JP3353316B2 - Method and apparatus for detecting surface or internal information of sample - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting surface or internal information of a sample for detecting two-dimensional internal information on the surface or inside of the sample by utilizing a photoacoustic effect.

[0002]

[Prior Art] Photoacoustic Effect
In 1881 Tyndall, Bell,
Discovered by Rentogen et al. That is,
As shown in FIG. 30, when the intensity-modulated light (intermittent light) 19 is used as excitation light and condensed and irradiated on the sample 7 by the lens 5, heat is generated in the light absorption region V _op 21 and the heat diffusion length This is a phenomenon in which the thermal diffusion region V _th 23 given by μ _s 22 is periodically diffused, and an elastic wave (ultrasonic wave) is generated by the thermal strain wave. The ultrasonic wave, that is, the photoacoustic signal is detected using a microphone (acousto-electrical transducer), a piezoelectric element, or an optical interferometer, and a signal component synchronized with the modulation frequency of the excitation light is obtained. Information can be obtained. The thermal diffusion length μ _s 22 is obtained by setting the modulation frequency of the excitation light to f _L , the thermal conductivity k, the density ρ,
And the specific heat c, it is given by the following equation (Equation 1).

[0003]

(Equation 1)

Regarding the method of detecting the photoacoustic signal, see, for example, the document “Non-destructive inspection; Vol. 36, No. 10, p.
0 to p. 736 (October 1987) "and" IEI 1986 Ultra Sonics Symposium; pp. 515-526 (1986) (IEEE1
986ULTRA-SONICS SYMPOSIU
M; p. 515-526 (1986) ".

An example will be described with reference to FIG. The parallel light emitted from the laser 1 is intensity-modulated by an acousto-optic modulator (AO modulator) 2, and the intermittent light, that is, the excitation light is converted into a parallel light 1 having a desired beam diameter by a beam expander 3.
After being set to 9, the light is reflected by the half mirror 4 and condensed by the lens 5 on the surface of the sample 7 on the XY stage 6. Ultrasonic waves are generated by the thermostrictive waves generated from the condensing section 21 on the sample 7, and at the same time, minute displacement occurs on the surface of the sample 7. This minute displacement is detected by a Michelson interferometer described below. After the parallel light emitted from the laser 8 is expanded to a desired beam diameter by the beam expander 9, it is split into two optical paths by the half mirror 10, one of which is used as the probe light 24 as the lens 5.
The light is condensed on the condensing part 21 on the sample 7 by the above. The other irradiates the reference mirror 11. The reflected light from the sample 7 and the reflected light from the reference mirror 11 interfere with each other on the half mirror 10, and the interference light is condensed on a photoelectric conversion element 13 such as a photodiode by a lens 12. After the photoelectrically converted interference intensity signal is amplified by the preamplifier 14,
It is sent to the lock-in amplifier 16. Lock-in amplifier 1
6, a transmitter 15 used for driving the acousto-optic modulator 2 is used.
, And only the modulation frequency component included in the interference intensity signal is extracted. This frequency component has information on the surface or inside of the sample 7 corresponding to the frequency. From Equation 1, the thermal diffusion length μ _s21 can be changed by changing the modulation frequency, and information in the depth direction of the sample can be obtained. If there is a defect such as a crack in the thermal diffusion region V _th23, the amplitude of the modulation frequency component in the interference intensity signal and the phase with respect to the modulation frequency signal change, so that the existence thereof can be known. The XY stage movement signal and the output signal from the lock-in amplifier 16 are processed by a computer 17, and a photoacoustic signal at each point on the sample is output to a display 18 such as a monitor television as two-dimensional image information.

[0006]

The above prior art is an extremely effective means capable of detecting a photoacoustic signal in a non-contact and nondestructive manner, but has the following problems.

That is, in the conventional photoacoustic detection optical system shown in FIG. 29, when two-dimensional internal information of a sample is to be obtained, excitation light for generating a photoacoustic effect and a sample generated by the photoacoustic effect are used. It is necessary to relatively two-dimensionally scan the sample with a probe light for detecting a minute displacement of the surface. Since the two-dimensional scanning is a so-called point scanning in which information is detected one by one, an enormous detection time is required to scan the entire surface of the sample.
This enormous detection time is the biggest reason that photoacoustic detection technology has not been applicable to the inspection of internal defects of a sample in a production line. Further, depending on the sample, the reflectance of the surface may be different depending on the location. In that case, in the related art, the reflected light intensity of the probe light includes not only the internal information but also the information of the surface reflectance, and it has been difficult to accurately detect only the internal information. Furthermore, depending on the sample, the shape of the surface may not be flat and may be uneven depending on the location. In that case, in the prior art, the phase of the reflected light of the probe light changes due to the unevenness of the sample surface, and includes not only the internal information but also the unevenness information on the surface, and it is difficult to accurately detect only the internal information. There was a problem that there is.

An object of the present invention is to provide a simple structure and to be less susceptible to the reflectivity distribution and unevenness distribution on the sample surface.
An object of the present invention is to provide a method for detecting surface or internal information of a sample and a device therefor, which enable high-speed detection of two-dimensional internal information on the surface or inside.

[0009]

In order to achieve the above object, the present invention provides a method for detecting surface or internal information of a sample,
A first light intensity-modulated at a desired frequency is applied to a band-shaped region on the surface of the sample to generate a photoacoustic effect or a photothermal effect in the band-shaped region on the surface or inside the sample below the band-shaped region. Then, the second light is applied to a strip-shaped region on the surface of the sample, and the reflected light from the sample surface due to the irradiation of the second light interferes with the reference light, and the interference light generated by this interference is converted by the photoelectric conversion element. Detecting and separating information of a plurality of small regions constituting the band-shaped region on the surface of the sample from the detected interference light or a plurality of small regions inside the sample below the band-shaped region for each of the plurality of small regions. Detected.

In order to achieve the above object, according to the present invention, a method of detecting the surface or internal information of a sample by irradiating the surface of the sample with first light, which is intensity-modulated at a desired frequency and shaped into a band, is applied. A photoacoustic effect or a photothermal effect is generated inside the sample on the surface of the region irradiated with the first light or on the surface of the region irradiated with the first light, which is formed into a band shape on the sample. The formed second light is irradiated to the region of the surface of the sample irradiated with the first light, and the reflected light from the sample surface due to the irradiation of the second light interferes with the reference light, and the interference generated by this interference The light is detected by the photoelectric conversion element, and a plurality of small areas constituting the area irradiated with the first light on the surface of the sample from the detected interference light or the lower side of the sample irradiated with the first light are sampled. Separately detect information in multiple small areas inside multiple small areas Was Unishi.

[0011]

[0012]

[0013]

[0014]

In order to achieve the above object, according to the present invention, a sample surface or internal information detecting device is emitted from a first light source for emitting first light, and from the first light source. First irradiating means for modulating the intensity of the first light at a desired frequency to irradiate a band-shaped region on the surface of the sample, second light source means for emitting the second light, and the second light source means A second light emitting means for irradiating a second light emitted from the first light to a band-shaped area of the surface of the sample irradiated with the first light, a reference light means for generating a reference light, and a second light emitting means Detecting means for detecting the interference light due to the interference by causing the reflected light generated on the sample surface by the second light to interfere with the reference light generated by the reference light means, and a signal obtained by detecting the interference light by the detecting means Process to form a plurality of small areas or strips that constitute a strip-shaped area on the surface of the sample. It was constructed and a processing means for separating and detecting information of the lower plurality of small regions within the sample of the frequency for each of a plurality of small regions.

In order to achieve the above object, according to the present invention, a surface of a sample or an internal information detecting device is provided with a table means on which a sample is placed and which can be moved in at least one axial direction, and a first light beam. A first light source means for emitting light, and a first light emitted from the first light source means is intensity-modulated at a desired frequency and shaped into a band to irradiate a surface of a sample placed on a table means. Irradiating means, a second light source means for emitting the second light, and an area of the sample surface irradiated with the first light by shaping the second light emitted from the second light source means into a band shape Second irradiation means for irradiating the sample, reference light means for generating a reference light, and second light irradiating the second irradiation means on a position of the sample surface irradiated with the first irradiation means. The reflected light interferes with the reference light generated by the reference light means. And image detection means for detecting an image of Wataruhikari,
The signal of the interference light image detected and obtained by the image detecting means is processed to obtain information on a plurality of small regions constituting a band-shaped region on the surface of the sample or a plurality of small regions inside the sample below the band-shaped region. And a processing means for separating and detecting each of a plurality of small areas.

In order to achieve the above object, according to the present invention, the surface of the sample or the internal information detecting device is emitted from the first light source means for emitting the first light and the first light source means. First irradiation means for simultaneously irradiating a plurality of regions on the surface of the sample with first light, second light source means for emitting second light, and second light emitted from the second light source means A second irradiation means for simultaneously irradiating a plurality of regions on the surface of the sample irradiated with the first light, a reference light means for generating reference light, and a second irradiation means for irradiating the first light on the surface of the sample. The interference light detecting means for detecting the interference light due to the interference by causing the reflected light generated on the sample surface by the light of No. 2 to interfere with the reference light generated by the reference light means, and detecting the interference light with the interference light detecting means A plurality of small areas that form a band-shaped area on the surface of the sample by processing the obtained signal Others were constructed and a processing means for separately detecting the lower plurality of small regions information within the sample of strip-shaped regions for each of a plurality of small regions.

In order to achieve the above object, according to the present invention, the surface of the sample or the internal information detecting device is emitted from the first light source means for emitting the first light and the first light source means. First irradiation means for simultaneously irradiating a plurality of regions on the surface of the sample with first light, second light source means for emitting second light, and second light emitted from the second light source means A second irradiation means for simultaneously irradiating a plurality of regions on the surface of the sample irradiated with the first light, a reference light means for generating reference light, and a second irradiation means for irradiating the first light on the surface of the sample. Interference light detecting means for causing the reflected light generated on the sample surface by the light of No. 2 to interfere with the reference light generated by the reference light means, and capturing and detecting an image of the interference light due to the interference; By processing the image signal obtained by capturing the light image, the band-shaped area on the surface of the sample is processed. It was constructed and a processing means for separately detecting the lower plurality of small regions information within the sample of a plurality of small areas or strip region formed for each of the plurality of small regions.

