JP2020176842A - Optical unit, optical measurement device, and optical measurement method - Google Patents

Abstract

To provide an optical unit, optical measurement device, and optical measurement method capable of correctly visualizing an irradiation position (measurement position) of measurement light including an area other than a visible area within a wavelength range.SOLUTION: An optical unit comprises: a probe for radiating measurement light including an area other than a visible area within a wavelength range to a sample along a first optical axis, and also receiving reflection light of the measurement light generated in the sample; a first beam splitter arranged on the first optical axis; a second beam splitter for guiding observation light to the first beam splitter so as to allow the observation light including a visible area within a wavelength range to be radiated to a sample along the first optical axis; and an imaging section for receiving light whose optical path is changed into a second optical axis by the first beam splitter between reflection light of measurement light generated in a sample and reflection light of observation light generated in the sample, and outputting a picked-up image indicating an image of received light. The imaging section has sensitivities in both of at least a part of a wavelength range of observation light and at least a part of a wavelength range of measurement light.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical unit, an optical measuring device, and an optical measuring method for measuring the optical characteristics of a sample.

A microscopic measuring device is known as an example of an optical measuring device for measuring the optical characteristics of a sample. The microscopic measuring device measures physical quantities such as reflectance, refractive index, film thickness, and extinction coefficient of an arbitrary sample via an optical system that magnifies and reduces light. The microscopic measuring device has a problem that it is difficult to adjust the measurement position with respect to the sample (or the focal position which is the position on the sample on which the optical system forms an image). Regarding the adjustment of the measurement position with respect to the sample, the following prior art is known in which the irradiation position is realized on the sample by projecting visible light along the same optical path as the measurement light (the following patents). References 1 to 4 and the like).

Japanese Unexamined Patent Publication No. 2005-098835 (Patent Document 1) relates to an optical distance measuring method and an apparatus for measuring a distance in a non-contact manner using low coherence light, and has a low coherence light for measurement on a measurement target surface. Visible light is emitted and the photodetector is configured to emit only low coherence light. By adopting such a configuration, the visibility of the measurement point on the measurement target surface can be ensured, and the distance between the measurement head and the measurement target surface is measured without using visible light as measurement noise light. can do.

Japanese Patent Application Laid-Open No. 2016-090383 (Patent Document 2) refers to near-infrared laser light on a measurement target by synthesizing visible light with a near-infrared laser light with a wavelength synthesizer and emitting it to the measurement target. When the configuration in which the irradiation location is presented by visible light is adopted, the irradiation position of the near-infrared laser light and the irradiation position of the visible light on the measurement object due to the chromatic aberration generated between the near-infrared laser light and the visible light. To solve the problem that the two may not match, a solution for correctly presenting the irradiation position of the invisible laser beam used for the measurement is disclosed.

Japanese Patent Application Laid-Open No. 2009-270939 (Patent Document 3) uses wideband light as detection light for measurement, and the distance between the exit side end face of the condensing lens and the measurement object that emits the detection light toward the measurement object. Discloses an optical displacement meter that measures by utilizing the interference between the reflected light from the object to be measured and the reflected light from the end face on the exit side. The optical displacement meter has a guide light light source device that generates visible light as a guide light for displaying the irradiation position of the detection light on the work.

Japanese Unexamined Patent Publication No. 2006-139027 (Patent Document 4) discloses a microscope illuminating device capable of accurately irradiating a guide light for grasping the irradiation position of the stimulating light at the same position as the stimulating light with a relatively simple configuration. ..

Japanese Unexamined Patent Publication No. 2005-098835 Japanese Unexamined Patent Publication No. 2016-090383 JP-A-2009-270939 Japanese Unexamined Patent Publication No. 2006-139027

In the prior art disclosed in Patent Documents 1 to 4 described above, visible light indicating the irradiation position is projected on the sample, and the user confirms the measurement position based on the projected visible light. However, when measuring optical characteristics using light other than the visible region (infrared region, ultraviolet region, etc.) (also referred to as "invisible region"), visible light is projected due to chromatic aberration generated in the optical system. It may not be possible to confirm whether or not the current position matches the actual measurement position.

An object of the present invention is to provide an optical unit, an optical measuring device, and an optical measuring method capable of more accurately visualizing an irradiation position (measurement position) of measurement light including a wavelength range other than the visible range.

An optical unit according to an embodiment of the present invention is a probe that irradiates a sample with measurement light having a wavelength range other than the visible range along the first optical axis and receives reflected light of the measurement light generated in the sample. , The observation light is first so that the first beam splitter arranged on the first optical axis and the observation light including the visible region in the wavelength range illuminate the sample along the first optical axis. Of the second beam splitter leading to the beam splitter, the reflected light of the measurement light generated in the sample, and the reflected light of the observation light generated in the sample, the first beam splitter receives the light whose optical path is changed to the second optical axis. It also includes an imaging unit that outputs an captured image showing an image of the received light. The imaging unit has sensitivity to at least a part of the wavelength range of the observation light and at least a part of the wavelength range of the measurement light.

The wavelength range of the measurement light may include a near infrared region. The wavelength range of the observation light may be configured so as not to overlap with the wavelength range of the measurement light.

The second beam splitter may be located on the second optical axis. The observation light source that generates the observation light may be arranged on the third optical axis associated with the second beam splitter.

The second optical axis may be orthogonal to the first optical axis. The third optical axis may be orthogonal to the second optical axis and may be non-parallel to the first optical axis.

The first beam splitter may be made of a pellicle film.
The optical unit may further include an intensity adjusting means for adjusting the intensity balance between the reflected light of the measurement light incident on the imaging unit and the reflected light of the observation light.

The intensity adjusting means may include an optical filter arranged in front of the imaging unit.
The intensity adjusting means is a means for changing the process of synthesizing the output signal from the imaging unit for the wavelength range of the measurement light and the output signal from the imaging unit for the wavelength range of the observation light, and for the wavelength range of the measurement light. Any of the means for changing the ratio of the sensitivity of the imaging unit to the sensitivity of the imaging unit with respect to the wavelength range of the observation light may be included.

An optical measuring device according to another embodiment of the present invention is optically connected to the above-mentioned optical unit and a probe of the optical unit, receives reflected light of measurement light guided through the probe, and includes optical characteristics. Includes a measurement unit that outputs measurement results.

The measurement unit has a means for calculating the reflectance spectrum of the sample based on the reflected light of the measurement light, a means for calculating the wave number conversion reflectance spectrum by a predetermined wave number conversion for the reflectance spectrum, and a wave number for the wave number conversion reflectance spectrum. Calculate at least one of the optical film thickness of the sample, the film thickness of the sample, and the distance to the sample as optical characteristics based on the means for calculating the power spectrum by Fourier transforming and the position of the peak appearing in the power spectrum. It may include means of doing so.

