JP2013002859A - Inspection apparatus and inspection method using terahertz wave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection apparatus using a terahertz wave which is capable of easily aligning a measuring target when inspecting a defect (air bubble) in a laminate such as a coating or epi-layer of a semiconductor wafer for preventing the corrosion of a metal utilizing a reflection wave of the terahertz wave, and an inspection method.SOLUTION: An inspection apparatus comprises a terahertz wave oscillation antenna 5 which oscillates a terahertz wave by radiating first laser light, a time delay mechanism 7 which gives time delay to second laser light, a terahertz wave receiving antenna 8 which detects the terahertz wave in detection timing based on the second laser light and generates a detection signal corresponding to strength of the detected terahertz wave, a state detection section which detects whether or not a measuring target 100 is positioned and tilted in a predetermined state, and an inspection section 54 which inspects the presence/absence of a defect in the measuring target on the basis of a peak value of time-series signal strength data based on the detection signal generated by the terahertz wave receiving antenna in the case where the measuring target is positioned and tilted in the predetermined state and the time delay given by the time delay mechanism 7 is varied.

Description

  The present invention relates to an inspection apparatus and an inspection method for inspecting a defect (in particular, a bubble) of an inspection object using a terahertz wave.

  In recent years, attention has been focused on terahertz waves in the middle region between radio waves and light waves. The use of terahertz waves has been delayed because transmission and reception are difficult. However, the use of terahertz waves has become possible due to recent advances in laser and semiconductor technologies. Although there are differences depending on the academic field, the terahertz wave indicates a region of 30 μm to 3 mm in wavelength and 100 GHz to 10 THz in frequency.

  Conventionally, there is an apparatus for inspecting a physical quantity or physical property of an inspection object by using the terahertz wave. For example, a particle diameter measuring apparatus for measuring the particle diameter of an object based on the transmittance of the terahertz wave is provided. Exists.

JP 2004-61455 A JP 2006-71412 A

  In addition to the inspection apparatus using the terahertz wave transmittance as described above, the object to be measured is irradiated with the terahertz wave, and the reflected wave is used to prevent the corrosion of the metal film or semiconductor wafer. An inspection apparatus for inspecting defects (bubbles) in a laminate such as a layer is also conceivable. In such a case, there are problems that it is difficult to align the measurement object and that the intensity of the reflected wave is weak.

  Inspection equipment using reflected waves of terahertz waves calculates the reflectivity from the signal strength of the reference and the signal strength of the measurement object, and the reflectivity when there is no bubble is different from the reflectivity when there is a bubble. Determine the presence or absence of bubbles. Alternatively, an inspection apparatus using a reflected wave of a terahertz wave determines the presence or absence of a bubble because the reflected terahertz wave intensity when there is no bubble is different from the reflected terahertz wave intensity when there is a bubble.

  In determining the presence or absence of air bubbles, conventional inspection equipment, for example, installs an aluminum mirror instead of placing a measurement object as a reference, irradiates the aluminum mirror with terahertz waves, and determines the signal intensity of the reflected wave. taking measurement. After that, place the measurement object in place of the aluminum mirror, irradiate the measurement object with terahertz waves, measure the signal intensity of the reflected wave, and compare it with the reference case. The position and angle of the reflecting surface of the aluminum mirror and the object to be measured must match.

  If the positions of the reflecting surfaces do not match, the diameter of the terahertz wave to the measurement object is different, and the intensity of the terahertz wave changes every time measurement is performed, making it difficult to determine the presence or absence of bubbles. Further, if the angles of the reflecting surfaces do not match, the intensity of the terahertz wave that reaches the terahertz wave receiving antenna is different, and the intensity of the terahertz wave changes every measurement, making it difficult to determine the presence or absence of bubbles.

  Furthermore, since the irradiation intensity of the terahertz wave is limited, there is a problem that when the intensity of the reflected wave is weak, accurate measurement cannot be performed in the inspection apparatus using the reflected wave of the terahertz wave as described above. Arise.

  SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art. Defects (bubbles) in a laminate such as a coating film or an epilayer of a semiconductor wafer for preventing metal corrosion using reflected waves of terahertz waves. It is an object of the present invention to provide an inspection apparatus and an inspection method using a terahertz wave that can easily align a measurement object and improve the intensity of a reflected wave when performing an inspection.

