Semiconductor inspection apparatus and semiconductor inspection method

Abstract

The semiconductor inspection apparatus (1A) includes: an inspection optical system (11) that irradiates a semiconductor device (D) with a probe light and outputs reflected light; an optical measurement unit (20) that detects the reflected light and outputs an electrical signal showing the time waveform of its intensity changing over time; a signal conversion unit (30) that modulates the intensity of the measurement light based on the electrical signal and outputs an optical signal corresponding to the electrical signal; a waveform measurement unit (40) that measures the time waveform of the optical signal; and a waveform analysis unit (52) that calculates the time waveform of the electrical signal based on the measurement result of the optical signal. The waveform measurement unit (40) has: a stripe tube including a photoelectric surface, a scanning electrode, and a fluorescent surface that includes an input optical signal; and an imaging element that captures a fluorescent image generated on the fluorescent surface and outputs a waveform image; the waveform analysis unit (52) calculates the time waveform of the electrical signal based on the waveform image. Thus, a semiconductor inspection apparatus and inspection method capable of high-speed measurement of the time change of the intensity of reflected light when a probe light is irradiated onto a semiconductor device are realized.

Description

Technical Field

[0001] This disclosure relates to a semiconductor inspection apparatus and a semiconductor inspection method for inspecting semiconductor devices. Background Technology

[0002] As methods for checking the operating state of semiconductor devices, there are known methods such as EOP (Electro-Optical Probing), EOFM (Electro-Optical Frequency Mapping), LVP (Laser Voltage Probing), LVI (Laser Voltage Imaging) (for example, see Patent Documents 1 and 2).

[0003] In EOP (Electronic Operating Procedure), a semiconductor device whose state changes over time by applying a voltage pattern of a predetermined period is illuminated from the back with a probe light of a predetermined wavelength. The operating state of the semiconductor device is checked by measuring the change in the intensity of the reflected light over time. In EOFM (Electronic Operating Frequency), a spectrum analyzer is used to perform frequency analysis on the reflected light from the semiconductor device, and the parts operating at a predetermined frequency are imaged.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2022 / 064798

[0007] Patent Document 2: International Publication No. 2007 / 136681

[0008] Patent Document 3: European Patent Application Publication No. 0197196

[0009] Patent Document 4: European Patent Application Publication No. 0344986 Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] In the aforementioned semiconductor inspection methods such as EOP and EOFM, the upper limit of measurable frequency when using an oscilloscope or digitizer to measure the electrical signal output from the photodetector that detects reflected light is approximately 7-8 GHz. On the other hand, with the continuous improvement of LSI performance, it is sometimes necessary to measure jitter on the order of 10 ps when inspecting such semiconductor devices. However, in conventional inspection equipment, it is difficult to measure such high-speed temporal changes in reflected light intensity with sufficient accuracy.

[0012] Furthermore, in the aforementioned inspection methods, the intensity variation over time in the reflected light from the semiconductor device caused by the application of a voltage pattern is sometimes weak. In such cases, to measure the weak intensity variation of the reflected light with a sufficient signal-to-noise ratio, it is advisable to accumulate the electrical signal output from the photodetector multiple times. However, in conventional inspection apparatuses, it is difficult to accumulate the electrical signal at high speed.

[0013] The purpose of this implementation is to provide a semiconductor inspection apparatus and method capable of high-speed measurement of the time-varying intensity of reflected light when a probe light is irradiated onto a semiconductor device to be inspected.

[0014] Means for solving technical problems

[0015] The embodiment is a semiconductor inspection apparatus. The semiconductor inspection apparatus includes: (1) an inspection optical system that illuminates a first wavelength of probe light onto a semiconductor device whose state changes over time according to a predetermined test cycle, and outputs reflected light that has been reflected from the probe light in the semiconductor device; (2) an optical measurement unit that has a photodetector that detects the reflected light output from the inspection optical system, and outputs an electrical signal having a time waveform corresponding to the time change of the intensity of the reflected light; (3) a signal conversion unit that has a measurement light source that provides a second wavelength of measurement light different from the first wavelength, and an optical modulator that modulates the intensity of the measurement light based on the electrical signal output from the optical measurement unit, and outputs the measurement light modulated by the optical modulator as an optical signal having a time waveform corresponding to the time waveform of the electrical signal; (4) a waveform measurement unit that measures the intensity of the measured light from the second wavelength of the semiconductor device. The time waveform of the optical signal output by the signal conversion unit is measured; and (5) the waveform analysis unit determines the time waveform of the electrical signal based on the measurement result of the time waveform of the optical signal by the waveform measurement unit; (6) the waveform measurement unit includes a stripe tube and an imaging element, the stripe tube includes: a photoelectric surface that generates electrons according to the input of the optical signal; a scanning electrode that scans the electrons from the photoelectric surface along a predetermined scanning direction at a scanning period set according to the test period; and a fluorescent surface that receives the electrons scanned by the scanning electrode and generates a fluorescent image representing the time waveform of the optical signal; the imaging element captures the fluorescent image generated on the fluorescent surface of the stripe tube and outputs a waveform image; (7) the waveform analysis unit determines the time waveform of the electrical signal based on the waveform image output from the imaging element.

[0016] The implementation method is a semiconductor inspection method. The semiconductor inspection method includes: (1) an inspection step, irradiating a semiconductor device with a state that changes over time according to a predetermined test cycle with a probe light of a first wavelength, and outputting reflected light that has reflected the probe light in the semiconductor device; (2) an optical measurement step, using a photodetector that detects the reflected light output in the inspection step, outputting an electrical signal having a time waveform corresponding to the time change of the intensity of the reflected light; (3) a signal conversion step, using an optical modulator that modulates the intensity of a measurement light of a second wavelength different from the first wavelength based on the electrical signal output in the optical measurement step, outputting the measurement light modulated by the optical modulator as an optical signal having a time waveform corresponding to the time waveform of the electrical signal; (4) a waveform measurement step, measuring the light output in the signal conversion step... The time waveform of the signal is measured; and (5) a waveform analysis step, based on the measurement result of the time waveform of the optical signal in the waveform measurement step, the time waveform of the electrical signal is obtained; and (6) a waveform measurement step, using a stripe tube including a photoelectric surface, a scanning electrode and a fluorescent surface, to photograph the fluorescent image generated on the fluorescent surface of the stripe tube and output a waveform image, wherein the photoelectric surface generates electrons according to the input of the optical signal, the scanning electrode scans the electrons from the photoelectric surface along a predetermined scanning direction at a scanning period set according to the test period, and the fluorescent surface inputs the electrons scanned by the scanning electrode and generates a fluorescent image showing the time waveform of the optical signal; (7) a waveform analysis step, based on the waveform image output in the waveform measurement step, the time waveform of the electrical signal is obtained.

[0017] Another implementation is a semiconductor inspection device. The semiconductor inspection apparatus includes: (1) an inspection optical system that irradiates a semiconductor device with a first wavelength of probe light onto the semiconductor device whose state changes over time according to a predetermined test cycle, and outputs reflected light that has been reflected by the probe light in the semiconductor device; (2) an optical measurement unit that has a photodetector that detects the reflected light output from the inspection optical system and outputs an electrical signal having a time waveform corresponding to the time change of the intensity of the reflected light; (3) a signal conversion unit that has a measurement light source that supplies a measurement light of a second wavelength different from the first wavelength, and an optical modulator that modulates the intensity of the measurement light based on the electrical signal output from the optical measurement unit, and outputs the measurement light modulated by the optical modulator as an optical signal having a time waveform corresponding to the time waveform of the electrical signal; (4) a waveform measurement unit that has a stripe camera that measures the time waveform of the optical signal output from the signal conversion unit; (5) a waveform analysis unit that calculates the time waveform of the electrical signal based on the measurement result of the time waveform of the optical signal by the waveform measurement unit; (6) the stripe camera that outputs a waveform image showing the time waveform of the optical signal based on the input of the optical signal; and (7) the waveform analysis unit that calculates the time waveform of the electrical signal based on the waveform image output from the stripe camera.

[0018] In the aforementioned semiconductor inspection apparatus and method, a probe light of a first wavelength is irradiated onto the semiconductor device to be inspected, and its reflected light is detected using a photodetector, thereby generating an electrical signal with a time waveform corresponding to the time change of the intensity of the reflected light. Then, the electrical signal is converted into an optical signal of a second wavelength by an optical modulator, and a waveform measurement unit comprising a stripe tube and constituting a stripe camera is used to measure the time waveform of the optical signal, and the time waveform of the electrical signal is determined based on the obtained waveform image.

[0019] With this configuration, by converting an electrical signal into an optical signal and then using a stripe tube for waveform measurement, it is possible to measure the time waveform of the electrical signal corresponding to the time change in the intensity of reflected light from a semiconductor device at high speed. Furthermore, in this configuration, by appropriately setting the first wavelength of the probe light and the second wavelength of the measurement light, which is different from the first wavelength, it is possible to effectively balance the inspection of the semiconductor device using the probe light with the waveform measurement of the optical signal using the stripe tube, which modulates the intensity of the measurement light with an electrical signal, thereby enabling high-precision measurement of the time change in the intensity of reflected light.

[0020] Invention Effects

[0021] The semiconductor inspection apparatus and semiconductor inspection method according to the embodiments can measure the time change of the intensity of reflected light when a semiconductor device to be inspected is irradiated with a probe light of a predetermined wavelength at high speed. Attached Figure Description

[0022] Figure 1 This is a block diagram that schematically illustrates the configuration of one embodiment of a semiconductor inspection apparatus.

[0023] Figure 2 This is a block diagram showing an example of the specific configuration of the voltage application section, the inspection optical system, and the optical measurement section.

[0024] Figure 3 This is a block diagram that schematically illustrates the configuration of a first embodiment of an electrical signal measuring device including a signal conversion unit and a waveform measurement unit.

[0025] Figure 4 This is a diagram showing an example of the configuration of an optical modulator in a signal conversion section.

[0026] Figure 5 This is a diagram showing an example of the structure of the stripe tube in the waveform measurement section.

[0027] Figure 6 This is a side view showing an example of the configuration of the waveform measurement unit.

[0028] Figure 7 The diagram shows an example of the configuration of the input optical system in the waveform measurement unit, as shown in (a) the top view and (b) the side view.

[0029] Figure 8 (a) shows a diagram of the light signal incident on the photoelectric surface of the stripe tube, and Figure 8 (b) shows a scan of the electron image on the fluorescent surface.

[0030] Figure 9 This is an example diagram showing the optical image of an input light signal corresponding to the photoelectric surface of a striped tube, and the fluorescent image generated on the fluorescent surface.

[0031] Figure 10 (a) shows a waveform image obtained when the optical signal generation in the signal conversion unit is in the ON state, and Figure 10 (b) is an example of a substrate image obtained with the optical signal generation in the OFF state.

[0032] Figure 11 It concerns the measurement results of electrical signals on an oscilloscope, and... Figure 3 The graph shows the measurement results from the electrical signal measuring device.

[0033] Figure 12 The diagram shows the relationship between (a) the intensity of reflected light, (b) the intensity of the electrical signal, and (c) the intensity of the optical signal.

[0034] Figure 13 These are (a) top view and (b) side view of a first modified example showing the configuration of the input optical system of the waveform measurement unit.

[0035] Figure 14 These are (a) top view and (b) side view of a second modified example showing the configuration of the input optical system of the waveform measurement unit.

[0036] Figure 15 These are (a) top view and (b) side view of a third modified example showing the configuration of the input optical system of the waveform measurement unit.

[0037] Figure 16 This is a diagram showing the configuration of a second embodiment of the electrical signal measuring device.

[0038] Figure 17 This is a schematic diagram illustrating the main scan and retrace (return scan) in a stripe tube.

[0039] Figure 18 This diagram illustrates an example of the setting of the measurement period and the phase of the scan cycle in a striped tube.

[0040] Figure 19 This is a diagram showing the configuration of a third embodiment of the electrical signal measuring device.

[0041] Figure 20 It's about in Figure 19 The diagram shown illustrates the input of two optical signals to the photoelectric surface in the configuration shown.

[0042] Figure 21 This is a diagram showing the configuration of a fourth embodiment of the electrical signal measuring device. Detailed Implementation

[0043] The embodiments of the semiconductor inspection apparatus and semiconductor inspection method will now be described in detail with reference to the accompanying drawings. Furthermore, in the description of the drawings, the same symbols are used to denote the same elements, and repeated descriptions are omitted. Also, the dimensions and scale of the drawings may not necessarily be consistent with the description.

