 25 is formed in the CV characteristic measuring device 41 as a measurement target for CV characteristics, instead of the capacitor structure 20 in the second embodiment. The other configurations are the same as those of the second embodiment, and the same reference numerals are used for the same components.

[0086] The mercury probe 42a is an example of a movable electrode that can be moved away from the layer side of the insulator 11 to the stack (stack 25 in the fourth embodiment) including at least a layer of the insulator 11 and a layer of the semiconductor 12. In detail, the mercury probe 42a is an electrode formed of a cylindrical structure such as a cylinder containing mercury fluid having both elasticity and conductivity, and is arranged to face the support electrode 2b as shown in FIG. 6. The mercury probe 42a has a driving unit (not shown) and can move in a direction approaching or moving away from the support electrode 2b (for example, a direction indicated by a thick double-sided arrow in FIG. 6). The mercury probe 42a moves toward the insulator 11 of the stack 25 arranged on the support electrode 2b, for example, and contacts the insulator 11 by applying the mercury fluid exposed from the cylindrical structure to the surface of the insulator 11. The mercury probe 42a moves away from the insulator 11 by moving the mercury fluid in a direction away from the surface of the insulator 11. In the mercury probe 42a in the fourth embodiment, the viscosity of the mercury fluid, the inner diameter of the cylindrical structure, and the like are set so that a part of the mercury fluid does not remain on the surface of the insulator 11 when the mercury probe 42a is separated from the surface of the insulator 11. As shown in Fig. 6, the mercury probe 42a is electrically connected to the DC bias power supply 4, the AC power supply 5, and the measurement unit 8 (the capacitance measuring device 6 and the voltmeter 7 in the fourth embodiment) via wiring or the like.

[0087] 6, the capacitor structure 40 is formed by sandwiching the laminate 25 between the mercury probe 42a and the supporting electrode 2b in the layer thickness direction. In the fourth embodiment, the capacitor structure 40 before light irradiation by the light source 3 is formed by the mercury probe 42a, the supporting electrode 2b, and the laminate 25 before light irradiation. The capacitor structure 40 after light irradiation by the light source 3 is formed by the mercury probe 42a, the supporting electrode 2b, and the laminate 25 after light irradiation.

[0088] (Method of measuring CV characteristics of capacitor structure) Next, a CV characteristic measuring method according to a fourth embodiment of the present invention will be described. The CV characteristic measuring method according to the fourth embodiment is the same as the above-mentioned second embodiment, except that the first electrode to be brought into contact with the surface of the insulator 11 as the measurement sample is replaced from the transparent electrode 2a to a movable mercury probe 42a. That is, the photoexcited charge amount measuring method to which the CV characteristic measuring method according to the fourth embodiment is applied is realized by using the mercury probe 42a as the first electrode and sequentially performing each process of steps S101 to S106 shown in FIG. 3. The CV characteristic measuring method according to the fourth embodiment is a method for measuring the CV characteristic of the capacitor structure 40 required for measuring the photoexcited charge amount Q of the insulator 11, and is realized by performing at least each process of steps S103 and S104 shown in FIG. 3 using the above-mentioned CV characteristic measuring device 41 (see FIG. 6).

[0089] Specifically, in the first CV characteristic measurement step (step S101) in this embodiment 4, the laminate 25 is placed on the support electrode 2b of the CV characteristic measurement device 41, and the mercury probe 42a is brought into contact with the layer of the insulator 11 in this laminate 25, thereby forming the pre-light-irradiation capacitor structure 40. The formation of the laminate 25 is similar to that in the above-mentioned embodiment 2.