  In order to solve the above problems, an inspection apparatus using a terahertz wave according to the present invention is generated by a light splitting unit that splits a laser beam into a first laser beam and a second laser beam, and the light splitting unit. A terahertz wave oscillating unit that oscillates a terahertz wave when irradiated with the first laser beam, a time delay unit that gives a time delay to the second laser beam emitted by the light splitting unit, and a time delay by the time delay unit A terahertz wave detecting unit that detects a terahertz wave oscillated by the terahertz wave oscillating unit at a detection timing based on the second laser beam given, and generates a detection signal according to the intensity of the detected terahertz wave; A position and an inclination of a measurement object installed so as to reflect the terahertz wave in a terahertz waveguide between the terahertz wave oscillating unit and the terahertz wave detecting unit are predetermined. A state detection unit for detecting whether the state is in a state, and the position and inclination of the measurement object detected by the state detection unit are in a predetermined state, and the time delay given by the time delay unit is changed. And an inspection unit for inspecting whether there is a defect in the measurement object based on a peak value of time-series signal intensity data based on a detection signal generated by the terahertz wave detection unit.

It is a figure which shows the structure of the test | inspection apparatus using the terahertz wave of the form of Example 1 of this invention. It is a figure which shows the detailed structure of the terahertz wave oscillation antenna in the test | inspection apparatus using the terahertz wave of the form of Example 1 of this invention. It is a figure which shows the detailed structure of the terahertz wave receiving antenna in the test | inspection apparatus using the terahertz wave of the form of Example 1 of this invention. It is a figure which shows the laser intensity of the 3rd laser beam measured by a light-receiving part in the test | inspection apparatus using the terahertz wave of the form of Example 1 of this invention. It is a time waveform figure of the terahertz wave at the time of installing an aluminum mirror as a reference in the inspection device using the terahertz wave of the form of Example 1 of the present invention. It is a figure which shows the structure of the test | inspection apparatus using the terahertz wave of the form of Example 2 of this invention. It is a figure which shows the structure at the time of providing the matching layer in the test | inspection apparatus using the terahertz wave of the form of Example 2 of this invention. It is a figure which shows the structure of the test | inspection apparatus using the terahertz wave of the form of Example 3 of this invention. It is a figure which shows the detailed structure of the matching layer vicinity in the test | inspection apparatus using the terahertz wave of the form of Example 3 of this invention. It is a figure which shows another structural example of the test | inspection apparatus using the terahertz wave of the form of Example 3 of this invention. It is a figure which shows the detailed structure of the matching layer vicinity in another structural example of the test | inspection apparatus using the terahertz wave of the form of Example 3 of this invention. It is a figure which shows another structural example of the test | inspection apparatus using the terahertz wave of the form of Example 3 of this invention.

  Hereinafter, embodiments of an inspection apparatus and an inspection method using a terahertz wave according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an inspection apparatus using a terahertz wave according to a first embodiment of the present invention. The configuration of the inspection apparatus will be described with reference to FIG. The inspection apparatus according to this embodiment includes a laser 1, a beam splitter 2, a mirror 3, a lens 4, a terahertz wave oscillation antenna 5, a parabolic mirror 6, a time delay mechanism 7, a terahertz wave receiving antenna 8, a knife edge 9, and a lens 10. , A laser light source 11, a light receiving unit 12, a signal generator 50, a lock-in amplifier 51, a data holding unit 52, a display device 53, and a data processing unit 54.

  In addition, the laser 1, the beam splitter 2, the mirror 3, the lens 4, the terahertz wave oscillation antenna 5, the terahertz wave receiving antenna 8, the parabolic mirror 6, the time delay mechanism 7, the measurement object 100 described later, the laser light source 11, and the lens 10, the knife edge 9, and the light-receiving part 12 shall be on the same plane.

  The laser 1 emits laser light. The intensity of this laser light changes within a few picoseconds. The laser 1 may use a laser diode, and may use a femtosecond pulse laser instead of the laser diode. The wavelength of the laser light may be any wavelength that can excite a low-temperature grown gallium arsenide substrate of a terahertz wave oscillation antenna 5 and a terahertz wave receiving antenna 8 described later, and is, for example, about 780 nm to 830 nm. Further, the laser output intensity of the laser 1 only needs to be an intensity that outputs about 30 mW on the emitter side and about 10 mW on the detector side.

  The beam splitter 2 corresponds to the light splitting unit of the present invention, and splits the laser beam emitted by the laser 1 into a first laser beam and a second laser beam.

  The mirror 3a reflects the first laser beam emitted from the beam splitter 2 in a predetermined direction.

  The lens 4a condenses the first laser light reflected by the mirror 3a.

  The terahertz wave oscillating antenna 5 corresponds to the terahertz wave oscillating unit of the present invention, and oscillates terahertz waves when the first laser light emitted from the beam splitter 2 is irradiated through the mirror 3a and the lens 4a.

