JP5496070B2 - Insulation defect detector for semiconductor devices - Google Patents

Description

  The present invention relates to an insulation defect detection device for a semiconductor device, and more particularly to an insulation defect detection device for a semiconductor device for detecting an insulation defect of a high voltage device such as a power module.

  In recent years, the demand for power modules has increased as a device for efficient use of electrical energy. Power modules are required to have high insulation reliability, and insulation inspection is performed before shipment. However, partial discharge that was not detected in the initial stage may occur due to voltage application for a long time. The reason for this is that initial electrons are necessary for partial discharge to occur in the defect, but in the case of a minute defect, the initial electrons are difficult to be supplied, so there is a high possibility that they will not be detected by inspection before shipment. . Therefore, in order to ensure the long-term reliability of the product, it is required that the insulation inspection can be performed in a short time during the initial inspection.

  As a conventional inspection method, there is a method in which initial electrons are supplied to a defective portion by irradiating X-rays and inspected in a short time (see, for example, Patent Document 1).

JP-A-9-105766

  However, the defect inspection apparatus used in the conventional inspection method as described in Patent Document 1 described above is composed of a partial discharge measurement apparatus and an X-ray irradiation apparatus, and a measurement system of the partial discharge measurement apparatus is connected to a power source. Built-in and directly connected to the sample to detect the current pulse, so if the defect is very small, the discharge charge is small and may not be detected. There was a problem that could not.

  In addition, in a sample with a SiC chip mounting module, etc., where the insulation structure is downsized, the defect in question becomes smaller and the amount of discharge charge is smaller, and as a result, it is harder to detect. There was a problem that an accurate measurement was required.

  The present invention has been made to solve such problems, and a semiconductor device capable of high-precision detection in a short time without requiring long-term voltage application by a partial discharge measurement method using electromagnetic wave detection. An object of the present invention is to provide an insulation defect detection device.

  The present invention includes a voltage applying unit that applies a voltage to a sample that is a target for detection of insulation defects, an X-ray irradiating unit that irradiates the sample with X-rays, and an antenna. When the X-ray irradiation is performed, the partial discharge measuring means for detecting electromagnetic waves emitted from the partial discharge inside the sample by the antenna, the sample is stored when performing the detection, and the inner wall surface An X-ray shielding housing capable of reflecting electromagnetic waves, wherein the presence or absence of an insulation defect in the sample is detected based on a detection result of the electromagnetic waves emitted from the partial discharge. It is an insulation defect detection device.

  The present invention includes a voltage application unit that applies a voltage to a sample that is a target for detection of insulation defects, an X-ray irradiation unit that irradiates the sample with X-rays, and an antenna, When the X-ray irradiation is performed, the partial discharge measuring means for detecting electromagnetic waves emitted from the partial discharge inside the sample by the antenna, the sample is stored when performing the detection, and the inner wall surface An X-ray shielding housing capable of reflecting electromagnetic waves, wherein the presence or absence of an insulation defect in the sample is detected based on a detection result of the electromagnetic waves emitted from the partial discharge. Since it is an insulation defect detection device, the partial discharge measurement method based on electromagnetic wave detection enables high-precision detection in a short time without the need for long-term voltage application.