[0090] In step S101, the CV characteristic measuring device 41 measures the CV characteristic of the capacitor structure 40 before light irradiation using the capacitance measuring device 6 and the voltmeter 7. The measurement of the CV characteristic by the CV characteristic measuring device 41 in step S101 is the same as that in the above-mentioned embodiment 2, except that the transparent electrode 2a in contact with the layer of the insulator 11 is replaced with a mercury probe 42a. That is, in this step S101, the capacitance C of the capacitor structure 40 before light irradiation is measured by the capacitance measuring device 6, and the applied voltage V of the capacitor structure 40 before light irradiation is measured by the voltmeter 7. The CV characteristic of the capacitor structure 40 before light irradiation is represented by a correlation line Y1 (see FIG. 2) showing the correlation between the capacitance C of the capacitor structure 40 before light irradiation measured by the capacitance measuring device 6 and the applied voltage V of the capacitor structure 40 before light irradiation measured by the voltmeter 7.

[0091] Next, in the first flat band voltage derivation step (step S102) in the fourth embodiment, the flat band voltage V FB 1 is derived. This flat band voltage V FB The derivation process of 1 is the same as that of the above-described embodiment 2, except that the CV characteristics of the capacitor structure 40 before light irradiation are used.

[0092] Next, in the light irradiation step (step S103) in the present embodiment 4, the CV characteristic measuring device 41 separates the mercury probe 42a from the laminate 25, and irradiates the laminate 25 with light 3a from the light source 3 from the layer side of the insulator 11. In this step S103, the mercury probe 42a is an example of a movable electrode that can be separated from the laminate 25, and is separated from the laminate 25 when the light source 3 irradiates the laminate 25 with light 3a. In detail, the mercury probe 42a moves in a direction that separates the mercury fluid from the surface of the insulator 11, and thereby separates from the layer of the insulator 11 in the laminate 25. After the mercury probe 42a is separated from the layer of the insulator 11 as described above, the light source 3 irradiates the laminate 25 before light irradiation with light 3a from the layer side of the insulator 11. At this time, the light source 3 irradiates light 3a onto a surface portion of the insulator 11 including at least the portion to be measured (preferably the entire surface of the insulator 11). The portion to be measured of the insulator 11 is the portion of the entire surface of the insulator 11 that is in contact with the mercury probe 42a. Charges are generated in the insulator 11 due to photoexcitation when the light 3a from the light source 3 is irradiated. The charge generated by photoexcitation in the insulator 11 is stored in the insulator 11 because the charge blocking layer 23 blocks the charge from moving toward the semiconductor 12 layer side.

[0093] Next, in the second CV characteristic measurement step (step S104) in the present embodiment 4, the laminate 25 before light irradiation is irradiated with light 3a from the light source 3 to obtain the laminate 25 after light irradiation. In step S104, the CV characteristic measurement device 41 forms a capacitor structure 40 after light irradiation using the mercury probe 42a, the support electrode 2b, and the laminate 25 after light irradiation, and measures the CV characteristics of the capacitor structure 20 after light irradiation using the capacitance measurement device 6 and the voltmeter 7. In detail, the mercury probe 42a contacts the laminate 25 after light irradiation from the light source 3 from the layer side of the insulator 11. That is, the mercury probe 42a moves toward the insulator 11 of the laminate 25 after light irradiation, and contacts the layer of the insulator 11 in the laminate 25 after light irradiation by applying mercury fluid to the surface of the insulator 11. As a result, the capacitor structure 40 after light irradiation in the present embodiment 4 is formed.

[0094] The measurement of the CV characteristics by the CV characteristic measuring device 41 in step S104 is the same as that in the above-described embodiment 2, except that the first electrode in contact with the layer of the insulator 11 after light irradiation is replaced from the transparent electrode 2a to the mercury probe 42a, i.e., the measurement target of the CV characteristics is the capacitor structure 40 after light irradiation. In such step S104, the capacitance C of the capacitor structure 40 after light irradiation is measured by the capacitance measuring device 6, and the applied voltage V of the capacitor structure 40 after light irradiation is measured by the voltmeter 7. The CV characteristics of the capacitor structure 40 after light irradiation are represented by a correlation line Y2 (see FIG. 2) showing the correlation between the capacitance C of the capacitor structure 40 after light irradiation measured by the capacitance measuring device 6 and the applied voltage V of the capacitor structure 40 after light irradiation measured by the voltmeter 7.