  FIG. 2 is a diagram illustrating a detailed configuration of the terahertz wave oscillating antenna 5 in the inspection apparatus using the terahertz wave according to the present embodiment. As shown in FIG. 2, the terahertz wave oscillation antenna 5 has a configuration in which a low-temperature grown gallium arsenide substrate 22 is provided on a silicon lens 25, and a signal generator 50 is connected to the electrode 20 on the low-temperature grown gallium arsenide substrate 22. It is connected. The electrode 20 has a shape such as a dipole or a bow tie, and gold is mainly used as a material. Further, the silicon lens 25 uses a hemispherical lens or a super hemispherical lens. Further, the laser beam 23 indicated by a black circle indicates an irradiation position of the first laser beam irradiated to the gap.

  The signal generator 50 applies a voltage to the terahertz wave oscillation antenna 5 and modulates the terahertz wave with a repetition frequency of, for example, 11 kHz and ± 10 V. An optical chopper may be used instead of the signal generator 50. When an optical chopper is used, it is installed between the beam splitter 2 and the terahertz wave oscillation antenna 5 or between the beam splitter 2 and the terahertz wave receiving antenna 8.

  The parabolic mirror 6 is a mirror for guiding the terahertz wave oscillated by the terahertz wave oscillation antenna 5 to the terahertz wave receiving antenna 8. The parabolic mirror 6 may be any one that does not attenuate terahertz waves, and examples thereof include metals (iron, aluminum, etc.).

  The mirror 3 b reflects the second laser light emitted by the beam splitter 2 in a predetermined direction and guides it into the time delay mechanism 7.

  The time delay mechanism 7 corresponds to the time delay unit of the present invention, and gives a time delay to the second laser light emitted from the beam splitter 2 and incident through the mirror 3b. As an example of the specifications required for the time delay mechanism 7, the time delay mechanism 7 only needs to have a moving range of the internal mirror of 2 cm to 5 cm. The moving speed may be 20 kpps (Pulse per second) at the maximum and 1 kpps at the minimum. Moreover, the movement pitch should just operate | move every 10 micrometers and movement accuracy should just be 0.015 mm.

  The mirrors 3c and 3d reflect the second laser light emitted by the time delay mechanism 7 in a predetermined direction.

  The lens 4b condenses the second laser light reflected by the mirrors 3c and 3d. The beam splitter 2, the mirrors 3a, 3b, 3c, 3d, and the lenses 4a, 4b can withstand the output intensity of the laser beam from the laser 1, and the laser has a femtosecond order pulse or less than several picoseconds. It is preferable that the laser beam whose intensity changes does not change.

  The terahertz wave receiving antenna 8 corresponds to the terahertz wave detecting unit of the present invention, and the terahertz wave oscillated by the terahertz wave oscillating antenna 5 at the detection timing based on the second laser beam given the time delay by the time delay mechanism 7. And a detection signal corresponding to the detected intensity of the terahertz wave is generated. The terahertz wave receiving antenna 8 may be any device that can receive terahertz waves, and examples thereof include a silicon bolometer.

  FIG. 3 is a diagram illustrating a detailed configuration of the terahertz wave receiving antenna 8 in the inspection apparatus using the terahertz wave according to the present embodiment. As shown in FIG. 3, the terahertz wave receiving antenna 8 has the same configuration as the terahertz wave oscillating antenna 5, and a low-temperature grown gallium arsenide substrate 22 is provided on the silicon lens 25. However, a lock-in amplifier 51 is connected to the electrode 20 on the low-temperature grown gallium arsenide substrate 22 of the terahertz wave receiving antenna 8 instead of the signal generator 50.

The lock-in amplifier 51 amplifies the detection signal generated by the terahertz wave receiving antenna 8 in synchronization with the reference signal of the signal generator 50. The lock-in amplifier 51 only needs to have about 10 ⁸ current amplification.

  The measurement object 100 is a laminate such as a coating film for preventing metal corrosion or an epi layer of a semiconductor wafer, and is installed in a terahertz waveguide between the terahertz wave oscillation antenna 5 and the terahertz wave reception antenna 8. Yes. The measurement object 100 reflects the terahertz wave and contributes to the formation of the terahertz waveguide, and is installed so that the reflected wave is guided to the terahertz wave receiving antenna 8.

  In some cases, bubbles may enter between the metal and the coating film or between the semiconductor wafer and the epi layer, and the inspection apparatus according to the present embodiment determines whether or not bubbles exist in the laminate of the measurement object 100. Can be inspected.

  The laser light source 11, the lens 10, the knife edge 9, and the light receiving unit 12 correspond to the state detection unit of the present invention, and reflect the terahertz wave in the terahertz waveguide between the terahertz wave oscillation antenna 5 and the terahertz wave receiving antenna 8. It is detected whether the position and inclination of the measuring object 100 installed so as to be in a predetermined state.

  The laser light source 11 irradiates the measurement object 100 with the third laser light.

  The lens 10 condenses the third laser light irradiated by the laser light source 11 and reflected by the measurement object 100.