[0044] Figure 1 This is a block diagram schematically illustrating the configuration of one embodiment of the semiconductor inspection apparatus. The semiconductor inspection apparatus 1A according to this embodiment is a device for inspecting a semiconductor device D by irradiating it with probe light. Its configuration includes a semiconductor inspection unit 10, a light measurement unit 20, a probe light source 21, an electrical signal measurement device 2A, a control device 50, an input unit 53, a display unit 54, and a scan control unit 55. Furthermore, the semiconductor inspection apparatus 1A also includes a second light measurement unit 61, a second waveform measurement unit 62, and a frequency analysis unit 63.

[0045] Furthermore, in the following figures, the double lines between the various parts of the device represent the transmission paths of light such as probe light, reflected light, measurement light, and optical signals. Single-mode optical fibers or similar optical fibers are preferably used as such transmission paths. Alternatively, spatial transmission paths utilizing lenses or mirrors may be used, depending on the transmission conditions. Additionally, the single lines and arrows between the various parts of the device represent the transmission paths of electrical signals, synchronization signals, trigger signals, control signals, etc., or the optical paths of probe light and reflected light pointing towards the semiconductor device D.

[0046] become Figure 1 The semiconductor device D of the semiconductor inspection apparatus 1A shown can be any semiconductor device. Specifically, examples include integrated circuits (ICs) with PN junctions such as transistors, or logic devices, memory devices, and analog devices of large-scale integrated circuits (LSIs).

[0047] Furthermore, the semiconductor device D can also be a mixed-signal device composed of combinations of the above-mentioned devices, or a power semiconductor device (power device) such as a MOS transistor, bipolar transistor, or IGBT used for high current / high voltage. The inspection of the semiconductor device D performed by the semiconductor inspection apparatus 1A is conducted using methods such as EOP and EOFM, including verifying the operating status of each part of the device and identifying the location of the fault. Furthermore, the various parts of the semiconductor device D that are subject to inspection can include, for example, transistors, diodes, capacitors, and wiring that are subject to applied voltage.

[0048] The semiconductor inspection unit 10 is configured to include an inspection optical system 11 and a voltage application unit 12. The inspection optical system 11 irradiates the semiconductor device D, which is to be inspected, with a first wavelength of probe light supplied from the probe light source 21 via the light measurement unit 20. In addition, the inspection optical system 11 outputs the reflected light, which has reflected the probe light at the semiconductor device D, to the light measurement unit 20.

[0049] Illuminating a semiconductor device D with probe light is typically done from the back side of the device, such as the Si substrate side. Therefore, light with a wavelength that can transmit through silicon is used as the probe light. In this case, the first wavelength of the probe light is preferably set in the wavelength range of 1050 nm to 5000 nm. Specifically, light with a wavelength of 1.3 μm can be used as such a probe light, for example.

[0050] The detection light supplied from the detection light source 21 can be either coherent or incoherent. Specifically, the detection light source 21 can be, for example, a laser light source, an SLD (Super Luminescent Diode), an ASE (Amplified Spontaneous Emission) light source, or an LED (Light Emitting Diode).

[0051] The voltage application unit 12 applies a test pattern that repeats over time at a predetermined test cycle to the semiconductor device D. During this time, the state of each part of the semiconductor device D, to which the test pattern is applied, changes over time with the voltage change test cycle. The optical measurement unit 20 supplies probe light output from the probe light source 21 to the inspection optical system 11, and simultaneously inputs reflected light from the semiconductor device D output from the inspection optical system 11. The intensity of the reflected light from the semiconductor device D changes over time with the test cycle according to the time-varying state of the semiconductor device D.

[0052] Figure 2This is a block diagram illustrating an example of the specific configuration of the voltage application unit 12, the inspection optical system 11, and the optical measurement unit 20. In this configuration example, the voltage application unit 12 is configured as a test head 12a and a test plate 12b having a semiconductor tester (LSI tester). The test head 12a mounts a semiconductor device D via the test plate 12b and repeatedly applies a test pattern containing a predetermined operating pulse signal for driving the semiconductor device D to the semiconductor device D. This application is performed in the aforementioned test cycle.

[0053] The test head 12a includes, for example, a pulse generator that generates operating pulse signals for driving transistors contained in the semiconductor device D, a test section that inputs operating pulse signals to the semiconductor device D, and a power supply. Furthermore, the test board 12b is a semiconductor substrate on which the semiconductor device D is mounted. The test board 12b includes peripheral chips, circuits, and terminals required for the operation of the semiconductor device D.

[0054] The inspection optical system 11 is configured to include a stage 14, a scanning optical system 15, an imaging optical system 16, and an objective lens 17. The scanning optical system 15, the imaging optical system 16, and the objective lens 17 are arranged within the dark box 13, placed on the stage 14. The objective lens 17 is positioned between the imaging optical system 16 and the semiconductor device D. In this configuration example, multiple objective lenses are provided as the objective lens 17, and they can be switched via a turret 18. For example, the multiple objective lenses 17 may include a low-magnification (e.g., 5x) objective lens and a high-magnification (e.g., 50x) objective lens.

[0055] The scanning optical system 15 guides the probe light from the probe light source 21, via the light measurement unit 20 and the optical fiber, to the imaging optical system 16. To reduce light reflection, the output end of the probe light in the optical fiber is preferably of type APC (Automatic Power Control). The scanning optical system 15 is configured as a light scanner including light scanning elements such as a Galvano-mirror and a MEMS mirror, and scans and sets the probe light illumination position of the semiconductor device D under the control of the scanning control unit 55.

[0056] The imaging optics system 16 guides the probe light from the scanning optics system 15 to the objective lens 17 via a predetermined optical path. The objective lens 17 converges the probe light onto a predetermined illumination position in the semiconductor device D. Additionally, the reflected light (return light) generated by illuminating the semiconductor device D with the probe light is input to the optical measurement unit 20 via the objective lens 17, the imaging optics system 16, the scanning optics system 15, and the optical fiber. The wavelength of this reflected light is the same as that of the probe light, which is a first wavelength. Furthermore, an impregnation lens may be provided between the objective lens 17 and the semiconductor device D as needed.

[0057] In the reflected light from semiconductor device D, the reflectivity and absorptivity of the probe light undergo subtle changes (approximately tens of ppm / V) due to the electric field, heat generated at the measurement point where the probe light is irradiated, and the resulting changes in carrier density. This leads to a slight time-varying change in the intensity of the reflected light. By measuring this time-varying change in the intensity of the reflected light, semiconductor device D can be inspected.

[0058] The optical measurement unit 20 comprises an optical coupler 22, an optical amplifier 23, an optical splitter 24, a photodetector 25, and an AC amplifier 26. The optical coupler 22 is optically coupled to the probe light source 21, the optical amplifier 23, and the scanning optical system 15 via an optical fiber, outputting the probe light input from the probe light source 21 to the scanning optical system 15, and outputting the reflected light from the semiconductor device D input from the scanning optical system 15 to the optical amplifier 23. Furthermore, the connection between the optical coupler 22 and the scanning optical system 15 can, for example, use an FC adapter for an APC.

[0059] Specifically, the optical coupler 22 can be, for example, a PBS-type optical coupler or a circulator-type optical coupler. When the optical coupler 22 is a PBS-type optical coupler, a λ / 4 wavelength plate can also be provided in the scanning optical system 15. Alternatively, when the optical coupler 22 is a circulator-type optical coupler, a λ / 2 wavelength plate can also be provided in the scanning optical system 15. A Faraday rotator can also be provided in the scanning optical system 15 instead of the aforementioned wavelength plate. Furthermore, an optical splitter can also be used as the optical coupler 22.

[0060] Within the gain-unsaturated range and the unsaturated range of the subsequent photodetector 25, optical amplifier 23 amplifies the intensity of the reflected light from semiconductor device D input from optical coupler 22, and outputs the amplified reflected light to optical splitter 24. Specifically, optical amplifier 23 can be, for example, a semiconductor optical amplifier, fiber optic amplifier, solid-state optical amplifier (SOA), tapered optical amplifier, boost optical amplifier, etc. Furthermore, optical amplifiers using crystals, gases, liquids, etc., as amplification media can also be used as optical amplifier 23.

[0061] Optical splitter 24 is optically coupled to photodetector 25, second optical measurement unit 61, and optical amplifier 23 via optical fiber, outputting reflected light from optical amplifier 23 to photodetector 25 and second optical measurement unit 61 at a predetermined splitting ratio. Specifically, optical splitter 24 can be, for example, a 90:10 optical splitter. In this case, light from optical amplifier 23 is split in optical splitter 24 to photodetector 25 and second optical measurement unit 61 at a splitting ratio of 90:10. Furthermore, the connection between optical splitter 24 and second optical measurement unit 61 can be, for example, using an FC connector.

[0062] The photodetector 25 detects the amplified reflected light input from the light splitter 24 and outputs an electrical signal (detection signal) representing the detection result. The electrical signal output from the photodetector 25 has a time waveform based on the time variation of the intensity of the reflected light from the semiconductor device D. As the photodetector 25, a PIN photodiode (PIN-PD) capable of high-speed detection is preferably used, for example.

[0063] When using a high-speed optical sensor such as a PIN-PD as the photodetector 25, single-mode fiber is generally used as the input. Therefore, it is preferable that the input fiber, optical coupler, etc., are all composed of a combination of single-mode fibers. However, such a light guiding system can also be composed of an optical system that combines a half-mirror, a polarizing beam splitter, a collimator, etc. In addition to the PIN-PD, other photodiodes such as avalanche photodiodes (APDs) and photomultiplier tubes can also be used as the photodetector 25.

[0064] AC amplifier 26 amplifies the AC component of the detection signal input from photodetector 25 and outputs the amplified electrical signal to electrical signal measuring device 2A. Through signal amplification in AC amplifier 26, the time-varying intensity component of the detection signal is extracted, and the offset level of the electrical signal before being input to electrical signal measuring device 2A is appropriately adjusted and set. The operation of this offset reset will be explained further later.

[0065] Refer again Figure 1 The electrical signal measuring device 2A comprises a signal conversion unit 30 and a waveform measuring unit 40. The signal conversion unit 30 converts the electrical signal input from the AC amplifier 26 of the optical measuring unit 20 into an optical signal for signal waveform measurement, and outputs the converted optical signal to the waveform measuring unit 40. The waveform measuring unit 40 measures the time waveform of the optical signal input from the signal conversion unit 30 and outputs the measurement result to the control device 50. Furthermore, the configuration of the electrical signal measuring device 2A will be described in detail later.

[0066] The control device 50 comprises an inspection control unit 51 and a waveform analysis unit 52. The inspection control unit 51 controls and performs the inspection of the semiconductor device D in the semiconductor inspection device 1A by controlling the operation of various components such as the semiconductor inspection unit 10, the optical measurement unit 20, the detection light source 21, the scanning control unit 55, and the electrical signal measurement device 2A. The waveform analysis unit 52, based on the measurement results of the time waveform of the optical signal input from the waveform measurement unit 40 of the electrical signal measurement device 2A, calculates the time waveform of the electrical signal generated in the optical measurement unit 20 according to the change in the intensity of the reflected light over time.

[0067] In addition, Figure 1 The configuration shown includes an input unit (input device) 53 and a display unit (display device) 54 relative to the control device 50. The input unit 53, for example, is a keyboard, mouse, etc., and is used to input information required for semiconductor inspection, electrical signal measurement, waveform analysis, etc. in the semiconductor inspection apparatus 1A. The display unit 54, for example, is a liquid crystal display, etc., and is used to display the inspection results of the semiconductor device D, the waveform analysis results of the electrical signals, etc.

[0068] Specifically, the control device 50 can be configured as a computer, for example, having a CPU as a processing unit and ROM, RAM, and external storage devices as storage units. In this case, the computer functions as both an inspection control device and a waveform analysis device. Furthermore, the inspection control unit 51 and the waveform analysis unit 52 can be configured as different computers, or as a single computer.

[0069] exist Figure 1 In the semiconductor inspection apparatus 1A shown, the second optical measurement unit 61, the second waveform measurement unit 62, and the frequency analysis unit 63 are apparatus components that perform EOP and EOFM using the same methods as conventional inspection apparatuses. The second optical measurement unit 61 is, for example, composed of a photodetector such as an avalanche photodiode and an amplifier. The second waveform measurement unit 62 is, for example, composed of a digitizing board or a digital oscilloscope. The frequency analysis unit 63 is, for example, composed of a spectrum analyzer or a lock-in amplifier for acquiring EOFM images.

[0070] In this configuration, the electrical signal measuring device 2A functions as a high-speed digitization unit, and the second waveform measuring unit 62 functions as a low-speed digitization unit. Furthermore, a sinusoidal synchronization signal and a rectangular trigger signal are output from the voltage application unit 12 of the semiconductor inspection unit 10. These synchronization signals and trigger signals are supplied to various parts of the device, such as the electrical signal measuring device 2A, the second waveform measuring unit 62, and the frequency analysis unit 63, as needed. Moreover, the synchronization signal is not limited to the aforementioned sinusoidal signal; for example, it could also be a rectangular wave signal.