[0095] Next, in the second flat band voltage derivation step (step S105) in the fourth embodiment, the flat band voltage V FB 2 is derived. This flat band voltage V FB The derivation process of 2 is similar to that of the above-described embodiment 2, except that the CV characteristics of the capacitor structure 40 after light irradiation are used.

[0096] The CV characteristics measurement method according to the present embodiment 4 includes each of steps S101 to S105 in the present embodiment 4. After each step of the CV characteristics measurement method is performed, the photoexcited charge amount deriving step S106 is performed as in the above-mentioned embodiment 2, and the photoexcited charge amount measurement method according to the present embodiment 4 is completed.

[0097] The photoexcited charge amount derivation step (step S106) of the fourth embodiment is the flat band voltage V FB 1 and the flat band voltage V FB2 is used, the present embodiment is the same as the embodiment 2. That is, in step S106, the photoexcited charge amount Q of the insulator 11 in the capacitor structure 40 of the present embodiment 4 is increased to the flat band voltage V FB 1. V FB 2. Capacitance C in the charge storage state I and is derived based on equations (1) and (2). In the fourth embodiment, the capacitance C I is, for example, the capacitance in a state where charges are stored in the layer of the semiconductor 12 included in the capacitor structure 40 before light irradiation. The capacitance C I corresponds to the capacitance of the insulating region of the capacitor structure 40 (in this embodiment 4, the region of the insulator 11 layer and the charge blocking layer 23), and can be derived from the capacitance C at which the capacitance becomes maximum in response to the applied voltage V in the CV characteristics of the capacitor structure 40 before light irradiation.

[0098] In the first CV characteristic measurement step (step S101) in the present embodiment 4, the laminate 25 formed by laminating the layer of the semiconductor 12, the charge blocking layer 23, and the layer of the insulator 11 is placed on the support electrode 2b of the CV characteristic measurement device 41, and the insulator 11 of the laminate 25 is brought into contact with the mercury probe 42a to form the capacitor structure 40, but the CV characteristic measurement method according to the present embodiment 4 is not limited to this. For example, in the CV characteristic measurement method according to the present embodiment 4, the layer of the semiconductor 12 may be fixedly placed on the support electrode 2b in advance, and the laminate of the insulator 11 and the charge blocking layer 23 before light irradiation may be interposed between the layer of the semiconductor 12 on the support electrode 2b and the mercury probe 42a to form the capacitor structure 40 before light irradiation. Alternatively, a laminate of a semiconductor layer 12 and a charge blocking layer 23 may be fixedly disposed on the support electrode 2b in advance, and the pre-light-irradiation capacitor structure 40 may be formed by interposing the pre-light-irradiation insulator 11 between the charge blocking layer 23 in the laminate on the support electrode 2b and the mercury probe 42a.

[0099] The above-mentioned method can reduce the time and effort required to prepare the laminate 25, and can easily prepare a measurement sample. In addition, even if the capacitor structure 40 is re-formed by sequentially switching the multiple insulators 11 every time the measurement of the CV characteristics of the capacitor structure 40 after light irradiation is completed, the characteristic difference of the semiconductor 12 can be eliminated between the multiple capacitor structures 40 whose CV characteristics are measured. This can reduce the measurement error of the CV characteristics, so that the CV characteristics of the capacitor structure 40 can be accurately measured, and thus the photoexcited charge amount Q of the insulator 11 can be accurately derived.