  The light receiving unit 12 receives the third laser light collected by the lens 10 and detects the intensity of the third laser light. The detection result of the third laser light intensity by the light receiving unit 12 is displayed on a display device or a display device 53 (not shown).

  The knife edge 9 is provided between the lens 10 and the light receiving unit 12 and can shield the third laser light condensed by the lens 10 by adjusting the position.

  The operation of the state detection unit constituted by these will be described later.

  The data holding unit 52 and the data processing unit 54 correspond to the inspection unit of the present invention, and the position and the inclination of the measurement object 100 detected by the state detection unit are in a predetermined state and are given by the time delay mechanism 7. Based on the peak value of the time-series signal intensity data based on the detection signal generated by the terahertz wave receiving antenna 8 when the time delay is changed, the presence or absence of a defect in the measurement object 100 is inspected. For example, this inspection unit holds signal intensity data when an aluminum mirror is installed instead of the measurement object 100 as a reference, and estimates the presence or absence of a defect in the measurement object 100 by referring to this. .

  To describe each configuration, the data holding unit 52 holds signal intensity data based on the detection signal generated by the terahertz wave receiving antenna 8. In addition, the data processing unit 54 refers to the data holding unit 52 in order to inspect the measurement object 100 for defects (bubbles) based on the peak value indicated by the signal intensity data held in the data holding unit 52. In general, when bubbles are present in the laminate of the measurement object 100, terahertz waves are scattered, and the peak value of the time-series signal intensity data is smaller than that of the reference.

  The display device 53 is a device for displaying the signal intensity data based on the detection signal output from the lock-in amplifier 51 and the result of the inspection performed by the inspection unit (the data holding unit 52 and the data processing unit 54).

  The display device 53 also has a role as a control device that controls the amount of time delay by moving the mirror inside the time delay mechanism 7. The display device 53 does not necessarily have a role as a display device and a role as a control device. For example, a “display device” and a “control device” that controls the time delay mechanism 7 are separately provided. May be provided.

  Next, the operation of the present embodiment configured as described above will be described. Here, it is assumed that the inspection apparatus of this embodiment determines the presence or absence of bubbles in the laminate of the measurement object 100.

  First, the user installs the measuring object 100 in the terahertz waveguide so as to reflect the terahertz wave. The measurement object 100 is a laminate such as a coating film for preventing metal corrosion or an epi layer of a semiconductor wafer, and is installed such that the reflected wave is guided to the terahertz wave receiving antenna 8.

  When measuring the reflected wave of the measuring object 100, the measuring object 100 needs to be installed in the same place as the aluminum mirror measured as a reference in advance. That is, the state detection unit in the inspection apparatus of the present embodiment detects whether or not the position and the inclination of the measurement object 100 installed so as to reflect the terahertz wave in the terahertz waveguide are in a predetermined state ( State detection step).

  In order to install the measuring object 100 at the same angle and the same position as the aluminum mirror, the inspection apparatus of this embodiment includes a state detection unit (laser light source 11, lens 10, knife edge 9, and light receiving unit 12). It can be confirmed that the measurement object 100 is installed at the same place as the aluminum mirror for measuring the reference terahertz waveform.

  The laser light source 11 may be newly installed, or the laser light of the laser 1 may be branched and used. When an aluminum mirror is installed as a reference, the third laser beam obtained by branching the laser beam from the laser light source 11 or the laser 1 is applied to the aluminum mirror. The lens 10 is installed so that the third laser light reflected by the aluminum mirror passes. The lens 10 is installed between the laser light source 11 and the measurement object 100 or between the measurement object 100 and the knife edge 9. The light receiving unit 12 is installed so as to receive laser light.

  The knife edge 9 is installed on a stage that can finely adjust the X, Y, and Z axes. By moving the position of the knife edge 9 and measuring the laser intensity with the light receiving unit 12, the state detection unit of the inspection apparatus of the present embodiment measures the position and diameter of the third laser light that has passed through the lens 10. Can do. FIG. 4 is a diagram illustrating the laser intensity of the third laser light measured by the light receiving unit 12 in the inspection apparatus using the terahertz wave of the present embodiment. The horizontal axis indicates the position of the knife edge 9, and the vertical axis indicates the laser intensity. The peak width indicates the laser width, and the peak position indicates the laser position.

  When measuring the measurement object 100, the user repeatedly performs measurement until the peak intensity can be measured at a measurement point of the measurement object 100 at the same peak position as when the aluminum mirror is installed, The measuring object 100 is moved to the same place as the aluminum mirror.

  For example, since the diameter of the third laser light that has passed through the lens 10 changes according to the distance between the aluminum mirror (or the measurement object 100) and the lens 10, the user can adjust the diameter by adjusting the diameter. The distance between the aluminum mirror up to 10 and the measuring object 100 can be made uniform. Further, when the measurement object 100 and the aluminum mirror have different angles, the position of the reflected third laser light is also different. Therefore, the user can adjust the position of the third laser light so that the aluminum mirror is aligned. And the measurement object 100 can be aligned at the same angle.