The optical film thickness of the first beam splitter may be determined to be less than the lower limit of the measurable optical film thickness determined based on the upper and lower limits of the measurement wavelength range of the measuring unit.

The optical measurement method according to still another embodiment of the present invention includes a step of irradiating the sample with the measurement light generated by the measurement light source in the wavelength range other than the visible region along the first optical axis and the visible region. The step of irradiating the sample with the observation light having the above in the wavelength range along the first optical axis, the step of receiving the reflected light of the measurement light generated in the sample and outputting the measurement result including the optical characteristics, and the step occurring in the sample. Of the reflected light of the measurement light and the reflected light of the observation light generated in the sample, the image pickup unit receives the light whose optical path is changed to the second optical axis by the first beam splitter arranged on the first optical axis. , Including the step of outputting an captured image showing an image of the received light. The imaging unit has sensitivity to at least a part of the wavelength range of the observation light and at least a part of the wavelength range of the measurement light.

According to an embodiment of the present invention, the irradiation position (measurement position) of the measurement light including the wavelength range other than the visible range can be visualized more accurately.

It is a schematic diagram which shows the structural example of the optical measuring apparatus according to this Embodiment. It is a schematic diagram which shows the functional configuration example of the measurement unit which comprises the optical measurement apparatus according to this embodiment. It is a schematic diagram which shows an example of the optical system of the spectroscopic measurement part shown in FIG. It is a schematic diagram which shows the main part of the optical system of the optical unit according to this embodiment. It is a schematic diagram which shows the optical path of the measurement light and the reflected light of the measurement light in the optical unit according to this embodiment. It is a schematic diagram which shows the optical path of the reflected light of the measurement light in the optical unit which follows this embodiment. It is a schematic diagram which shows the optical path of the observation light in the optical unit which follows this embodiment. It is a schematic diagram which shows the optical path of the reflected light of the observation light in the optical unit which follows this embodiment. It is a schematic diagram which shows the field of view of the image pickup part in the optical unit which follows this embodiment. It is a schematic diagram which shows another form of the optical system of the optical unit which follows this embodiment. It is a schematic diagram which shows the structural example of the 2D image sensor adopted by the image pickup part of the optical unit which follows this embodiment. It is a schematic diagram which shows another structural example of the 2D image sensor adopted by the image pickup part of the optical unit which follows this Embodiment. It is a figure which shows an example of the image pickup result by the image pickup part of the optical unit which follows this embodiment. It is a figure for demonstrating the relationship between the wavelength range and the periodicity of an interference waveform at the time of measuring the sample which has the lower limit value of the optical film thickness that can be measured by using the optical measuring apparatus according to this Embodiment. It is a flowchart which shows the measurement procedure of the sample using the optical measuring apparatus according to this embodiment. It is a figure which shows the measurement example of the sample using the optical measuring apparatus according to this embodiment. It is a figure which shows the measurement example of the sample using the optical measuring apparatus according to this embodiment. It is a figure which shows the measurement example of the sample using the optical measuring apparatus according to this embodiment.

Embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

<A. Configuration example of optical measuring device 1>
First, a configuration example of the optical measuring device 1 according to the present embodiment will be described.

FIG. 1 is a schematic view showing a configuration example of an optical measuring device 1 according to the present embodiment. With reference to FIG. 1, the optical measuring device 1 is typically a microscopic measuring device including an optical unit 2, a measuring unit 100, and a display device 200. Although FIG. 1 illustrates an optical measuring device 1 composed of three devices, all or a part of the three devices may be integrated to form an optical measuring device.

The optical measuring device 1 irradiates the sample SMP with light for measurement (hereinafter, also referred to as “measurement light”), and calculates the optical characteristics of the sample SMP based on the reflected light from the sample SMP. As the optical characteristics, typically, the optical film thickness of the sample SMP, the film thickness of the sample SMP, the distance from the reference position to the surface of the sample SMP, and the like are assumed.

The measurement unit 100 functions as a light source that generates measurement light, and also functions as a light receiving unit that receives reflected light from the sample SMP and outputs a measurement result. The branch fiber 41 and the branch fiber 42 branched by the fiber coupler 43 of the Y-type fiber 40 are connected to the measurement unit 100. As will be described later, the measurement light is provided to the optical unit 2 via the branch fiber 41, and the reflected light from the sample SMP is incident on the measurement unit 100 via the branch fiber 42.

Typical examples of the sample SMP include a semiconductor substrate, a thin film-formed glass substrate, a functional resin, and a functional plastic having a special surface shape and fine structure.

Further, the optical measuring device 1 irradiates the sample SMP with observation light (hereinafter, also referred to as “observation light”) in order to observe the state of the sample SMP during measurement. An captured image of the reflected light generated by reflecting the observation light by the sample SMP is also output.

The optical measuring device 1 according to the present embodiment measures the optical characteristics of the sample SMP using light having a wavelength range other than the visible region (infrared region, ultraviolet region, etc.) as the measurement light. At this time, by irradiating the sample SMP with light having a visible region in the wavelength range as observation light and taking an image with the imaging unit, the surface state of the sample SMP can be observed at the same time as the measurement. At this time, by including the information indicating the measurement state in the surface state of the observed sample SMP, the measurement position on the sample SMP can be confirmed more reliably. Further, by adopting a beam splitter and a related optical system as described later, it is possible to suppress a decrease in the intensity of light used for measurement, improve measurement accuracy, and speed up measurement time.

In the following description, a configuration in which light including the near-infrared region in the wavelength range is used as the measurement light will be illustrated, but the measurement light is not limited to this, and light including the infrared region in the wavelength range may be used as the measurement light. Alternatively, light having an ultraviolet region in the wavelength range may be used as the measurement light. Further, the wavelength range of the measurement light may include a part of the visible range as long as it does not overlap with the wavelength range of the observation light. That is, it is preferable that the wavelength range of the observation light does not overlap with the wavelength range of the measurement light so as not to cause a measurement error.

(A1: Configuration example of the optical unit 2)
First, a configuration example of the optical unit 2 constituting the optical measuring device 1 will be described.

The optical unit 2 is sometimes referred to as a "coaxial epi-illumination microscopic unit" because the sample SMP is irradiated with the measurement light and the observation light along the same optical axis AX1.

With reference to FIG. 1, the optical unit 2 includes a stage 10, a lower cylinder portion 12, an upper cylinder portion 14, a light emitting / receiving probe 16, an imaging lens 20, a main beam splitter 22, and an observation light source 24. , A sub-beam splitter 26, a macro lens 28, an imaging unit 30, and an optical filter 32.