It is a block diagram which shows the apparatus structure of the insulation defect detection apparatus of the semiconductor device which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the relationship between the partial discharge charge amount at the time of X-ray irradiation and the time of non-irradiation, and a partial discharge start voltage with a graph. It is a flowchart which shows the implementation procedure of the insulation defect detection apparatus of the semiconductor device which concerns on Embodiment 1 of this invention. It is a perspective view which shows the positional relationship of arrangement | positioning of each antenna in the insulation defect detection apparatus of the semiconductor device which concerns on Embodiment 2 of this invention. It is a sectional side view which shows measuring the reflected wave of the electromagnetic wave in the housing | casing wall surface in the insulation defect detection apparatus of the semiconductor device concerning Embodiment 2 of this invention with an antenna. It is a sectional side view which shows arrangement | positioning of the metal plate for electromagnetic waves reflection inside the X-ray shielding housing | casing in the insulation defect detection apparatus of the semiconductor device concerning Embodiment 3 of this invention. It is a perspective view shown about the dimension inside the apparatus housing | casing in the insulation defect detection apparatus of the semiconductor device which concerns on Embodiment 4 of this invention. It is a schematic diagram which shows arrangement | positioning of the antenna at the time of resonance in the insulation defect detection apparatus of the semiconductor device which concerns on Embodiment 4 of this invention. It is a block diagram which shows the apparatus structure which added the movable reflecting plate of the insulation defect detection apparatus of the semiconductor device which concerns on Embodiment 5 of this invention. It is a figure which shows the effect of the reflection by the movable reflecting plate of the insulation defect detection apparatus of the semiconductor device which concerns on Embodiment 5 of this invention. It is a figure which shows the X-ray irradiation to the sample by the X-ray reflection by the movable reflecting plate of the insulation defect detection apparatus of the semiconductor device concerning Embodiment 6 of this invention. It is a figure which shows the X-ray irradiation to the sample by X-ray reflection by the angle change of the movable reflecting plate of the insulation defect detection apparatus of the semiconductor device concerning Embodiment 6 of this invention. It is a figure which shows measuring the reflected wave of the electromagnetic wave by making the reflecting plate of the insulation defect detection apparatus of the semiconductor device concerning Embodiment 7 of this invention into a curved surface shape with an antenna. It is a figure which shows that an electromagnetic wave resonant frequency changes with the distance between reflecting plates of the insulation defect detection apparatus of the semiconductor device which concerns on Embodiment 8 of this invention.

Embodiment 1 FIG.
FIG. 1 is a diagram showing an apparatus configuration according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a sample that is a detection target of an insulation defect, and reference numeral 2 denotes a sample stage made of a dielectric that can transmit electromagnetic waves for placing the sample 1. Reference numeral 3 denotes a high-voltage power source for applying a voltage to the sample 1, and 4 denotes an X-ray generation unit that is provided above the sample stage 2 and irradiates the sample 1 with X-rays 5. Reference numeral 6 denotes an antenna for detecting an electromagnetic wave signal emitted from a partial discharge inside the sample 1. Although a single antenna 6 may be provided, a plurality (antennas 6a and 6b) may be provided as shown in FIG. Reference numeral 7 denotes an X-ray shielding casing made of a lead plate capable of shielding X-rays. The X-ray generation unit 4 accommodates the sample 1, the sample stage 2, the X-ray generation unit 4, and the antenna 6 therein. This is to prevent X-rays 5 from being emitted outside. Further, the inner wall of the X-ray shielding housing 7 reflects electromagnetic waves. 8 is an X-ray control unit that controls the operation of the X-ray generation unit 4, and 9 is a partial discharge detector for detecting the occurrence of partial discharge based on the electromagnetic wave signal detected by the antenna 6. Reference numeral 10 denotes a measurement control unit that controls operations of the high-voltage power supply 3, the X-ray control unit 8, and the partial discharge detector 9.

  In this configuration, the sample 1 is placed on the sample stage 2, a voltage is applied to the sample 1 by the high voltage power supply 3, and the X-ray 5 is irradiated from the X-ray generation unit 4 to the sample 1. At this time, an electromagnetic wave signal emitted from the partial discharge inside the sample 1 is detected by the antenna 6. If no electromagnetic wave signal is detected, it is determined that there is no insulation defect in the sample 1. Conversely, if an electromagnetic wave signal is detected, it is determined that the insulation defect exists in the sample 1.

  At this time, the antenna 6 is a flat antenna. In the case of a flat antenna, there are advantages such as being easy to install inside the apparatus and having directivity but good sensitivity. The antenna 6 is directed in the direction of the sample 1 and is arranged at a plurality of locations in order to improve measurement sensitivity. In the example of FIG. 1, the antenna 6 a is installed below the sample table 2, and the antenna 6 b is installed on the side of the sample table 2. As a matter of course, the measurement sensitivity is improved as the number of antennas 6 increases. However, if the antenna 6 is installed between the sample 1 and the X-ray generation unit 4, the sample 1 and the X-ray generation unit 4 are prevented from being irradiated with X-rays. Avoid installing between. At this time, if the antenna 6 and the sample stage 2 are placed in close contact with each other when the antenna 6 and the sample stage 2 are brought into close contact with each other, measurement cannot be performed well due to fluctuations in the surface electric field. Therefore, as shown in FIG. To do. At this time, when an electromagnetic wave is radiated from the sample 1, not only the electromagnetic wave radiated toward the antenna 6 but also the electromagnetic wave radiated in the direction without the antenna 6 is reflected on the wall surface of the X-ray shielding casing 7. Therefore, the reflected wave can also be measured by the antenna 6, and as a result, the measurement sensitivity can be improved. In addition, the detection frequency of the antenna is set to a high frequency (several hundred MHz to several GHz) that is not easily affected by noise. Further, the irradiation direction of the X-ray 5 may not be from above the sample 1 as shown in FIG.