  That is, since the state detection unit in the inspection apparatus of the present embodiment measures the position and diameter of the laser beam by moving the knife edge 9, the measurement object 100 is installed at the place where the aluminum mirror is installed. It is possible to confirm that the measuring object 100 is installed at the same position as the aluminum mirror by operating.

  Next, actual inspection will be described. The laser 1 emits laser light. The beam splitter 2 splits the laser light emitted from the laser 1 into a first laser light and a second laser light (light splitting step). Here, the first laser light is laser light on the emitter side toward the terahertz wave oscillation antenna 5. The second laser light is laser light on the detector side that faces the terahertz wave receiving antenna 8.

  The laser light (first laser light) on the emitter side is collected by the lens 4 a and applied to the terahertz wave oscillation antenna 5. The terahertz wave oscillation antenna 5 irradiated with the first laser beam oscillates a terahertz wave when a voltage is applied by the signal generator 50 (terahertz wave oscillation step).

  The oscillated terahertz wave is reflected by the parabolic mirror 6 and applied to the terahertz wave receiving antenna 8. On the other hand, the laser beam (second laser beam) on the detector side is applied to the terahertz wave receiving antenna 8 as in the emitter side.

  At this time, the optical components are installed so that the optical distance from the beam splitter 2 through the terahertz wave oscillation antenna 5 to the terahertz wave receiving antenna 8 matches the distance from the beam splitter 2 to the terahertz wave receiving antenna 8.

  The terahertz wave oscillated from the terahertz wave oscillation antenna 5 is a pulse, and the pulse width is several picoseconds. Therefore, one pulse cannot be received at a time. Therefore, the inspection apparatus of this embodiment causes the terahertz wave oscillating antenna 5 to transmit the terahertz wave repeatedly, changes the optical distance of the time delay mechanism 7 to generate a time delay, and sets each point of the terahertz wave to one point. Terahertz waves are measured by measuring them one by one.

  That is, the time delay mechanism 7 gives a time delay to the second laser light emitted from the beam splitter 2 and incident through the mirror 3b (time delay step).

  The terahertz wave receiving antenna 8 detects the terahertz wave oscillated by the terahertz wave oscillating antenna 5 at the detection timing based on the second laser beam given the time delay by the time delay mechanism 7, and sets the intensity of the detected terahertz wave. A corresponding detection signal is generated (terahertz wave detection step).

  Specifically, electrons are excited by irradiating the gap of the terahertz wave receiving antenna 8 with the second laser light, and a minute current flows through the electrode 20 by irradiating the terahertz waves there. The lock-in amplifier 51 synchronizes with the signal generator 50 and detects and amplifies this minute current as a detection signal.

  In addition, in order to measure the terahertz waveform for reference, the user performs measurement when an aluminum mirror is installed as a reference instead of the measurement object 100 in advance. FIG. 5 is a time waveform diagram of a terahertz wave when an aluminum mirror is installed as a reference in the inspection apparatus using the terahertz wave of the present embodiment.

  Next, the inspection apparatus using the terahertz wave according to the present embodiment calculates the peak intensity of the detection signal by the lock-in amplifier 51 and compares it with the peak intensity of the reference held in advance. Specifically, the inspection unit (the data holding unit 52 and the data processing unit 54) is configured so that the position and the inclination of the measurement object 100 detected by the state detection unit are in a predetermined state (here, an aluminum mirror measured as a reference). Measurement object based on the peak value of the time-series signal intensity data based on the detection signal generated by the terahertz wave receiving antenna 8 when the time delay given by the time delay mechanism 7 is changed. The object 100 is inspected for defects (bubbles) (inspection step).

  For example, the data processing unit 54 compares the peak value of the time-series signal intensity data when the pre-held aluminum mirror is installed with the peak value of the time-series signal intensity data when the measurement object 100 is installed. If the peak value when the measurement object 100 is installed is smaller than the peak value in the case of the aluminum mirror with a predetermined difference or more, it is determined that bubbles are present in the laminate of the measurement object 100. .

  Finally, the display device 53 displays on the display or the like whether or not there is a defect in the measurement object 100 that is found by inspection by the inspection unit (the data holding unit 52 and the data processing unit 54).

  As described above, according to the inspection apparatus and the inspection method using the terahertz wave according to the form of the first embodiment of the present invention, the coating film or the semiconductor wafer for preventing the corrosion of the metal by using the reflected wave of the terahertz wave. When inspecting a defect (bubble) in a laminate such as an epi layer, the measurement object 100 can be easily aligned.