In the stage 10, the sample SMP is arranged and the arrangement position of the sample SMP is changed along the plane orthogonal to the optical axis AX1. The stage 10 may have a configuration (XY stage) in which the stage 10 moves in two orthogonal axial directions along a plane orthogonal to the optical axis AX1, or a configuration in which the distance and the angle are changed with reference to the optical axis AX1 (the stage 10). Rθ stage) may be used. Further, the stage 10 may be configured to change the position of the sample SMP by manual operation (manual stage), or change the position of the sample SMP according to a command from the upper personal computer (upper PC). It may be configured (automatic stage).

A lower cylinder portion 12 and an upper cylinder portion 14 are arranged parallel to the optical axis AX1 on the upper part of the stage 10. A light emitting / receiving probe 16 is arranged on the upper part of the upper tubular portion 14. A connector 18 provided at one end of the Y-shaped fiber 40 is optically connected to the light receiving probe 16.

The light emitting / receiving probe 16 irradiates the sample SMP with the measurement light along the optical axis AX1 and receives the reflected light of the measurement light generated in the sample SMP. More specifically, the light emitting / receiving probe 16 has an imaging lens 20 positioned at the center of the optical axis AX1. The measurement light emitted from the connector 18 is converged by the imaging lens 20 so as to be imaged by the sample SMP.

Inside the lower tubular portion 12, the main beam splitter 22 is arranged at a position intersecting the optical axis AX1, and the imaging unit 30 is arranged in association with the main beam splitter 22. For the main beam splitter 22, a light distribution thin film may be used in order to suppress the attenuation of the transmitted measurement light as much as possible. As an example of the light distribution thin film, a pellicle film having high transmittance can be used.

A part of the measurement light transmitted through the imaging lens 20 and propagating toward the sample SMP passes through the main beam splitter 22 and heads toward the sample SMP along the optical axis AX1. A part of the measurement light incident on the sample SMP is reflected on the front surface, the inside or the back surface of the sample SMP, and propagates in the opposite direction along the optical axis AX1. When the reflected light of the measurement light generated by the reflection in the sample SMP is incident on the main beam splitter 22, a part thereof is transmitted through the main beam splitter 22 and is incident on the light emitting / receiving probe 16, and another part is incident. , Reflected by the main beam splitter 22 and incident on the imaging unit 30. That is, the reflected light of the measurement light generated by irradiating the sample SMP with the measurement light is incident on both the light emitting / receiving probe 16 (measurement unit 100) and the image pickup unit 30.

Further, the sub-beam splitter 26 is arranged in association with the main beam splitter 22, and the observation light source 24 is arranged in association with the sub-beam splitter 26. The sub-beam splitter 26 is arranged on the optical axis AX2, and the observation light source 24 is arranged on the optical axis AX3 associated with the sub-beam splitter 26. The sub-beam splitter 26 guides the observation light to the main beam splitter 22 so that the observation light from the observation light source 24 is applied to the sample SMP along the optical axis AX1. As the sub-beam splitter 26, a half mirror or the like may be used. As described above, the sub-beam splitter 26 is arranged outside the optical path of the measurement light, that is, at a position not intersecting the optical axis AX1 so as not to affect the optical path of the measurement light.

The observation light source 24 generates observation light including at least a wavelength range in the visible range. As the observation light source 24 that generates observation light including the wavelength range of the visible range, a white LED (light emitting diode) or the like may be adopted. The observation light generated by the observation light source 24 is reflected by the sub-beam splitter 26 and incident on the main beam splitter 22, and is reflected by the main beam splitter 22 toward the sample SMP along the optical axis AX1. A part of the observation light incident on the sample SMP is reflected on the front surface, the inside or the back surface of the sample SMP, and propagates in the opposite direction along the optical axis AX1. When the reflected light of the observation light generated by the reflection by the sample SMP is incident on the main beam splitter 22, a part of the reflected light is reflected by the main beam splitter 22 and incident on the imaging unit 30.

The reflected light of the observation light generated by irradiating the sample SMP with the observation light is incident on the imaging unit 30. The reflected light of the observation light may also enter the measurement unit 100 via the light emitting / receiving probe 16, but it is blocked by the cut filter (see FIG. 3) of the measurement unit 100 as described later, so that the measurement can be performed. There is no substantial effect.

The image pickup unit 30 includes a two-dimensional image pickup element that outputs an observation image according to the intensity of the incident light, and has sensitivity to at least a part of the wavelength range of the measurement light and at least a part of the wavelength range of the observation light. There is. As described above, the imaging unit 30 receives the light whose optical path is changed on the optical axis AX2 by the main beam splitter 22 among the reflected light of the measurement light generated in the sample SMP and the reflected light of the observation light generated in the sample SMP. The imaging unit 30 outputs an captured image showing an image of the received light.

Here, the imaging unit 30 has sensitivity to at least a part of the wavelength range of the observation light and at least a part of the wavelength range of the measurement light. That is, the sensitivity range of the imaging unit 30 may include not only the visible region of the observation light but also the near infrared region of the measurement light. As a result, the imaging unit 30 outputs an captured image including information on the reflected light of the measurement light and the reflected light of the observation light generated from the sample SMP. The image captured by the imaging unit 30 is output to the display device 200. As the imaging unit 30, a CCD image sensor, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, or the like may be typically adopted.

A macro lens 28 is arranged in front of the imaging unit 30. The macro lens 28 adjusts the field of view of the imaging unit 30.

An optical filter 32 is arranged in front of the macro lens 28. The optical filter 32 adjusts the intensity balance between the reflected light of the measurement light and the reflected light of the observation light incident on the imaging unit 30 by attenuating the components in the predetermined wavelength range (details will be described later). ).

(A2: Configuration example of measurement unit 100)
Next, a configuration example of the measurement unit 100 constituting the optical measurement device 1 will be described.

FIG. 2 is a schematic view showing a functional configuration example of the measurement unit 100 constituting the optical measurement device 1 according to the present embodiment. With reference to FIG. 2, the measurement unit 100 includes a measurement light source 110, a spectroscopic measurement unit 120, a calculation unit 130, and an interface 140.

The measurement unit 100 is optically connected to the light emitting / receiving probe 16 of the optical unit 2, receives the reflected light of the measurement light guided through the light emitting / receiving probe 16, and outputs the measurement result. The optical unit 2 and the measurement unit 100 are optically connected by a Y-shaped fiber 40 having two branches at one end. As the Y-type fiber 40, one having a single mode structure is used.