[0071] Next, for Figure 1The structure and operation of the electrical signal measuring device 2A used in the semiconductor inspection device 1A shown will be explained.

[0072] Figure 3 This is a block diagram schematically illustrating the configuration of a first embodiment of an electrical signal measuring device including a signal conversion unit 30 and a waveform measurement unit 40. The electrical signal measuring device 2A according to this embodiment is configured as a stripe oscilloscope using a stripe camera (see, for example, Patent Documents 3 and 4). Furthermore, as... Figure 3 As shown, the electrical signal measuring device 2A may include a waveform analysis unit (waveform analysis device) 52 of the control device 50 as needed.

[0073] In addition, Figure 3 The diagram illustrates the optical measurement unit 20, test head 12a, and delay generator (DG) 19 connected to the test head 12a, relative to the electrical signal measurement device 2A, and conveniently represents them as an electrical signal supply unit 80. In the electrical signal supply unit 80, the optical measurement unit 20 functions as an electrical signal output unit 81, the test head 12a functions as a synchronization signal output unit 82, and the delay generator 19 functions as a trigger signal output unit 83. The delay generator 19 adjusts the delay time and pulse width of the signal supplied from the test head 12a and outputs it as a trigger signal.

[0074] The signal conversion unit 30 is configured to include a measurement light source 31, an optical attenuator 32, and an optical modulator 33. The measurement light source 31 provides measurement light of a second wavelength that is different from the first wavelength of the probe light used in semiconductor testing. This measurement light is continuous light from an optical signal source input to the waveform measurement unit 40. As the measurement light, light of a wavelength that can be modulated by the optical modulator 33 and can be used for waveform measurement in the waveform measurement unit 40 via the stripe tube 42 (described later) is used.

[0075] In this case, the second wavelength of the measurement light is preferably set in the wavelength range of 115 nm to 1600 nm, taking into account the sensitivity distribution of the photoelectric surface used in the stripe tube 42, and more preferably in the wavelength range of 200 nm to 1050 nm to obtain sufficient sensitivity. Specifically, light with a wavelength of 850 nm or 780 nm can be used as such a measurement light. Furthermore, in order to suppress the degradation of time resolution caused by dispersion within the optical fiber, narrowband light is preferably used as the measurement light.

[0076] Specifically, the measurement light source 31 can be, for example, a laser light source, an SLD (superluminescent diode), an LED (light-emitting diode), etc. The measurement light source 31 used is preferably selected based on the type of modulator used as the light modulator 33. The measurement light output from the measurement light source 31 is attenuated and adjusted in intensity in the light attenuator 32 before being input as continuous light to the light modulator 33.

[0077] In the optical modulator 33, an electrical signal from the optical measurement unit 20 is input as a modulation control signal. Based on the electrical signal input from the optical measurement unit 20, the optical modulator 33 modulates the intensity of the measurement light supplied from the measurement light source 31, and outputs the modulated measurement light as an optical signal with a time waveform corresponding to the time waveform of the electrical signal. The optical modulator 33 uses a device configured to perform analog light intensity modulation.

[0078] As an optical modulator 33, specifically, for example, an EO (Electro-Optic) modulator, an AO (Acousto-Optic) modulator, an MO (Magneto-Optic) modulator, or a Pockels cell can be used. However, regarding the Pockels cell, it presents problems in modulating weak electrical signals because it requires a voltage of around several hundred volts. Furthermore, the bandwidth of the AO modulator is limited to around several hundred MHz. In addition, the MO modulator requires a relatively large magnetic field (current).

[0079] Considering these points, an EO modulator is preferably used as the optical modulator 33. This allows for appropriate intensity modulation of the measurement light based on a high-speed electrical signal. Furthermore, when using an EO modulator, AO modulator, or MO modulator as the optical modulator 33, a laser light source is preferably used as the measurement light source 31. Moreover, when using a Pockels cell as the optical modulator 33, an SLD or LED is preferably used as the measurement light source 31.

[0080] Figure 4 This diagram illustrates an example configuration of the optical modulator 33 in the signal conversion unit 30. In this example configuration, the optical modulator 33 includes an EO crystal 330, optical waveguides 331-334 formed on the crystal 330, an RF electrode 335, a bias electrode 336, and ground electrodes 337a-337d, and is configured as an EO modulator capable of optical intensity modulation. Specifically, lithium niobate (LiNbO3) can be used, for example, as the EO crystal 330.

[0081] exist Figure 4In the configuration shown, an input optical waveguide 331 is disposed on the left side of a rectangular EO crystal 330, and an output optical waveguide 334 is disposed on the right side. The input optical waveguide 331 is branched into a first branch optical waveguide 332 and a second branch optical waveguide 333 by a 50:50 optical coupler. Furthermore, these first and second branch optical waveguides 332 and 333 are again combined by a 50:50 optical coupler and connected to the output optical waveguide 334.

[0082] The measurement light, which is the target of modulation, is input from the measurement light source 31 into the input optical waveguide 331 and branched to the first and second branch optical waveguides 332 and 333 via the input-side optical coupler. Furthermore, the branched light guided in the first and second branch optical waveguides 332 and 333 respectively interferes when combined at the output-side optical coupler, and is output from the output optical waveguide 334 as interference light with a predetermined intensity. The interference light output from the output optical waveguide 334 becomes the optical signal input to the waveform measurement unit 40 as the target of time waveform measurement.

[0083] An RF electrode 335 is disposed on the input side and a bias electrode 336 is disposed on the output side between the first and second branch waveguides 332 and 333. A ground electrode 337a is disposed across the first branch waveguide 332 and a ground electrode 337b is disposed across the second branch waveguide 333, relative to the RF electrode 335. Furthermore, a ground electrode 337c is disposed across the first branch waveguide 332 and a ground electrode 337d is disposed across the second branch waveguide 333, relative to the bias electrode 336.

[0084] In the above configuration, the shaded area between electrodes in the figure represents the region where an electric field is applied to the optical waveguide by applying a voltage to the RF electrode 335 or the bias electrode 336. When an electric field is applied to the EO crystal 330, the refractive index within the optical waveguide formed in the region where the electric field is applied changes. Consequently, the optical path difference between the first and second branch optical waveguides 332 and 333 changes, and the intensity of the interference light output from the output optical waveguide 334 changes.

[0085] An electrical signal from the optical measurement unit 20 is applied to the RF electrode 335 located on the input side of the EO crystal 330 to modulate the intensity of the measurement light. Thus, the optical modulator 33 performs the conversion from an electrical signal to an optical signal. Additionally, a voltage applied to the bias electrode 336 is used for phase adjustment of the light interference, for example, as described below, for offset adjustment during the signal conversion from an electrical signal to an optical signal.

[0086] As described above, in the optical modulator 33 using an EO modulator, the polarization direction of the modulated light is determined, and a longer interference distance than that of the interferometer in the optical modulator 33 is required. Therefore, a laser is preferably used as the measurement light to be modulated. Furthermore, especially when the Z-direction in the crystal is the up-down direction as shown in the figure, the change in refractive index is opposite when the electric field applied along the Z-axis is in the opposite direction, thus enabling modulation of light at a lower voltage and higher speed. Alternatively, a thin-film EO modulator utilizing a photonic integrated circuit (PIC) can also be used as the optical modulator 33.

[0087] Refer again Figure 3 The waveform measurement unit 40 includes an input optical system 41, a stripe tube 42, an output optical system (imaging optical system) 43, an imaging element 44, and a synchronization unit 45, and is configured as a stripe camera. Furthermore, the waveform measurement unit 40, including the stripe tube 42, receives a rectangular wave trigger signal from the delay generator 19, and a synchronization signal, such as a sine wave from the test head 12a, is input via the synchronization unit (synchronization circuit) 45.

[0088] The configuration of the stripe camera, which includes the waveform measurement unit 40 with stripe tube 42, will be described. Figure 5 This is a perspective view showing an example of the structure of the striped tube 42. Additionally, Figure 6 This is a side view showing an example of the configuration of the waveform measurement unit 40 including the stripe tube 42. In this configuration example, the stripe tube 42 includes a peripheral tube 420, a photoelectric surface 421, an accelerating electrode 422, a vertical scanning electrode 423, a horizontal scanning electrode 424, a microchannel plate (MCP) 425, and a fluorescent surface 426. Alternatively, the MCP 425 can be omitted from the stripe tube 42.

[0089] Additionally, in the following figures, such as Figure 5 As shown in the xyz orthogonal coordinate system, regarding the configuration of the stripe tube 42, the input optical system 41, and the output optical system 43, the direction of propagation of the light signal and electrons is set as the z-axis direction, the electron scanning direction in the stripe tube 42, which is orthogonal to the z-axis direction, is set as the y-axis direction, and the direction orthogonal to both the z-axis and y-axis directions is set as the x-axis direction. Furthermore, Figure 6 This is a side view of the waveform measurement unit 40 as viewed from the x-axis direction.

[0090] exist Figure 5In the configuration shown, the peripheral tube 420 extending along the z-axis has a photoelectric surface 421 on its input side and a phosphor surface 426 on its output side opposite to the photoelectric surface 421. An optical signal from the signal conversion unit 30 is incident on the photoelectric surface 421 through the input optical system 41, forming an optical image P1 on the photoelectric surface 421. The photoelectric surface 421 generates electrons (photoelectrons) according to the input optical signal. The number of electrons generated on the photoelectric surface 421 is based on the intensity of the optical signal at each moment. Electrons emitted from the photoelectric surface 421 are accelerated along the z-axis by the accelerating electrode 422 within the peripheral tube 420.

[0091] Within the peripheral tube 420 between the photoelectric surface 421 and the phosphor surface 426, the aforementioned vertical scanning electrode 423, horizontal scanning electrode 424, and MCP 425 are sequentially arranged from the photoelectric surface 421 side. The vertical scanning electrode 423, by applying a scanning voltage with a predetermined pattern, scans electrons from the photoelectric surface 421 along a predetermined scanning direction (y-axis direction) at a scanning period set based on the test cycle in the semiconductor inspection unit 10. The electrons scanned by the scanning electrode 423 are multiplied by the MCP 425 and then incident on the phosphor surface 426. The phosphor surface 426 has a size of, for example, φ18mm.

[0092] Furthermore, at this time, the electronic image P2 formed on the fluorescent surface 426 moves along the y-axis direction over time through the electronic scanning of the scanning electrode 423. Thus, on the fluorescent surface 426, a fluorescent image showing the time waveform of the light signal input to the photoelectric surface 421 is generated with the y-axis direction as the time axis. Additionally, in Figure 5 For ease of illustration, the movement of electron image P2 along the y-axis is schematically shown on the incident surface of MCP425. Furthermore, the horizontal scanning electrode 424 is used when it is necessary to scan and move electron image P2 along the x-axis, which is orthogonal to the normal scanning direction.

[0093] like Figure 6 As shown, the fluorescence image generated on the fluorescent surface 426 of the stripe tube 42 is input to the imaging element 44 through the output optical system 43. The imaging element 44 captures the fluorescence image generated on the fluorescent surface 426 and outputs a waveform image as a two-dimensional image. The imaging element 44 uses a two-dimensional imaging element such as a CMOS imaging element or a CCD imaging element; specifically, for example, it uses a CMOS camera with a pixel count of 2048×2048 and a pixel size of 6.5μm×6.5μm. Furthermore, in Figure 6 In the configuration shown, the output optical system 43 is composed of lenses 430 and 431.

[0094] The waveform image acquired in the imaging element 44, like the fluorescence image on the phosphor surface 426, shows the time waveform of the light signal input to the waveform measurement unit 40 with the y-axis as the time axis. Figure 3 Based on the waveform image output from the imaging element 44, the time waveform of the electrical signal corresponding to the time waveform of the optical signal is determined. This time waveform of the electrical signal corresponds to the time change in the intensity of the reflected light from the semiconductor device D in the semiconductor inspection unit 10. Therefore, by referring to the time waveform of the electrical signal obtained in the waveform analysis unit 52, the semiconductor device D can be inspected.

[0095] Furthermore, to accurately measure the minute temporal changes in the intensity of reflected light in the semiconductor inspection section 10, the following configuration can be adopted: Optical signals from the signal conversion section 30 are repeatedly input into the waveform measurement section 40 over multiple cycles, and a fluorescence image of the time waveform accumulated over multiple cycles of optical signals is generated on the phosphor surface 426 of the stripe tube 42. Similarly, the waveform image acquired in the imaging element 44 is also an image of the time waveform accumulated over multiple cycles of optical signals.