  That is, when the inspection is performed using the reflected wave of the terahertz wave, the position and the angle of the reflecting surface of the aluminum mirror as the reference and the measurement object 100 must be the same. There is a problem that alignment is difficult. If the positions of the reflecting surfaces do not match, the diameter of the terahertz wave to the measurement object is different, and the intensity of the terahertz wave changes every time measurement is performed, making it difficult to determine the presence or absence of bubbles. Further, if the angles of the reflecting surfaces do not match, the intensity of the terahertz wave that reaches the terahertz wave receiving antenna is different, and the intensity of the terahertz wave changes every measurement, making it difficult to determine the presence or absence of bubbles.

  However, the inspection apparatus and inspection method of the present embodiment includes the state detection unit (the laser light source 11, the lens 10, the knife edge 9, and the light receiving unit 12), so that the position and angle of the measurement object 100 are predetermined. Since it can be detected whether or not it is in a state, the measurement object 100 can be easily aligned and the presence or absence of bubbles can be accurately determined.

  Next, the configuration of the inspection apparatus using the terahertz wave according to the second embodiment of the present invention will be described. FIG. 6 is a diagram illustrating a configuration of an inspection apparatus using a terahertz wave according to the second embodiment of the present invention. The difference from the inspection apparatus of the first embodiment shown in FIG. 1 is that the knife edge 9, the lens 10, the laser light source 11, and the light receiving unit 12 are not provided, but a control device 55 is provided instead.

  The control device 55 can control the amount of time delay by moving the mirror inside the time delay mechanism 7 and adjust the position by controlling the X and θ axes of the stage on which the measurement object 100 is installed. can do.

  The control device 55 and the data processing unit 54 in this embodiment correspond to the state detection unit of the present invention, and reflect the terahertz wave in the terahertz waveguide between the terahertz wave oscillation antenna 5 and the terahertz wave reception antenna 8. It is detected whether or not the position and inclination of the measuring object 100 installed in is in a predetermined state.

  That is, the control device 55 in the state detection unit of the present embodiment controls the stage on which the measurement object 100 is installed to change the position and inclination of the measurement object 100 and also controls the time delay mechanism 7. Change the time delay. The data processing unit 54 in the state detection unit of the present embodiment has the position and the inclination of the measurement object 100 in a predetermined state based on time-series signal intensity data based on the detection signal generated by the terahertz wave receiving antenna 8. Whether or not is detected.

  Other configurations are the same as those of the first embodiment, and redundant description is omitted.

  Next, the operation of the present embodiment configured as described above will be described. First, in order to measure the reference, the user performs measurement by installing an aluminum mirror, and obtains time-series signal intensity data as shown in FIG. The data holding unit 52 stores the peak position of the acquired reference time-series signal intensity data.

  Next, the user installs the measurement object 100. The control device 55 adjusts the position by controlling the X axis of the stage on which the measurement object 100 is installed. Specifically, the control device 55 controls the amount of time delay by shifting the measurement object 100 little by little in the X direction and moving the mirror inside the time delay mechanism 7 each time the measurement object 100 is shifted. Thereby, the data holding unit 52 can obtain time-series signal intensity data as shown in FIG. 5 for the measurement object 100 for each point in the X direction. The data processing unit 54 compares the peak position of the reference time-series signal intensity data with the peak position of the time-series signal intensity data of the measurement object 100, and when the measurement object 100 is located at any point in the X direction. Detect whether the peak positions match.

  The control device 55 adjusts the position in the X direction of the stage on which the measurement target 100 is installed so that the peak position of the reference matches the peak position of the measurement target 100.

  Thereafter, the control device 55 adjusts the position by controlling the θ axis of the stage on which the measurement object 100 is installed. Regarding the adjustment of the θ axis, the control device 55 controls the amount of time delay by shifting the measuring object 100 little by little in the θ direction and moving the mirror inside the time delay mechanism 7 each time the object is shifted. Thereby, the data holding unit 52 can obtain time-series signal intensity data as shown in FIG. 5 for the measurement object 100 for each point in the θ direction.

  The data processing unit 54 detects at which angle in the θ direction the peak intensity of the time-series signal intensity data of the measurement object 100 is the strongest when the measurement object 100 is located. The control device 55 adjusts the position (angle) in the θ direction of the stage on which the measurement object 100 is installed so that the peak intensity of the measurement object 100 is the strongest.

  In this manner, the control device 55 performs adjustment in the X direction so that the peak position of the reference and the peak position of the measurement object 100 coincide with each other, and further the θ direction so that the peak intensity of the measurement object 100 becomes the strongest. Make adjustments.

  The inspection unit (the data holding unit 52 and the data processing unit 54) changes the time delay given by the time delay mechanism 7 because the position and inclination of the measurement object 100 detected by the state detection unit are in a predetermined state. In this case, the presence or absence of a defect (bubble) in the measurement object 100 is inspected based on the peak value of the time series signal intensity data based on the detection signal generated by the terahertz wave receiving antenna 8.