The measurement light source 110 generates measurement light. The measurement light generated by the measurement light source 110 may typically include the near infrared region in the wavelength range. An ASE (Amplified Spontaneous Emission) light source may be adopted as the measurement light source 110 that generates measurement light including the near infrared region in the wavelength range. Further, the measurement light source 110 preferably generates incoherent light as measurement light. The measurement light source 110 is optically connected to the branch fiber 41 of the Y-type fiber 40, and the measurement light propagates to the optical unit 2 via the branch fiber 41.

The spectroscopic measurement unit 120 is optically connected to the branch fiber 42 of the Y-type fiber 40, and receives the reflected light from the sample from the optical unit 2 (that is, the light generated by the measurement light reflected by the sample or the like). Then, the intensity distribution showing the intensity of the received light for each wavelength is output as the measurement result (see FIG. 3 for details).

The calculation unit 130 calculates various optical characteristics of the sample based on the measurement results output from the spectroscopic measurement unit 120. As the optical characteristics of the sample, at least one of the optical film thickness of the sample SMP, the film thickness of the sample SMP, and the distance from the reference position to the sample SMP may be calculated. In this case, the measurement result of the spectroscopic measurement unit 120 includes the spectrum of the reflected light or the transmitted light from the sample, and the arithmetic unit 130 performs frequency analysis of the spectrum from the spectroscopic measurement unit 120 to obtain the thickness of the sample. Is calculated. The arithmetic unit 130 may be implemented using a processor that executes a program, or may be a hard-wired device such as an FPGA (field-programmable gate array), an ASIC (application specific integrated circuit), or a SoC (system on a chip). It may be implemented using.

The interface 140 exchanges measurement results including optical characteristics calculated by the calculation unit 130 with a higher-level PC (not shown). As the interface 140, a known transmission medium such as Ethernet (registered trademark), wireless LAN, or USB (universal serial bus) can be used.

As a measurement result, between the measurement unit 100 and the upper PC, in addition to the calculated optical characteristics of the sample, data used in the calculation process such as the reflectance spectrum of the sample, attribute information at the time of measurement, and the imaging unit 30 You may exchange images captured by.

The power supply unit may be arranged inside or outside the measurement unit 100.
FIG. 3 is a schematic view showing an example of the optical system of the spectroscopic measurement unit 120 shown in FIG. The spectroscopic measurement unit 120 outputs an intensity distribution (spectrum) for each wavelength of the incident light. With reference to FIG. 3, the spectroscopic measurement unit 120 includes a slit 121, a shutter 122, a cut filter 123, a collimating mirror 124, a diffraction grating 125, a focus mirror 126, and a detection unit 127.

The slit 121 is arranged following the branched fiber 42 of the Y-shaped fiber 40, and adjusts the spot diameter of the incident light.

The shutter 122 is configured to be able to block the light incident on the detection unit 127. The shutter 122 is used for resetting the detection unit 127 and the like. The shutter 122 typically employs a mechanical structure driven by electromagnetic force.

The cut filter 123 limits wavelength components outside the detection wavelength range included in the light incident on the detection unit 127. It is preferable that the cut filter 123 blocks wavelength components outside the detection wavelength range as much as possible.

The collimating mirror 124 reflects the light (diffused light) incident on the slit 121 and converts it into parallel light, and propagates the light converted into parallel light toward the diffraction grating 125.

The diffraction grating 125 separates the incident light according to the wavelength and guides it to the detection unit 127. Specifically, the diffraction grating 125 is a reflection type diffraction grating, and is configured so that a diffracted wave for each predetermined wavelength interval is reflected in each corresponding direction. When light is incident on the diffraction grating 125 having such a configuration, each wavelength component contained therein is reflected in the corresponding direction and incident on the corresponding detection element of the detection unit 127. As the diffraction grating 125, a blazeed holographic plane grating is typically adopted.

The focus mirror 126 reflects the light reflected by the diffraction grating 125 in the direction corresponding to the wavelength, and forms an image on the detection surface of the detection unit 127.

The detection unit 127 has a plurality of detection elements, and outputs an electric signal indicating the intensity of light incident on each detection element. That is, the detection unit 127 outputs an electric signal showing a spectrum showing the intensity of each wavelength component contained in the light dispersed by the diffraction grating 125. As the detection unit 127, a linear image sensor in which a plurality of detection elements having sensitivity in the near infrared region are linearly arranged is typically adopted. As the detection element, InGaAs (indium gallium arsenide) is typically adopted.

<B. Optical system of optical measuring device 1>
Next, the optical system of the optical measuring device 1 will be described in more detail.

FIG. 4 is a schematic view showing a main part of the optical system of the optical unit 2 according to the present embodiment. With reference to FIG. 4, the light emitting / receiving probe 16 forms a measurement light on the sample SMP on the optical axis AX1. A main beam splitter 22 is arranged on the optical axis AX1 connecting the light receiving probe 16 and the sample SMP. An optical filter 32, a macro lens 28, and an imaging unit 30 are arranged on the optical axis AX2 corresponding to the reflecting surface of the main beam splitter 22. An observation light source 24 is arranged on the optical axis AX3 corresponding to the reflection surface of the sub-beam splitter 26.

As shown in FIG. 4, the optical axis AX2 is orthogonal to the optical axis AX1, and the optical axis AX3 is orthogonal to the optical axis AX2. The optical axis AX3 is non-parallel to the optical axis AX1.

Hereinafter, the measurement light, the reflected light of the measurement light, the observation light, and the optical path of the reflected light of the observation light will be described.

FIG. 5 is a schematic view showing an optical path of the measurement light ML1 and the reflected light ML2 of the measurement light in the optical unit 2 according to the present embodiment. With reference to FIG. 5, the measurement light ML1 generated by the measurement unit 100 is irradiated from the light emitting / receiving probe 16 and propagates along the optical axis AX1 to enter the sample SMP. A part of the measurement light ML1 incident on the sample SMP is reflected on the front surface, the inside or the back surface of the sample SMP to become the reflected light ML2 of the measurement light, and propagates toward the light emitting / receiving probe 16 along the optical axis AX1.

FIG. 6 is a schematic view showing an optical path of the reflected light ML3 of the measurement light in the optical unit 2 according to the present embodiment. With reference to FIG. 6, a part of the reflected light generated by the measurement light ML1 reflected on the front surface, the inside or the back surface of the sample SMP is propagating toward the light emitting / receiving probe 16 along the optical axis AX1. , Reflected by the main beam splitter 22. The light reflected by the main beam splitter 22 propagates toward the image pickup unit 30 along the optical axis AX2 as the reflected light ML3 of the measurement light.

