JP6756494B2 - Signal amplification device and semiconductor inspection device - Google Patents

Description

The present invention relates to a technique for amplifying the signal strength of a target signal to be detected.

When detecting a signal of a specific frequency, signal detection may be performed using a superheterodyne type detector (spectrum analyzer). Such a detection device is disclosed in, for example, Patent Document 1.

FIG. 4 is a schematic configuration diagram of a general detection device 900. The detector 900 includes a mixing circuit 910, a local oscillator 920, a filter circuit 930, an amplifier circuit 940, and a detector 950.

The mixing circuit 910 multiplies the target signal (frequency f _S ) and the local oscillation signal (frequency f _LO ) from the local oscillator 920 to produce a sum frequency signal (frequency f _S + f _LO ) and a difference frequency signal (frequency f _S −). f _LO ) is generated. The filter circuit 930 removes the sum frequency signal from the signals output from the mixing circuit 910. The amplifier circuit 940 amplifies the intensity of the difference frequency signal (frequency f _S− f _LO ) output from the filter circuit 930 and outputs it to the detector at 950.

In this way, in the detector 900, when the intensity of the target signal to be detected is very small, the frequency is converted into a signal (difference frequency signal) in the frequency band in which the amplification factor of the amplifier circuit 940 is sufficient, and the target signal is detected. Detected by vessel 950.

Japanese Unexamined Patent Publication No. 6-2430669

In the conventional detection device 900, it is possible to amplify a minute signal by each of the mixing circuit 910 and the amplifier circuit 940, but a technique for appropriately amplifying the signal strength of the target signal before inputting to the mixing circuit 910 is known. Absent.

An object of the present invention is to provide a new technique for amplifying the signal strength of a target signal to be detected.

In order to solve the above problems, the first aspect is a signal amplification device that amplifies the signal strength of the target signal, in which a distribution unit that distributes the target signal and n (n is a natural number) that multiplies the two signals. a front mixing section which have a number of pre-stage mixing circuit, a local oscillation circuit outputting a local oscillation signal, a signal output from the preceding stage mixing unit, a first subsequent mixing circuit for multiplying and said local oscillation signal The rear-stage mixing unit includes a rear-stage mixing unit and a filter unit that attenuates a specific frequency component among the signals output from the rear-stage mixing unit, and the front-stage mixing unit includes two target signals distributed by the distribution unit. What was seen including a first of said pre-stage mixing circuit for multiplying the case of n = 1, the front mixing section outputs a signal from the first of the pre-stage mixing circuit to the first subsequent mixing circuit, n In the case of> 1, the pre-stage mixing section includes the second to n-th pre-stage mixing circuits, and the k-th (k is an integer of 2 or more and n or less) the pre-stage mixing circuit is the first (k-1). ) Is multiplied by the signal output from the pre-stage mixing circuit and one of the target signals distributed by the distribution unit, and the pre-stage mixing unit transfers the signal from the n-th pre-stage mixing circuit to the first. Output to the subsequent mixing circuit .

The second aspect is the signal amplification device according to the first aspect, and the pre-stage mixing unit has an odd number of the pre-stage mixing circuits.

The third aspect is a signal amplifying apparatus according to the first or second state like, the local oscillation signal, the smaller than the frequency f _S of the target signal, and can pass through the filter circuit such a frequency f _LO, the subsequent mixing section further comprises an output signal of the first subsequent mixing circuit and the second subsequent mixing circuit for multiplying an output signal of the preceding stage mixing unit.

The fourth aspect is the signal amplification device according to the second aspect, in which the frequency of the local oscillation signal output by the local oscillation signal is fixed.