[0100] As described above, in the fourth embodiment of the present invention, a movable electrode that can be separated from the laminate 25 is used as the first electrode that contacts the laminate 25 from the layer side of the insulator 11, the movable electrode is separated from the laminate 25, the laminate 25 is irradiated with light 3a from the light source 3 from the layer side of the insulator 11, the capacitor structure 40 after light irradiation is formed by the movable electrode, the support electrode 2b, and the laminate 25 after light irradiation, and the CV characteristics of the capacitor structure 40 after light irradiation are measured, and the other configurations are the same as those of the second embodiment. Therefore, the same effects as those of the second embodiment can be obtained, and light can be irradiated to a wide range of surface parts including the parts of the entire surface of the insulator 11 that contact the electrodes, and as a result, the CV characteristics of the capacitor structure 40 including the insulator 11 after light irradiation can be more easily measured. In addition, since the mercury probe 42a is used as the movable electrode, it is possible to prevent contact scratches or indentations of the probe electrode from being made on the surface of the insulator 11 that is the target of light irradiation. As a result, the CV characteristics of the capacitor structure 40 including the insulator 11 after light irradiation can be stably measured.

[0101] In the above-mentioned first to fourth embodiments, the first electrode, the second electrode, the light source, the DC bias power supply, the AC power supply, the capacitance meter, and the voltmeter constituting the CV characteristic measuring device, and the laminate interposed between the first electrode and the second electrode are accommodated inside the darkroom formed by the housing 9, but the present invention is not limited to this. For example, the darkroom may accommodate at least the first electrode, the second electrode, and the laminate constituting the capacitor structure to be measured, and the light source for light irradiation, which need to be shielded from external light in light irradiation to measure the CV characteristics.

[0102] In the above-mentioned third and fourth embodiments, the laminate 25 including the semiconductor 12 layer, the charge blocking layer 23, and the insulator 11 layer is exemplified as the laminate including the insulator 11 to be measured, but the present invention is not limited thereto. For example, in the CV characteristic measuring device 31 of the third embodiment including the wavelength changing unit 33 for changing the wavelength of the light 3a from the light source 3, the capacitor structure 20 for measuring the CV characteristic may be formed by interposing the laminate 15 including the semiconductor 12 layer and the insulator 11 layer between the transparent electrode 2a and the support electrode 2b. In the CV characteristic measuring device 41 of the fourth embodiment including the mercury probe 42a as a movable electrode that can be brought into contact with the insulator 11 in a separable manner, the capacitor structure 40 for measuring the CV characteristic may be formed by interposing the laminate 15 including the semiconductor 12 layer and the insulator 11 layer between the mercury probe 42a and the support electrode 2b. That is, the CV characteristic measuring device according to the present invention may be a combination of the above-mentioned first to fourth embodiments.

[0103] In the above-described fourth embodiment, the mercury probe 42a is exemplified as the movable electrode that is in contact with the insulator 11 so as to be separable from the insulator 11, but the present invention is not limited to this. For example, the movable electrode is not limited to the mercury probe 42a, and may be an electrode other than the mercury probe 42a. EXAMPLES

[0104] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[0105] <Example 1> In Example 1, the CV characteristics of the measurement sample were measured using the CV characteristics measurement device 41 (see FIG. 6) according to the above-mentioned embodiment 4. The measurement sample of Example 1 was a laminated body formed by laminating a polyimide film (an example of the insulator 11) on a P-type silicon wafer (an example of the semiconductor 12). The thickness of the polyimide film in this laminated body was 1 [μm]. The electrode diameter of the mercury probe 42a was 0.17 [cm]. In Example 1, the measurement sample was stored in a darkroom by the housing 9 of the CV characteristics measurement device 41 in order to block external light other than the light 3a (irradiation light) from the light source 3. The CV characteristics of this measurement sample were measured in this darkroom.