[0019]

[0020]

[0021]

[0022]

In a photoacoustic signal detection device, light whose intensity is modulated at a desired frequency is irradiated onto the surface of a band-shaped inspection region of a sample to generate a photoacoustic effect or a photothermal effect on or in the band-shaped inspection region. And irradiates light onto the surface of the strip-shaped inspection area of the sample, detects interference light between the reflected light and the reference light by a photoelectric conversion element having a conjugate relationship with the sample surface, and detects the detected interference light intensity. From the signal, the thermal distortion of the same frequency component as the intensity modulation frequency caused by the photoacoustic effect or the photothermal effect in the belt-like inspection area is detected, and the surface or internal information of the specimen-like inspection area of the sample is obtained from the thermal strain of the frequency component. Can be detected, and the photoacoustic signal can be detected at a much higher speed than in the conventional method.

Further, by making the intensity-modulated light irradiated on the sample into a beam having a continuous linear shape on the sample,
It is possible to simultaneously excite the strip-shaped inspection region on the sample, and it is possible to detect a photoacoustic signal at a much higher speed than in the conventional method.

Further, by forming the intensity-modulated light irradiated on the sample into a spot beam train linearly arranged on the sample, it is possible to simultaneously excite the band-like inspection area on the sample, which is different from the conventional method. It is possible to detect a photoacoustic signal at a much higher speed.

Further, by setting the interval between the spot beam arrays so that the thermal diffusion regions of the respective spot beams do not overlap each other, it is possible to independently detect photoacoustic signals in each band-shaped inspection region, and to obtain a photoacoustic image. Detection resolution is improved.

Further, by using a detector composed of a plurality of storage-type photoelectric conversion elements to detect interference light,
Photoacoustic signals in the band-shaped inspection area can be extracted almost simultaneously, and photoacoustic signals can be detected at a much higher speed than in the conventional method.

Further, by using a detector comprising a plurality of non-storage type photoelectric conversion elements for detecting interference light, it becomes possible to extract photoacoustic signals in a band-like inspection area almost at the same time. It is possible to detect a photoacoustic signal at a much higher speed.

Also, by using a detector in which the interference light intensity signal is output as a one-dimensional signal in time series from a plurality of photoelectric conversion elements, it is possible to extract photoacoustic signals in the band-like inspection area almost simultaneously. Thus, it is possible to detect a photoacoustic signal at a much higher speed than the conventional method.

Further, by using a detector in which an interference light intensity signal is simultaneously output in parallel from a plurality of photoelectric conversion elements, it becomes possible to extract photoacoustic signals in a band-like inspection area almost simultaneously, and the conventional method. This makes it possible to detect a photoacoustic signal at a much higher speed than that of the first embodiment.

Further, in order to detect interference light, a detector comprising a plurality of storage type photoelectric conversion elements is used, and each storage type photoelectric conversion element of the detector is stored and output within a desired storage time. By detecting the signal 2n times while shifting the phase of the interference light intensity signal by π / n, and calculating the thermal distortion of the same frequency component as the intensity modulation frequency based on the 2n pieces of signal data, an analog signal is obtained. It is possible to use digital processing instead of frequency filtering processing, and as a result, it is possible to detect a photoacoustic signal with high sensitivity and high accuracy, which is less affected by harmonic components. Also, just one
By means of the detectors, it becomes possible to simultaneously detect the reflectance distribution on the sample surface, the uneven distribution on the sample surface, the amplitude distribution of the photoacoustic signal, and the phase distribution of the photoacoustic signal and a total of four surface and internal information, High-speed composite evaluation of the sample becomes possible. In addition, it is possible to detect a photoacoustic signal in which the reflectance distribution on the sample surface, the unevenness distribution on the sample surface, and the fluctuation of the optical path are corrected, and the sample surface and internal information can be detected with high sensitivity and stability.

As a method of shifting the phase of the interference light intensity signal output from the detector comprising the storage type photoelectric conversion element by π / n, an optical frequency between the reflected light from the sample surface and the reference light is used. , The intensity modulation frequency, and the accumulation time of the accumulation type photoelectric conversion element are each combined into a desired value, so that the reflectance distribution of the specimen surface and the specimen surface can be measured by only one detector. , The amplitude distribution of the photoacoustic signal, and the phase distribution of the photoacoustic signal, and a total of four surface and internal information can be detected at the same time, and a high-speed composite evaluation of the sample can be performed. In addition, it is possible to detect a photoacoustic signal in which the reflectance distribution on the sample surface, the unevenness distribution on the sample surface, and the fluctuation of the optical path are corrected, and the sample surface and internal information can be detected with high sensitivity and stability.

Further, by detecting the thermal distortion of the same frequency component as the above-mentioned intensity modulation frequency simultaneously and in parallel for a plurality of photoelectric conversion elements from the interference light intensity signals output in parallel from the detector in parallel, This makes it possible to detect a photoacoustic signal at a much higher speed than that of the first embodiment.

Further, by setting the intensity modulation frequency such that the thermal diffusion length based on the photoacoustic effect or the photothermal effect is equal to or longer than the depth of the internal interface of the sample to be measured, Inspection of the interface becomes possible.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

First, a first embodiment of the present invention will be described with reference to FIGS.
2 will be described. FIG. 1 shows a photoacoustic detection optical system according to the first embodiment. This optical system comprises an excitation optical system 201, a heterodyne Twyman-Green interference optical system 202 for detecting a photoacoustic signal, and a signal processing system 203. Ar laser 3 of the excitation optical system 201
The parallel beam 32 emitted from 1 (wavelength 515 nm) is incident on the acousto-optic modulator 33. Now, in FIG. 1, a sine wave 98 having a frequency f _C0 shown in FIG.
From the oscillator 87 and the frequency f shown in FIG.
Each of the rectangular waves 99 of _L (f _L <f _C0 ) is input to the signal synthesizer 88, and the product of both waveforms is obtained to generate a modulation signal 100 shown in FIG. I do. As a result, the first-order diffracted light 35 whose frequency is shifted by f _C0 is output intermittently at the frequency f _L from the acousto-optic modulation element 33. That is, as the excitation light, the intensity modulated beam modulation frequency f _L which is frequency shifted by f _C0 is obtained.
The zero-order light 34 is shielded by the stop 36. After passing the intensity-modulated beam 35 through the beam splitter 37, the beam is expanded to a desired beam diameter by a beam expander 38, further converted into an elliptical beam 40 by a cylindrical lens (cylindrical lens) 39, and a dichroic prism 41 (wavelength 60).
0 nm or less is reflected, and 600 nm or more is transmitted), and then the pupil 43 of the objective lens 42, that is, x
Focus light only in the direction. On the other hand, since the cylindrical lens 39 can be regarded as a plate glass having no curvature in the y direction, it is incident as parallel light on the rear focal position 44 of the objective lens. As a result, as shown in FIG. 4, on the front focal position of the objective lens, that is, on the surface of the sample 47, one stripe beam 101 having a width in the x direction and being focused in the y direction is obtained as an excitation beam. Can be In the beam splitter 37, about 10% of the light beam 49 of the intensity-modulated beam 35 is reflected and detected by a photoelectric conversion element 50 such as a photodiode.
Sent to The oscillator 87 compares the set frequency f _L sent from the modulation signal control circuit 90 with the measured frequency f _L X detected by the photoelectric conversion element 50, and finely adjusts the oscillation frequency so that they match. The oscillator 87 has a PLL (Pha
(se Lock Loop) circuit and the like.