A fifth aspect is a semiconductor inspection apparatus, which comprises a holding unit for holding a semiconductor sample, a light beam irradiating unit for irradiating the semiconductor sample with a light beam for generating a terahertz wave from the semiconductor sample, and the semiconductor. It includes a terahertz wave detection unit for detecting the terahertz wave radiated from the sample, and a detection wave device you detecting a signal output from the terahertz wave detecting unit, wherein the detection device amplifies the signal strength of the target signal A signal amplification device and a detector for detecting the signal strength of the signal amplified by the signal amplification device are provided, and the signal amplification device includes a distribution unit that distributes a target signal and n (multiplying two signals). n is a pre-stage mixing circuit having (natural number) number of pre-stage mixing circuits, and the pre-stage mixing unit includes a first pre-stage mixing circuit that multiplies two target signals distributed by the distribution unit. , N = 1, the pre-stage mixing unit outputs a signal from the first pre-stage mixing circuit to the first rear-stage mixing circuit, and when n> 1, the pre-stage mixing unit starts from the second stage. The k-th (k is an integer of 2 or more and n or less) pre-stage mixing circuit including the n-th pre-stage mixing circuit includes a signal output from the pre-stage mixing circuit of the (k-1) th and said. The target signals distributed by the distribution unit are multiplied by each other, and the front-stage mixing unit outputs a signal from the nth front-stage mixing circuit to the first rear-stage mixing circuit .

According to the signal amplification device according to the first aspect, the original amplitudes can be multiplied by multiplying the target signals by the pre-stage mixing circuit. As a result, the signal strength of the original target signal can be amplified.

Moreover , the target signal amplified by the pre-stage mixing section can be converted to a desired frequency according to the local oscillation signal, and unnecessary components can be removed by filtering. This makes it possible to suitably detect the target signal.

Further, by inputting the target signal to each of the plurality of pre-stage mixing circuits connected in series, the amplitude of the target signal can be multiplied by the number of times according to the number of pre-stage mixing circuits. Therefore, the target signal can be theoretically amplified without limit.

According to the signal amplification device according to the second aspect, the difference frequency component of the signals output from the last pre-stage mixing circuit of the pre-stage mixing unit can be set to a constant. As a result, unnecessary components can be removed, so that detection can be preferably performed.

According to the signal amplification device according to the third aspect, the output signal of the first post-stage mixing circuit can be converted into the frequency of the local oscillation signal by the second post-stage mixing circuit. Therefore, by selecting the frequency of the locally oscillated signal according to the filter circuit, good detection can be performed even if frequency noise is present in the target signal.

According to the signal amplification device according to the fourth aspect, by fixing the frequency of the locally oscillated signal, it is not necessary to adjust the frequency of the locally oscillated signal. This makes it possible to easily detect the target signal. Further, by using a local oscillator having a fixed frequency of the local oscillation signal, noise can be significantly reduced as compared with the case of using a voltage controlled oscillator (VCO or VCXO) having a variable frequency.

According to the semiconductor inspection device according to the fifth aspect, the signal strength of the terahertz wave radiated from the semiconductor sample can be satisfactorily detected by amplifying it by the signal sub-device of the detection device.

It is a schematic block diagram of the detection apparatus which concerns on 1st Embodiment. It is a schematic block diagram of the detection apparatus which concerns on 2nd Embodiment. It is a schematic block diagram of the semiconductor inspection apparatus which concerns on 3rd Embodiment. It is a schematic block diagram of a general detection apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the components described in this embodiment are merely examples, and the scope of the present invention is not limited to them. Further, in the drawings, for the sake of easy understanding, the dimensions and numbers of each part may be exaggerated or simplified as necessary.

<1. First Embodiment>
FIG. 1 is a schematic configuration diagram of the detection device 1 according to the first embodiment. The detection device 1 has a configuration particularly suitable for detecting a high frequency signal such as a terahertz wave. The detector 1 includes distribution units 10 and 11, a front-stage mixing unit 20, a local oscillator 30, a rear-stage mixing unit 40, a bandpass filter 50, an amplifier circuit 60, and a detector 70.

The distribution unit 10 distributes the target signal (frequency is f _S ) to be detected to each of the n pre-stage mixing circuits FM1 to FMn included in the pre-stage mixing unit 20 (n is an integer of 1 or more). .. The target signal is preferably a voltage signal, but may be a current signal.

The distribution unit 10 may be a branch portion in which one or a plurality of branch wires are electrically connected to one wire. As a means for connecting the conducting wires, welding, soldering, crimping, winding, or a connecting member such as an alligator clip may be used. Each of the target signals distributed by the distribution unit 10 to each of the pre-stage mixing circuits FM1 to FMn has substantially the same amplitude. In addition, in order to realize strict distribution of the target signal, the distribution unit 10 may be configured by a circuit using an operational amplifier or the like. However, it is not essential that the amplitudes of the target signals after distribution are the same.