  When X-rays 5 are irradiated to the insulating defect portion generated in the sample 1, since initial electrons are induced inside the defect, discharge is likely to occur, and as shown in FIG. As a result, the partial discharge start voltage decreases. However, even when the X-ray 5 is not irradiated, a charge is supplied to the defective portion by applying a voltage for a long time, and a discharge start voltage equivalent to that at the time of the X-ray 5 irradiation can be obtained. That is, by irradiating and measuring X-rays 5, the same effect as applying a long-time voltage can be obtained, and long-term reliability can be evaluated in a short time. Therefore, the inspection process time can be shortened by introducing the insulation defect detection device of the present invention into the production line.

  A flowchart of the measurement procedure of the present invention is shown in FIG. First, the sample 1 is placed on the sample stage 2, connected to the high voltage power source 3, and a test voltage is applied (step S1). Subsequently, the X-ray generation unit 4 irradiates the sample 1 with X-rays 5 (step S2). Next, the partial discharge detector 9 determines whether or not the partial discharge is detected by the antenna 6 as a result of the irradiation (step S3). If the partial discharge is detected, it is determined that the sample 1 has an insulation defect and becomes an NG product (failed product) (step S4). If it is not detected, it is determined that the sample 1 has no insulation defect, This is an OK product (accepted product) (step S5). After the discharge is determined, the voltage application by the high voltage power supply 3 is stopped (step S6), and the X-ray irradiation by the X-ray generator 4 is stopped (step S7), thereby completing the inspection. By controlling the high-voltage power supply 3, the X-ray control unit 8, and the partial discharge detector 9 collectively by the measurement control unit 10 in this series of flows, inspection can be automated.

  With this defect detection method, the insulation reliability of equipment such as a power module can be evaluated. The power module here is applicable to all modules such as silicone gel-sealed high-voltage models equipped with all chips such as Si and SiC chips, and mold-type modules by transfer molding of epoxy resin. There is no.

  As described above, the insulation defect detection device of the semiconductor device according to the first embodiment is a device that detects insulation defects by X-ray irradiation and partial discharge measurement, and applies a high voltage to the sample 1. Sample 1 is irradiated with X-ray 5, voltage application means composed of a power source 3, partial discharge measuring means composed of an antenna 6 and partial discharge detector 9 for detecting electromagnetic waves emitted from the partial discharge inside the sample 1 Since the X-ray irradiating means composed of the X-ray generating section 4 and the X-ray shielding casing 7 for storing the sample 1 at the time of measurement are provided, the initial electron supply by the X-ray irradiation provides a long-term Insulation defect inspection can be carried out with high accuracy without requiring voltage application. In addition, since the electromagnetic wave of the discharge is detected by the antenna 6, the reflected wave of the electromagnetic wave is also measured using the X-ray shielding housing 7, so that the antenna 6 is radiated in the direction where the antenna 6 is not installed. Since the electromagnetic wave can be detected by the reflected wave, the measurement sensitivity is improved and the detection accuracy can be improved.

Embodiment 2. FIG.
In the present embodiment, in the configuration described in the above-described first embodiment, the directional antenna 6 is further provided at a total of three locations below the sample 1 and at two lateral sides as shown in FIG. Place them so that they are orthogonal to each other. Further, the antenna 6 is disposed so that the antenna 6 faces the front of the wall surface of the opposite X-ray shielding casing 7 across the sample 1. That is, the configuration of FIG. 4 is a configuration in which the antenna 6c is further added to the configuration of FIG. Since other configurations are the same as those in FIG. 1, reference is made to FIG. 1, and description and illustration thereof are omitted here.