  Other operations are the same as those in the first embodiment, and redundant description is omitted.

  As described above, according to the inspection apparatus according to the second embodiment of the present invention, even if the control device 55 is used as the state detection unit instead of the knife edge 9, the lens 10, the laser light source 11, and the light receiving unit 12. The effect similar to Example 1 can be acquired.

  As a modification, the inspection apparatus of Example 1 or Example 2 can also provide the matching layer 101 on the surface of the measurement object 100. FIG. 7 is a diagram showing a configuration when the matching layer 101 is provided in the inspection apparatus using the terahertz wave according to the first or second embodiment of the present invention.

  The matching layer 101 is provided on the surface of the measurement object 100 on the side that reflects the terahertz wave, has a refractive index of 1 / √2 of the measurement object 100, and has a thickness of 1 of the wavelength λ of the terahertz wave. / 4 (= λ / 4).

  Compared with the case where it enters the measurement object 100 from the air, the intensity of the terahertz wave incident on the measurement object 100 can be improved by installing the matching layer 101, and the intensity of the reflected wave is also improved. For example, if the measurement object 100 is polycarbonate, the matching layer 101 is made of a material having a refractive index of 1.12. If the wavelength is 600 μm, the thickness of the matching layer 101 is 150 μm.

  As described above, the inspection apparatus including the matching layer 101 uses the reflected wave of the terahertz wave to inspect defects (bubbles) in a laminate such as a coating film or an epitaxial layer of a semiconductor wafer to prevent metal corrosion. When performed, the intensity of the reflected wave can be improved.

  FIG. 8 is a diagram illustrating a configuration of an inspection apparatus using a terahertz wave according to the third embodiment of the present invention. However, although not shown in the drawing, the inspection apparatus of the present embodiment includes a state detection unit as in the first and second embodiments. Therefore, the inspection apparatus shown in FIG. 8 is a state detection unit (knife edge 9, lens 10, laser light source 11, and light receiving unit 12) similar to FIG. 1, or a state detection unit (control device 55) similar to FIG. ). The difference from the configuration of the inspection apparatuses of Examples 1 and 2 is that a matching layer 101 is provided.

  Unlike the matching layer 101 described with reference to FIG. 7, the matching layer 101 shown in the present embodiment is provided so as to fill the terahertz waveguide between the terahertz wave oscillation antenna 5 and the terahertz wave receiving antenna 8, and the measurement object 100 or more. And a refractive index equal to or lower than that of ultra-high resistance silicon used for the terahertz wave oscillation antenna 5 and the terahertz wave receiving antenna 8. FIG. 9 is a diagram showing a detailed configuration in the vicinity of the matching layer 101 in the inspection apparatus using the terahertz wave according to the present embodiment.

  Other configurations are the same as those of the first and second embodiments, and a duplicate description is omitted.

  Next, the operation of the present embodiment configured as described above will be described. Basically, it is the same as the operation of the inspection apparatus of the first and second embodiments. The terahertz wave oscillated from the terahertz wave oscillating antenna 5 passes through the matching layer 101 and is irradiated onto the measurement object 100, and the reflected terahertz wave passes through the matching layer 101 and reaches the terahertz wave receiving antenna 8.

  Other operations are the same as those in the second embodiment, and redundant description is omitted.

  As described above, according to the inspection apparatus according to the third embodiment of the present invention, not only the same effects as those of the first and second embodiments can be obtained, but also the terahertz wave can be obtained because the matching layer 101 is provided. The intensity of the reflected wave can be improved. In particular, since the inspection apparatus of the present embodiment includes the matching layer 101 provided so as to fill the terahertz waveguide, it is not necessary to irradiate the terahertz wave in the air. In addition, the intensity of the terahertz wave can be further improved.

  As a modified example, the matching layer 101 may include a terahertz wave lens 13 provided so that the terahertz wave is focused on the measurement object 100. FIG. 10 is a diagram illustrating another configuration example of the inspection apparatus using the terahertz wave according to the present embodiment, and the terahertz wave lens 13 is provided in the matching layer 101. FIG. 11 is a diagram showing a detailed configuration near the matching layer 101 in the inspection apparatus shown in FIG.

  In the case of the configuration having the matching layer 101 as in the third embodiment, the distances between the terahertz wave oscillation antenna 5 and the terahertz wave receiving antenna 8 and the measurement object 100 are inevitably reduced, and the matching layer is further reduced. There is also a concern that the terahertz wave spreads in the region 101. In view of this, this inspection apparatus is provided with a terahertz wave lens 13 as shown in FIGS. 10 and 11, and by focusing the terahertz wave to the object 100 to be measured, it is possible to more accurately determine the presence or absence of bubbles. it can.