Each of the pre-stage mixing circuits FM1 to FMn of the pre-stage mixing unit 20 is a mixer that generates and outputs a mixed signal by multiplying two input signals. The pre-stage mixing circuits FM1 to FMn are connected in series.

The same target signal distributed from the distribution unit 10 is input to the first-stage mixing circuit FM1 connected first. The pre-stage mixing circuit FM1 inputs a signal obtained by multiplying the same target signals to the second-stage pre-stage mixing circuit FM2. Further, the pre-stage mixing circuit FMk connected to the k-th (k is an integer of 2 or more and less than n) is a signal input from the pre-stage mixing circuit FM (k-1) connected to the (k-1) th. , The signal obtained by multiplying the target signal input from the distribution unit 10 is input to the (k + 1) th connected pre-stage mixing circuit FM (k + 1). The mixing unit 20 has an amplification function for amplifying the amplitude of the target signal by the pre-stage mixing circuits FM1 to FMn.

Two target signals having the same amplitude, period and phase are input to the pre-stage mixing circuit FM1. Here, when the target signal that is distributed to the mixing circuit FM1 put the .alpha.sin _{(f S),} the signal output by the pre-stage mixing circuit FM1 is represented by the formula (1).

As shown in equation (1), the signal output by the pre-stage mixing circuit FM1 amplitude (= alpha ^2/2) is the original target signal amplitude (= alpha), ingredients multiply the amplitude alpha of the target signal ( = Α ² ). Therefore, if α is larger than the square root of “2” (√2), it means that the original signal is amplified. The distribution unit 10 and the pre-stage mixing unit 20 are the minimum configuration examples of the signal amplification device.

Here, in order to facilitate understanding, the constant "cos0" and the coefficient of the amplitude α (= −1 / 2) will be omitted below.

The front mixing circuit FM2, a signal A1 from the preceding mixing circuit FM1, a target signal _{(= α · sin (f S} )) and are input. That is, the signal A2 output by the pre-stage mixing circuit FM2 is simply represented by the equation (2).

Similarly, the signal output by the pre-stage mixing circuit FM3 is represented by the equation (3).

The signal output by the previously connected pre-stage mixing circuit FMn is represented by the equation (4) when n is an even number and the equation (5) when n is an odd number.

As shown by the formula (4) or the formula (5), the pre-stage mixing unit 20 amplifies the signal strength of the target signal input to the detection device 1 by the number of the pre-stage mixing circuits FM1 to FMn. be able to.

The distribution unit 11 distributes the signal output from the front-stage mixing circuit FMn connected to the end of the front-stage mixing unit 20 to each of the two rear-stage mixing circuits PM1 and PM2 of the rear-stage mixing unit 40. Like the distribution unit 10, the distribution unit 11 may be a branch portion in which a branch lead wire is electrically connected to the lead wire. Further, the distribution unit 11 may be a circuit using an operational amplifier or the like.

The local oscillator 30 inputs a local oscillation signal having a frequency of f _LO (hereinafter, referred to as “LO signal”) to the first post-stage mixing circuit PM1 of the post-stage mixing unit 40.

The latter-stage mixing circuits PM1 and PM2 included in the latter-stage mixing unit 40 are mixers that generate and output a mixed signal by multiplying two signals.

The latter-stage mixing circuit PM1 is generated by multiplying the signal input from the distribution unit 11 (the signal input from the first-stage mixing unit 20) and the LO signal (= βsin (f _LO )) input from the local oscillator 30. The signal is input to the subsequent mixing circuit PM2. For example, assuming that the number of front-stage mixing circuits FM1 to FMn is an odd number, it is represented by the equation (5), and if the LO signal is βsin (f _LO ), the signal output by the rear-stage mixing circuit PM1 is expressed by the equation (5). It is represented by 6).

The rear-stage mixing circuit PM2 uses the bandpass filter 50 to generate a mixed signal generated by multiplying the signal input from the distribution unit 11 (the signal input from the front-stage mixing unit 20) and the signal input from the rear-stage mixing circuit PM1. input. Assuming that the signal input from the latter-stage mixing circuit PM1 is represented by the equation (6), the signal output by the latter-stage mixing circuit PM2 is the equation (7) obtained by multiplying the equation (5) and the equation (6). It is represented by.

As shown by Equation 7, the frequencies of the signals output from the post-stage mixing circuit PM2 are theoretically "2 (n + 1) f _S + f _LO ", "2 (n + 1) f _S- f _LO ", and "f". Includes " _LO ".