[0106] In the measurement of the CV characteristics in Example 1, a measurement sample was placed on the support electrode 2b of the CV characteristics measuring device 41 in such a direction that the P-type silicon wafer was in contact with the support electrode 2b, and the mercury probe 42a was lowered and brought into contact with the surface of the polyimide film of the measurement sample. This formed a capacitor structure consisting of the support electrode 2b, the P-type silicon wafer, the polyimide film, and the mercury probe 42a. Next, the CV characteristics measuring device 41 applied a DC bias voltage to this capacitor structure by the DC bias power supply 4, and applied an AC voltage by the AC power supply 5. At this time, the DC bias voltage was set to -50 [V] or more and 50 [V] or less. The frequency of the AC voltage was set to 100 [kHz]. The CV characteristics measuring device 41 measured the capacitance C and applied voltage V of the capacitor structure in this state by the capacitance measuring device 6 and the voltmeter 7, respectively, thereby measuring the CV characteristics of this capacitor structure.

[0107] 7 is a diagram showing an example of the measurement results of the CV characteristic in Example 1 of the present invention. In Example 1, as shown in FIG. 7, a correlation line Y1 showing the correlation between the capacitance C of the capacitor structure before light irradiation and the applied voltage V was obtained as the CV characteristic of this capacitor structure before light irradiation. Based on this obtained correlation line Y1, the flat band voltage V of the capacitor structure before light irradiation was calculated as shown in FIG. FB We were able to derive 1.

[0108] Thereafter, the CV characteristic measuring device 41 separated the mercury probe 42a, which had been in contact with the polyimide film of the capacitor structure, from the polyimide film, and irradiated the surface of the polyimide film from which the mercury probe 42a had been removed with light 3a from the light source 3. At this time, the light 3a was LED light with a wavelength of 470 [nm]. The intensity of the light 3a was 4 [μW / cm 2 The irradiation time of the light 3a was 30 minutes. In this state, the CV characteristic measuring device 41 measured the capacitance C and applied voltage V of the capacitor structure after light irradiation using the capacitance measuring device 6 and the voltmeter 7 under the same conditions as those for the CV characteristics before light irradiation, respectively, thereby measuring the CV characteristics of the capacitor structure after light irradiation. As a result, as shown in FIG. 7, a correlation line Y2 showing the correlation between the capacitance C and applied voltage V of the capacitor structure after light irradiation was obtained as the CV characteristics of the capacitor structure after light irradiation. Based on the obtained correlation line Y2, the flat band voltage V of the capacitor structure after light irradiation was calculated as shown in FIG. 7. FB We were able to derive 2.

[0109] Next, in Example 1, the flat band voltages V before and after the light irradiation are FB 1. V FB 2, based on the above-mentioned formula (1), the flat band voltage difference ΔV shown in FIG. FB The flat band voltage difference ΔV FB Based on the CV characteristics of the capacitor structure before light irradiation in Example 1 (see the correlation line Y1 in FIG. 7), the capacitance C I The obtained capacitance CI The flat band voltage difference ΔV FB and capacitance C I Using the above formula (2), the photoexcited charge Q of the polyimide film was derived. The photoexcited charge Q obtained is the amount of charge increased by photoexcitation in the polyimide film, and is 1.5×10 -9 It was [C].

[0110] <Example 2> In Example 2, the CV characteristics of the measurement sample were measured using the CV characteristics measuring device 41 in the same manner as in Example 1. The measurement sample in Example 2 was a laminate in which a thermally oxidized film (SiO2), which is an example of the charge blocking layer 23, was laminated on the surface of a P-type silicon wafer similar to that in Example 1, and a polyimide film similar to that in Example 1 was laminated on the thermally oxidized film. That is, in this laminate, the thermally oxidized film was interposed between the P-type silicon wafer and the polyimide film. The thickness of this thermally oxidized film was 50 [nm]. The volume resistance value of this thermally oxidized film was calculated by multiplying the volume resistance value of the polyimide film (=1×10 17 [Ω cm]), specifically, 1×10 18 The electrical conductivity was [Ω·cm]. The mercury probe 42a of the CV characteristic measuring device 41 was the same as in Example 1. The measurement sample in Example 2 was stored in a darkroom defined by the housing 9 of the CV characteristic measuring device 41 to block external light, as in Example 1. The CV characteristics of this measurement sample were measured in this darkroom.