The excitation optical system 201 will be described in more detail with reference to FIG. 3A and 3B, the focal position of the cylindrical lens 39 coincides with the rear focal position 44 of the objective lens 42, and the front focal position of the objective lens coincides with the surface of the sample 47. I have.
Accordingly, as shown in FIG. 3A, the beam 40 emitted from the cylindrical lens 39 in the x direction is focused on the rear focal position 44 of the objective lens 42, so that the objective lens 4
The beam 46 coming out of 2 becomes parallel light and is incident on the surface of the sample 47. On the other hand, as shown in FIG. 3B, in the y direction, the cylindrical lens 39 can be regarded as a plate glass having no curvature, so that the beam 40 emitted from the cylindrical lens 39 enters the objective lens 42 as parallel light, Beam 46 emitted from objective lens 42
Is focused on the surface of the sample 47. As a result, as shown in FIG. 4, a single stripe beam 101 having a width in the x direction and converging in the y direction is obtained as an excitation beam on the surface of the sample 47. Now, as a sample, as shown in FIG.
4, a Cu wiring pattern 102 formed as an insulator;
Consider 103. FIG. 5 is a cross-sectional view showing the internal structure of the sample and a heat diffusion region generated by the excitation beam. The sample 47 has a structure in which Cu patterns 102 and 103 having a thickness of 20 μm are formed as wiring patterns on a ceramic substrate 109 using polyimide 104 having a thickness of 20 μm as an insulator. Internal crack 10 in Cu wiring pattern
7 and peeling 108 at the interface between the underlying substrate and the Cu pattern are internal defects to be detected. Here, an important point is a difference in thermal properties between the Cu patterns 102 and 103 and the polyimide 104 around the Cu patterns 102 and 103. That is, the thermal conductivity k of Cu is 403.
^{[J · m ~ 1 · k ~} 1 · s ~ 1 ], the density [rho 8.93 [× 10
⁶ g · m ~ ³ ] and the specific heat c is 0.38 [J · g ~ ¹ · k- ¹ ], while the thermal conductivity k of the polyimide is 0.288.
^{[J · m ~ 1 · k ~} 1 · s ~ 1 ], the density [rho 1.36 [× 10
⁶ g · m ~ ^3], the specific heat c is 1.13 ^{[J · g ~ 1 · k ~} 1 ], in particular the thermal conductivity k of Cu is polyimide it 14
It is 00 times. Thus, when the intensity modulation frequency f _L of the excitation light is set to 50 kHz and the above value is substituted into Expression 1, Cu
The thermal diffusion length _μs in the pattern portions 102 and 103 is about 2
7 μm, and the thermal diffusion length in the polyimide portion 104 is about 1.
1 μm. As a result, as shown in FIG. 5, the heat given in the stripe-shaped light absorption region 105 formed by the stripe-shaped excitation beam 101 is greatly diffused in the Cu pattern portions 102 and 103 to be inspected, and Thermal diffusion region 106 is formed so as to cover the cross section of the Cu pattern including the interface with the substrate. On the other hand, in the polyimide portion 104 outside the inspection target, the heat is diffused small, and the heat diffusion region is formed only on the surface portion. As a result, as shown in FIG. 4 and FIG.
Is irradiated so as to cover the plurality of Cu wiring patterns 102 and 103, an ultrasonic wave (thermoelastic wave) is generated along a light absorption region 105 by a thermostrictive wave generated based on a photoacoustic effect or a photothermal effect, 47 Minute displacement distribution 11 on the surface
0 (broken line) is generated, and the internal information (internal crack 107, peeling defect 108) of each of the Cu wiring patterns 102 and 103 and the internal information of the polyimide portion 104 are merged into the minute displacement distribution 110, respectively. But independently reflected. That is, the excitation beam 1 in the form of a stripe
By using 01, a plurality of inspection objects having high thermal contrast can be excited simultaneously and independently detected,
The two-dimensional internal information of the sample can be detected at high speed. Next, the configuration and function of the heterodyne Twyman-Green interference optical system 202 for detecting the distribution 110 (broken line) of the minute displacement on the sample surface based on the photoacoustic effect will be described with reference to FIGS. . In FIG. 1, the deflection direction of the linearly polarized light beam 52 emitted from the He-Ne laser 51 (wavelength 633 nm) is set at 45 ° with respect to the x-axis and the y-axis as indicated by 111 in FIG. Here, the direction perpendicular to the plane of FIG.
A direction perpendicular to the direction is defined as an x-axis. 6A of the incident light beam 52 by the polarization beam splitter 53.
The p-polarization component 54 indicated by 12 is a polarization beam splitter 53
And enters the acousto-optic modulation element 62. The s-polarized light component 55 indicated by 113 in FIG. 6A is reflected by the polarization beam splitter 53. FIG. 2A from the oscillator 91
The sine wave of the same frequency f _C1 that shown in input to the acousto-optic modulation element 62, to obtain a first-order diffracted light 64 of the p-polarized light frequency shifted by f _C1. The zero-order light 63 is blocked by the stop 65. The p-polarized first-order diffracted light 64 is reflected by the mirror 66 and then passes through the polarization beam splitter 61. On the other hand, the s-polarized light component 55 reflected by the polarization beam splitter 53 is reflected by a mirror 56,
7 is incident. A sine wave having the same frequency f _C2 (f _C1 ≠ f _C2 ) as shown in FIG. 2A is input from the oscillator 91 to the acousto-optic modulation element 57, and the s-polarized light 1 whose frequency is shifted by f _C2 is output.
Next-order diffracted light 59 is obtained. The zero-order light 58 is blocked by the stop 60. The s-polarized first-order diffracted light 59 is reflected by the polarization beam splitter 61 and combined with the p-polarized first-order diffracted light 64 that has passed through the polarization beam splitter 61. The combined light 67 forms two-frequency orthogonally polarized light, that is, a light beam orthogonal to the directions of 112 and 113 and having a frequency difference of f _C1 -f _{C2 from} each other, as shown in FIG. 6B. After passing the combined light 67 through the beam splitter 68, the beam is expanded to a desired beam diameter by a beam expander 70, and further converted into an elliptical beam by a cylindrical lens (cylindrical lens) 71. This elliptical beam is split into a p-polarized beam 72 and an s-polarized beam 74 by a polarizing beam splitter 73. After passing through the dichroic prism 41, the p-polarized beam 72 is frequency-shifted by f _C1 , and then condensed on the pupil 43 of the objective lens 42, that is, on the rear focal position 44 only in the x direction. On the other hand, since the cylindrical lens 71 can be regarded as a plate glass having no curvature in the y direction, it is incident on the rear focal position 44 of the objective lens 42 as parallel light as it is. The beam emitted from the objective lens 42 is a λ / 4 plate 4
After 5 passes, the beam becomes a circularly polarized beam 145. As shown in FIG. 4, the probe beam has a width in the x direction at the same position as the excitation beam 101 at the front focal position of the objective lens, that is, on the surface of the sample 47. One stripe beam 190 focused in the direction is obtained. As shown in FIG. 7, the reflected light from the sample 47 has a distribution 110 (broken line) of a small displacement generated on the surface of the sample 47 by the photoacoustic effect as phase distribution information. In FIG. 1, the reflected light from the sample 47 becomes an s-polarized beam after passing through the λ / 4 plate 45, is reflected by the polarizing beam splitter 73 through the same optical path again after passing through the objective lens 42.

On the other hand, the s-polarized beam 74 split by the polarizing beam splitter 73 is frequency-shifted by f _C2 , becomes circularly polarized after passing through the λ / 4 plate 75, and enters the reference mirror 76. The circularly-polarized beam reflected by the reference mirror 76 becomes p-polarized light after passing through the λ / 4 plate 75 again, and passes through the polarization beam splitter 73 as reference light. 114 in FIG.
Denotes the polarization direction of the reflected light from the sample 47 reflected by the polarization beam splitter 73, and 115 denotes the polarization direction of the reflected light from the reference mirror 76. Since they are orthogonal to each other, they do not interfere with each other. Then, a polarizing plate 79 is inserted after the imaging lens 78, and its polarization direction is set to a 45 ° direction as shown by 116 in FIG. 8, so that the two reflected lights interfere with each other and f _B = f _C1 −f _C2 . Heterodyne interference light 80 having a beat frequency is obtained. The heterodyne interference light 80 includes, as optical phase distribution information, a one-dimensional distribution in the x direction of minute displacement generated on the surface of the sample 47 due to the photoacoustic effect. This interference light 80 is converted to a center wavelength 63
After removing stray light through a 3 nm interference filter 81,
The imaging lens 78 forms an image on a storage type solid-state imaging device 82 such as a CCD one-dimensional sensor. Since the imaging surface of the CCD one-dimensional sensor 82 and the surface of the sample 47 have an image-forming relationship, naturally, stripe-like interference light forms an image on the imaging surface similarly to the probe beam formed on the surface of the sample 47. The beam splitter 68 reflects about 10% of the light beam of the combined light 67 of the two-frequency orthogonally polarized light. Both polarization components of the beam light, the polarization direction interfere with each other by the polarizing plate 83 was 45 ° direction as shown in 116 of FIG. 8, the beat signal _{f B X = f C1 X-} f C2 X is a photodiode or the like Is detected by the photoelectric conversion element 85. This beat signal is sent to a CCD one-dimensional sensor drive control circuit 93 via an amplifier circuit 92. The drive control circuit 93 compares the computer and set the beat frequency f _B sent from the 96 and measurement frequency f _B X detected by the photoelectric conversion element 85, a computer 96 and a modulation signal control circuit so they match 90 Through
The frequency f _C1 or f _C2 of the sine wave output from the oscillator 91 is finely adjusted. The oscillator 91 has a PLL (Phase
LockLoop) circuit and the like.

The heterodyne Twyman-Green interference optical system 202 will be described in more detail with reference to FIGS. As shown in FIGS. 3A and 3B, similarly to the excitation optical system 201, the focal position of the cylindrical lens 71 coincides with the rear focal position 44 of the objective lens 42, and the front focal point of the objective lens. The position coincides with the surface of the sample 47. Therefore, as shown in FIG.
With respect to the direction, the p-polarized beam 72 emitted from the cylindrical lens 71 is focused on the rear focal point 44 of the objective lens 42, so that the beam 145 emitted from the objective lens 42 becomes parallel light and enters the surface of the sample 47. That is. On the other hand, as shown in FIG. 3B, in the y direction, the cylindrical lens 71 can be regarded as a plate glass having no curvature, so that the beam 72 emitted from the cylindrical lens 71 enters the objective lens 42 as parallel light. The beam 145 emitted from the objective lens 42 is focused on the surface of the sample 47. As a result, as shown in FIG.
7 has the same width as the excitation beam in the x direction at the same position as the excitation beam 101,
One stripe beam 190 focused in the direction is obtained. On the other hand, as shown in FIGS. 3A and 3B, the focal position of the cylindrical lens 71 and the position of the reference mirror 76 match. Accordingly, as shown in FIG.
The polarized beam 74 is condensed on a reference mirror 76, and enters as parallel light in the y direction as shown in FIG.

As shown in FIGS. 9A and 9B, the front focal position of the objective lens 42 coincides with the surface of the sample 47, and the rear focal position 44 of the objective lens 42 is The rear focal position coincides with the front focal position, and the rear focal position of the imaging lens 78 coincides with the imaging surface of the CCD one-dimensional sensor 82. That is, this optical system is a double telecentric imaging optical system. Therefore, as shown in FIG. 3A, in the x direction, the parallel reflected light from the surface of the sample 47 is focused on the rear focal position 44 after passing through the objective lens 42, becomes parallel light again after passing through the imaging lens 78, and becomes one-dimensional CCD. The light enters the sensor 82. On the other hand, in the y-direction, the divergent reflected light from the surface of the sample 47 becomes parallel light after passing through the objective lens 42, and becomes a focal point on the rear side after passing through the imaging lens 78, that is, on the CCD one-dimensional sensor 82 as shown in FIG. Focus on As a result, on the CCD one-dimensional sensor 82,
As in the case of the probe beam 190 on the sample 47, one stripe beam having a width in the x direction and focusing in the y direction is obtained. On the other hand, as shown in FIGS. 9A and 9B, the position of the reference mirror 76 matches the front focal position of the imaging lens 78. Accordingly, in the x direction, the divergent reflected light from the reference mirror 76 becomes parallel light after passing through the imaging lens 78 and enters the CCD one-dimensional sensor 82 as shown in FIG. In the y direction, after passing through the imaging lens 78, the light is focused on the rear focal position, that is, on the CCD one-dimensional sensor 82. Therefore, the heterodyne interference light obtained by the reflected light from the sample 47 and the reference light from the reference mirror 76 becomes the same stripe beam as the probe beam light 72 on the CCD one-dimensional sensor 82, and a one-dimensional optical interference signal in the x direction is detected. Is done.