FIG. 7 is a schematic view showing the optical path of the observation light OL1 in the optical unit 2 according to the present embodiment. With reference to FIG. 7, the observation light OL1 generated by the observation light source 24 propagates along the optical axis AX3, enters the sub-beam splitter 26, changes the propagation direction to the optical axis AX2, and further, the main beam splitter. It is incident on 22 and the propagation direction is changed to the optical axis AX1. Then, the observation light OL1 is incident on the sample SMP.

FIG. 8 is a schematic view showing an optical path of the reflected light OL2 of the observation light in the optical unit 2 according to the present embodiment. With reference to FIG. 8, a part of the observation light OL1 incident on the sample SMP is reflected on the front surface, the inside or the back surface of the sample SMP to become the reflected light OL2 of the observation light, and the light emitting / receiving probe 16 is along the optical axis AX1. Propagate towards. The reflected light OL2 is reflected by the main beam splitter 22 in the process of propagating toward the light emitting / receiving probe 16 along the optical axis AX1. The reflected light OL2 reflected by the main beam splitter 22 propagates toward the image pickup unit 30 along the optical axis AX2.

FIG. 9 is a schematic view showing the field of view of the imaging unit 30 in the optical unit 2 according to the present embodiment. With reference to FIG. 9, the imaging unit 30 can output an observation image in which two lights, the reflected light ML3 of the measurement light and the reflected light OL2 of the observation light, are combined.

As described above, since the imaging unit 30 has sensitivity in the wavelength range of the observation light and the measurement light, the optical characteristics of the sample SMP are measured in addition to the surface state of the sample SMP visualized by visible light. It is also possible to observe the measurement light itself for this purpose.

In the prior art of embodying the irradiation position on the sample SMP by projecting visible light along the same optical path as the measurement light, the position is not necessarily the measurement position on the sample SMP on which visible light is projected due to chromatic aberration or the like. May not match. In the optical measuring device 1 according to the present embodiment, since the observation light applied to the sample SMP can be directly observed, such a problem does not occur and the measurement position on the sample SMP can be confirmed more reliably.

FIG. 10 is a schematic view showing another embodiment of the optical system of the optical unit 2 according to the present embodiment. FIG. 10 shows an optical system for measuring the distance from the reference position to the surface of the sample SMP as optical characteristics.

In the optical system shown in FIG. 10, a transmission optical member 34 is added on the optical axis AX1 as compared with the optical system shown in FIG. The transmission optical member 34 has a reference surface that serves as a reference position for distance measurement. The distance between the reference surface and the sample SMP surface can also be measured with reference to the reference surface of the transmission optical member 34.

For details on measuring the distance to the sample SMP, refer to, for example, Japanese Patent No. 6402273.

<C. Strength balance adjustment>
In the optical measuring device 1 according to the present embodiment, the imaging unit 30 receives the reflected light of the measurement light and the reflected light of the observation light. Since each light has a different light source, wavelength range, optical path, and the like, it is preferable to adjust the intensity balance when the same imaging unit 30 captures images at one time. That is, the optical measuring device 1 may be equipped with an intensity adjusting function for adjusting the intensity balance between the reflected light of the measurement light incident on the imaging unit 30 and the reflected light of the observation light. By implementing such an intensity adjustment function, both the reflected light of the measurement light whose wavelength range is in the near-infrared region and the reflected light of the observation light whose wavelength range is the visible region can be suppressed without causing saturation or bleeding. , Can image with good contrast.

Hereinafter, some methods for adjusting the strength balance will be described.
(B1: Optical filter)
Typically, by arranging an optical filter (optical filter 32 shown in FIG. 1) in front of the imaging unit 30, the intensity balance can be adjusted between the reflected light of the measurement light and the reflected light of the observation light. That is, as the intensity adjusting function, an optical filter arranged in front of the imaging unit 30 may be adopted. Basically, the intensity balance is adjusted by attenuating the reflected light having a relatively high intensity.

(1) When the intensity of the reflected light of the measurement light> the intensity of the reflected light of the observation light When the intensity of the reflected light of the measurement light is larger than the intensity of the reflected light of the observation light, the intensity of the reflected light of the measurement light is attenuated. I need to let you. In such a case, an optical filter having a function of transmitting light on the short wavelength side and attenuating light on the long wavelength side can be used. As such an optical filter, a heat ray absorbing filter, a short pass filter, a cold filter, a notch filter, an interference filter and the like can be used.

(2) When the intensity of the reflected light of the measurement light <the intensity of the reflected light of the observation light When the intensity of the reflected light of the observation light is larger than the intensity of the reflected light of the measurement light, the intensity of the reflected light of the observation light is attenuated. I need to let you. In such a case, an optical filter having a function of transmitting light on the long wavelength side and attenuating light on the short wavelength side can be used. As such an optical filter, a long-pass filter, an infrared transmission filter, a notch filter and the like can be used.

Note that in one embodiment of the optical measuring device 1 according to the present embodiment, the intensity of the reflected light of the measurement light is greater at about 10 ⁵ times the order as compared to the intensity of the reflected light of the observation light, cut filter The intensity balance was adjusted by arranging two heat ray absorbing filters (blocking characteristics: about 85% at a wavelength of 500 nm and about 0.2% at a wavelength of 1000 nm) as 123.

Regarding what kind of optical filter is adopted, it is necessary to consider the spectral sensitivity characteristics of the imaging unit 30 to be used. Therefore, in the actually set-up optical system, it is preferable to appropriately select the optimum optical filter while considering the output wavelength band and intensity ratio of the measurement light (near infrared region) and the observation light (visible region).

By adjusting the intensity balance using the optical filter in this way, when observing the surface state of the sample SMP (imaging the reflected light of the observation light) and when confirming the irradiation position of the measurement light (reflection of the measurement light). It is not necessary to make the imaging conditions of the imaging unit 30 different from those of (light imaging). That is, since the observation of the surface state of the sample SMP and the confirmation of the irradiation position of the measurement light can be imaged at the same time under the same imaging conditions, the convenience during the measurement operation can be enhanced.

(B2: Sensitivity characteristics of the imaging unit 30)
By changing the sensitivity characteristic of the imaging unit 30, the intensity balance may be adjusted between the reflected light of the measurement light (near infrared region) and the reflected light of the observation light (visible region).

FIG. 11 is a schematic view showing a configuration example of a two-dimensional image sensor adopted by the image pickup unit 30 of the optical unit 2 according to the present embodiment. With reference to FIG. 11, the CCD image sensor 302, which is a two-dimensional image sensor adopted by the image pickup unit 30, is partitioned so as to detect each of the visible region and the near infrared region.