[0096] In order to properly perform the inspection of the semiconductor device D, the stripe camera of the waveform measurement unit 40 controls the measurement operation of the optical signal time waveform based on the synchronization signal or trigger signal supplied from the voltage application unit 12. Specifically, the waveform measurement unit 40 has two measurement modes for measuring the time waveform of the optical signal: single scan mode and synchronous scan mode.

[0097] In single-scan mode, the waveform measurement unit 40 synchronizes with the rectangular wave trigger signal of the test head 12a or the delay generator 19 to perform a single measurement. At this time, the scanning voltage applied to the scanning electrode 423 is, for example, a linearly changing voltage pattern. Furthermore, the test period for voltage application in the semiconductor tester can be freely set. In addition, in single-scan mode, multiple single measurements can be repeated to accumulate time waveforms.

[0098] In synchronous scanning mode, the waveform measurement unit 40 is synchronized with the sinusoidal synchronization signal of the test head 12a to measure the accumulated waveform over multiple cycles. At this time, the scanning voltage applied to the scanning electrode 423 is controlled by the synchronization unit 45 and, like the synchronization signal, is, for example, a sinusoidal voltage pattern. In this mode, for example, a high time accuracy of 800 fs or less can be achieved. However, in this mode, the test cycle in the semiconductor tester is limited to an integer multiple of the synchronization signal period.

[0099] The optical signal input conditions of the photoelectric surface 421 of the stripe tube 42 and the configuration of the input optical system 41 provided in front of the stripe tube 42 will be described. In the above configuration, the shot noise generated based on the amount of light signal input to the stripe tube 42 determines the noise floor of the measurement. At this time, increasing the amount of light is preferable to reduce the proportion of shot noise, but the photoelectric surface 421 has an upper limit with respect to the input light density. In addition, when performing multiple cumulative measurements of the time waveform of the optical signal, the resulting degradation of the photoelectric surface also becomes a problem.

[0100] Considering these points, in order to reduce the light density incident on the photoelectric surface and suppress its degradation, the input optical system 41 preferably inputs the light signal as a linear light image extending along a direction intersecting the scanning direction (y-axis direction) in the stripe tube 42 to the photoelectric surface 421. Thus, as... Figure 5 Compared to the case where the optical signal is input as a point-like optical image P1, the input light density can be reduced. Furthermore, regarding the image formation direction of the linear optical image in this case, it is preferable to set it to a direction orthogonal to the scanning direction (x-axis direction).

[0101] Figure 7 This is a diagram showing an example of the configuration of the input optical system 41 in the waveform measurement unit 40. Figure 7 middle, Figure 7 (a) shows a top view viewed from the y-axis direction. Figure 7 (b) shows a side view viewed from the x-axis direction. Additionally, Figure 7 The lens configuration and schematic diagram of the input optical system 41 shown are illustrated in the figure. Figure 6 The lenses have the same structure.

[0102] Figure 6 and Figure 7 The input optical system 41 shown is composed of a cylindrical lens 410, a lens 411, and a lens 412, sequentially starting from the input side of the optical signal from the signal conversion unit 30 (the fiber end where the optical signal is output). Thus, by using the cylindrical lens 410 in the input optical system 41, it is possible to achieve... Figure 7 As shown in the diagram, a linear light image is formed on the photoelectric surface 421, as if the light rays are spreading out.

[0103] Figure 8 This is a schematic diagram illustrating the optical and electronic images formed in the stripe tube 42. Figure 8 middle, Figure 8 (a) is a diagram showing the light image P3 of the light signal incident on the photoelectric surface 421 of the stripe tube 42. Figure 8 (b) is a scan of the electron image P4 on the fluorescent surface 426. Additionally, Figure 8 The optical image P3 and electronic image P4 shown are in use Figure 7It is formed in the configuration of the input optical system 41 shown.

[0104] like Figure 8 As shown in (a), the optical signal is input to the photoelectric surface 421 as a linear optical image P3 extending along the x-axis. Additionally, as... Figure 8 As shown in (b), a linear electronic image P4 corresponding to the light image P3 and extending along the x-axis is formed on the fluorescent surface 426. The electronic image P4 is scanned in the y-axis direction to generate a fluorescent image representing the time waveform of the light signal.

[0105] Figure 9 This is an image showing an example of a fluorescence image generated on the fluorescence surface 426 corresponding to a linear optical image of the light signal input to the photoelectric surface 421 of the stripe tube 42. Here, the fluorescence image corresponding to the linear electron image is directly measured without performing an electron scan caused by the scanning electrode 423. Furthermore, with... Figure 9 The linear light image on the photoelectric surface 421 corresponding to the fluorescent image shown has a length of about 5 mm in the x-axis direction and a width of about 15 μm in the y-axis direction.

[0106] in addition, Figure 10 An example is shown of an image obtained by imaging the fluorescent image generated on the fluorescent surface 426 by imaging element 44 during a typical measurement involving an electronic scan induced by scanning electrode 423. Figure 10 middle, Figure 10 Image (a) shows a waveform image obtained when the optical signal generation in the signal conversion unit 30 is ON. Figure 10 (b) shows the base image obtained with the light signal generation set to OFF. Figure 10 In waveform image (a), fluorescence images obtained by scanning linear electron images were measured.

[0107] pass Figures 1-3 The semiconductor inspection method performed by the semiconductor inspection apparatus 1A and the electrical signal measurement apparatus 2A shown includes an inspection step, an optical measurement step, a signal conversion step, a waveform measurement step, and a waveform analysis step. In the inspection step, in the semiconductor inspection unit 10, a probe light is irradiated onto the semiconductor device D, and reflected light from the semiconductor device D is output. Alternatively, in the inspection step, a voltage application unit 12 can be used to apply a predetermined test pattern to the semiconductor device D.

[0108] In the optical measurement step, the optical measurement unit 20, including the photodetector 25, detects reflected light from the semiconductor device D and outputs an electrical signal having a time waveform corresponding to the time change in the intensity of the reflected light. In the signal conversion step, in the signal conversion unit 30 of the electrical signal measurement device 2A, based on the electrical signal output from the optical measurement unit 20, the measurement light is intensity modulated by the optical modulator 33 and output as an optical signal having a time waveform corresponding to the time waveform of the electrical signal.

[0109] In the waveform measurement step, the waveform measurement unit 40 of the electrical signal measurement device 2A uses a stripe tube 42 and an imaging element 44 to measure the time waveform of the optical signal output from the signal conversion unit 30, and outputs the obtained waveform image. In the waveform analysis step, the waveform analysis unit 52 of the control device 50 calculates the time waveform of the electrical signal based on the waveform image output from the waveform measurement unit 40, and thereby performs a predetermined inspection on the semiconductor device D.

[0110] The effects of the semiconductor inspection apparatus 1A, the electrical signal measuring apparatus 2A, and the semiconductor inspection method according to the above embodiments will be explained.

[0111] Figures 1 to 8 In the semiconductor inspection apparatus 1A and semiconductor inspection method shown, a probe light of a first wavelength from a probe light source 21 is irradiated onto the semiconductor device D to be inspected. The reflected light is detected by a photodetector 25, generating an electrical signal with a time waveform corresponding to the time change of the intensity of the reflected light. Then, after the electrical signal is converted into an optical signal of a second wavelength by an optical modulator 33, the time waveform of the optical signal is measured by a waveform measurement unit 40 including a stripe tube 42, and the time waveform of the electrical signal is determined based on the waveform image acquired by the imaging element 44.

[0112] With this configuration, by converting the electrical signal into an optical signal and then using the stripe tube 42 to perform waveform measurement, the time waveform of the electrical signal corresponding to the time change of the reflected light intensity of the semiconductor device D can be measured at high speed. Furthermore, in the above configuration, by appropriately setting the first wavelength of the probe light and the second wavelength of the measurement light, which is different from the first wavelength, it is possible to effectively balance the inspection of the semiconductor device D using the probe light and the waveform measurement of the optical signal using the stripe tube 42, which modulates the intensity of the measurement light with an electrical signal, thereby enabling high-precision measurement of the time change of the reflected light intensity.

[0113] Figure 11 This is a graph showing the measurement results of the time waveform of the electrical signal. Figure 11 In the chart, the horizontal axis represents time (ps), and the vertical axis represents signal strength (au). Additionally, in Figure 11In the diagram, chart G1 shows the measurement results of electrical signals measured using a 20GHz oscilloscope, and chart G2 shows the results of measurements using... Figure 3 The measurement results are shown by the electrical signal measuring device 2A.

[0114] Here, pulsed laser light from a femtosecond laser was detected using a 40 GHz band PIN-PD, and the output electrical signal was measured. The laser wavelength was 1550 nm, the repetition rate was 100 MHz, and the pulse width was less than 100 fs. Furthermore, in the measurement results shown in Figure G1, a 20 GHz band DPO72004C oscilloscope manufactured by Tektronix was used.

[0115] Regarding the measurement results of graph G2, the cumulative velocity of the stripe camera in waveform measurement unit 40 is 50MHz, the frame rate is 60Hz, and the cumulative time is 1.6 seconds (exposure time 10ms, 100 frames). The cumulative time of the substrate image used for subtraction, described later, is also 1.6 seconds. Figure 11 As shown in the graphs, in the configuration of the above embodiment, high-speed accumulation, which is impossible to achieve with an oscilloscope, is performed in the measurement of weak signals, thereby obtaining a good time waveform. Furthermore, the measured waveform's FWHM is 31.85 ps in graph G1 and 19.21 ps in graph G2.

[0116] In the inspection apparatus 1A and inspection method of the above embodiments, in the waveform measurement unit 40, the fluorescent surface 426 of the stripe tube 42 can also be configured to generate a fluorescent image after the time waveform of the light signal of multiple cycles with respect to the test period of the semiconductor device D is accumulated.

[0117] In this configuration, by converting the electrical signal into an optical signal and then measuring the waveform using the stripe tube 42, and by accumulating the time waveform of the optical signal during the generation of a fluorescence image through the phosphor surface 426 and the acquisition of the waveform image through the imaging element 44, multiple accumulations of the electrical signal time waveform can be optically performed at high speed. Furthermore, in this configuration, the number of accumulations of the optical signal time waveform is preferably set appropriately based on conditions such as the reflected light intensity of the semiconductor device D being measured. For example, in a stripe camera, during a 40MHz synchronous scan, the number of accumulations per second, determined by the test cycle, is typically within a maximum range of 40 million times per second.

[0118] In the inspection apparatus 1A and inspection method of the above embodiments, a voltage application unit 12 may be provided to apply a test pattern of voltage variation over time to the semiconductor device D, and the waveform measurement unit 40 may be configured to control the measurement operation of the time waveform of the optical signal based on the synchronization signal or trigger signal supplied from the voltage application unit 12.

[0119] In this case, by applying a test pattern to the semiconductor device D, the state of the semiconductor device D changes over time with the test cycle. Then, by using a synchronization signal or trigger signal from the voltage application unit 12 to control the measurement operation of the optical signal time waveform in the waveform measurement unit 40, including the stripe tube 42, the time change of the reflected light intensity of the semiconductor device D caused by the application of the test pattern can be measured well.

[0120] In the inspection apparatus 1A and inspection method of the above embodiments, regarding the wavelength settings of the probe light and the measurement light, as described above, it is preferable that the first wavelength of the probe light is set in a wavelength range of 1050 nm to 5000 nm, and the second wavelength of the measurement light is set in a wavelength range of 200 nm to 1050 nm. This allows for a good balance between the inspection of the semiconductor device D using the probe light and the waveform measurement of the measurement light using the stripe tube 42, where the light signal is intensity-modulated by an electrical signal.

[0121] Furthermore, regarding the application of streak cameras in semiconductor inspection apparatuses, for example, a structure could be considered where the infrared reflected light from the probe light of a semiconductor device D is directly measured using a streak camera. However, within the infrared wavelength range used for semiconductor inspection, the quantum efficiency of the streak tube photoelectric surface is low, for example, about 1%, which is insufficient for adequate measurement efficiency. Moreover, infrared photoelectric surfaces suitable for this wavelength range also suffer from low manufacturing yield. In contrast, as described above, by generating an electrical signal through the detection of reflected light, converting the electrical signal into an optical signal of another wavelength, and then measuring it with a streak camera, waveform measurement can be performed with high efficiency and high speed.

[0122] In the inspection apparatus 1A and inspection method described above, the waveform analysis unit 52 can also be configured to correct the waveform image obtained in the signal conversion unit 30 when the optical signal generation is in the ON state, based on a substrate image obtained when the optical signal generation is in the OFF state. In this way, by correcting the waveform image based on the substrate image in the waveform analysis unit 52 and using the corrected waveform image to determine the time waveform of the electrical signal, the change in reflected light intensity over time can be measured with high precision.