In the following, the signal processing system 203
A method for extracting the amplitude and phase of the minute displacement on the surface of the sample 47 based on the photoacoustic effect from the output signal of the CD one-dimensional sensor 82 without being affected by the reflectance distribution and the unevenness distribution on the surface of the sample 47 will be described. I do. Now, let the wavelength of the probe beam light 72 incident on the surface of the sample 47 be λ,
The amplitude is 1, the reflection coefficient on the surface of the sample 47 is a _s , the reflection coefficient on the reference optical path is a _r , and the optical phase difference between the optical path of the probe light and the reference optical path including the phase change due to the unevenness on the surface of the sample 47. , Φ represents a minute displacement of the surface of the sample 47 due to the photoacoustic effect, and θ represents a phase change amount with respect to the intensity modulation signal. The heterodyne interference light I incident on one pixel of the CCD one-dimensional sensor 82 is expressed by the following equation (Equation 2). It is represented by

[0041]

(Equation 2)

Further, from A≪λ, the above equation is approximately
(Formula 3)

[0043]

(Equation 3)

Here, A · cos (2πf _L t + θ)
Is a term representing the complex amplitude of the minute displacement of the surface of the sample 47 generated based on the photoacoustic effect. CCD one-dimensional sensor 82
Of the detection signal I _D (n + i) (n +
i is the number of times of accumulation / output of the CCD one-dimensional sensor 82) is given by the following equation, where α / f _B is the accumulation time of the sensor.

[0045]

(Equation 4)

Next, with respect to (Equation 4), a condition satisfying the following items is obtained.

(1) Second term ≠ 0 (2) Phase shift amount for accumulation / output number i in the second term = π / 2 or π / 4 (3) Third term ≠ 0 (4) In the third term Phase shift amount with respect to the number of accumulation / output times i = π / 2 (5) Fourth term = 0 The obtained condition is that p and s are integers and α is a non-integer, and the following equations (5) and (6) are obtained. It is on the street.

[0048]

(Equation 5)

[0049]

(Equation 6)

For example, if s = 6 and p = 2, α = 2
１ ／, f _L = 50 kHz, f _B = 210 kHz can be set, and (Formula 4) becomes the form of the following formula (Formula 7).

[0051]

(Equation 7)

Note that the above parameter α = 21/8, f _L
= 50 kHz and f _B = 210 kHz are all set by the computer 96 and sent to the CCD one-dimensional sensor drive control circuit 93 and the modulation signal control circuit 90, respectively, and based on the values of the parameters, drive the CCD one-dimensional sensor and the oscillator 87 and 9
1 is controlled. The method of setting the sensor accumulation time α / f _B is determined by the CCD one-dimensional sensor drive control circuit 93.
From the set beat frequency f _B sent from the computer 96 and the above parameter α, a read shift pulse for a CCD one-dimensional sensor having a frequency f _B / α is generated.
This is realized by driving the dimension sensor 82. .

In Equation 7, the first term is a DC component, and the second term is a phase shift amount of π / 4 with respect to the number i of accumulation / output, and
A modulation component relating to the optical phase difference φ between the optical path of the probe light and the reference optical path including the phase change due to the irregularities on the surface of the sample 47. The third term is that the phase shift amount with respect to the accumulation / output number i is π / 2. 47 are modulation components related to the optical phase difference φ between the optical path of the probe light and the reference optical path, including the phase change due to the unevenness of the surface 47, the amplitude A of the photoacoustic signal, and the phase θ. When signals from i = 1 to i = 8 with respect to Equation 7, that is, signals for one cycle for the second term and two cycles for the third term are obtained, the following equations (Equation 8), (Equation 9), (Equation 10) (Equation 11) are obtained. ) (Equation 12) (Equation 13) (Equation 14) (Equation 15)

[0054]

(Equation 8)

[0055]

(Equation 9)

[0056]

(Equation 10)

[0057]

[Equation 11]

[0058]

(Equation 12)

[0059]

(Equation 13)

[0060]

[Equation 14]

[0061]

(Equation 15)

Actually, after the detection signal I _D (n + i) from the CCD one-dimensional sensor 82 is amplified by the amplification circuit 94,
As shown in FIG. 10, in consideration of the SN ratio of the signal, etc.,
The data set from i = 1 to i = 8 for the formula is 10
A total of 80 stored / output data sets are stored in the two-dimensional memory 95. Assuming that the number of pixels of the CCD one-dimensional sensor 82 is 256, 256 × 80 pieces of data are stored. If the data of the w-th pixel at the time of (n + i) -th accumulation / output is represented by (n + i, w),
The order of storing in the two-dimensional memory 95 is (n + 1, 1), (n + 1, 2), (n + 1, 3), ..., (n + 1, 256), (n + 2, 1), (n + 2, 2), (n + 2,3), ..., (n + 2,256), (n + 3,1), (n + 3,2), (n + 3,3), ..., (n + 3,256),:: (n + 80,1), (n + 80 , 2), (n + 80, 3),..., (N + 80, 256). On the other hand, when reading out from the two-dimensional memory 95, 80 accumulated / output data sets are sequentially read out for each pixel as described below and sent to the computer 96.

(N + 1,1), (n + 2,1), (n + 3,1),..., (N + 80,1), (n + 1,2), (n + 2,2), (n + 3,2),. (n + 80,2), (n + 1,3), (n + 2,3), (n + 3,3),..., (n + 80,3):: (n + 1,256), (n + 2,256), (n + 3,256) ,..., (N + 80, 256) The calculator 96 performs the following calculation process using 80 accumulation / output data sets for each pixel to obtain the reflectance a _s ^{2 of} the surface of the sample 47 and the reflectance of the surface of the sample 47. The optical phase difference φ between the optical path of the probe light and the reference optical path including the phase change due to the unevenness, the amplitude A of the photoacoustic signal whose reflectance on the surface of the sample 47 is corrected, and the phase change due to the unevenness on the surface of the sample 47 are corrected. The phase θ of the photoacoustic signal is obtained.

First, the reflectance a _s ² of the surface of the sample 47 is expressed by the following equation (8).
By taking the sum from to Eq. 15, the following equation (Equation 16) is obtained.

[0065]

(Equation 16)

The optical phase difference φ between the optical path of the probe light and the reference optical path including the phase change due to the unevenness of the surface of the sample 47 is:
From Equation (8), Equation (10), Equation (12), and Equation (14),
It is given by the following equation (Equation 17).

[0067]

[Equation 17]

The amplitude of the photoacoustic signal, that is, the small displacement A on the surface of the sample 47 is expressed by the following equations (8), (9), (12), and (1).
From the expressions 3) and (Expression 16), the corrected reflectance of the surface of the sample 47 is given by the following expression (Expression 18).

[0069]

(Equation 18)

The phase of the photoacoustic signal, that is, the phase change θ of the excitation light with respect to the intensity-modulated signal is expressed by the following equations (8), (9), (12), (13), and (16). From the equations and (Equation 17), the following equation (Equation 19) is given as a form in which the phase change due to the unevenness on the surface of the sample 47 is corrected.

[0071]

[Equation 19]

FIGS. 11A, 11B and 11C are examples of photoacoustic signal detection in this embodiment. FIG.
In (a), due to the internal crack 120, the minute displacement 110 (broken line) on the surface of the Cu wiring pattern 102 is reduced.
Compared to the surface of the normal Cu wiring pattern 103,
You can see that it is getting bigger. The distribution 121 of the amplitude A of the photoacoustic signal in FIG. 3B and the phase θ of the photoacoustic signal before correcting the phase change due to the unevenness on the surface of the sample 47 in FIG.
In the distribution 124 of + φ, signals 123 (FIG. (B)) and 126 (FIG. (C)) of the internal crack appear strongly.

On the other hand, FIGS. 12 (a), (b) and (c)
Is a detection example of a photoacoustic signal in the present embodiment when the surface of the sample 47 has a concavo-convex distribution. As shown in FIG. 12B, the distribution 137 of the phase θ + φ of the photoacoustic signal before the phase correction is performed.
Is affected by the phase change due to the irregularities on the surface of the sample 47,
The signal-to-noise ratio is greatly reduced, and it is extremely difficult to recognize the internal crack 135. However, as shown in FIG. 14C, the distribution 139 of the phase signal θ after the phase correction by Expression 19 is performed.
Thus, the signal 141 of the internal crack 135 can be clearly recognized without being affected by the phase change due to the unevenness of the surface of the sample 47.

The detection signal from the CCD one-dimensional sensor is processed by the computer 96 while sequentially scanning the sample 47 in the xy directions by the xy stage 48, whereby a two-dimensional photoacoustic image of the entire surface of the sample 47 is obtained. TV monitor 97
Is output to

As described above, according to the present embodiment, a plurality of measurement points are arranged in parallel by using a stripe-like excitation beam instead of the so-called point scanning method of detecting information one by one as in the prior art. Simultaneous excitation and use of optical interference to detect photoacoustic signals generated at each point, and by detecting interference light simultaneously in parallel, photoacoustic signals at multiple measurement points on the sample can be detected simultaneously in parallel. , It is possible to detect the two-dimensional internal information of the sample at high speed.