[0111] In the measurement of the CV characteristics in Example 2, a measurement sample was placed on the support electrode 2b of the CV characteristics measuring device 41 in such a direction that the P-type silicon wafer was in contact with the support electrode 2b, and the mercury probe 42a was lowered and brought into contact with the surface of the polyimide film of the measurement sample. This formed a capacitor structure consisting of the support electrode 2b, the P-type silicon wafer, the thermal oxide film, the polyimide film, and the mercury probe 42a. Next, the CV characteristics measuring device 41 applied a DC bias voltage to this capacitor structure by the DC bias power supply 4, and applied an AC voltage by the AC power supply 5. At this time, the DC bias voltage was set to -50 [V] or more and 100 [V] or less. The frequency of the AC voltage was set to 100 [kHz]. The CV characteristics measuring device 41 measured the capacitance C and applied voltage V of the capacitor structure in this state by the capacitance measuring device 6 and the voltmeter 7, respectively, thereby measuring the CV characteristics of this capacitor structure.

[0112] 8 is a diagram showing an example of the measurement results of the CV characteristic in Example 2 of the present invention. In Example 2, as shown in FIG. 8, a correlation line Y1 showing the correlation between the capacitance C of the capacitor structure before light irradiation and the applied voltage V was obtained as the CV characteristic of this capacitor structure before light irradiation. Based on this obtained correlation line Y1, the flat band voltage V of the capacitor structure before light irradiation was calculated as shown in FIG. FB We were able to derive 1.

[0113] Thereafter, the CV characteristic measuring device 41 separated the mercury probe 42a, which had been in contact with the polyimide film of the capacitor structure, from the polyimide film, and irradiated the surface of the polyimide film from which the mercury probe 42a had been removed with light 3a from the light source 3. At this time, the light 3a was LED light with a wavelength of 470 [nm]. The intensity of the light 3a was 4 [μW / cm 2The irradiation time of the light 3a was 30 minutes. In this state, the CV characteristic measuring device 41 measured the capacitance C and applied voltage V of the capacitor structure after light irradiation using the capacitance measuring device 6 and the voltmeter 7 under the same conditions as those for the CV characteristics before light irradiation, respectively, thereby measuring the CV characteristics of the capacitor structure after light irradiation. As a result, as shown in FIG. 8, a correlation line Y2 showing the correlation between the capacitance C and applied voltage V of the capacitor structure after light irradiation was obtained as the CV characteristics of the capacitor structure after light irradiation. Based on the obtained correlation line Y2, the flat band voltage V of the capacitor structure after light irradiation was calculated as shown in FIG. 8. FB We were able to derive 2.

[0114] Next, in Example 2, the flat band voltages V before and after the light irradiation were FB 1. V FB 2, based on the above-mentioned formula (1), the flat band voltage difference ΔV FB The flat band voltage difference ΔV FB Based on the CV characteristics of the capacitor structure before light irradiation in Example 2 (see the correlation line Y1 in FIG. 8), the capacitance C I The obtained capacitance C I The flat band voltage difference ΔV FB and capacitance C I Using the above formula (2), the photoexcited charge Q of the polyimide film was derived. The photoexcited charge Q obtained is the amount of charge increased by photoexcitation in the polyimide film, and is 6.7×10 -9 It was [C].