  In this configuration, when partial discharge occurs, the electromagnetic wave radiated from the sample 1 toward the direction without the antenna 6 is reflected by the wall surface (inner wall) of the X-ray shielding housing 7 as shown in FIG. Since it returns to the front surface of the antenna 6, the reflected wave is detected by the antenna 6, so that it can be detected. Further, even if the antenna 6 cannot be detected angularly by one reflection, it can be detected by any one of three orthogonal antennas 6 by repeating the reflection on the wall surface of the X-ray shielding housing 7. An effect close to that obtained when four are arranged at four or more locations can be obtained.

  Specifically, the antenna 6a basically detects a reflected wave of an electromagnetic wave reflected by the ceiling (upper inner wall) of the X-ray shielding casing 7, and the antennas 6b and 6c basically have an X-ray shielding casing. The reflected wave of the electromagnetic wave reflected by the side wall (side inner wall) 7 is detected. However, not only this but each antenna 6a-6c is the reflected wave repeatedly reflected by the wall surface of the X-ray shielding housing | casing 7 also about the reflected wave which was not detected angularly by one reflection as mentioned above. Anything that can be detected is also detected.

  However, the antenna 6 may be a rod antenna or the like having a low directivity instead of a flat antenna, but in that case, the sensitivity is reduced instead of the necessity of being installed at a plurality of locations.

  As described above, according to the insulation defect detection device for a semiconductor device according to the second embodiment, the same effect as in the first embodiment described above can be obtained, and, in the second embodiment, directivity can be obtained. A plurality of antennas 6 are used, and the direction of the antennas 6 is set so as to face the front of the wall surface of the opposite X-ray shielding casing 7 with the sample 1 interposed therebetween, and is directed in a direction orthogonal to the wall surface. Since it did in this way, the effect that the reflected wave of the electromagnetic wave radiated | emitted toward the wall surface of the X-ray shielding housing | casing 7 on the opposite side which pinched | interposed the sample 1 seeing from the antenna 6 can be detected efficiently is acquired. .

Embodiment 3 FIG.
In the present embodiment, in the configuration described in the first embodiment, as shown in FIG. 6, the inner wall surface of the X-ray shielding housing 7 is made of a copper plate having higher conductivity than the lead plate. The configured electromagnetic wave reflecting metal plate 12 (12a to 12d) is attached as an electromagnetic wave reflecting plate. At this time, the surface of the copper plate is smooth and has no irregularities in order to increase the reflectance. Thereby, the intensity | strength of a reflected wave increases and a measurement sensitivity improves. That is, the configuration of FIG. 6 is a configuration in which a metal plate 12 attached to the inner wall surface of the X-ray shielding casing 7 is added to the configuration of FIG. Since other configurations are the same as those in FIG. 1, reference is made to FIG. 1, and description and illustration thereof are omitted here.

  In FIG. 6, four electromagnetic wave reflecting metal plates 12 are attached to the inner wall surface of the X-ray shielding casing 7, but this is based on the relationship shown in the figure. It is attached to all six inner wall surfaces of the X-ray shielding housing 7. Although not necessarily attached to all six surfaces, it is desirable to attach to all six surfaces in consideration of improvement in reflectance and measurement sensitivity. Further, the metal plate 12 is not necessarily provided on the entire inner wall surface of the X-ray shielding housing 7, but is desirably provided on the entire wall surface.

  As described above, according to the insulation defect detection device for a semiconductor device according to the third embodiment, the same effects as those of the first embodiment described above can be obtained. Since the metal plate 12 having a high electromagnetic wave reflectance is installed on the inner wall surface of the shielding housing 7, the effect of improving the measurement sensitivity can be obtained by improving the electromagnetic wave reflectance of the housing wall surface. It is done.

Embodiment 4 FIG.
In the present embodiment, in the configuration described in the first embodiment, the distance between the wall surfaces is set so that the detection frequency of the antenna 6 becomes the resonance frequency of the electromagnetic wave 11 that occurs inside the X-ray shielding housing 7. The sensitivity of detection was improved by adjusting each width of the measurement. When the X-ray shielding case 7 is a rectangular parallelepiped, the following is between the resonance frequency f and the dimensions of the internal space of the X-ray shielding case 7 (height: a, width: b, depth: d in FIG. 7). The dimensions of the internal space of the X-ray shielding housing 7 (height: a, width: b, depth: d in FIG. 7) are adjusted so that the following equation (1) holds. Here, c is the speed of light, and m, n, and s are integers of 0 or more.