Further, according to the present embodiment, only one CC
The D1D sensor can simultaneously detect the reflectance information on the sample surface, the unevenness distribution on the sample surface, the amplitude distribution of the photoacoustic signal, and the phase distribution of the photoacoustic signal, and a total of four surface and internal information. Multiple evaluations are possible.

Further, according to this embodiment, it is possible to detect a photoacoustic signal in which the reflectance distribution on the sample surface, the unevenness distribution on the sample surface, and the fluctuation of the optical path are corrected, and the sample surface and the internal information can be detected with high sensitivity. And stable detection becomes possible.

Further, according to the present embodiment, the thermal diffusion length based on the photoacoustic effect is set to be equal to or greater than the depth of the interface between the Cu wiring pattern to be inspected and the ceramic substrate. By setting the intensity modulation frequency of the excitation beam, it is possible to inspect the internal interface.

Further, according to the present embodiment, when a photoacoustic signal is extracted from an optical interference signal, digital processing is used instead of analog frequency filtering processing. Highly accurate photoacoustic signal detection becomes possible.

In this embodiment, an example of applying the present invention to a sample having a plurality of inspection objects having high thermal contrast has been described. However, application to a sample made of a uniform material including internal cracks is sufficiently possible. is there. Even in this case, the above-described effects can be expected because simultaneous excitation of a plurality of measurement points on the sample is possible. FIGS. 13 to 2 show a second embodiment of the present invention.
1 will be described. FIG. 13 shows a photoacoustic detection optical system according to the second embodiment. This optical system includes an excitation optical system 301, a heterodyne differential interference optical system 302 for detecting a photoacoustic signal, and a signal processing system 303. In excitation optical system 301, a description is omitted configuration and functions of the parts to obtain an intensity-modulated beam 35 of the modulation frequency f _L is the same as the first embodiment. After passing the intensity-modulated beam 35 through the beam splitter 37, the beam is expanded to a desired beam diameter by a beam expander 38, and further condensed by a cylindrical lens (cylindrical lens) 150 to a focal position 159 thereof only in the y direction. This focal position 159 coincides with the front focal position of the off-axis relay lens 152, and the beam after passing through the relay lens 152 becomes parallel light again, and becomes a dichroic prism 153 (reflection below 600 nm wavelength, transmission above 600 nm). After the reflection, the pupil of the objective lens 154, that is, the rear focal position 155
Incident on On the other hand, in the x direction, since the cylindrical lens 150 can be regarded as a plate glass having no curvature, a beam incident on the relay lens 152 as parallel light remains on the rear side of the objective lens 154 corresponding to the rear focal position of the relay lens 152. The light is focused at the focal position 155. As a result, the front focal position of the objective lens 154, that is, the sample 47
Has a width in the x direction as an excitation beam and y
A single stripe beam 186 focused in the direction is obtained. In the beam splitter 37, as in the first embodiment, about 10% of the light beam 4 of the intensity modulated beam 35 is changed.
9 is reflected and detected by a photoelectric conversion element 50 such as a photodiode, and then sent to an oscillator 87 via an amplifier circuit 89. The oscillator 87 compares the set frequency f _L sent from the modulation signal control circuit 90 with the measured frequency f _L X detected by the photoelectric conversion element 50, and finely adjusts the oscillation frequency so that they match. The oscillator 87 has a PLL (Phase L
ock Loop) circuit and the like.

The excitation optical system 301 will be described in more detail with reference to FIG. 14A and 14B, the focal position 159 of the cylindrical lens 150, the front focal position of the off-axis relay lens 152, the rear focal position of the relay lens 152, and the objective lens 154 are shown.
, The front focal position of the objective lens 154 and the surface of the sample 47 coincide with each other. Therefore, as shown in FIG.
The beam 151 emitted from the cylindrical lens 150 is condensed at its focal position 159, that is, at the front focal position of the relay lens 152. The beam after passing through the relay lens 152 becomes parallel light again and enters the objective lens 154. The beam 156 emitted from the lens 154 is
It is focused on the surface. In addition, the relay lens 152
Is off-axis, the light-collecting position is shifted from the center of the objective lens 154. On the other hand, FIG.
As shown in the figure, with respect to the x direction, the cylindrical lens 1
Since the beam 50 can be regarded as a plate glass having no curvature, the beam 151 emitted from the cylindrical lens 150 is incident on the relay lens 152 as parallel light, and
The light is focused on the rear focal position 155 of the objective lens 154 that matches the rear focal position of the second lens. As a result, the objective lens 154
Is emitted as parallel light on the surface of the sample 47. As a result, as shown in FIG. 15, a single stripe beam 186 having a width in the x direction and converging in the y direction is obtained as an excitation beam on the surface of the sample 47.

FIG. 16 shows a case where the above-mentioned stripe-shaped excitation beam 186 is applied to a sample composed of Cu wiring patterns 102 and 103 in which an organic polymer material 104 such as polyimide is formed as an insulator, similarly to the first embodiment. 3 shows a distribution 185 (broken line) of a minute displacement on the sample surface based on the photoacoustic effect generated along the light absorption region 183. As in the first embodiment, the minute displacement distribution 185 includes:
The internal information (internal crack 107, peeling defect 108) of each of the Cu wiring patterns 102 and 103 and the internal information of the polyimide portion 104 are independently reflected without being fused. That is, the excitation beam 1 in the form of a stripe is
If 86 is used, a plurality of inspection objects having high thermal contrast can be excited at the same time, and two-dimensional internal information of the sample can be detected at high speed.

Next, the structure and function of the heterodyne differential interference optical system 302 for detecting the distribution 185 (broken line) of the minute displacement on the sample surface based on the photoacoustic effect will be described.
This will be described with reference to FIGS. 13 and 17 to 21. In the heterodyne differential interference optical system 302 shown in FIG. 13, two-frequency orthogonally polarized light, that is, as shown in FIG.
The configuration and function of the portion that obtains the combined light 67 that is orthogonal to each other in the direction of 3 and has a frequency difference of f _C1 −f _{C2 from} each other are completely the same as those in the first embodiment, and a description thereof will be omitted. still,
Here, the direction perpendicular to the paper surface of FIG. 13 is defined as the x-axis, and the direction perpendicular thereto is defined as the y-axis. After passing the combined light 67 of the two-frequency orthogonal polarization through the beam splitter 68, the beam is expanded to a desired beam diameter by the beam expander 70, and further made into an elliptical beam by a cylindrical lens (cylindrical lens) 160. In the y direction, the cylindrical lens 1
Since the elliptical beam 60 can be regarded as a plate glass having no curvature, the elliptical beam is reflected by the beam splitter 162 while being parallel light in the y direction, and is reflected by the cylindrical lens 16.
Wollaston prism 163 placed at zero focal position
(It is also possible to use a lotion prism) so that the light is separated into a p-polarized beam 164 and an s-polarized beam 165 both of which are parallel light. Since the position of the Wollaston prism 163 coincides with the front focal position of the relay lens 166, the principal rays of the two beams after passing through the relay lens 166 are parallel to each other, and each beam is focused on the rear focal point of the relay lens 166. The light is focused at the position 187. Since the rear focal position 187 of the relay lens 166 coincides with the front focal position of the relay lens 168, the chief rays of the two beams after passing through the relay lens 168 pass through the dichroic prism 153 and pass through the dichroic prism 153. Focusing is performed on the rear focal position 155 of the objective lens 154 that matches the side focal position. At the same time, the two beams are incident on the rear focal point 155 of the objective lens 154 with the respective parallel lights remaining unchanged. On the other hand, x
Regarding the direction, the beam emitted from the cylindrical lens 160 is focused on the Wollaston prism 163,
After passing through the relay lens 166, the light becomes parallel light. After passing through the dichroic prism 153 by the relay lens 168, the light is focused on the rear focal point 155 of the objective lens 154. As a result, a single stripe beam 18 having a width in the x direction and converging in the y direction is provided as an excitation beam on the front focal position of the objective lens 154, that is, on the surface of the sample 47.
6 is obtained. After passing through the λ / 4 plate 45, the two beams emitted from the objective lens 154 become circularly polarized beams 169 and 170, respectively. As shown in FIG. 186
A stripe beam 181 having a width in the x direction and converging in the y direction is obtained as a probe beam at the same position as that of the excitation beam 186.
As a reference beam, a stripe beam 182 having a width in the x direction and converging in the y direction is obtained as the reference beam at a position slightly away from the reference beam. As shown in FIG. 17, the reflected light from the position of the probe beam 181 of the sample 47 has a distribution 185 (broken line) of a small displacement generated on the surface of the sample 47 by the photoacoustic effect as phase distribution information.
The reference beam 182 is the excitation beam 1 in FIG.
It is assumed that the laser beam 86 is incident at a position outside the range in which the minute displacement 185 of the surface of the sample 47 occurs due to 86, that is, outside the range of the thermal diffusion region 184 and as close to the probe beam 181 as possible as shown in FIG. In FIG. 13, sample 4
The reflected light from the positions of the probe beam 181 and the reference beam 182 passes through the λ / 4 plate 45, becomes an s-polarized beam and a p-polarized beam, passes through the objective lens 42, passes through the same optical path again, and passes through the Wollaston prism 163. , And passes through the beam splitter 162. FIG.
Reference numeral 114 denotes the polarization direction of the reflected light from the position of the probe beam 181, and reference numeral 115 denotes the polarization direction of the reflected light from the position of the reference beam 182. Since they are orthogonal to each other, they do not interfere with each other. Therefore, a polarizing plate 79 is inserted after the imaging lens 78, and its polarization direction is set to a 45 ° direction as shown by 116 in FIG.
Both reflected light heterodyne interference light 171 having a beat frequency of the interference and f _B = f _C1 -f _C2 is obtained. The heterodyne interference light 171 includes, as optical phase distribution information, a one-dimensional distribution in the x direction of a minute displacement generated on the surface of the sample 47 due to the photoacoustic effect. When the interference light 171 has a center wavelength of 6
After removing stray light through a 33 nm interference filter 81, an image is formed on an accumulation type solid-state image sensor 82 such as a CCD one-dimensional sensor by an imaging lens 78. Since the imaging surface of the CCD one-dimensional sensor 82 and the surface of the sample 47 have an image-forming relationship, naturally, stripe-like interference light forms an image on the imaging surface similarly to the probe beam formed on the surface of the sample 47. The beam splitter 68 reflects about 10% of the light beam of the combined light 67 of the dual-frequency orthogonal polarization similarly to the first embodiment. Both polarization components of the beam light, the polarization direction interfere with each other by the polarizing plate 83 was 45 ° direction as shown in 116 of FIG. 8, the beat signal _{f B X = f C1 X-} f C2 X is a photodiode or the like Is detected by the photoelectric conversion element 85. This beat signal passes through an amplifier circuit 92 and the CCD 1
It is sent to the dimension sensor drive control circuit 93. In the drive control circuit 93, the set beat frequency f
Comparing _B and the measurement frequency f _B X detected by the photoelectric conversion element 85 via the computer 96 and the modulation signal control circuit 90 so that they are identical sine wave of frequency f _C1 output from the oscillator 91 Or finely adjust f _C2 . Oscillator 91
Is constituted by a PLL (Phase Lock Loop) circuit or the like.