[0123] The acquisition of this substrate image, and the reference correction of the waveform image therefrom, can be used, for example, to correct measurement efficiency deviations (gain correction) caused by different positions of the phosphor surface 426 of the stripe tube 42 or the imaging element 44. Furthermore, the reference correction described above is also effective for correcting measurement characteristic drift caused by time variations in the semiconductor inspection apparatus 1A.

[0124] For example, the EO modulator used in the optical modulator 33 of the signal conversion unit 30 exhibits characteristic drift due to heat, and even with gain correction, the drift may still occur. In this case, it is preferable to take heat dissipation measures for the optical modulator 33 and simultaneously correct the characteristic drift caused by time variations in the waveform image acquired by the waveform measurement unit 40.

[0125] In the correction of characteristic drift caused by time variation, it is preferable to switch between waveform image acquisition and substrate image acquisition within a short time to obtain sufficient correction effect. However, in this device, since high-speed signals need to be processed, it is difficult to use switches or the like for measurement switching. Therefore, in the above-mentioned measurement switching, for example, ON / OFF switching via power control of the SOA used as optical amplifier 23, ON / OFF switching of the PIN-PD used as photodetector 25, ON / OFF switching of AC amplifier 26, etc. can be used. In particular, as the fastest method with the least impact on gain characteristics, ON / OFF switching of the SOA of optical amplifier 23 is preferred.

[0126] In the inspection apparatus 1A and inspection method of the above embodiments, the optical measurement unit 20 may have an optical amplifier 23 that amplifies and outputs the reflected light output from the inspection optical system 11, and the photodetector 25 may be configured to detect the reflected light amplified by the optical amplifier 23. Furthermore, the photodetector 25 of the optical measurement unit 20 may be a PIN-PD.

[0127] Based on these structures, the measurement of reflected light from the semiconductor device D via the optical measurement unit 20 and the output of electrical signals can be performed at high speed and with high precision. In other words, during the inspection of the semiconductor device D, the amount of probe light needs to be set to a level that does not damage the semiconductor device D, and the amount of reflected light is also relatively small. For example, when using an immersion lens that achieves an NA of 1 or more, the upper limit of the amount of probe light is approximately several mW, and the upper limit of the amount of reflected light from the semiconductor device D is approximately 0.1 mW.

[0128] Therefore, when directly detecting reflected light through the photodetector 25, for example, an APD can be used as the photodetector 25. However, the capacitance of the APD is relatively large, making it difficult to adequately handle high-speed signal measurements. In contrast, by setting an optical amplifier 23 such as an SOA in front of the photodetector 25, it is possible to use a high-speed optical sensor such as a PIN-PD as the photodetector 25, and combine it with waveform measurement using a streak camera, thus enabling suitable high-speed signal measurements.

[0129] In the inspection apparatus 1A and inspection method of the above embodiments, the optical measurement unit 20 may be configured to have an amplification element such as an AC amplifier 26 that amplifies the AC component of the detection signal output from the photodetector 25 and outputs it as an electrical signal.

[0130] With this structure, by removing the DC component of the detection signal and amplifying only the AC component offset reset in the AC amplifier 26 after the photodetector 25, the intensity time-varying component in the detection signal can be extracted, and the offset level of the electrical signal before optical signal conversion in the signal conversion unit 30 can be appropriately adjusted and set. Furthermore, in addition to the AC amplifier 26, other components for DC component removal or AC component extraction can be used as amplification elements for extracting and amplifying the AC component of the detection signal.

[0131] Here, the relationship between the intensity and time variation of reflected light, the time waveform of electrical signal, and the time waveform of optical signal in the semiconductor inspection apparatus 1A described above, as well as the setting of the signal offset level, will be explained. Figure 12 It is a graph showing the relationship between (a) the intensity of reflected light from semiconductor device D, (b) the intensity of electrical signal generated in optical measurement unit 20, and (c) the intensity of optical signal generated in signal conversion unit 30.

[0132] For example, when illuminated with probe light of wavelength 1.3 μm, the intensity of the reflected light from semiconductor device D is approximately 0.1 mW, as described above. At this time, in Figure 12 In the reflected light intensity shown in (a), if the intensity level (DC component) A0 of the reflected light is set to 1, then the shot noise level at 1σ is 2.25% with a bandwidth of 100 GHz. In contrast, the signal level (AC component) A1 of the time-varying intensity of the reflected light used for semiconductor inspection is very small, ranging from 0.001% to 0.01%.

[0133] For the reflected light, the signal level of the electrical signal generated in the light measurement unit 20, which includes the light amplifier 23, the light detector 25, and the AC amplifier 26, is, for example, Figure 12 As shown in (b), the detection signal output from the photodetector 25 contains both DC and AC components, just like the intensity of the reflected light. However, by removing the DC component of the detection signal and amplifying only the AC component in the AC amplifier 26, the signal level corresponding to the intensity level A0 of the reflected light becomes almost zero. Furthermore, the shot noise level is approximately 300 mV at 1σ. On the other hand, the signal level B1 corresponding to the signal level A1 of the time-varying intensity of the reflected light is approximately 0.15 mV to 1.5 mV.

[0134] Furthermore, the signal level of the optical signal generated based on the electrical signal modulated by the measured light intensity in the optical modulator 33, for example, Figure 12 As shown in (c). Figure 12In (c), curve C5 shows a sinusoidal relationship between the voltage (vertical axis) of the electrical signal applied to the EO modulator constituting the optical modulator 33 and the intensity (horizontal axis) of the generated optical signal.

[0135] like Figure 12 As shown in (c), in the signal conversion from electrical signal to optical signal in the optical modulator 33, in order to improve the sensitivity to voltage changes in the electrical signal and improve the linearity of the signal conversion, as indicated by the signal level C0, it is preferable to apply a bias voltage as an offset, set such that when the voltage of the electrical signal is zero, the amount of transmitted light measured is a predetermined amount, for example, 50% of the maximum transmitted light amount. In this case, for the voltage change range C1 of the electrical signal, the intensity change range C2 of the converted optical signal can be sufficiently wide. Furthermore, through such offset adjustment in the optical measurement unit 20 and the signal conversion unit 30, the measurement of the time change of reflected light intensity and the accumulation of its time waveform can be performed with high accuracy and appropriateness. Regarding the maximum value of the optical signal intensity, considering the upper limit of the incident light density on the photoelectric surface, it is preferable to appropriately set it to be consistent with or below the upper limit using the optical attenuator 32, etc.

[0136] The measurement conditions for the time-varying intensity of reflected light in the above structure will be explained in more detail. Removing the DC component is crucial when measuring and accumulating optical signals. Optical sensors suffer from saturation issues, limiting the amount of light that can be measured. Therefore, measuring the time-varying intensity of optical signals without removing the DC component leads to problems such as increased shot noise ratio and reduced AC component measurement efficiency.

[0137] First, consider the detection side of the optical signal. As a concrete example, a waveform composed of 2000 data points within 1 second is created from 100 frames of an image captured by a 2000×2000 pixel streak camera. Assuming the saturation charge of one pixel is 30k, then over 1 second, the maximum number of electrons that one data point can contain is 2000×30k×100, or 6 billion. Furthermore, over 1 second, the total number of electrons in the data is 12 trillion.

[0138] Under the above conditions, the shot noise reference S / N for the signal quantity is 1 / 77000. In reality, since measurements at the saturation limit are difficult, assuming it's around half saturation, the S / N becomes 1 / √2, and the noise level relative to the signal quantity is approximately 1 / 50000. At this point, as mentioned above, the signal level of the EOP is approximately one ten-thousandth to one hundred-thousandth of the light quantity; therefore, on the image acquisition side, the ideal S / N is approximately 0.5 to 5.

[0139] Next, consider the input side of the optical signal. As mentioned above, the amount of reflected light in the EOP is, for example, approximately 0.1 mW. Furthermore, the number of photons at this time, converted to a wavelength of 1.3 μm, is approximately 660 trillion per second. The expected S / N ratio at this time is also approximately 2.3 to 23 for a 2000-point waveform. Here, 1 / 6 of the aperture time in the synchronous scanning mode is considered.

[0140] However, when the reflected light is directly input into the streak camera in practice, considering the durability of the streak camera's photoelectric surface (approximately 10 μW, which is 1 / 10 of the light intensity), the quantum efficiency (1 / 100 when using an infrared crystal photoelectric surface), and the utilization efficiency of the internal electrons (1 / 10), the S / N ratio will decrease to 1 / 100, approximately 0.02 to 0.2. In other words, when measuring without eliminating offset, the limiting factor for measuring S / N is the shot noise determined by the number of electrons within the streak camera.

[0141] In contrast, as described above, by eliminating the offset via an AC amplifier or the like, the measured signal-to-noise ratio (S / N) can be improved while suppressing the amount of light input to the photoelectric surface. In the system configured above, the offset (component) can be set to, for example, 1 / 10. Thus, while maintaining the amount of light input to the photoelectric surface, the S / N can be improved by approximately 10 times by increasing the ratio of the optical signal amplitude to the shot noise determined by the number of electrons.

[0142] Furthermore, by inputting light only within the aperture time, the average light intensity can be increased by 6 times, and by shifting the wavelength to set the quantum efficiency to 20%, the number of electrons can be increased by 20 times. However, due to the shorter wavelength of the light signal, the quantum noise increases by approximately 25%. In summary, in the measurements constructed above, the expected S / N ratio can be improved by approximately 90 times, reaching approximately 1.8 to 18.0. That is, through the aforementioned shift elimination, the upper limit of S / N limited by the detection side can be exceeded.

[0143] The above explanation is based on the assumption of measurement at the fastest synchronization frequency. However, when the test cycle of the semiconductor tester is an integer multiple of the synchronization frequency, a light quantity margin will occur on both the photoelectric side and the camera side. Therefore, in this case, the instantaneous input light quantity can be increased accordingly. This can alleviate the problem of reduced signal-to-noise ratio (S / N) caused by the extended cycle in typical EOP (Electronic Optical Programming).

[0144] The setting of the cumulative number of times the time waveform is accumulated when performing signal measurement using the electrical signal measuring device 2A is explained. As described above, the shot noise level in the reflected light measurement is 2.25% at a bandwidth of 100 GHz and 0.225% at a bandwidth of 1 GHz. Furthermore, the signal level is 0.001% to 0.01%.

[0145] At this point, for example, to obtain a time waveform with an S / N ratio of 10 or higher, with a bandwidth of 1 GHz and a signal level of 0.001%, the required number of accumulations is 2250 squared, or approximately 5 million. Furthermore, if the bandwidth increases tenfold, the required number of accumulations also simply increases tenfold; for example, the required number of accumulations for a 10 GHz bandwidth is 50 million, and the required number of accumulations for a 40 GHz bandwidth is 200 million.

[0146] If the signal strength relative to the noise is high, the required number of accumulations will decrease; for example, if the signal-to-noise ratio (S / N) increases tenfold, the required number of accumulations becomes 1 / 100. Furthermore, as a method to improve the S / N ratio, increasing the light intensity can be considered to change the ratio of shot noise to signal. However, as mentioned above, the intensity of the probe light needs to be set within a range that does not damage the semiconductor device D. Therefore, increasing the signal strength in this way is sometimes difficult. Considering practical conditions in semiconductor inspection, the number of accumulations of the time waveform in reflected light measurement is preferably set in a range, for example, between 1 million and 1 billion.

[0147] Here is a specific example of an inspection method for a semiconductor device D performed using a semiconductor inspection apparatus 1A. First, a pattern image or EOFM image of the semiconductor device D, which is the object of inspection, is acquired, and a measurement target position is set on the semiconductor device D. Next, a normal EOP measurement is performed using the second light measurement unit 61 and the second waveform measurement unit 62 to obtain a time waveform representing the time-varying intensity of reflected light from the semiconductor device D. Furthermore, a measurement range is set for performing EOP measurements using an electrical signal measurement apparatus 2A with a streak camera.

[0148] Next, the time waveform obtained by EOP measurement is displayed on the display unit 54, and the actual measurement period (measurement start time and time width) to be measured is set and selected in the waveform. Then, for the set measurement period, the light measurement unit 20 and the electrical signal measurement device 2A are used to perform the measurement. The waveform analysis unit 52 calculates the time waveform representing the time change of the reflected light intensity, and the measurement result is displayed on the display unit 54. In addition, if there are multiple measurement periods to be measured, the same measurement can be repeated multiple times as needed while changing the phase. Furthermore, waveform image acquisition and substrate image acquisition can be performed alternately for reference correction.

[0149] The configuration of the input optical system 41 of the streak camera in the waveform measurement unit 40 will be further explained. As described above, the input optical system 41 preferably inputs the optical signal as a linear optical image onto the photoelectric surface 421. As an example of its specific configuration, in Figure 7The diagram shows an input optical system 41 consisting of cylindrical lens 410, lens 411, and lens 412. However, regarding the configuration of the input optical system 41, apart from... Figure 7 In addition to its constituent parts, various other constituent parts can also be used.