The bandpass filter 50 passes a signal near the frequency f _{LO of the} LO signal output by the local oscillator 30 and performs filtering to attenuate signals in other frequency bands. The bandpass filter 50 filters the signal input from the post-stage mixing circuit PM2 of the post-stage mixing unit 40 and inputs it to the amplifier circuit 60.

For example, it is assumed that the signal represented by the equation (7) is input to the bandpass filter 50. When the frequency f _{S of the} target signal is sufficiently larger than the frequency f _{LO of the} LO signal, the bandpass filter 50 changes the frequency from “2 (n + 1) f _S + f _LO ” to “2 (n + 1) f _S − f _LO ”. It is possible to attenuate the component of the frequency f _LO and specifically pass the signal of the component of the frequency f _LO (= α ^{2 (n + 1)} β sin (f _LO )).

The amplifier circuit 60 generates an amplified signal obtained by amplifying the signal input from the bandpass filter 50 and outputs it to the detector 70. The amplifier circuit 60 has a frequency characteristic, and here, the amplifier circuit 60 has a frequency characteristic for amplifying a signal in the vicinity of the frequency f _LO .

The detector 70 detects a signal input from the amplifier circuit 60, and corrects the detected signal according to various parameters (for example, the number of mixing circuits of the pre-stage mixing unit 20). As a result, the detector 70 detects the target signal whose frequency is converted from f _S to f _LO .

As described above, according to the detection device 1, the pre-stage mixing unit 20 multiplies the amplitude α of the target signal by the number (n) of the pre-stage mixing circuits FM1 to FMn in which the amplitude α is connected in series. Can be done. Therefore, the signal strength of the target signal can be amplified. Further, since the signal strength can be amplified according to the number of the pre-stage mixing circuits, the limit of the amplification factor can be theoretically eliminated.

Further, by setting the number of the pre-stage mixing circuits FM1 to FMn to an odd number, the difference frequency component, which is a low frequency component, can be set to a certain number among the signals output from the last pre-stage mixing circuit FMn. As a result, unnecessary components can be removed, so that detection can be preferably performed.

Further, in the case of the conventional detection device 900 shown in FIG. 4, it is necessary to adjust the frequency f _{LO of the} local oscillator according to the target signal (frequency f _S ). Therefore, when the target signal has frequency noise, frequency fluctuation occurs in the input signal to the filter circuit 930. This frequency fluctuation may affect a target minute signal in the input signal to the amplifier circuit 940. On the other hand, in the detection device 1, the distribution unit 11 and the rear-stage mixing unit 40 can convert the frequency component of the signal output from the front-stage mixing unit 20 into the frequency f _{LO of the} LO signal. That is, it can be detected at the frequency f _LO of the LO signal without depending on the frequency f _S of the target signal. Therefore, the task of adjusting the frequency of the LO signal in accordance with the frequency f _S of the target signal is not required, it can be fixed frequency f _LO of the LO signal. As a result, the detection of the target signal can be greatly simplified.

Further, in the case of the conventional detection device 400, a voltage controlled oscillator (VCO or VCXO) is used for the local oscillator 920 in order to change the frequency of the LO signal. In this case, noise generated from the voltage controlled oscillator is unavoidable and may affect a target minute signal. On the other hand, in the case of the detection device 1, a low frequency oscillator such as a crystal oscillator can be used as the local oscillator 30 having a fixed oscillation frequency. As a result, noise can be significantly reduced as compared with the case of using a voltage controlled oscillator (VCO or VCXO) having a variable frequency. Therefore, a weak target signal can be detected more preferably.

In the above embodiment, the pre-stage mixing unit 20 includes a plurality of pre-stage mixing circuits FM1 to FMn. However, the pre-stage mixing unit 20 may include only one pre-stage mixing circuit FM1. In this case, for example, it is assumed that the signal of interest 80MHz is input to the detection device 1, the oscillation frequency _{f LO} to the local oscillator 30 and employing the crystal oscillation circuit of 455 kHz. In this case, a signal having a frequency component of 160 MHz is output to the distribution unit 11 from the pre-stage mixing circuit FM1 of the pre-stage mixing unit 20. Then, signals having frequency components of 160 MHz + 455 kHz and 160 MHz-455 kHz are output from the latter stage mixing circuit PM1 and input to the latter stage mixing circuit PM2. Further, signals having frequency components of 320 MHz + 455 kHz, 455 kHz and 320 MHz-455 kHz are output from the post-stage mixing circuit PM2 and input to the bandpass filter 50. The 455 kHz signal that has passed through the bandpass filter 50 is input to the amplifier circuit 60, and its signal strength is amplified. Then, the signal strength of the amplified 455 kHz signal is detected by the detector 70.