  FIG. 12 is a diagram illustrating another configuration example of the inspection apparatus using the terahertz wave according to the present embodiment. The inspection apparatus that transmits the terahertz wave instead of reflecting the measurement object 100 is described above. The case where the matching layer 101 is applied is shown. Since the inspection apparatus in this case does not reflect the terahertz wave, a state detection unit for adjusting the position of the measurement object 100 is not necessary, but the intensity of the terahertz wave is provided by including the matching layer 101. Can be improved.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Laser 2 Beam splitter 3a, 3b, 3c, 3d Mirror 4a, 4b Lens 5 Terahertz wave oscillation antenna 6 Parabolic mirror 7 Time delay mechanism 8 Terahertz wave receiving antenna 9 Knife edge 10 Lens 11 Laser light source 12 Light receiving part 13 Terahertz wave Lens 20 Electrode 22 Low-temperature grown gallium arsenide substrate 23 Laser beam 25 Silicon lens 50 Signal generator 51 Lock-in amplifier 52 Data holding unit 53 Display device 54 Data processing unit 55 Controller 100 Measuring object 101 Matching layer

Claims (7)

A light splitting section for splitting the laser light into a first laser light and a second laser light;
A terahertz wave oscillating unit that oscillates a terahertz wave by being irradiated with the first laser light emitted by the light splitting unit;
A time delay unit that gives a time delay to the second laser light emitted by the light splitting unit;
A terahertz wave oscillated by the terahertz wave oscillating unit is detected at a detection timing based on the second laser beam given a time delay by the time delay unit, and a detection signal corresponding to the intensity of the detected terahertz wave is generated. A terahertz wave detection unit;
Detects whether or not the position and the inclination of the measurement object installed so as to reflect the terahertz wave in the terahertz waveguide between the terahertz wave oscillating unit and the terahertz wave detecting unit are in a predetermined state. A state detector;
A detection signal generated by the terahertz wave detection unit when the position and inclination of the measurement object detected by the state detection unit are in a predetermined state and the time delay given by the time delay unit is changed An inspection unit that inspects the presence or absence of a defect of the measurement object based on a peak value of time-series signal intensity data based on
An inspection apparatus using terahertz waves, comprising: The state detection unit
A laser light source for irradiating the measurement object with a third laser beam;
A lens that collects the third laser light irradiated by the laser light source and reflected by the measurement object;
A light receiving unit for detecting the intensity of the third laser beam condensed by the lens;
A knife edge that is provided between the lens and the light-receiving unit, and can shield the third laser beam condensed by the lens by adjusting the position;
The inspection apparatus using a terahertz wave according to claim 1.   The state detection unit controls the stage on which the measurement object is installed to change the position and inclination of the measurement object, and also controls the time delay unit to change the time delay, so that the terahertz wave The terahertz according to claim 1, wherein it is detected whether or not the position and inclination of the measurement object are in a predetermined state based on time-series signal intensity data based on a detection signal generated by a detection unit. Inspection equipment using waves.   A matching layer provided on a surface of the measurement object that reflects terahertz waves and having a refractive index of 1 / √2 of the measurement object and a thickness of ¼ of the wavelength λ of the terahertz waves; The inspection apparatus using the terahertz wave according to any one of claims 1 to 3.   Provided to fill a terahertz waveguide between the terahertz wave oscillating unit and the terahertz wave detecting unit, and having a refractive index higher than that of the measurement object, and the terahertz wave oscillating unit and the terahertz wave detecting unit The inspection apparatus using a terahertz wave according to any one of claims 1 to 3, further comprising a matching layer having a refractive index equal to or lower than that of the ultrahigh resistance silicon used.   6. The inspection apparatus using terahertz waves according to claim 5, further comprising a lens provided in the matching layer so that the terahertz wave is focused on the measurement object. A light splitting step for splitting the laser light into a first laser light and a second laser light;
A terahertz wave oscillating step of oscillating a terahertz wave by being irradiated with the first laser light emitted by the light splitting step;
A time delay step of giving a time delay to the second laser light emitted by the light splitting step;
The terahertz wave oscillated by the terahertz wave oscillating step is detected at the detection timing based on the second laser beam given the time delay by the time delay step, and a detection signal corresponding to the intensity of the detected terahertz wave is generated. Terahertz wave detection step;
A state detecting step for detecting whether or not the position and inclination of the measurement object installed to reflect the terahertz wave in the terahertz waveguide are in a predetermined state;
The detection signal generated by the terahertz wave detection step when the position and inclination of the measurement object detected by the state detection step are in a predetermined state and the time delay given by the time delay step is changed An inspection step for inspecting the measurement object for defects based on the peak value of the time-series signal intensity data based on
An inspection method using terahertz waves, comprising:

Images