  At this time, the position of the antenna 6 is arranged at a position where the amplitude of the standing wave becomes large.

  Here, as a simple form, when formula (1) is developed with n = s = 0, when the wavelength of the electromagnetic wave is λ, a = (λ / 2) × m, where a is an integral multiple of the half wavelength of the electromagnetic wave. It becomes. For example, if the frequency is 1 GHz, λ / 2 = 15 cm. Therefore, if a is an integral multiple of 15 cm, an electromagnetic wave that resonates in the a direction can be detected.

  At this time, since the amplitude of the electric field varies depending on the position of the standing wave, the antenna 6 should not be installed at the node of the standing wave where the amplitude of the electric field is 0 as in the antenna 6a shown in FIG. As described above, the measurement is performed by installing the antinode of the standing wave that can secure the amplitude of the electric field.

  As described above, according to the insulation defect detection device for a semiconductor device according to the fourth embodiment, the same effects as those of the first embodiment described above can be obtained. Further, in the fourth embodiment, FIG. As shown in FIG. 5, the detection frequency of the antenna 6 depends on the internal frequency of the X-ray shielding housing 7 (height: a, width: b, depth: d) in FIG. As described above, the internal dimensions of the X-ray shielding housing 7 are adjusted (that is, designed to such dimensions), and the resonance frequency of the electromagnetic waves inside the X-ray shielding housing 7 is measured to improve detection sensitivity. The effect that it can be made is acquired. In the standing wave section, the amplitude of the electric field is 0, and if an antenna is installed in the vicinity of the standing wave, sufficient measurement cannot be performed. Therefore, in Embodiment 4, when measuring a resonating electromagnetic wave, the antenna is Since it is installed in a place other than the vicinity of the node of the standing wave, it is possible to sufficiently measure the electromagnetic wave.

Embodiment 5 FIG.
FIG. 9 shows a configuration in which a movable reflector 13 capable of moving the position is installed in addition to the configuration of FIG. The movable reflector 13 is composed of a pair of movable reflectors 13a and 13b. In FIG. 9, a position controller 14 for controlling the positions of the movable reflectors 13a and 13b is provided. The position control unit 14 is installed outside the X-ray shielding housing 7. In FIG. 1, two antennas 6 a and 6 b are provided as the antenna 6, but in FIG. 9, only one antenna 6 is provided. However, the present invention is not limited to this, and a plurality of antennas may be provided as long as the movement of the movable reflectors 13a and 13b is not hindered, and a necessary number may be provided as appropriate. In the configuration of FIG. 9, the position of the antenna 6 can be moved. Therefore, the positions of the movable reflectors 13a and 13b and the antenna 6 are controlled from the outside of the housing by the position control unit 14. The operation of the position control unit 14 is controlled by the measurement control unit 10. The above is the difference from FIG. Other configurations and operations are the same as those in FIG. 1, and thus description thereof is omitted here.

  The movable reflectors 13 a and 13 b are provided in the vicinity of the sample 1 and on both sides of the sample 1 so as to face each other. In the example of FIG. 9, the movable reflecting plate 13a is provided on the antenna 6 side. Here, by installing the movable reflectors 13a and 13b in the vicinity thereof in accordance with the dimensions of the sample 1, the propagation distance of the reflected wave to the antenna 6 can be shortened. At this time, when the movable reflector 13a on the same side as the antenna 6 is moved so that the reflector 2a and the wiring are not hindered so that the reflectors 13a and 13b can approach the vicinity of the specimen 1, Moves the antenna 6 at the same time so as not to hinder the movement of the reflector 13a. The positions of the movable reflectors 13a and 13b are individually controlled by the position controller 14. At this time, as shown in FIG. 10A, when the movable reflecting plate 13 b is separated from the sample 1, the reflected wave of the electromagnetic wave 11 incident obliquely on the movable reflecting plate 13 b may not be received by the antenna 6. is there. In that case, as shown in FIG. 10B, the reflected wave of the electromagnetic wave 11 radiated in the same manner is easily received by the antenna 6 by bringing the movable reflecting plate 13 b closer to the sample 1.