In the case of this example, the front-stage mixing circuit FM1 and the rear-stage mixing circuit PM2 multiply the original amplitude α by the amplitude α twice, so that the signal obtained by the cube of the amplitude α is output to the detector 70. Become. In the detector 70, the signal strength of the original target signal can be specified by appropriately correcting the signal input from the amplifier circuit 60 according to the amplification factor, so that the detection of the target signal can be appropriately performed.

<2. Second Embodiment>
Next, the second embodiment will be described. In the following description, elements having the same functions as the elements already described may be given the same code or a code to which an alphabet is added, and detailed description may be omitted.

FIG. 2 is a schematic configuration diagram of the detection device 1A according to the second embodiment. In the detection device 1A, the distribution unit 11 is omitted. Further, the rear-stage mixing section 40A includes a rear-stage mixing circuit PM1, but the second-stage mixing circuit PM2 is omitted.

The latter-stage mixing circuit PM1 inputs a signal obtained by multiplying the signal input from the first-stage mixing unit 20 and the LO signal input from the local oscillator 30 to the low-pass filter 50A. That is, signals having frequency components of (n + 1) f _S + f _LO and (n + 1) f _S −f _LO are input to the low-pass filter 50A from the subsequent mixing circuit PM1. The low-pass filter 50A selectively passes the low-frequency component (n + 1) fs-f _LO and inputs it to the amplifier circuit 60.

Also in the detection device 1A, it is possible to amplify the signal strength of the target signal by one or more pre-stage mixing circuits included in the pre-stage mixing unit 20. Therefore, the detection of the target signal can be preferably performed.

However, when the signal strength is very small and a high frequency (for example, 1 MHz or more or 10 MHz or more) target signal is detected, it is necessary to appropriately select the low-pass filter 50A and the amplifier circuit 60. In addition, it may be necessary to adjust the frequency f _LO of the LO signal generated by the local oscillator 30 according to the target signal. Therefore, when the signal strength is very small and the signal strength is high, it is preferable to adopt the detection device 1 according to the first embodiment.

<3. Third Embodiment>
FIG. 3 is a schematic configuration diagram of the semiconductor inspection device 100 according to the third embodiment. The semiconductor inspection device 100 detects (detects) a terahertz wave (0.1 THz to 30 THz) emitted from the semiconductor sample S1 by irradiating the semiconductor sample S1 with a light beam having a predetermined wavelength. By measuring the intensity of the generated terahertz wave, the characteristics or defects of the semiconductor sample S1 can be inspected. The semiconductor sample S1 is, for example, an electronic device such as a transistor formed of a semiconductor such as Si, Ge, or GaAs, an integrated circuit (IC or LSI), a resistor or a capacitor, or a power device using a wide-gap semiconductor. Further, the semiconductor sample S1 may be an electronic device (photo device) that utilizes the photoelectric effect, such as a photodiode, an image sensor such as a CMOS sensor or a CCD sensor, a solar cell, or an LED.

The semiconductor inspection device 100 includes a detection device 1, a light beam irradiation unit 80, a terahertz wave detection unit 82, a stage 84, and a delay unit 86.

The light beam irradiation unit 80 includes a femtosecond laser 801. The femtosecond laser 801 emits pulsed light (pulse light LP1) having a wavelength in the ultraviolet to infrared region including a visible light region of 200 nm (nanometer) or more and 2.5 μm (micrometer) or less, for example. As a specific example, linearly polarized pulsed light having a central wavelength of around 800 nm, a period of several kHz to several hundred MHz, and a pulse width of about 10 to 150 femtoseconds is emitted from the femtosecond laser 801. Of course, other wavelength regions (eg, visible light wavelengths such as blue wavelength (450 to 495 nm), green wavelength (495 to 570 nm), ultraviolet wavelength (200 to 380 nm), near infrared (0.7 to 2.5 μm)). ) May be emitted.