[0150] Figure 13 These are (a) a top view and (b) a side view showing a first modified example of the configuration of the input optical system 41 in the waveform measurement unit 40. In this first modified example, the input optical system 41 is composed of a lens 413 and a cylindrical lens 414, sequentially arranged from the input side of the optical signal. With this configuration, it can also... Figure 7 Similarly, the structure forms a linear light image on the photoelectric surface 421.

[0151] Furthermore, the cylindrical lens 410 is disposed in the pre-stage of the lens configuration of the input optical system 41. Figure 7 The configuration, along with the cylindrical lens 414 positioned in the subsequent stage, Figure 13 In their configuration, the cylindrical lenses are arranged in different directions. Furthermore, in... Figure 13 In the configuration shown, the cylindrical lens 414 of the later stage also serves as the imaging lens.

[0152] Figure 14 These are (a) a top view and (b) a side view showing a second modified example of the configuration of the input optical system 41 in the waveform measurement unit 40. In this second modified example, the input optical system 41 is composed of a lens 413, a cylindrical lens 414, a lens 415, and a lens 416, sequentially arranged from the input side of the optical signal. Figure 14 The composition is in Figure 13 Based on the existing structure, a relay optical system consisting of lenses 415 and 416 was added.

[0153] Figure 15 These are (a) a top view and (b) a side view showing a third modified example of the configuration of the input optical system 41 in the waveform measurement unit 40. The input optical system 41 in the third modified example is composed of a lens 417, a Powell lens 418, and a lens 419, sequentially from the input side of the optical signal. A Powell lens is a lens that expands parallel light into a fan shape; by combining it with a conventional lens or a cylindrical lens, it can form a fine and uniform linear light image.

[0154] In addition, Figure 15 In the configuration shown, the subsequent lens 419 can also be replaced with a combination of two cylindrical lenses with different orientations and orthogonal optical axes. In this case, it is easier to adjust the imaging position of the light. In addition, for the formation of linear light images, besides the cylindrical lenses and Powell lenses mentioned above, a combination of deformable prism pairs and slits can also be used, for example. Generally speaking, the input optical system 41 preferably includes at least one of a cylindrical lens, a Powell lens, and a deformable prism pair.

[0155] The structure and operation of the electrical signal measuring device used in the semiconductor inspection apparatus 1A will be further explained.

[0156] Figure 16 This is a block diagram schematically illustrating the configuration of a second embodiment of an electrical signal measuring device including a signal conversion unit 30 and a waveform measurement unit 40. The configuration of the electrical signal measuring device 2B in this embodiment, regarding the waveform measurement unit 40 and... Figure 3 The configurations shown are the same, but the configuration of the signal conversion unit 30 is different. Furthermore, in Figure 16 The waveform analysis unit 52 of the control device 50, which constitutes part of the electrical signal measuring device 2B, is omitted from the illustration.

[0157] The signal conversion unit 30 is configured to include a measurement light source 31, an optical attenuator 32, a conversion control optical modulator 34, and an optical modulator 33. The configuration of the measurement light source 31, the optical attenuator 32, and the optical modulator 33 is as follows... Figure 3 The structures shown are the same.

[0158] A conversion control optical modulator 34 is disposed between the optical attenuator 32 and the optical modulator 33. Based on measurement conditions such as the test cycle in the semiconductor inspection unit 10, it controls the ON / OFF operation of the signal conversion unit 30, which converts electrical signals into optical signals. Specifically, the conversion control optical modulator 34 controls the ON / OFF operation of the signal conversion by switching the passage / non-passage of the measurement light from the optical attenuator 32, based on a trigger signal input from the delay generator 19 or a control signal input from the inspection control unit 51 of the control device 50.

[0159] In this way, by providing a conversion control optical modulator 34 in the signal conversion unit 30, which is different from the optical modulator 33 used for signal conversion, various measurement controls can be performed based on the specific measurement conditions in the semiconductor inspection apparatus 1A. In addition, as the conversion control optical modulator 34, an EO modulator, an AO modulator, an MO modulator, a Pockels cell, etc., can be used, just like the optical modulator 33, and an EO modulator is particularly preferred.

[0160] As a control for the signal conversion operation using the optical modulator 34 for conversion control, for example, control corresponding to the main scan and retrace in the stripe tube 42 of the waveform measurement unit 40 can be performed. Here, Figure 17 This diagram schematically illustrates the main scan and retrace in the stripe tube 42. In the stripe tube 42, for example in synchronous scan mode, electrons are scanned by a sinusoidal scan voltage, in which case the main scan in the original scan direction and the retrace in the opposite direction are repeated alternately.

[0161] In this case, such as Figure 17 As shown, electron images P5 generated by the main scan and P6 generated by the retrace scan are alternately input on the fluorescent surface 426. If the electron image pattern generated by the retrace scan is superimposed on the electron image pattern generated by the main scan and is measured, the target time waveform cannot be measured correctly.

[0162] In contrast, Figure 16 In the configuration shown, the conversion control light modulator 34 provided in the signal conversion unit 30 is controlled such that the signal conversion operation is set to ON during the main scan corresponding to the stripe tube 42, and the signal conversion operation is set to OFF during the retrace period. Therefore, it is possible to selectively measure only the electronic image pattern generated by the main scan.

[0163] Furthermore, regarding the measurement control of the main scan and retrace in the stripe tube 42, in addition to the configuration using the conversion control optical modulator 34 of the signal conversion unit 30 as described above, various other configurations can be used. For example, the horizontal scanning electrode 424 of the stripe tube 42 (see reference) can be used. Figure 5 A configuration in which a voltage is applied to a predetermined pattern on the phosphor surface 426, thereby shifting the electronic image to a position outside the phosphor surface 426 during retrace.

[0164] Alternatively, a configuration can be used to modulate the high voltage applied to the stripe tube 42, modulate the voltage applied to the MCP425, etc. Furthermore, instead of the MCP425, an image intensifier can be provided between the stripe tube 42 and the output optical system 43, and the ON / OFF state of the image intensifier can be controlled based on the main scan and retrace.

[0165] However, in these configurations, even during the retrace period when no time waveform measurement is performed, the light image of the optical signal is incident on the photoelectric surface 421, thus causing degradation of the photoelectric surface 421. In contrast, according to the configuration described above, which uses the conversion control optical modulator 34 of the signal conversion unit 30 to control the ON / OFF operation of the signal conversion, the light image of the optical signal does not incident on the photoelectric surface 421 during the retrace period, thus suppressing degradation of the photoelectric surface 421. Furthermore, regarding the placement of the conversion control optical modulator 34, in... Figure 16 It can be configured as a pre-stage of the optical modulator 33, but it can also be configured as a post-stage of the optical modulator 33.

[0166] Furthermore, regarding the control of the measurement period and measurement conditions of the electrical signal's time waveform in the electrical signal measuring device 2B, in addition to controlling the measurement period via the conversion control optical modulator 34, phase control during waveform measurement is also possible. Specifically, for example, in the waveform measuring unit 40, the stripe tube 42 can also be configured to adjust the phase of the scanning cycle based on the period of the electrical signal's time waveform to be measured within the test cycle of the semiconductor inspection unit 10. With this configuration, various measurement controls can be performed based on specific measurement conditions.

[0167] Figure 18 This is a diagram illustrating an example of the phase settings for the measurement period and scan cycle in a stripe tube. Figure 18 The following are shown from top to bottom: (a) the synchronization signal supplied from the test head 12a, (b) the trigger signal supplied from the test head 12a or the delay generator 19, (c) the measurement period T1 set as the period during which the waveform measurement is required in the time waveform of the electrical signal (the time change of the intensity of the reflected light), (d) the scanning voltage pattern in the stripe tube 42, and (e) the control signal pattern supplied to the optical modulator 34 for conversion control.

[0168] exist Figure 18 In the example shown, in each test cycle of the semiconductor inspection unit 10, such as Figure 18 As shown in (c), a measurement period (measurement time window) T1 is set for inspecting semiconductor device D. Furthermore, based on this measurement period T1, as... Figure 18 As shown in (e), the control signal pattern for the optical modulator 34 for switching control is determined, thereby controlling the ON / OFF of the signal switching operation.

[0169] Furthermore, in the striped tube 42, such as Figure 18 As shown in (d), in order to include the measurement period T1 of the time waveform within the main scan period, the timing of the electronic scan is delayed by time T2 from the synchronization signal, thereby adjusting the phase of the scan cycle. Thus, by setting the measurement period of the time waveform through the conversion control optical modulator 34 of the signal conversion unit 30, and setting and adjusting the phase of the electronic scan cycle in the stripe tube 42, waveform measurement can be performed under the desired conditions. Alternatively, the phase adjustment can be achieved, for example, using the phase delay function of the stripe camera. Or, alternatively, a phase delay device can be installed on the synchronization line connecting the test head 12a of the electrical signal supply unit 80 and the waveform measurement unit 40 to perform the phase adjustment.

[0170] Figure 19This is a block diagram schematically illustrating the configuration of a third embodiment of an electrical signal measuring device including a signal conversion unit 30 and a waveform measurement unit 40. The configuration of the electrical signal measuring device 2C in this embodiment, regarding the waveform measurement unit 40 and... Figure 3 The configurations shown are the same, but the configuration of the signal conversion unit 30 is different. Furthermore, in Figure 19 In the diagram, the waveform analysis unit 52 of the control device 50, the supply of the synchronization signal from the test head 12a, and the supply of the trigger signal from the delay generator 19 are omitted.

[0171] The signal conversion unit 30 comprises a measurement light source 31, an optical attenuator 32, an optical modulator 33, an optical coupler 35, a first optical delay unit 36a, and a second optical delay unit 36b. The configuration of the measurement light source 31, the optical attenuator 32, and the optical modulator 33 is related to... Figure 3 The structures shown are the same.

[0172] Optical coupler 35 branches the optical signal (modulated measurement light) input from optical modulator 33 and outputs it to first optical delay unit 36a and second optical delay unit 36b. First optical delay unit 36a delays the optical signal by a first delay time before outputting it to waveform measurement unit 40. Second optical delay unit 36b delays the optical signal by a second delay time before outputting it to waveform measurement unit 40. The first and second delay times can be different or the same. Furthermore, one of the first and second delay times can be zero.

[0173] In order to measure their time waveforms, the two optical signals from the first and second optical delayers 36a and 36b are preferably input to different regions on the photoelectric surface 421 of the stripe tube 42. Figure 20 It shows about Figure 19 The diagram shows the input of two optical signals to the photoelectric surface 421 in the configuration shown.

[0174] exist Figure 20 In the configuration shown, the optical signal from the first optical delayer 36a is incident as an image P7 onto the left-hand region of the photoelectric surface 421 in the diagram, via cylindrical lenses 410a, 411a, and mirror 428. Similarly, the optical signal from the second optical delayer 36b is incident as an image P8 onto the right-hand region of the photoelectric surface 421 in the diagram, via cylindrical lenses 410b, 411b, and mirror 428. This allows for the measurement of the time waveforms of the optical signals from the first and second optical delayers 36a and 36b, respectively.

[0175] In this way, by generating two optical signals in the signal conversion unit 30, each of which has a time waveform corresponding to the time waveform of the electrical signal and has different conversion conditions, and measuring the time waveform of each of these optical signals in the waveform measurement unit 40, various measurements can be performed.

[0176] For example, in Figure 19 The configuration shown can be further configured. Figure 16 The optical modulator 34 used for conversion control in the configuration performs ON / OFF signal conversion operations and makes the delay times in the first and second optical delayers 36a and 36b different from each other, thereby enabling eye diagram observation. Regarding the number of optical signals generated in the signal conversion unit 30, in the above configuration example, it is two optical signals, but it could also be configured to generate three or more optical signals.

[0177] Figure 21 This is a block diagram schematically illustrating the configuration of a fourth embodiment of an electrical signal measuring device including a signal conversion unit 30 and a waveform measurement unit 40. The configuration of the electrical signal measuring device 2D in this embodiment, regarding the waveform measurement unit 40 and... Figure 3 The configurations shown are the same, but the configuration of the signal conversion unit 30 is different. Furthermore, the diagrams of the waveform analysis unit 52, etc., of the control device 50 are omitted, and... Figure 19 same.

[0178] The signal conversion unit 30 is configured with a measurement light source 31, an optical attenuator 32, an optical coupler 37, and first and second optical modulators 33a and 33b. The configuration of the measurement light source 31 and the optical attenuator 32 is similar to... Figure 3 The structures shown are the same.