  As described above, according to the insulation defect detection device for a semiconductor device according to the fifth embodiment, the same effects as those of the first embodiment described above can be obtained. Movable reflectors 13a and 13b for reflecting electromagnetic waves that can be moved are provided, and the position control unit 14 performs position control on the movable reflectors 13a and 13b so that the reflector can be brought closer to the sample 1. Since the reflection plate can be installed in the vicinity of 1, the measurement sensitivity of the antenna 6 can be further improved by the reflected wave from the reflection plate.

  In the above description, the example in which the position of the movable reflectors 13a and 13b is separately controlled has been described. However, the present invention is not limited to this, and the position control unit 14 may perform position control simultaneously in conjunction with the two. It may be. Further, it may be configured such that position control is performed separately or whether position control is performed in conjunction with each other.

  In the above description, an example in which two movable reflectors 13 are provided has been described. However, the present invention is not limited to this, and only one or three or more may be provided. Further, all of them may be movable, but only a part may be movable, and the others may be fixed reflectors. Furthermore, the fixed reflecting plate may be designed so as to be removable, and may be attached and used as necessary.

Embodiment 6 FIG.
FIG. 11 is a partial configuration diagram showing the configuration of the insulation defect detection device for a semiconductor device according to the sixth embodiment. In FIG. 11, X-ray irradiation to the sample by X-ray reflection by a movable reflecting plate is shown. In FIG. 11, only the sample 1, the sample stage 2, the X-ray generation unit 4, and the movable reflectors 13 a and 13 b are illustrated, and the other configurations are not illustrated, but are not illustrated. 9 is the same as that in FIG. 9, and therefore, FIG. 9 will be referred to and description thereof will be omitted here.

  In the present embodiment, as shown in FIG. 11, the X-ray generator 4 emits X-rays 5 so that the X-rays 5 irradiated from the X-ray generator 4 spread radially, and the X-rays In accordance with the irradiation angle θ of the X-ray 5 and the distance d2 between the X-ray source of the X-ray generation unit 4 and the sample 1 so that the reflecting surface of the movable reflecting plate 13 is exactly within the irradiation range of 5, The position control unit 14 adjusts the distance d1 between the sample 1 and the reflecting plates 13a and 13b to be short. Desirably, the moving range of the movable reflecting plate 13 is determined so that the reflecting surface of the movable reflecting plate 13 always falls within the irradiation range of the X-rays 5 even if the movable reflecting plate 13 moves. A plate 13 is installed. The X-rays 5 incident on the movable reflectors 13a and 13b pass through the reflectors 13a and 13b according to the energy, but a part of the X-rays 5 is reflected in the direction of the sample 1 by scattering. Generally, the lower the X-ray energy, the easier it is to reflect. X-rays irradiated by this scattering are irradiated to the sample 1 from a direction different from the X-rays directly irradiated from the X-ray generation unit 4.

  When the method as described above is used, for example, when there is a wiring such as copper that prevents X-ray irradiation inside the sample 1 and there is a portion where X-rays are not effectively irradiated inside the sample 1, X-rays from different directions are used. Can also irradiate that part.

  X-ray scattering has the property of being easily scattered forward and backward in the incident direction, and X-rays scattered inside the movable reflectors 13a and 13b are reflected by the movable reflectors 13a and 13b due to attenuation. It is easy to go in the normal direction of the surface. Therefore, as shown in FIG. 12, if the installation angle of the movable reflectors 13a and 13b is also variable and the incident angle φ of the X-ray 5 to the movable reflectors 13a and 13b is increased, the reflected X-rays can be more effectively obtained from the sample 1. Therefore, the optimum state of X-ray irradiation can be adjusted by changing the angle. The angle control may be performed by the position control unit 14.

  The X-ray reflection component on the movable reflectors 13a and 13b is due to backscattering. Therefore, in order to increase the intensity of the backscattered rays, the movable reflector 13 uses a metal (aluminum or the like) that easily causes backscattering, and has a thickness that is equal to or greater than the thickness at which saturation backscattering is performed according to the metal and the X-ray energy. By doing so, the sample 1 can be irradiated with X-rays more effectively.