The heterodyne type differential interference optical system 302 will be described in more detail with reference to FIGS. 18, 19, 20, and 21. As shown in FIGS. 18 and 19, the focal position of the cylindrical lens 160 and the Wollaston lens
Prism 163 position, Wollaston prism 163
, The front focal position of the relay lens 166, the rear focal position 187 of the relay lens 166, and the relay lens 168.
, The rear focal position of the relay lens 168 and the rear focal position 155 of the objective lens 154, and further, the front focal position of the objective lens 154 and the surface of the sample 47 coincide with each other. Therefore, as shown in FIG. 18, in the y direction, the cylindrical lens 160 can be regarded as a plate glass having no curvature, so that the combined light 161 of the two-frequency orthogonally polarized light output from the cylindrical lens 160 remains parallel to the Wollaston prism 163. After being incident, it is split into a p-polarized beam 164 and an s-polarized beam 165, both of which are parallel light. Since the position of the Wollaston prism 163 coincides with the front focal position of the relay lens 166, the principal rays of the two beams after passing through the relay lens 166 are parallel to each other, and each beam is focused on the rear focal point of the relay lens 166. The light is focused at the position 187. The rear focal position 187 of the relay lens 166 matches the front focal position of the relay lens 168,
The chief rays of the two beams are the rear focal position 155 of the objective lens 154 coincident with the rear focal position of the relay lens 168.
Focus on At the same time, the two beams remain parallel light and enter the rear focal point 155 of the objective lens 154, so that the two beams 16
9 and 170 both converge on the surface of the sample 47. The principal rays of both beams are parallel to each other.

On the other hand, as shown in FIG. 19, in the x direction, the beam emitted from the cylindrical lens 160 is condensed on the Wollaston prism 163, passes through the relay lens 166, becomes parallel light, and is further converted into an objective lens by the relay lens 168. The light is condensed at the rear focal position 155 of the 154. Therefore, the beams 169 and 170 emitted from the objective lens 154 are both collimated and incident on the surface of the sample 47. As a result, as shown in FIG.
7, a stripe beam 181 having a width in the x-direction and converging in the y-direction as the excitation beam 186 is obtained as a probe beam at the same position as the excitation beam 186, and slightly from the probe beam 181. A striped beam 1 having a width in the x direction and focused in the y direction, similar to the probe beam 181, as a reference beam at a distant position.
82 is obtained.

As shown in FIG. 20 and FIG.
The front focal position of 54 is the position of the surface of the sample 47 and the objective lens 1.
The rear focal position 155 of the 54 is the rear focal position of the relay lens 168, the front focal position of the relay lens 168 is the rear focal position 187 of the relay lens 166, and the front focal position of the relay lens 166 is the Wollaston prism 163.
And the position of the Wollaston prism 163 coincide with the front focal position of the imaging lens 78, and the rear focal position of the imaging lens 78 coincides with the imaging surface of the CCD one-dimensional sensor 82. That is, this optical system is a double telecentric imaging optical system. Therefore, as shown in FIG.
With respect to the direction, the principal rays of the two divergent reflected lights from the surface of the sample 47 pass through the objective lens 154, and then move to the rear focal position 155.
And at the same time, the two beams enter the relay lens 168 while remaining parallel light. Objective lens 154
Since the rear focal position 155 of the relay lens 168 coincides with the rear focal position of the relay lens 168, the principal rays of the two beams after passing through the relay lens 168 are parallel to each other, and at the same time, the two beams are respectively reflected by the relay lens 168. The light is focused on the front focal position, that is, the rear focal position 187 of the relay lens 166. The two beams after passing through the relay lens 166 are combined by the Wollaston prism 163, and after passing through the imaging lens 78 as parallel light, the rear focal position, ie, C
The light is focused on the CD one-dimensional sensor 82. On the other hand, as shown in FIG. 21, with respect to the x direction, two parallel reflected lights from the surface of the sample 47 pass through the objective lens 154, and then move to the rear focal position 1
The light is condensed at 55, becomes parallel light after passing through the relay lens 168, and is condensed at the front focal position of the relay lens 166, that is, at the position of the Wollaston prism 163. Further, after passing through the imaging lens 78, the light becomes parallel light again and the CCD one-dimensional sensor 8
2 is incident. As a result, like the probe beam 181 and the reference beam 182 on the sample 47, the CCD one-dimensional sensor 82 has a width in the x direction and a focus in the y direction.
A stripe beam of books is obtained. That is, the heterodyne interference light obtained by each reflected light from the probe beam 181 and the reference beam 182 becomes a stripe beam on the CCD one-dimensional sensor 82, and a one-dimensional optical interference signal in the x direction is detected. The configuration and the function of the signal processing system 303 are exactly the same as those of the signal processing system 203 in the first embodiment, and the output signal of the CCD one-dimensional sensor 82 is used based on the photoacoustic effect as in the first embodiment. The amplitude and phase of the minute displacement on the surface of the sample 47 caused by
7 can be extracted without being affected by the reflectance distribution and the unevenness distribution on the surface.

While sequentially scanning the sample 47 in the xy directions by the xy stage 48, the detection signal from the CCD one-dimensional sensor is processed by the computer 96, whereby a two-dimensional photoacoustic image of the entire surface of the sample 47 is obtained. TV monitor 97
Is output to

As described above, according to the present embodiment, not the so-called point scanning method in which information is detected one point at a time as in the prior art, but a stripe-like excitation beam as in the first embodiment. Excitation of multiple measurement points in parallel at the same time, using optical interference to detect photoacoustic signals generated at each point,
By simultaneously detecting the interference light in parallel, photoacoustic signals at a plurality of measurement points of the sample can be simultaneously detected in parallel, and the two-dimensional internal information of the sample can be detected at high speed.

Further, according to the present embodiment, as in the first embodiment, the reflectance distribution on the sample surface, the unevenness distribution on the sample surface, the amplitude distribution of the photoacoustic signal, and the The phase distribution of the photoacoustic signal and the total of four surface and internal information can be simultaneously detected, and a composite evaluation of the sample can be performed.

Further, according to the present embodiment, similarly to the first embodiment, it is possible to detect a photoacoustic signal in which the reflectance distribution on the sample surface, the unevenness distribution on the sample surface, and the fluctuation of the optical path are corrected. Highly sensitive and stable detection of surface and internal information is possible.

Further, according to the present embodiment, similarly to the first embodiment, the thermal diffusion length based on the photoacoustic effect is the inspection target C
By setting the intensity modulation frequency of the excitation beam to be equal to or greater than the depth of the interface between the u wiring pattern and the ceramic substrate, the internal interface can be inspected.

Further, according to the present embodiment, similar to the first embodiment, when a photoacoustic signal is extracted from an optical interference signal, digital processing is used instead of analog frequency filtering processing. And the detection of a photoacoustic signal with high sensitivity and high accuracy is possible.

Further, in this embodiment, the interference optical system for detecting the minute displacement of the sample surface based on the photoacoustic effect is a differential interference optical system. In other words, the reference light is not obtained from a separately provided reference mirror, but the reflected light from the sample surface of the reference beam incident near the probe light is used as the reference light. And the same optical system, the fluctuation of the optical path length between the two lights and the shift of the wavefront are greatly reduced, and the detection accuracy and the detection sensitivity of the photoacoustic signal are greatly improved. Furthermore,
Since there is no need to provide a separate reference optical path, the optical system is simplified, its stability is improved, and the detection accuracy of the photoacoustic signal is improved.

In this embodiment, an example of applying the present invention to a sample having a plurality of inspection objects having high thermal contrast has been described. However, application to a sample made of a uniform material including internal cracks is sufficiently possible. is there. Even in this case, the above-described effects can be expected because simultaneous excitation of a plurality of measurement points on the sample is possible.