[0179] Optical coupler 37 splits the measurement light input from optical attenuator 32 and outputs it to first optical modulator 33a and second optical modulator 33b. Electrical signals from optical measurement unit 20 are input to the first and second optical modulators 33a and 33b. The first and second optical modulators 33a and 33b modulate the measurement light intensity based on the electrical signals input from optical measurement unit 20, and output the modulated measurement light as an optical signal with a time waveform corresponding to the time waveform of the electrical signals.

[0180] The two optical signals from the first and second optical modulators 33a and 33b are preferably input to different regions on the photoelectric surface 421 of the stripe tube 42. Furthermore, in this configuration, the electrical signals input to the first and second optical modulators 33a and 33b can be different, or optical delayers can be provided for each of the first and second optical modulators 33a and 33b. With this configuration, it is also possible to... Figure 19 The configuration shown is subjected to various measurements in the same manner.

[0181] The semiconductor inspection apparatus and method are not limited to the above-described embodiments and configurations, and various modifications can be made. For example, regarding the configuration of the optical measurement unit 20, in... Figure 2 The configuration includes an optical amplifier 23, a photodetector 25, and an AC amplifier 26. However, the optical amplifier 23 and AC amplifier 26 can be omitted if not needed. Furthermore, the configuration of the semiconductor inspection unit 10 is not limited to... Figure 1 , Figure 2 The configuration shown can be used in various ways.

[0182] Furthermore, the configuration of the electrical signal measuring device 2A is not limited to... Figure 3 , Figure 16 , Figure 19 , Figure 21 The configuration shown can specifically be used in various ways. For example, in Figure 19 or Figure 21 The configuration shown can also be further configured. Figure 16 The optical modulator 34 is used for conversion control in the configuration. Furthermore, in the stripe tube 42 of the waveform measurement unit 40, the horizontal scanning electrode 424 and MCP 425 can be omitted if not needed. Additionally, regarding... Figure 12 The signal level and offset adjustment settings shown can be adapted to various configurations depending on the configuration of the optical measurement unit 20 and the electrical signal measurement device.

[0183] The semiconductor inspection apparatus according to the first embodiment described above includes: (1) an inspection optical system that irradiates a semiconductor device with a state that changes over time according to a predetermined test cycle with a probe light of a first wavelength and outputs reflected light that has been reflected by the probe light in the semiconductor device; (2) an optical measurement unit that has a photodetector that detects the reflected light output from the inspection optical system and outputs an electrical signal having a time waveform corresponding to the time change in the intensity of the reflected light; and (3) a signal conversion unit that has a measurement light source that supplies a measurement light of a second wavelength that is different from the first wavelength, and an optical modulator that modulates the intensity of the measurement light based on the electrical signal output from the optical measurement unit, and outputs the measurement light modulated by the optical modulator as an optical signal having a time waveform corresponding to the time waveform of the electrical signal. (4) A waveform measurement unit that measures the time waveform of the optical signal output from the signal conversion unit; (5) A waveform analysis unit that determines the time waveform of the electrical signal based on the measurement result of the time waveform of the optical signal by the waveform measurement unit; (6) The waveform measurement unit includes: a stripe tube that includes a photoelectric surface that generates electrons according to the input of the optical signal, a scanning electrode that scans the electrons from the photoelectric surface along a predetermined scanning direction according to a scanning period set according to the test period, and a fluorescent surface that inputs the electrons scanned by the scanning electrode and generates a fluorescent image representing the time waveform of the optical signal; and an imaging element that captures the fluorescent image generated on the fluorescent surface of the stripe tube and outputs a waveform image; (7) A waveform analysis unit that determines the time waveform of the electrical signal based on the waveform image output from the imaging element.

[0184] The semiconductor inspection method according to the first embodiment described above includes: (1) an inspection step, wherein a first wavelength probe light is irradiated onto a semiconductor device whose state changes over time during a predetermined test cycle, and reflected light is output from the semiconductor device after the probe light has been reflected; (2) an optical measurement step, wherein an electrical signal having a time waveform corresponding to the time change in intensity of the reflected light is output using a photodetector that detects the reflected light output in the inspection step; (3) a signal conversion step, wherein an optical modulator that modulates the intensity of a second wavelength measurement light different from the first wavelength based on the electrical signal output in the optical measurement step is used to output the measurement light modulated by the optical modulator as an optical signal having a time waveform corresponding to the time waveform of the electrical signal; and (4) a waveform measurement step, wherein the semiconductor device is subjected to a test cycle in which the state changes over time, and the semiconductor device reflects the probe light; (5) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been reflected; (6) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been reflected; (7) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been reflected; (8) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been reflected; (9) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been reflected; (10) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been reflected; (11) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been reflected; (12) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been reflected; (13) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been reflected; (14) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been reflected; (15) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been reflected; (16) an optical measurement step, wherein the semiconductor device reflects the probe light after the probe light has been (5) Waveform analysis step, based on the measurement result of the time waveform of the light signal obtained in the waveform measurement step, to determine the time waveform of the electrical signal; (6) Waveform measurement step, using a stripe tube, to photograph the fluorescence image generated on the fluorescent surface of the stripe tube and output the waveform image, the stripe tube comprising: a photoelectric surface that generates electrons according to the input of the light signal; a scanning electrode that scans electrons from the photoelectric surface along a predetermined scanning direction at a scanning period set according to the test period; and a fluorescent surface that receives electrons scanned by the scanning electrode and generates a fluorescence image displaying the time waveform of the light signal; (7) Waveform analysis step, based on the waveform image output in the waveform measurement step, to determine the time waveform of the electrical signal.

[0185] The semiconductor inspection apparatus according to the thirteenth aspect of the above embodiments includes: (1) an inspection optical system that irradiates a semiconductor device whose state changes over time during a predetermined test cycle with a probe light of a first wavelength and outputs reflected light from the semiconductor device after the probe light has been reflected; (2) a light measurement unit that has a photodetector for detecting the reflected light output from the inspection optical system and outputs an electrical signal having a time waveform corresponding to the time change in the intensity of the reflected light; and (3) a signal conversion unit that has a measurement light source for supplying a measurement light of a second wavelength different from the first wavelength and a signal conversion unit for converting the measurement light based on the electrical signal output from the light measurement unit. (3) An intensity-modulated optical modulator outputs the measured light modulated by the optical modulator as an optical signal with a time waveform corresponding to the time waveform of the electrical signal; (4) A waveform measurement unit has a stripe camera that measures the time waveform of the optical signal output from the signal conversion unit; and (5) A waveform analysis unit that calculates the time waveform of the electrical signal based on the measurement result of the time waveform of the optical signal obtained by the waveform measurement unit; (6) The stripe camera outputs a waveform image of the time waveform of the optical signal based on the input of the optical signal; and (7) The waveform analysis unit calculates the time waveform of the electrical signal based on the waveform image output from the stripe camera.

[0186] In the second type of semiconductor inspection apparatus, in the configuration of the first type described above, the fluorescent surface of the stripe tube in the waveform measurement unit can also be configured to generate a fluorescent image that accumulates the time waveform of the optical signal for multiple cycles with respect to the test period.

[0187] In the second form of the semiconductor inspection method, in the configuration of the first form described above, in the waveform measurement step, the fluorescent surface of the stripe tube can also be configured to generate a fluorescent image that accumulates the time waveform of the optical signal for multiple cycles with respect to the test period.

[0188] In the above configuration, after the electrical signal is converted into an optical signal, a stripe tube is used to measure the waveform. Furthermore, when generating a fluorescent image through a fluorescent surface and acquiring a waveform image through an imaging element, the time waveform of the optical signal is accumulated multiple times in an optical manner, thereby enabling high-speed accumulation of the time waveform of the electrical signal.

[0189] In the third type of semiconductor inspection apparatus, in the configuration of the first or second type described above, a voltage application unit may be further included to apply a test pattern of voltage variation over time to the semiconductor device during the test cycle; the waveform measurement unit may also be configured to control the measurement operation of the time waveform of the optical signal based on a synchronization signal or trigger signal supplied from the voltage application unit.

[0190] In the third form of the semiconductor inspection method, in the configuration of the first or second form described above, a voltage application step may be further included, in which a test pattern in which the voltage changes over time within a test cycle is applied to the semiconductor device; in the waveform measurement step, the measurement operation of the time waveform of the optical signal may be controlled based on the synchronization signal or trigger signal supplied in the voltage application step.

[0191] In the above configuration, by applying a test pattern to the semiconductor device, the state of the semiconductor device changes over time within the test cycle. Then, by controlling the measurement operation of the time waveform of the optical signal in the waveform measurement unit, including the stripe tube, using a synchronization signal or trigger signal from the voltage application unit, it is possible to appropriately measure the time change in the intensity of reflected light from the semiconductor device caused by the application of the test pattern.

[0192] In the fourth type of semiconductor inspection apparatus, in any of the configurations of the first to third types described above, the optical measurement unit may have an optical amplifier that amplifies and outputs reflected light from the inspection optical system, and the photodetector may be configured to detect the reflected light amplified by the optical amplifier. Furthermore, in any of the configurations described above, the photodetector of the optical measurement unit in the semiconductor inspection apparatus may be a PIN photodiode.

[0193] Based on these configurations, it is possible to perform high-speed and high-precision optical measurement of reflected light from semiconductor devices and output electrical signals.

[0194] In the fifth type of semiconductor inspection apparatus, in any of the configurations of the first to fourth types described above, the optical measurement unit may have an amplification element, such as an AC amplifier, which amplifies the AC component of the detection signal output from the photodetector and outputs it as an electrical signal.

[0195] Based on this configuration, by amplifying only the AC component of the detection signal in the post-amplification element of the photodetector, the time variation of the signal intensity in the detection signal can be extracted, and the offset level of the electrical signal can be appropriately adjusted and set before the signal conversion unit performs the conversion to an optical signal.

[0196] In the semiconductor inspection apparatus of the sixth form, in any of the configurations of the first to fifth forms described above, the optical modulator of the signal conversion unit may be an EO modulator.

[0197] In this way, by using an EO modulator as an optical modulator to modulate the intensity of the measurement light, the conversion of electrical signals to optical signals can be performed well.

[0198] In the semiconductor inspection apparatus of the seventh type, in any of the configurations of the first to sixth types described above, the signal conversion unit may have a conversion control optical modulator that controls the ON / OFF of the signal conversion operation from electrical signal to optical signal according to the test cycle.

[0199] In the semiconductor inspection method of the fourth form, in any of the configurations of the first to third forms described above, in the signal conversion step, a conversion control optical modulator may be used, which controls the ON / OFF of the signal conversion operation from electrical signal to optical signal according to the test cycle.

[0200] In this case, in the semiconductor inspection apparatus of the eighth form, in the configuration of the seventh form described above, the optical modulator for switching control of the signal switching unit can be configured to turn the signal switching operation ON during the period corresponding to the main scan in the stripe tube, and turn the signal switching operation OFF during the period corresponding to the retrace.

[0201] Furthermore, in the fifth type of semiconductor inspection method, in the configuration of the fourth type described above, in the signal conversion step, the optical modulator for conversion control can be configured to turn the signal conversion operation ON during the period corresponding to the main scan in the stripe tube, and to turn the signal conversion operation OFF during the period corresponding to the retrace.

[0202] In this way, by providing a conversion control optical modulator in addition to the optical modulator used for signal conversion in the signal conversion section, various measurement controls can be performed according to specific measurement conditions, such as controlling the ON / OFF of the signal conversion operation based on the main scan and retrace in the stripe tube as described above. Furthermore, as with the optical modulator used for signal conversion, an EO modulator, for example, can be suitably used as the conversion control optical modulator.

[0203] In the ninth type of semiconductor inspection apparatus, in any of the configurations of the first to eighth types described above, in the waveform measurement unit, the stripe tube can adjust the phase of the scanning cycle according to the period of the electrical signal time waveform to be measured in the test cycle.

[0204] In the sixth type of semiconductor inspection method, in any of the configurations of the first to fifth types described above, in the waveform measurement step, the stripe tube can adjust the phase of the scanning cycle according to the period of the electrical signal time waveform to be measured in the test cycle.

[0205] In this way, by adjusting the phase composition of the scanning period in the stripe tube of the waveform measurement unit, various measurement controls can be performed according to specific measurement conditions.

[0206] In the semiconductor inspection apparatus of the tenth form, in any of the configurations of the first to ninth forms described above, the signal conversion unit may be configured to generate two or more optical signals as optical signals, each of which has a time waveform corresponding to the time waveform of an electrical signal, and the conversion conditions are different for each other.

[0207] In the semiconductor inspection method of the seventh form, in any of the above-mentioned first to sixth forms, in the signal conversion step, it can be configured to generate two or more optical signals, each of which has a time waveform corresponding to the time waveform of the electrical signal, and the conversion conditions are different for each other.