  As described above, according to the insulation defect detection device for a semiconductor device according to the sixth embodiment, the same effects as those of the first embodiment described above can be obtained. Further, the movable reflectors 13a and 13b having variable installation angles are provided so that the X-ray 5 is reflected in the direction of the sample 1 by scattering by the movable reflectors 13a and 13b. Since X-rays can be irradiated to the sample 1 from a direction different from the X-rays irradiated to the X-ray 1, for example, there is a wiring such as copper that prevents X-ray irradiation inside the sample 1 and is effective in the sample 1 inside. Even when there is a portion where X-rays are not irradiated, the portion can be irradiated with X-rays from another direction. Thereby, it can irradiate to the location where X-rays are hard to be irradiated by the obstacle in the sample.

  In the present embodiment, the X-ray 5 is irradiated so as to spread radially from the X-ray generation unit 4, and the movable reflectors 13 a and 13 b are generated by the control of the movement control unit 14. Since it can be installed so as to have a positional relationship that falls within the range of X-ray irradiation by the unit 4, the X-rays hitting the movable reflectors 13a and 13b are reliably scattered (reflected) toward the sample 1. Therefore, it is possible to reliably irradiate the sample 1 from a direction different from the irradiation direction from the X-ray generation unit 4, and to irradiate a place where X-rays are not easily irradiated by the obstacle in the sample 1. Measurement sensitivity can be improved, and detection accuracy can be further improved.

  Furthermore, in the present embodiment, the movable reflectors 13a and 13b are made of a metal having a characteristic of increasing the backscattering of the X-ray 5 and having a thickness. Since the sample 1 can be irradiated with X-rays more effectively, the effect of X-ray scattering can be further enhanced.

Embodiment 7 FIG.
FIG. 13 is a partial configuration diagram showing the configuration of the insulation defect detection device for a semiconductor device according to the seventh embodiment. FIG. 13 shows a reflected wave when the electromagnetic wave 11 radiated from the sample 1 is incident on the movable reflecting plate 13 at an angle. FIG. 13A shows a case where the movable reflector 13 is planar, and FIG. 13B shows a curved surface. In FIG. 13, only the sample 1, the sample stage 2, the antenna 6, and the movable reflector 13 are described, and the other configurations are not shown, but for other configurations that are not described, Since it is the same structure as FIG. 9, it shall refer to FIG. 9 and the description is abbreviate | omitted here.

  In the present embodiment, as shown in FIG. 13A, when the movable reflector 13 is planar, the electromagnetic wave 11 radiated from the sample 1 is incident on the movable reflectors 13a and 13b obliquely. Can be considered. In that case, the antenna 6 may not be able to effectively receive the reflected wave reflected by the movable reflectors 13a and 13b. Therefore, in the present embodiment, as shown in FIG. 13 (b), the movable reflector 13 is curved, and the positions of the movable reflectors 13c and 13d are controlled by the position control unit 14 so as to match it. Thus, the detection sensitivity can be improved by allowing the electromagnetic wave 11 from the sample 1 to be effectively reflected toward the antenna 6. As a matter of course, as shown in FIG. 13B, the movable reflecting plates 13c and 13d have a concave surface of the curved surface facing the sample 1 and a convex surface facing the outside. By doing so, the reflected wave reflected by the movable reflecting plate 13 by the electromagnetic wave 11 can be efficiently converged toward the antenna 6.

  As described above, according to the insulation defect detection device for a semiconductor device according to the seventh embodiment, the same effect as in the first embodiment described above can be obtained, and in addition, the movable reflection is achieved in the seventh embodiment. Since the plates 13c and 13d are curved so that the reflected wave of the electromagnetic wave can be converged toward the antenna 6, the reflected wave can be concentrated toward the antenna 6 and the sensitivity is further improved.

Embodiment 8 FIG.
FIG. 14 is a partial configuration diagram showing the configuration of the insulation defect detection device for a semiconductor device according to the eighth embodiment. FIG. 14 shows a case where the resonance frequency of the electromagnetic wave 1 occurring inside the housing is used. In FIG. 14, only the sample 1, the sample stage 2, the antenna 6, and the movable reflector 13 are described, and the other configurations are not shown, but for other configurations that are not described, Since it is the same structure as FIG. 9, it shall refer to FIG. 9 and the description is abbreviate | omitted here.