A third embodiment of the present invention will be described with reference to FIGS. FIG. 22 shows a photoacoustic detection optical system according to the third embodiment. This optical system includes an excitation optical system 201, a heterodyne Twyman-Green interference optical system 402 for detecting a photoacoustic signal, and a signal processing system 403. The configuration and the function of the excitation optical system 201 are completely the same as those of the first embodiment, and the description is omitted. The configuration of the heterodyne Twyman-Green interference optical system 402 is the same as that of the heterodyne-type Twyman-Green interference optical system 202 of the first embodiment except that the beat signal detecting beam splitter 68, the polarizing plate 83, and the photoelectric conversion element 85 are removed. Since the configuration is the same as that of the first embodiment except that the parallel output type photoelectric conversion element array 191 is used in place of the accumulation type CCD one-dimensional sensor 82 for detecting interference light, the description will be made. Is omitted. As shown in FIG. 23, the optical interference signals output from each pixel of the parallel output type photoelectric conversion element array 191 are amplified for each pixel by a preamplifier group 192 arranged by the same number as the number of pixels, and then the same. In the lock-in amplifier group 193 arranged by the same number as the number of pixels, the intensity modulation signal 50a detected by the photoelectric conversion element 50 is used as a reference signal, and the modulation frequency component included in the optical interference signal is used as a photoacoustic signal.
That is, the amplitude and phase of the minute displacement on the surface of the sample 47 generated based on the photoacoustic effect are simultaneously detected for all pixels.
The detected photoacoustic signal is converted into digital data by an AD converter group 194, and then sent to a parallel-in / serial-out type shift register 195 to be converted into a one-dimensional signal. The position signal of the xy stage 48 and the output signal from the shift register 195 are processed by the computer 96, and a photoacoustic signal at each point of the sample 47, that is, the sample 4
A two-dimensional photoacoustic image of the entire surface 7 is obtained and output to the TV monitor 97. In this embodiment, the non-storage type parallel output type photoelectric conversion element array 191 is used for interference light detection, but a storage type is also applicable. In that case, the signal processing system 403 can be used as it is, or the lock-in amplifier group 19
3 is removed, the accumulation time of the photoelectric conversion element array is controlled based on Equations 4 to 6 to obtain signals whose phases are shifted from each other, as in the first or second embodiment.
It is also possible to perform arithmetic processing by a computer based on Expression 19.

The present embodiment is applicable to a sample having a plurality of inspection objects having high thermal contrast as shown in FIGS. 4 and 5, and a sample made of a uniform material including internal cracks. Is also applicable.

As described above, according to the present embodiment, not the so-called point scanning method in which information is detected one point at a time as in the prior art, but a stripe-shaped system similar to the first and second embodiments. A plurality of measurement points are simultaneously excited in parallel using an excitation beam, and light interference is used to detect a photoacoustic signal generated at each point. Acoustic signals can be detected simultaneously in parallel, and two-dimensional internal information of the sample can be detected at high speed.

Further, if a storage type one-dimensional sensor is used in this embodiment, the reflectance distribution on the sample surface, the unevenness distribution on the sample surface, the light It is possible to simultaneously detect the amplitude distribution of the acoustic signal and the phase distribution of the photoacoustic signal, and a total of four surface and internal information, thereby enabling a composite evaluation of the sample.

Further, if a storage type one-dimensional sensor is used in the present embodiment, a photoacoustic signal in which the reflectance distribution on the sample surface, the unevenness distribution on the sample surface, and the fluctuation of the optical path are corrected, as in the first embodiment. Can be detected, and highly sensitive and stable detection of the surface and internal information of the sample becomes possible.

Further, if a storage type one-dimensional sensor is used in the present embodiment, the thermal diffusion length based on the photoacoustic effect can be measured at the interface between the Cu wiring pattern to be inspected and the ceramic substrate as in the first embodiment. The internal interface can be inspected by setting the intensity modulation frequency of the excitation beam so as to be equal to or longer than the depth.

Furthermore, if a storage type one-dimensional sensor is used in this embodiment, a digital processing is performed instead of an analog frequency filtering processing when extracting a photoacoustic signal from an optical interference signal, as in the first embodiment. Is used, the effect of the harmonic component is small, and the photoacoustic signal with high sensitivity and high accuracy can be detected.

The non-storage type photoelectric conversion element array 191
After storing the light interference signal output from each pixel in the two-dimensional memory, a photoacoustic signal can be detected by one lock-in amplifier as a one-dimensional signal read out for each pixel.

A fourth embodiment of the present invention will be described with reference to FIGS. FIG. 24 shows a photoacoustic detection optical system in the fourth embodiment. The optical system includes an excitation optical system 501, a heterodyne Twyman-Green interference optical system 202 for detecting a photoacoustic signal, and a signal processing system 203. The configurations and functions of the heterodyne type Twyman-Green interference optical system 202 and the signal processing system 203 are completely the same as those of the first embodiment, and therefore description thereof is omitted. In the first to third embodiments, a stripe-shaped excitation beam is used.
01 differs greatly in that a plurality of spot beam parallel irradiation optical systems 197 are employed. Other parts are the same as in the first to third embodiments. The multiple spot beam parallel irradiation optical system 197 will be described with reference to FIG. The expanded parallel light from the beam expander 38 becomes a stripe beam after passing through a mask 210 having a stripe-shaped opening 210a shown in FIG. The rear focal position of each micro lens is relay lens 2
13, the rear focal position of the relay lens 213 is the rear focal position 214 of the objective lens 42,
Further, the front focal position of the objective lens 42 coincides with the surface of the sample 47, respectively. Each beam from the one-dimensional micro lens array 210 is transmitted to the front focal point 212 of the relay lens 213.
After being condensed, the light becomes parallel light after passing through the relay lens 213, and is further condensed on the surface of the sample 47 as focused light after passing through the objective lens. The principal rays of each spot beam are parallel to each other. FIG. 27 shows how each spot beam irradiates the sample at the same time. still,
The number of spot beams is made equal to the number of pixels of the CCD one-dimensional sensor 82 for detecting light interference, and the interval is as shown in FIG.
17 does not overlap. The probe beam for heterodyne interference detection uses a striped beam as in the first to third embodiments. Signal processing system 203
And its function are exactly the same as those in the first embodiment. As in the first embodiment, the minute displacement of the surface of the sample 47 generated based on the photoacoustic effect from the output signal of the CCD one-dimensional sensor 82 Can be extracted without being affected by the reflectance distribution and the unevenness distribution on the surface of the sample 47.

While sequentially detecting the sample 47 in the xy directions by the xy stage 48, the detection signal from the CCD one-dimensional sensor is processed by the computer 96, whereby a two-dimensional photoacoustic image of the entire surface of the sample 47 is obtained. TV monitor 97
Is output to

This embodiment is applicable to a sample having a plurality of inspection objects having high thermal contrast as shown in FIGS. 4 and 5, and a sample made of a uniform material including internal cracks. Is also applicable.

As described above, according to this embodiment, instead of the so-called point scanning method of detecting information one point at a time as in the conventional case, a plurality of spot beams are simultaneously irradiated in parallel to irradiate a plurality of spot beams. The measurement points are excited simultaneously in parallel, and optical interference is used to detect the photoacoustic signal generated at each point.
By simultaneously detecting the interference light in parallel, photoacoustic signals at a plurality of measurement points of the sample can be simultaneously detected in parallel, and the two-dimensional internal information of the sample can be detected at high speed.

Further, according to the present embodiment, since the thermal diffusion regions of the respective excitation beams do not overlap, there is an effect that the detection resolution of the photoacoustic image is improved.

Further, according to this embodiment, as in the first embodiment, the reflectance distribution on the sample surface, the unevenness distribution on the sample surface, the amplitude distribution of the photoacoustic signal, and the The phase distribution of the photoacoustic signal and the total of four surface and internal information can be simultaneously detected, and a composite evaluation of the sample can be performed.

Further, according to the present embodiment, similarly to the first embodiment, it is possible to detect a photoacoustic signal in which the reflectance distribution on the sample surface, the unevenness distribution on the sample surface, and the fluctuation of the optical path are corrected. Highly sensitive and stable detection of surface and internal information is possible.

Further, according to the present embodiment, similarly to the first embodiment, the thermal diffusion length based on the photoacoustic effect is the inspection target C
By setting the intensity modulation frequency of the excitation beam to be equal to or greater than the depth of the interface between the u wiring pattern and the ceramic substrate, the internal interface can be inspected.

Further, according to the present embodiment, similar to the first embodiment, when a photoacoustic signal is extracted from an optical interference signal, digital processing is used instead of analog frequency filtering processing. And the detection of a photoacoustic signal with high sensitivity and high accuracy is possible.

In the present embodiment, a storage type CCD one-dimensional sensor is used for detecting interference light, but a non-storage type parallel output type photoelectric conversion element array as in the third embodiment can be applied. In that case, the signal processing system 403 in the third embodiment may be used.

In the above-described first to third embodiments, a one-dimensional striped excitation beam and a probe beam are used, but a two-dimensional beam having a certain area is used. Is also possible. In that case, of course, a two-dimensional sensor is used for detecting interference light. Similarly, also in the fourth embodiment, it is possible to arrange a plurality of spot beams in a two-dimensional shape and use a two-dimensional sensor.

[0114]

According to the present invention, it is possible to simultaneously and simultaneously excite the band-like inspection regions of a sample in parallel and utilize light interference for the detection of a photoacoustic signal generated in the band-like inspection region and to simultaneously detect interference light in parallel. Accordingly, photoacoustic signals in the band-shaped inspection region of the sample can be simultaneously detected in parallel, and there is a great effect that two-dimensional surface or internal information of the sample can be detected at high speed.

Further, a single sensor simultaneously detects a total of four surface and internal information, including the reflectance distribution on the sample surface, the unevenness distribution on the sample surface, the amplitude distribution of the photoacoustic signal, and the phase distribution of the photoacoustic signal. This has the effect that high-speed composite evaluation of the sample is possible.

In addition, it is possible to detect a photoacoustic signal in which the reflectance distribution on the sample surface, the unevenness distribution on the sample surface, and the fluctuation of the optical path are corrected, and the sample surface and internal information can be detected with high sensitivity and stability. It has the effect of becoming.

Further, by setting the intensity modulation frequency of the excitation beam such that the thermal diffusion length based on the photoacoustic effect is equal to or greater than the depth of the internal interface to be inspected, This has the effect that the inspection can be performed.

In extracting a photoacoustic signal from an optical interference signal, since digital processing is used instead of analog frequency filtering, the influence of harmonic components is small, and a highly sensitive and highly accurate photoacoustic signal is obtained. This has the effect of enabling detection.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a photoacoustic detection optical system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a modulation signal input to an acousto-optic modulation element.

FIG. 3 is a configuration diagram of an excitation optical system and a heterodyne interference optical system in a first embodiment.

FIG. 4 is a perspective view showing a planar structure of a sample and an excitation beam and a probe beam in the first embodiment.