[0208] In this way, by generating two or more different optical signals in the signal conversion unit and measuring the time waveforms of these optical signals in the waveform measurement unit, various measurements can be performed, such as measuring two optical signals with different delay times to observe eye patterns.

[0209] In the semiconductor inspection apparatus of the eleventh form, in any of the configurations of the first to tenth forms described above, the first wavelength of the probe light can be set in a wavelength range of 1050 nm to 5000 nm, and the second wavelength of the measurement light can be set in a wavelength range of 200 nm to 1050 nm.

[0210] In the semiconductor inspection method of the eighth form, in any of the above-mentioned first to seventh forms, the first wavelength of the probe light can be set in a wavelength range of 1050 nm to 5000 nm, and the second wavelength of the measurement light can be set in a wavelength range of 200 nm to 1050 nm.

[0211] By setting the first wavelength of the probe light and the second wavelength of the measurement light, which is different from the first wavelength, it is possible to effectively combine semiconductor device inspection using the probe light with waveform measurement using a stripe tube to modulate the intensity of the measurement light using an electrical signal.

[0212] In the twelfth type of semiconductor inspection apparatus, in any of the configurations of the first to eleventh types described above, the waveform analysis unit may be configured to correct the waveform image obtained in the signal conversion unit when the optical signal generation is ON, based on the substrate image obtained in the state where the optical signal generation is OFF.

[0213] In the ninth form of the semiconductor inspection method, in any of the configurations of the first to eighth forms described above, in the waveform analysis step, the waveform image obtained in the signal conversion step when the optical signal generation is ON is corrected based on the substrate image obtained in the state where the optical signal generation is OFF.

[0214] In this way, by correcting the waveform image based on the substrate image and using the corrected waveform image to determine the time waveform of the electrical signal, the temporal change of the reflected light intensity can be measured more accurately.

[0215] Industrial availability

[0216] The implementation method can be used as a semiconductor inspection apparatus and semiconductor inspection method capable of high-speed measurement of the time change in the intensity of reflected light when a probe light is irradiated onto a semiconductor device to be inspected.

[0217] Symbol Explanation

[0218] 1A…Semiconductor inspection apparatus, 2A~2D…Electrical signal measuring apparatus, D…Semiconductor device, 10…Semiconductor inspection section, 11…Inspection optical system, 12…Voltage application section, 12a…Test head, 12b…Test plate, 13…Dark box, 14…Stage, 15…Scanning optical system, 16…Imaging optical system, 17…Objective lens, 18…Turret, 19…Delay generator, 20…Optical measurement section, 21…Detection light source, 22…Optical coupler, 23…Optical amplifier, 24…Optical splitter, 25…Photodetector, 26…AC amplifier,

[0219] 30…Signal conversion unit, 31…Measuring light source, 32…Optical attenuator, 33…Optical modulator, 33a…First optical modulator, 33b…Second optical modulator, 34…Optical modulator for conversion control, 35…Optical coupler, 36a…First optical delay unit, 36b…Second optical delay unit, 37…Optical coupler, 40…Waveform measurement unit, 41…Input optical system, 42…Striped tube, 43…Output optical system, 44…Image sensor, 45…Synchronization unit, 50…Control device, 51…Inspection control unit, 52…Waveform analysis unit, 53…Input unit, 54…Display unit, 55…Scanning control unit, 61…Second optical measurement unit, 62…Second waveform measurement unit, 63…Frequency analysis unit,

[0220] 330…EO crystal, 331…input waveguide, 332…first branch waveguide, 333…second branch waveguide, 334…output waveguide, 335…RF electrode, 336…bias electrode, 337a~337d…ground electrode,

[0221] 410, 414… cylindrical lenses, 418… Powell lenses, 411, 412, 413, 415, 416, 417, 419… lenses, 430, 431… lenses,

[0222] 420… Peripheral tube, 421… Photoelectric surface, 422… Accelerating electrode, 423… Vertical scanning electrode, 424… Horizontal scanning electrode, 425… MCP, 426… Phosphor surface, 428… Mirror,

[0223] 80…Electrical signal supply unit, 81…Electrical signal output unit, 82…Synchronization signal output unit, 83…Trigger signal output unit.

Claims

1. A semiconductor inspection apparatus, comprising: An optical system is inspected, which illuminates a first wavelength of probe light onto a semiconductor device whose state changes over time according to a predetermined test cycle, and outputs reflected light that has been reflected by the semiconductor device. The optical measurement unit has a photodetector that detects the reflected light output from the inspection optical system and outputs an electrical signal having a time waveform corresponding to the time change in the intensity of the reflected light. The signal conversion unit has a measurement light source that supplies measurement light of a second wavelength different from the first wavelength, and an optical modulator that modulates the intensity of the measurement light based on the electrical signal output from the optical measurement unit, and outputs the measurement light modulated by the optical modulator as an optical signal having a time waveform corresponding to the time waveform of the electrical signal; A waveform measurement unit measures the time waveform of the optical signal output from the signal conversion unit; as well as The waveform analysis unit calculates the time waveform of the electrical signal based on the measurement results of the time waveform of the optical signal by the waveform measurement unit. The waveform measurement unit includes: A stripe tube includes: a photoelectric surface that generates electrons based on the input of the optical signal; a scanning electrode that scans electrons from the photoelectric surface along a predetermined scanning direction at a scanning period set according to the test period; and a fluorescent surface that generates a fluorescent image showing the time waveform of the optical signal by inputting electrons scanned by the scanning electrode; and An imaging element that captures the fluorescent image generated on the fluorescent surface of the striped tube and outputs a waveform image. The waveform analysis unit determines the time waveform of the electrical signal based on the waveform image output from the camera element.

2. The semiconductor inspection apparatus as claimed in claim 1, wherein, In the waveform measurement unit, the fluorescent surface of the stripe tube generates a fluorescence image by accumulating the time waveforms of the optical signal over multiple cycles with respect to the test period.

3. The semiconductor inspection apparatus as described in claim 1 or 2, wherein, It also includes a voltage application unit that applies a test pattern showing the voltage changing over time during the test cycle to the semiconductor device. The waveform measurement unit controls the measurement operation of the time waveform of the optical signal based on the synchronization signal or trigger signal supplied from the voltage application unit.

4. The semiconductor inspection apparatus according to any one of claims 1 to 3, wherein, The optical measurement unit has an optical amplifier that amplifies the reflected light output from the inspection optical system and outputs it, and the photodetector detects the reflected light amplified by the optical amplifier.

5. The semiconductor inspection apparatus according to any one of claims 1 to 4, wherein, The optical measurement unit has an amplification element that amplifies the AC component of the detection signal output from the photodetector and outputs it as the electrical signal.

6. The semiconductor inspection apparatus according to any one of claims 1 to 5, wherein, The optical modulator in the signal conversion unit is an EO modulator.

7. The semiconductor inspection apparatus according to any one of claims 1 to 6, wherein, The signal conversion unit has a conversion control optical modulator that controls the ON / OFF of the signal conversion operation from the electrical signal to the optical signal according to the test cycle.

8. The semiconductor inspection apparatus as claimed in claim 7, wherein, The optical modulator for conversion control in the signal conversion unit turns the signal conversion operation ON during the period corresponding to the main scan in the stripe tube, and turns the signal conversion operation OFF during the period corresponding to the retrace.

9. The semiconductor inspection apparatus according to any one of claims 1 to 8, wherein, In the waveform measurement unit, the stripe tube adjusts the phase of the scan cycle according to the period of the time waveform of the electrical signal to be measured in the test cycle.

10. The semiconductor inspection apparatus according to any one of claims 1 to 9, wherein, The signal conversion unit generates two or more optical signals as optical signals, each having a time waveform corresponding to the time waveform of the electrical signal and with different conversion conditions.

11. The semiconductor inspection apparatus according to any one of claims 1 to 10, wherein, The first wavelength of the probe light is set in the wavelength range of 1050nm to 5000nm, and the second wavelength of the measurement light is set in the wavelength range of 200nm to 1050nm.

12. The semiconductor inspection apparatus according to any one of claims 1 to 11, wherein, The waveform analysis unit corrects the waveform image obtained when the optical signal generation is ON, based on the base image obtained in the signal conversion unit when the optical signal generation is OFF.

13. A semiconductor inspection apparatus, comprising: An optical system is inspected, which illuminates a first wavelength of probe light onto a semiconductor device whose state changes over time according to a predetermined test cycle, and outputs reflected light that has been reflected by the semiconductor device. The optical measurement unit has a photodetector that detects the reflected light output from the inspection optical system and outputs an electrical signal having a time waveform corresponding to the time change in the intensity of the reflected light. The signal conversion unit has a measurement light source that supplies measurement light of a second wavelength different from the first wavelength, and an optical modulator that modulates the intensity of the measurement light based on the electrical signal output from the optical measurement unit, and outputs the measurement light modulated by the optical modulator as an optical signal having a time waveform corresponding to the time waveform of the electrical signal; The waveform measurement unit includes a stripe camera that measures the time waveform of the optical signal output from the signal conversion unit; as well as The waveform analysis unit calculates the time waveform of the electrical signal based on the measurement results of the time waveform of the optical signal by the waveform measurement unit. The stripe camera outputs a waveform image showing the time waveform of the light signal based on the input light signal. The waveform analysis unit determines the time waveform of the electrical signal based on the waveform image output from the stripe camera.

14. A semiconductor inspection method, comprising: The inspection step involves irradiating a semiconductor device with a first wavelength of probe light onto the device, whose state changes over time according to a predetermined test cycle, and outputting reflected light that has been reflected by the probe light in the semiconductor device. In the optical measurement step, a photodetector that detects the reflected light output in the inspection step is used to output an electrical signal having a time waveform corresponding to the time change in the intensity of the reflected light; In the signal conversion step, an optical modulator is used to intensity-modulate the measurement light of a second wavelength different from the first wavelength based on the electrical signal output in the optical measurement step, and the measurement light modulated by the optical modulator is output as an optical signal having a time waveform corresponding to the time waveform of the electrical signal; The waveform measurement step measures the time waveform of the optical signal output in the signal conversion step. as well as The waveform analysis step involves determining the time waveform of the electrical signal based on the measurement results of the time waveform of the optical signal obtained in the waveform measurement step. The waveform measurement step uses a stripe tube comprising: a photoelectric surface that generates electrons based on the input of the optical signal; a scanning electrode that scans the electrons from the photoelectric surface along a predetermined scanning direction according to a scanning period set according to the test period; and a stripe tube that inputs the electrons scanned by the scanning electrode and generates a fluorescent image of the time waveform of the optical signal, wherein the fluorescent image generated on the fluorescent surface of the stripe tube is photographed and a waveform image is output. The waveform analysis step determines the time waveform of the electrical signal based on the waveform image output in the waveform measurement step.

15. The semiconductor inspection method as described in claim 14, wherein, In the waveform measurement step, the fluorescent surface of the stripe tube generates the fluorescence image by accumulating the time waveforms of the optical signal over multiple cycles with respect to the test period.

16. The semiconductor inspection method as described in claim 14 or 15, wherein, It also includes a voltage application step of applying a test pattern of voltage variation over time during the test cycle to the semiconductor device. In the waveform measurement step, the measurement action of the time waveform of the optical signal is controlled based on the synchronization signal or trigger signal supplied in the voltage application step.

17. The semiconductor inspection method according to any one of claims 14 to 16, wherein, In the signal conversion step, an optical modulator for conversion control is used to control the ON / OFF operation of the signal conversion from the electrical signal to the optical signal according to the test cycle.

18. The semiconductor inspection method as described in claim 17, wherein, In the signal conversion step, the conversion control optical modulator sets the signal conversion action to ON during the period corresponding to the main scan in the stripe tube, and sets the signal conversion action to OFF during the period corresponding to the retrace.

19. The semiconductor inspection method according to any one of claims 14 to 18, wherein, In the waveform measurement step, the stripe tube adjusts the phase of the scan cycle according to the period of the time waveform of the electrical signal to be measured in the test cycle.

20. The semiconductor inspection method according to any one of claims 14 to 19, wherein, In the signal conversion step, two or more optical signals are generated as optical signals, each having a time waveform corresponding to the time waveform of the electrical signal and having different conversion conditions.

21. The semiconductor inspection method according to any one of claims 14 to 20, wherein, The first wavelength of the probe light is set in the wavelength range of 1050nm to 5000nm, and the second wavelength of the measurement light is set in the wavelength range of 200nm to 1050nm.

22. The semiconductor inspection method according to any one of claims 14 to 21, wherein, In the waveform analysis step, the waveform image obtained when the optical signal is generated in the ON state is corrected based on the base image obtained when the optical signal is generated in the OFF state during the signal conversion step.

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