  When the electromagnetic wave resonance is used as in the above-described fourth embodiment, the measurement frequency depends on the dimensions of the X-ray shielding casing 7, so that the usable frequency is limited. Therefore, in the present embodiment, as shown in FIG. 14, the movable reflectors 13a and 13b are moved, and the distance L between the movable reflectors 13a and 13b is variable. By doing so, resonance at an arbitrary frequency becomes possible. When electromagnetic waves in a certain frequency band are strongly emitted due to the discharge characteristics of the sample 1, the distance L between the movable reflectors 13a and 13b is set so that the antenna 6 has a frequency sensitivity suitable for the electromagnetic wave and resonance occurs at that frequency. Adjustment is performed by the control unit 14. For example, when it is desired to resonate at 1 GHz, L may be adjusted to be a multiple of 15 cm. In this way, when using the resonance of electromagnetic waves by calculating the length of L in advance based on the frequency to be resonated and adjusting L by the position control unit 14 so as to be the distance, An arbitrary frequency can be used as the measurement frequency without depending on the dimension of the X-ray shielding casing 7.

  As described above, according to the insulation defect detection device for a semiconductor device according to the eighth embodiment, the same effects as those of the first embodiment described above can be obtained. Such effects can be obtained.

  The method according to the eighth embodiment can cause resonance at an arbitrary frequency by making the distance L between the reflectors variable by the movable reflector 13, and the movable reflector 13 as described in the fifth embodiment is used. Although the feature is different from that of improving the reception effect of the reflected wave by approaching the sample 1, any of these effects can be selectively used by the position movement by the movable reflecting plate 13.

  1 sample, 2 sample stage, 3 high voltage power supply, 4 X-ray generator, 5 X-ray, 6, 6a, 6b, 6c antenna, 7 X-ray shielding housing, 8 X-ray controller, 9 partial discharge detector, 10 measurement control unit, 11 electromagnetic wave, 12, 12a, 12b, 12c, 12d electromagnetic wave reflection plate, 13, 13a, 13b, 13c, 13d movable reflection plate, 14 position control unit.

Claims (10)

Voltage applying means for applying a voltage to a sample which is a detection target of insulation defects;
X-ray irradiation means for irradiating the sample with X-rays;
A partial discharge measuring means for detecting an electromagnetic wave emitted from a partial discharge inside the sample by the antenna when having an antenna and applying the voltage and irradiating the X-ray;
An X-ray shielding housing capable of storing the sample when performing the detection and having an inner wall surface capable of reflecting electromagnetic waves;
An insulation defect detection device for a semiconductor device, wherein the presence or absence of an insulation defect in the sample is detected based on a detection result of the electromagnetic wave emitted from the partial discharge.   A directional antenna is used as the antenna, and the antenna is installed so that the direction of the antenna is directed toward the inner wall surface of the X-ray shielding housing on the opposite side across the sample. Item 2. An insulation defect detection device for a semiconductor device according to Item 1.   2. The insulation defect detection device for a semiconductor device according to claim 1, wherein a metal plate having a high electromagnetic wave reflectivity is provided on the inner wall surface of the X-ray shielding housing.   2. The internal dimension of the X-ray shielding casing is adjusted so that a detection frequency of the antenna becomes a frequency of an electromagnetic wave that resonates depending on an internal dimension of the X-ray shielding casing. 2. An insulation defect detection device for a semiconductor device according to 1.   5. The insulation defect detection device for a semiconductor device according to claim 4, wherein, when measuring the resonating electromagnetic wave, the antenna is installed at a place other than the vicinity of the node of the standing wave of the electromagnetic wave. A movable reflector for reflecting electromagnetic waves, movably installed in the X-ray shielding case;
2. The insulation defect detection device for a semiconductor device according to claim 1, further comprising a position control means for controlling a position of the movable reflector. The X-ray irradiation means irradiates the X-ray so that the X-ray spreads radially,
The insulation defect detection device for a semiconductor device according to claim 6 , wherein the movable reflector is installed in a positional relationship in which a reflection surface thereof falls within the X-ray irradiation range.   8. The insulation defect detection device for a semiconductor device according to claim 7, wherein the movable reflector is made of a metal having a characteristic that X-ray backscattering is likely to occur.   9. The semiconductor according to claim 6, wherein the movable reflecting plate is formed in a curved surface shape so that the reflected electromagnetic wave converges toward the antenna. 10. Device insulation defect detection device. The antenna detection frequency can be arbitrarily changed,
10. The insulation defect detection device for a semiconductor device according to claim 6, wherein the measurement is performed by resonating the electromagnetic wave by changing a distance between the movable reflectors. 11.

Images