[0115] The present invention is not limited to the above-mentioned embodiments 1 to 4 and examples 1 and 2. The present invention also includes configurations in which the above-mentioned components are appropriately combined. In addition, other embodiments, examples, operation techniques, etc. made by those skilled in the art based on the above-mentioned embodiments 1 to 4 are all included in the scope of the present invention. [Explanation of symbols]

[0116] 1, 21, 31, 41 CV characteristic measuring device 2a transparent electrode 2b Support electrode 3 light source 3a light 4 DC bias power supply 5 AC power supply 6 Capacitance Measuring Instrument 7. Voltmeter 8 Measuring part 9. Cabinet 10, 20, 40 capacitor structure 11 Insulators 12. Semiconductors 15, 25 laminate 23 Charge blocking layer 33 Wavelength change unit 42a Mercury Probe Y1, Y2 correlation line

Claims

1. a light irradiation step of irradiating a laminate including an insulator layer and a semiconductor layer with light from the insulator layer side to generate charges in the insulator by photoexcitation; a measuring step of measuring capacitance-voltage characteristics of a capacitor structure after light irradiation, the capacitor structure including a first electrode contacting the laminate from the insulator layer side, a second electrode contacting the laminate from the semiconductor layer side, and the laminate after light irradiation; Including, a charge blocking layer having a higher electrical resistance than the insulator is interposed between the insulator layer and the semiconductor layer in the laminate; The capacitance-voltage characteristic measuring method according to the present invention is characterized in that:

2. the first electrode is a transparent electrode that is transparent to the light irradiated to the laminate; The light irradiation step includes irradiating the laminate having a capacitor structure before light illumination, which is formed by the first electrode, the second electrode, and the laminate before light irradiation, with the light from the insulator layer side via the first electrode.

2. The method for measuring capacitance-voltage characteristics according to claim 1.

3. the first electrode is a movable electrode that is in separable contact with the stack; The light irradiation step includes irradiating the laminate with the light from the insulating layer side with the first electrode spaced apart from the laminate; the measuring step includes forming the capacitor structure after light irradiation using the first electrode, the second electrode, and the laminate after light irradiation, and measuring the capacitance-voltage characteristics of the capacitor structure after light irradiation.

2. The method for measuring capacitance-voltage characteristics according to claim 1.

4. The movable electrode is a mercury probe.

4. The method for measuring capacitance-voltage characteristics according to claim 3.

5. a first electrode that is in contact with a laminate including an insulator layer and a semiconductor layer from the insulator layer side; a second electrode in contact with the stack from the semiconductor layer side; a light source that irradiates the laminate with light from the insulating layer side; a DC power source that applies a DC bias voltage to a capacitor structure after light irradiation, the capacitor structure including the first electrode, the second electrode, and the laminate after light irradiation; an AC power source that applies an AC voltage to the capacitor structure after the light irradiation; A measurement unit for measuring the capacitance-voltage characteristics of the capacitor structure after light irradiation; a housing forming a darkroom in which at least the light source, the laminate, the first electrode, and the second electrode are housed; Equipped with The laminate further includes a charge blocking layer interposed between the insulator layer and the semiconductor layer and having a higher electrical resistance than the insulator. The capacitance-voltage characteristic measuring device is characterized by the above.

6. the first electrode is a transparent electrode that is transparent to the light from the light source; the light source irradiates the stack of a capacitor structure before light irradiation, which is formed by the first electrode, the second electrode, and the stack before light irradiation, with the light from the insulator layer side via the first electrode; 6. The capacitance-voltage characteristic measuring device according to claim 5.

7. the first electrode is a movable electrode that is in separable contact with the stack; the movable electrode is separated from the laminate when the light is irradiated to the laminate by the light source, and is in contact with the laminate after the light irradiation.

6. The capacitance-voltage characteristic measuring device according to claim 5.

8. The movable electrode is a mercury probe.

8. The capacitance-voltage characteristic measuring device according to claim 7.

9. Further comprising a wavelength changing unit that changes the wavelength of the light from the light source.

9. The capacitance-voltage characteristic measuring device according to claim 5, wherein the capacitance-voltage characteristic measuring device is a capacitance-voltage characteristic measuring device.

10. The semiconductor layer is provided on the second electrode.

10. The capacitance-voltage characteristic measuring device according to claim 5, wherein the capacitance-voltage characteristic measuring device is a capacitance-voltage characteristic measuring device.

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