FIG. 5 is a diagram showing a cross-sectional structure of a sample and a state of generation of a photoacoustic effect by a striped excitation beam in the first embodiment.

FIG. 6 is a diagram illustrating a polarization direction of a laser beam incident on a heterodyne interference optical system and a dual-frequency orthogonal polarization state.

FIG. 7 is a diagram showing a state of incidence of a striped probe beam on a sample surface in the first embodiment.

FIG. 8 is a diagram showing reflected light from a sample, reference light, and each polarization direction of a polarizing plate.

FIG. 9 is a configuration diagram of a detection unit of the heterodyne interference optical system in the first embodiment.

FIG. 10 is a diagram showing a configuration of data in a two-dimensional memory.

FIG. 11 is a diagram illustrating an example of detection of a photoacoustic signal in the first embodiment.

FIG. 12 is a diagram illustrating a detection example of a photoacoustic signal indicating an effect of phase correction in the first embodiment.

FIG. 13 is a diagram illustrating a photoacoustic detection optical system according to a second embodiment of the present invention.

FIG. 14 is a configuration diagram of an excitation optical system in a second embodiment.

FIG. 15 is a perspective view showing a planar structure of a sample and an excitation beam, a probe beam, and a reference beam in the second embodiment.

FIG. 16 is a diagram showing a cross-sectional structure of a sample and a state of generation of a photoacoustic effect by a stripe-like excitation beam in the second embodiment.

FIG. 17 is a diagram showing the state of incidence of a striped probe beam and a reference beam on a sample surface in the second embodiment.

FIG. 18 is a configuration diagram of a heterodyne interference optical system according to a second embodiment as viewed from the X-axis direction.

19 is a configuration diagram of the heterodyne interference optical system shown in FIG. 18 as viewed from the Y-axis direction.

FIG. 20 is a configuration diagram of a detection unit of a heterodyne interference optical system according to a second embodiment as viewed from the X-axis direction.

21 is a configuration diagram of a detection unit of the heterodyne interference optical system shown in FIG. 20, viewed from the Y-axis direction.

FIG. 22 is a diagram illustrating a photoacoustic detection optical system according to a third embodiment of the present invention.

FIG. 23 is a diagram illustrating a configuration of a signal processing system according to a third embodiment.

FIG. 24 is a diagram illustrating a photoacoustic detection optical system according to a fourth embodiment of the present invention.

FIG. 25 is a diagram showing a configuration of a multiple spot beam parallel irradiation optical system according to a fourth embodiment.

FIG. 26 is a diagram showing the shape of a mask of a multiple spot beam parallel irradiation optical system in a fourth embodiment.

FIG. 27 is a diagram showing a state in which a plurality of spot beams simultaneously irradiate a sample in the fourth embodiment.

FIG. 28 is a diagram showing a heat diffusion region generated by each spot beam in the fourth embodiment.

FIG. 29 is a diagram for explaining a conventional photoacoustic detection optical system.

FIG. 30 is a diagram illustrating the principle of the photoacoustic effect.

[Explanation of symbols]

1, 8 laser, 31 Ar laser, 51 He-Ne
Laser, 33, 57, 62 ... acousto-optic modulator, 39,
71, 150, 160 ... cylindrical lens, 42,
154: Objective lens, 82: CCD one-dimensional sensor, 5
0, 85: photoelectric conversion element, 95: two-dimensional memory, 96,
196: computer, 47: sample, 102, 103, 13
1, 132: Cu wiring pattern, 191: parallel output type photoelectric conversion element array, 193: lock-in amplifier group, 19
7: Multiple spot beam parallel irradiation optical system.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-36338 (JP, A) JP-A-2-243966 (JP, A) JP-A-3-156362 (JP, A) JP-A-3-3 282253 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 29/00-29/28

Claims (14)

(57) [Claims] A first light intensity-modulated at a desired frequency is applied to a band-like region on the surface of a sample, and light is emitted into the band-like region on the surface or inside the sample below the band-like region. An acoustic effect or a photothermal effect is generated, a second light is applied to a band-shaped region on the surface of the sample, and light reflected from the sample surface due to the irradiation of the second light interferes with reference light. The interference light generated by the photoelectric conversion element is detected by the photoelectric conversion element, and a plurality of small regions forming a band-like region on the surface of the sample or a plurality of small regions inside the sample below the band-like region from the detected interference light. A method for detecting surface or internal information of a sample, wherein region information is detected separately for each of the plurality of small regions. 2. A method of irradiating a surface of a sample with a first light which is intensity-modulated at a desired frequency and is shaped into a band, and irradiating the surface of the sample on the sample with the band-shaped first light irradiated with the first light. First
A photoacoustic effect or a photothermal effect is generated inside the sample below the surface of the region irradiated with the light, and the second light formed in a belt shape is irradiated with the first light on the surface of the sample. Irradiating the region, the reflected light from the sample surface by the irradiation of the second light interferes with the reference light, the interference light generated by the interference is detected by the photoelectric conversion element, the detected interference light from the detected interference light Information of a plurality of small regions constituting a region of the surface of the sample irradiated with the first light or a plurality of small regions inside the sample below the region irradiated with the first light is obtained. A method for detecting surface or internal information of a sample, wherein the detection is performed separately for each small area. 3. The method according to claim 1, wherein the first light and the second light are laser lights having different wavelengths from each other.
The method for detecting surface or internal information of a sample according to claim 1 or 2 . Wherein said reference beam, a second surface or internal information detected of a sample according to claim 1 or 2, characterized in that the those formed by branched light irradiated on the surface of the sample Method. 5. The internal information of the sample of the lower plurality of regions or the plurality of areas of the obtained the sample surface, reflectivity distribution of the sample surface, uneven distribution of the sample surface, the photoacoustic signal 3. The method according to claim 1, wherein the method includes information on an amplitude distribution and a phase distribution of a photoacoustic signal. And irradiating the said first light and said second light to the sample while moving the wherein said sample
The method for detecting surface or internal information of a sample according to claim 1 or 2 . Wherein said two-dimensional image based on the detected surface or internal information of the sample, surface or internal information detection method of a sample according to claim 5, wherein the displaying on the monitor screen. 8. The method according to claim 1, wherein the photoelectric conversion element is a storage type solid-state imaging device such as a CCD one-dimensional sensor. 9. A first light source for emitting a first light, and a first light emitted from the first light source is intensity-modulated at a desired frequency to irradiate a band-shaped region on the surface of the sample. A first irradiating means, a second light source means for emitting a second light, and a second light emitted from the second light source means in a strip shape on the surface of the sample irradiated with the first light. A second irradiating means for irradiating an area of the sample, a reference light means for generating a reference light, and a reflected light generated on the sample surface by the second light irradiated by the second irradiating means. Detecting means for interfering with the generated reference light to detect interference light due to the interference; and a plurality of processing means for processing a signal obtained by detecting the interference light with the detecting means to form a band-shaped region on the surface of the sample. Information of a plurality of small regions inside the sample below the small region or the band-shaped region. Surface or internal information detection apparatus of samples comprising the processing means for separately detecting each frequency. 10. A table on which a sample is placed and movable in at least one axis direction, a first light source for emitting a first light, and a first light emitted from the first light source. A first irradiating means for modulating the intensity at a desired frequency and shaping it into a band shape and irradiating the surface of the sample placed on the table means, a second light source means for emitting a second light, Forming a second light beam emitted from the second light source means into a band shape and irradiating the band on the surface of the sample with the first light beam;
Irradiating means, reference light means for generating reference light, and reflected light generated by the second light irradiated by the second irradiating means on the surface of the sample irradiated by the first irradiating means Image detection means for causing the interference with the reference light generated by the reference light means to detect an image of the interference light due to the interference, and processing the signal of the interference light image obtained by the detection by the image detection means Processing means for separating and detecting, for each of the plurality of small regions, a plurality of small regions constituting a band-shaped region on the surface of the sample or a plurality of small regions inside the sample below the band-shaped region; A device for detecting surface or internal information of a sample, comprising: 11. A first light source means for emitting a first light,
First irradiating means for simultaneously irradiating a plurality of regions on the surface of the sample with first light emitted from the first light source means, second light source means for emitting second light, and Forming a second light emitted from the light source means into a band shape and simultaneously irradiating a plurality of regions on the surface of the sample irradiated with the first light.
Irradiating means, reference light means for generating reference light, and reflected light generated on the sample surface by the second light radiated by the second irradiating means interferes with reference light generated by the reference light means Interference light detection means for detecting interference light due to the interference, and processing a signal obtained by detecting the interference light with the interference light detection means to form a plurality of small elements constituting a band-shaped region on the surface of the sample. Processing means for separating and detecting information of a plurality of small regions inside the sample below the region or the band-like region for each of the plurality of small regions, wherein the surface or internal information of the sample is provided. Detection device. 12. A first light source means for emitting a first light,
First irradiating means for simultaneously irradiating a plurality of regions on the surface of the sample with first light emitted from the first light source means, second light source means for emitting second light, and Forming a second light emitted from the light source means into a band shape and simultaneously irradiating a plurality of regions on the surface of the sample irradiated with the first light.
Irradiating means, reference light means for generating reference light, and reflected light generated on the sample surface by the second light radiated by the second irradiating means interferes with reference light generated by the reference light means Interference light detecting means for imaging and detecting an image of interference light due to the interference, and processing an image signal obtained by imaging the image of the interference light with the interference light detection means to form a band on the surface of the sample. Processing means for separating and detecting information on a plurality of small regions constituting the region or a plurality of small regions inside the sample below the band-shaped region for each of the plurality of small regions. Surface or internal information detection device for the sample. 13. The apparatus according to claim 13, wherein said first light source means and said second light source means each emit laser light.
A sample surface or internal information detecting device according to any one of claims 9 to 12 . 14. The surface of a sample according to claim 9 , wherein said reference light means generates reference light from second light emitted from said second light source means. Or an internal information detection device.