The pulsed light LP1 emitted from the femtosecond laser 801 is split into two by the beam splitter BE1. One of the divided pulsed lights is applied to the semiconductor sample S1 as inspection light LP11 (light beam). The inspection light LP11 is applied to the semiconductor sample S1 so that the optical axis of the inspection light LP11 is obliquely incident on the main surface (widest surface) of the semiconductor sample S1. In the example shown in FIG. 3, the irradiation angle is set so that the incident angle is 45 degrees. However, the incident angle is not limited to such an angle, and can be appropriately changed within the range of 0 degrees to 90 degrees.

The principle of generating a terahertz wave in a semiconductor sample such as the semiconductor sample S1 is as described in, for example, International Publication No. 2006-093265. That is, the sample is irradiated with a femtosecond pulsed laser, and photoexcited carriers are generated in the sample. The photoexcited carriers generated in the sample are accelerated by an electric field or diffusion in the sample to generate a transient current. Specifically, the surface electric field on the surface of the semiconductor accelerates the photoexcited carriers to generate a transient current. This transient current produces a terahertz wave (transient current effect).

The terahertz wave detection unit 82 includes a terahertz wave detector 821. The terahertz wave LT1 is appropriately focused by a parabolic mirror or the like, and is incident on the terahertz wave detector 821. The terahertz wave detector 821 has, for example, a light conduction switch (light conduction antenna). The detection light LP12 is incident on the photoconducting switch. The detection light LP12 is the other pulsed light obtained by splitting the pulsed light LP1 by the beam splitter BE1. When the terahertz wave LT1 is incident on the terahertz wave detector 821 and the detection light LP12 is incident on the terahertz wave detector 821, the electric field strength of the terahertz wave LT1 (hereinafter, also referred to as “THH intensity”) is instantaneously detected by the photoconduction switch. A current is generated according to (notation). The current signal corresponding to the electric field strength is sent to the detection device 1 and detected.

The terahertz wave detector 821 detects the electric field strength (terahertz wave intensity, hereinafter also referred to as “THH intensity”) of the terahertz wave LT1 generated in the semiconductor sample S1 in response to the irradiation of the detection light LP12. The terahertz wave detector 821 may be composed of an element different from the light conduction switch. As an element for detecting a terahertz wave, for example, a Schottky barrier diode or a nonlinear optical crystal can be adopted.

The stage 84 is a holding portion for holding the semiconductor sample S1. The semiconductor sample S1 is placed on the holding surface of the surface of the stage 84. The stage 84 may suck and hold the semiconductor sample S1 by providing one or a plurality of suction holes on the holding surface of the stage 84.

The delay unit 86 includes a delay stage 861 and a delay stage drive unit 863.

The delay stage 861 is provided on the optical path of the detection light LP12. The delay stage 861 includes a reflection mirror 8610 that reflects the detection light LP12 in parallel with the incident direction and shifted from the optical axis at the time of incident. The detection light LP12 reflected by the reflection mirror 8610 is guided to the terahertz wave detector 821 through a group of mirrors arranged on the optical path.

The delay stage drive unit 863 linearly reciprocates the delay stage 861 along the optical path of the detection light LP12. As a result, the optical path length of the detection light LP12 changes, so that the time for the detection light LP12 to reach the terahertz wave detector 821 can be delayed. Therefore, the timing at which the terahertz wave detector 821 detects the terahertz wave LT1 can be changed. The terahertz wave LT1 generated in this example is a pulse wave. Therefore, by giving a delay to the detection light LP12, the THz intensity can be detected in different phases. Although the delay unit 86 gives a delay to the detection light LP12, the inspection light LP11 may be delayed.

In the semiconductor inspection device 100, the femtosecond laser 801 emits pulsed light at a cycle of 80 MHz, so that a current signal indicating terahertz intensity is input to the detection device 1 at a cycle of 80 MHz. As described in the first embodiment, the detection device 1 can suitably detect such a high frequency signal.

By arranging a light conduction switch or the like that generates a terahertz wave on the optical path of the inspection light LP11, the semiconductor sample S1 can be irradiated with the terahertz wave. Then, the reflected (or transmitted) terahertz wave may be detected in the semiconductor sample S1. The detection device 1 can also be applied to the detection of this terahertz wave. Further, when irradiating a terahertz wave, the inspection target is not limited to the semiconductor sample, and various objects can be inspected.