More specifically, the CCD image sensor 302 includes a color filter 304, a near infrared absorption filter 306, and a photoelectric conversion unit 308. The color filter 304 is partitioned into a region that transmits light in each wavelength range of red (R), green (G), blue (B), and near infrared (IR). The near-infrared absorption filter 306 is arranged in association with each of the red (R), green (G), and blue (B) sections, and attenuates or blocks light in the near-infrared region. The photoelectric conversion unit 308 outputs an electric signal indicating the intensity of the incident light in each section. A dual pass filter (not shown) may be arranged in the front stage.

By adopting a two-dimensional image sensor as shown in FIG. 11, an electric signal showing an image in the visible region (red (R), green (G), blue (B)) and an image in the near infrared region (near infrared) are used. (IR))) can be output independently, so by adjusting the process of generating each image from these electrical signals, the intensity of each image included in the output captured image can be adjusted. it can.

As described above, as the intensity adjusting function, the output signal from the imaging unit 30 for the wavelength range of the measurement light (that is, the near infrared region) and the imaging unit 30 for the wavelength range of the observation light (that is, the visible region). A function of changing the process of synthesizing the output signal may be adopted.

FIG. 12 is a schematic view showing another configuration example of the two-dimensional image pickup device adopted by the image pickup unit 30 of the optical unit 2 according to the present embodiment. With reference to FIG. 12, the CMOS image sensor 310, which is a two-dimensional image sensor adopted by the image pickup unit 30, has a laminated thin film, and by changing the voltage applied to the laminated thin film, the sensitivity wavelength region ( Visible light / near infrared region) can be electronically controlled on a frame-by-frame basis at the same time for all pixels.

The CMOS image sensor 310 includes a microlens 312, a protective layer 314, a transparent electrode 316, an organic thin film 318 for the visible region, an organic thin film 320 for the near infrared region, a pixel electrode 322, a silicon substrate 324, and charge storage. Includes node 326 and power supply 328.

In the state shown in FIG. 12A, the voltage applied from the power supply 328 is Low, the signal charge 330 exists only in the organic thin film 318 for the visible region, and the signal is signaled in the organic thin film 320 for the near infrared region. Indicates a state in which the charge 330 does not exist. In this state, the CMOS image sensor 310 has sensitivity in the visible region.

On the other hand, in the state shown in FIG. 12B, the voltage applied from the power supply 328 is High, and the signal charge 330 is present in both the organic thin film 318 for the visible region and the organic thin film 320 for the near infrared region. Indicates the state. In this state, the CMOS image sensor 310 has sensitivity in the near infrared region.

By adopting a two-dimensional image sensor as shown in FIG. 12, an image in the visible region and an image in the near infrared region can be output independently, so the process of generating each image from these electric signals is adjusted. Therefore, the intensity of each image included in the output captured image can be adjusted.

As described above, as the intensity adjusting function, the ratio of the sensitivity of the imaging unit 30 to the wavelength range of the measurement light (that is, the near infrared region) and the sensitivity of the imaging unit 30 to the wavelength range of the observation light (that is, the visible region) is changed. You may adopt the function to make it.

By adopting the method of adjusting the intensity balance by changing the sensitivity characteristic of the imaging unit 30 as described above, it is possible to eliminate the need for an optical member such as an optical filter, so that cost reduction and compactification can be realized.

<D. Example of imaging result by imaging unit>
Next, an example of the imaging result by the imaging unit 30 of the optical measuring device 1 according to the present embodiment will be shown.

FIG. 13 is a diagram showing an example of an image pickup result by the image pickup unit 30 of the optical unit 2 according to the present embodiment. FIG. 13 shows an example of the measurement result of imaging a pattern wafer in which a metal electrode pattern is formed on a Si substrate as a sample SMP. A monochrome CCD imaging unit (manufacturer: SENTTECH, model: STC-SB133POEHS) was used as the imaging unit 30.

FIG. 13A shows an image captured by the imaging unit 30. As shown in FIG. 13A, in the image captured by the imaging unit 30, in addition to the surface shape of the sample SMP, the irradiation position (measurement position) of the measurement light can be confirmed.

FIG. 13B shows a profile of the shading value output by the imaging unit 30 corresponding to the XX cross section of FIG. 13A. As shown in FIG. 13B, the spot image portion of the measurement light has a high shading value, which means that the irradiation position of the measurement light can be sufficiently visually recognized in the image showing the surface shape of the sample SMP. ing.

Further, as shown in FIG. 13B, by adjusting the intensity balance between the reflected light of the measurement light and the reflected light of the observation light as described above, each reflection is performed in the captured image captured by the imaging unit 30. The difference in the shade value of the image due to light can be adjusted to an appropriate level.

Depending on the surface shape of the sample SMP (especially when measuring a sample SMP with a rough surface), it is assumed that the spot image of the measurement light cannot be visually recognized well due to the influence of diffused reflection on the surface of the sample SMP. .. In such a case, the irradiation position of the measurement light may be acquired in advance using a reference sample whose surface is a mirror surface, and the acquired irradiation position may be superimposed on the captured image displayed on the display device 200. Good.

<E. Optical characteristic calculation processing example>
Next, an example of the optical characteristic calculation process in the measurement unit 100 will be described.

The optical measuring device 1 according to the present embodiment measures the optical film thickness of the sample, the film thickness of the sample, and the distance to the sample as an example of the optical characteristics. Specifically, the optical measuring device 1 receives the reflected light generated by irradiating the sample with the measurement light, calculates the reflectance spectrum from the intensity distribution of each wavelength component contained in the reflected light, and refers to the reflectance spectrum. The wave number conversion reflectance spectrum is calculated by a predetermined wave number conversion, the wave number conversion reflectance spectrum is Fourier transformed with respect to the wave number to calculate the power spectrum, and the optical film thickness of the sample and the sample are calculated based on the positions of the peaks appearing in the power spectrum. Measure one or more of the film thickness and the distance to the sample. A method such as a fast Fourier transform can be used for frequency analysis. Further, when calculating the film thickness from the optical film thickness, the film thickness of the sample can be calculated by dividing the calculated optical film thickness by the refractive index n of the sample.

As described above, the measurement unit 100 includes a process of calculating the reflectance spectrum of the sample SMP based on the reflected light of the measurement light, a process of calculating the wave number conversion reflectance spectrum by a predetermined wave number conversion with respect to the reflectance spectrum, and a wave number. Based on the process of calculating the power spectrum by Fourier transforming the converted reflectance spectrum with respect to the number of waves, the process of calculating the power spectrum by Fourier transforming the reflectance spectrum, and the position of the peak appearing in the power spectrum, as optical characteristics, It is possible to execute a process of calculating at least one of the optical film thickness of the sample, the film thickness of the sample, and the distance to the sample.

Further, the film thickness may be calculated in consideration of the wavelength dependence of the refractive index of the sample. In this case, after calculating the reflectance spectrum R (λ) indicating the reflectance for each wavelength λ, the number of waves K (λ) = 2πn (λ) calculated from the known reflectance n (λ) for each wavelength. By introducing / λ, the wave number conversion reflectance R'≡R / (1-R) is calculated from the reflectance R of each wavelength. The power spectrum is calculated by Fourier transforming the wave number conversion reflectance spectrum consisting of the wave number conversion reflectance R'for each wavelength calculated with respect to the wave number K. The film thickness of the sample is calculated based on the position of the peak appearing in the calculated power spectrum. By calculating the film thickness in consideration of the wavelength dependence of the refractive index of the sample, the film thickness of the sample can be calculated with high accuracy. In addition, the thickness of each layer of the multilayer film contained in the sample can be calculated based on a plurality of peaks appearing in the power spectrum.

For detailed calculation processing, refer to, for example, Japanese Patent Application Laid-Open No. 2009-092454. The above-mentioned optical characteristic calculation process can be applied not only to the reflectance spectrum but also to the transmittance spectrum.

<F. Main beam splitter 22>
Next, the main beam splitter 22 will be described in more detail.

(F1: Structure of main beam splitter 22)
The optical measuring device 1 according to the present embodiment irradiates the sample SMP with the measurement light generated from the measurement unit 100, receives the reflected light of the irradiated measurement light with the measurement unit 100, and outputs the measurement result. It is preferable to eliminate as much as possible the factors that reduce the intensity of the measurement light in.

In the optical measuring device 1, it is preferable that only the main beam splitter 22 is substantially arranged on the optical path of the measurement light. Further, it is preferable that the transmittance of the main beam splitter 22 itself is as high as possible.

Specifically, in the optical measuring device 1 according to the present embodiment, a light distribution thin film is used as the main beam splitter 22. In particular, a pellicle film may be used as an example of the light distribution thin film. That is, the main beam splitter 22 may be made of a pellicle film. The pellicle membrane is composed of a carbon porous membrane and has a thickness of about several hundred nm to several tens of μm. As described above, by adopting an extremely thin light distribution thin film as the main beam splitter 22, attenuation with respect to the measurement light is suppressed as much as possible.

For example, if the transmittance of the pellicle film used as the main beam splitter 22 is 92%, the intensity of the measured light is about 85% (= 92% 2) even if the main beam splitter 22 is arranged on the optical axis AX1. Can be maintained at the power).

In this way, by reducing the number of optical members arranged on the optical axis AX1, which is the optical path of the measurement light, as much as possible, the intensity of the reflected light of the measurement light incident on the measurement unit 100 can be maintained, thereby improving the measurement accuracy. It is possible to improve and shorten the time required for measurement (tact time).

Further, when the measurement light, which is not parallel light but convergent light, is incident on the beam splitter, the optical path may change, but since the pellicle film is extremely thin, such a change in the optical path does not substantially occur. Therefore, there is no deviation between the images generated by the reflections on the front surface side and the back surface side of the beam splitter, and so-called ghost images are not substantially generated. That is, the main beam splitter 22 is arranged at a position where the luminous flux of the measurement light is a non-collimating beam, but a ghost image is not generated. Therefore, the image of the spot of the measurement light irradiated on the sample SMP and the surface of the sample SMP. Clear observation is possible by suppressing the blurring that occurs in the image showing the state.

(F2: Thickness of main beam splitter 22)
When combined with the measurement unit 100 as described above, it is preferable to design the optical film thickness of the main beam splitter 22 as follows. That is, when the optical unit 2 is applied to the spectroscopic interference type film thickness measurement, the optical film thickness (refractive index × actual thickness: nd) of the main beam splitter 22 is measured by the spectroscopic measurement unit 120 of the measurement unit 100. It is preferable that the lower limit value λ _min and the upper limit value λ _{max of the} possible wavelength range are less than the lower limit value d _min of the optical film thickness calculated according to the following equation (1).

That is, the optical film thickness of the main beam splitter 22 is determined so that nd <d _min . As described above, the optical film thickness of the main beam splitter 22 is determined to be less than the lower limit of the measurable optical film thickness determined based on the upper limit value and the lower limit value of the measurement wavelength range of the measurement unit 100. Is preferable.

FIG. 14 is a diagram for explaining the relationship between the wavelength range and the periodicity of the interference waveform when a sample SMP having a lower limit value of an optical film thickness that can be measured by using an optical measuring device according to the present embodiment is measured. Is. In FIG. 14, the lower limit value _{k min} of the wave number means the reciprocal of the upper limit value lambda _max in the wavelength range, the upper limit value _{k max} of the wave refers to the inverse of the lower limit lambda _min wavelength range.

As shown in FIG. 14, the lower limit value d _min of the optical film thickness calculated according to the equation (1) is within the measurable wavelength range (λ _{min to} λ _max ) of the spectroscopic measurement unit 120 for one cycle of the interference waveform. Corresponds to the optical film thickness when they match. That is, the lower limit value d _min of the optical film thickness means the optical film thickness when the number of data constituting one cycle of the interference waveform is the same as the number of detection elements of the detection unit 127.

If the wavelength range of the reflectance spectrum is less than one cycle of the interference waveform, the power spectrum obtained by Fourier transform does not have a peak derived from the interference waveform. Since the measurement light is transmitted to the main beam splitter 22, interference may occur in the main beam splitter 22 itself, but the film thickness of the sample SMP is calculated by satisfying the above-mentioned optical film thickness conditions. The power spectrum for this is not affected. That is, by setting the optical film thickness of the main beam splitter 22 to be _less than the lower limit value d _min of the optical film thickness calculated according to the equation (1), the main beam splitter 22 itself is used to calculate the film thickness of the sample SMP. The effect of interference caused by the above can be excluded from the measurement results.

(F3: Injection of observation light)
In the optical measuring device 1 according to the present embodiment, the main beam splitter 22 exerts three functions of separating the reflected light of the measurement light, injecting the observation light, and separating the reflected light of the observation light.

With reference to FIGS. 1, 7 and 8 again, the observation light source 24 is arranged on the optical axis AX3 orthogonal to the optical axis AX2 corresponding to the reflecting surface of the main beam splitter 22. That is, the sub-beam splitter 26 for injecting the observation light generated by the observation light source 24 is arranged on the optical path (optical axis AX2) formed by the reflection by the main beam splitter 22. In this way, by arranging the optical member for injecting the observation light on the optical axis AX2, which is an optical path different from the optical axis AX1 which is the optical path through which the measurement light propagates, the attenuation of the measurement light can be suppressed.