Although the present invention has been described in detail, the above description is exemplary in all aspects and the invention is not limited thereto. It is understood that a myriad of variations not illustrated can be envisioned without departing from the scope of the invention. Further, the configurations described in the above embodiments and the modifications can be appropriately combined or omitted as long as they do not conflict with each other.

1,1A Detector 10, 11 Distributor 20 Front-stage mixing unit 30 Local oscillator 40, 40A Rear-stage mixing unit 50 Bandpass filter (filter unit)
50A low-pass filter (filter section)
60 Amplifier circuit 70 Detector 80 Light beam irradiation unit 801 Femtosecond laser 82 Terahertz wave detector 821 Terahertz wave detector 84 Stage (holding unit)
100 Semiconductor inspection device FM1 to FMn Pre-stage mixing circuit LP11 Inspection light (optical beam)
LT1 Terahertz wave PM1 1st post-stage mixing circuit PM2 2nd post-stage mixing circuit f _LO Local oscillation signal frequency f _S Target signal frequency

Claims (5)

A signal amplification device that amplifies the signal strength of the target signal.
A distributor that distributes the target signal and
N multiplying two signals (n is a natural number) preceding the mixing section to have a number of pre-stage mixing circuit,
A local oscillator circuit that outputs a local oscillator signal and
A rear-stage mixing unit having a first rear-stage mixing circuit that multiplies the signal output from the front-stage mixing unit and the local oscillation signal.
Of the signals output from the latter-stage mixing section, a filter section that attenuates a specific frequency component and
With
The front mixing section, viewed contains the first of the pre-stage mixing circuit for multiplying two of said target signal each other that are distributed by the distribution unit,
When n = 1, the pre-stage mixing unit outputs a signal from the first pre-stage mixing circuit to the first post-stage mixing circuit.
When n> 1,
The pre-stage mixing unit includes the second to n-th pre-stage mixing circuits.
The k-th (k is an integer of 2 or more and n or less) pre-stage mixing circuit includes a signal output from the pre-stage mixing circuit of the (k-1) th (k-1) and one object distributed by the distribution unit. Multiply the signals
The front stage mixing unit is a signal amplification device that outputs a signal from the nth front stage mixing circuit to the first rear stage mixing circuit . The signal amplification device according to claim 1.
The pre-stage mixing unit is a signal amplification device having an odd number of the pre-stage mixing circuits. The signal amplification device according to claim 1 or 2.
The locally oscillated signal has a frequency f _LO that is smaller than the frequency f _{S of the} target signal and can pass through the filter circuit.
The latter mixing section
A signal amplification device further comprising a second rear-stage mixing circuit that multiplies the output signal of the first-stage mixing circuit with the output signal of the front-stage mixing unit. The signal amplification device according to claim 2.
A signal amplification device in which the frequency of the local oscillation signal output by the local oscillation signal is fixed. It is a semiconductor inspection device
A holding part that holds the semiconductor sample and
A light beam irradiation unit that irradiates the semiconductor sample with a light beam that generates a terahertz wave from the semiconductor sample.
A terahertz wave detection unit that detects terahertz waves radiated from the semiconductor sample,
A detection wave device you detecting a signal output from the terahertz wave detecting unit,
Equipped with a,
The detector is
A signal amplification device that amplifies the signal strength of the target signal,
A detector that detects the signal strength of the signal amplified by the signal amplification device, and
With
The signal amplification device is
A distributor that distributes the target signal and
A pre-stage mixing unit having n (n is a natural number) pre-stage mixing circuits that multiply two signals,
With
The pre-stage mixing unit includes a first pre-stage mixing circuit that multiplies the two target signals distributed by the distribution unit.
When n = 1, the pre-stage mixing unit outputs a signal from the first pre-stage mixing circuit to the first post-stage mixing circuit.
When n> 1,
The pre-stage mixing unit includes the second to n-th pre-stage mixing circuits.
The k-th (k is an integer of 2 or more and n or less) pre-stage mixing circuit includes a signal output from the pre-stage mixing circuit of the (k-1) th (k-1) and one object distributed by the distribution unit. Multiply the signals
The pre-stage mixing unit is a semiconductor inspection device that outputs a signal from the nth pre-stage mixing circuit to the first post-stage mixing circuit .

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