<G. Measurement procedure>
Next, a procedure for measuring the sample SMP using the optical measuring device 1 according to the present embodiment will be described.

FIG. 15 is a flowchart showing a measurement procedure of the sample SMP using the optical measuring device 1 according to the present embodiment. If necessary, preprocessing such as calibration may be executed.

With reference to FIG. 15, the user places the sample SMP on stage 10 (step S2).

Subsequently, the sample SMP is irradiated with the observation light including the visible region in the wavelength range along the optical axis AX1 (step S4). That is, the user turns on the observation light source 24 of the optical unit 2 and injects the observation light into the optical axis AX1. Then, while viewing the captured image displayed on the display device 200 in this state, the user adjusts the positions of the imaging unit 30 and the macro lens 28 so that the focus of the imaging unit 30 coincides with the surface of the sample SMP. (Step S6).

After the focus of the imaging unit 30 is adjusted to coincide with the surface of the sample SMP, the sample SMP is irradiated with the measurement light including the wavelength range other than the visible region along the optical axis AX1 (step S8). That is, the user turns on the measurement light source 110 of the measurement unit 100 and injects the measurement light into the optical axis AX1. Then, the user adjusts the position of the light emitting / receiving probe 16 and the like so that the focal point of the measurement light coincides with the surface of the sample SMP while observing the captured image displayed on the display device 200 in this state (step S10). .. When the focus of the measurement light is aligned with the surface of the sample SMP, the size of the spot image of the measurement light is minimized, and an image without blurring is displayed.

By the above processing, it becomes a measurable state.
Then, of the reflected light of the measurement light generated in the sample SMP and the reflected light of the observation light generated in the sample SMP, the light whose optical path is changed to the optical axis AX2 by the main beam splitter 22 arranged on the optical axis AX1 is the imaging unit 30. A captured image showing an image of the received light is output (step S12). In this state, the measurement unit 100 receives the reflected light of the measurement light generated in the sample SMP and outputs the measurement result (step S14). The processing for outputting the measurement result includes a processing for calculating the reflectance spectrum of the sample based on the reflected light of the measurement light, a processing for calculating the wave number conversion reflectance spectrum by a predetermined wave number conversion for the reflectance spectrum, and a wave number conversion reflection. Based on the process of calculating the power spectrum by Fourier transforming the reflectance spectrum with respect to the number of waves and the position of the peak appearing in the power spectrum, at least of the optical film thickness of the sample, the film thickness of the sample, and the distance to the sample It may include a process of calculating one.

In this way, the user refers to the sample SMP while referring to the image captured from the imaging unit 30 in a state where both the observation light for observing the surface state of the sample SMP and the measurement light are injected into the optical axis AX1. (For example, film thickness measurement and distance measurement) are performed.

By the above procedure, the measurement for the sample SMP is completed. When a plurality of sample SMPs are continuously measured, the steps shown in FIG. 15 are repeated. However, depending on the type and shape of the sample SMPs, the adjustment processing of steps S6 and S10 may be appropriately performed. It may be omitted.

<H. Measurement example>
Next, a measurement example of the sample SMP using the optical measuring device 1 according to the present embodiment will be shown.

16 to 18 are diagrams showing a measurement example of the sample SMP using the optical measuring device 1 according to the present embodiment. 16 to 18 show an example of the result of measuring the sample SMP in which ceramic is laminated on the transparent substrate layer. A color CMOS imaging unit (manufacturer: Allied Vision Technologies, model: Mako-G319C) was used as the imaging unit 30.

FIG. 16 shows the result of measuring the single layer portion of the sample SMP, FIG. 17 shows the result of measuring the laminated portion of the sample SMP, and FIG. 18 shows the measurement result of the laminated portion (void) of the sample SMP. The result is shown.

16 (A) to 18 (A) show images captured by the imaging unit 30 in each measurement state, and FIGS. 16 (B) to 18 (B) show measurements in each measurement state. The reflectance spectrum is shown, and FIGS. 16 (C) to 18 (C) show the power spectrum calculated in each measurement state.

With reference to FIG. 16A, the spot image of the measurement light can be confirmed at a position corresponding to the single layer portion. In this measurement state, it can be seen that only the peak of the transparent substrate layer of the sample SMP appears in the power spectrum shown in FIG. 16C.

With reference to FIG. 17A, a spot image of the measurement light can be confirmed at a position corresponding to the laminated portion. In this measurement state, it can be seen that in the power spectrum shown in FIG. 17C, peaks of both the ceramic layer and the transparent substrate layer of the sample SMP appear.

With reference to FIG. 18A, the spot image of the measurement light can be confirmed at a position corresponding to the laminated portion (void). In this measurement state, in the power spectrum shown in FIG. 18C, it is considered that in addition to the peaks of both the ceramic layer and the transparent substrate layer of the sample SMP, voids (bubbles) generated between the two layers are considered. It can be seen that the peak appears.

<I. Advantages>
In the prior art, a configuration has been adopted in which visible light indicating the irradiation position is projected onto the sample along the optical path of the measurement light, and the user confirms the measurement position based on the projected visible light. However, when measuring optical characteristics using measurement light other than the visible region (infrared region, ultraviolet region, etc.), the position where visible light is projected is the actual measurement position due to chromatic aberration that occurs in the optical system. In some cases, it may not be possible to confirm whether or not they match.

On the other hand, in the measuring device according to the present embodiment, the imaging unit captures a state in which the sample SMP is irradiated with the measurement light including the visible region as the wavelength range and the observation light including the visible region as the wavelength range. As a result, in addition to the surface condition of the sample SMP, the position where the measurement light is actually projected can be observed at the same time. As described above, according to the optical measuring device 1 according to the present embodiment, it is possible to visualize the actual irradiation position (measurement position) of the measurement light, which could not be confirmed by the prior art.

By displaying the captured image captured by the imaging unit on the display device 200, the surface state of the sample SMP and the irradiation position of the measurement light can be observed at the same time. Since the captured image can be observed during the measurement, the measurement can be performed while confirming the relationship between the measurement position and the measured reflectance spectrum and power spectrum, so that peak identification and analysis of the thickness of each layer can be facilitated. ..

Further, according to the optical measuring device 1 according to the present embodiment, the intensity balance is adjusted between the reflected light of the measurement light incident on the imaging unit and the reflected light of the observation light, so that the sample SMP can be obtained in the captured image. The surface condition and the spot image of the measurement light are properly represented.

Further, according to the optical measuring device 1 according to the present embodiment, one beam splitter is on the optical path from the sample SMP to the measurement unit 100 after the measurement light emitted from the measurement unit 100 is applied to the sample SMP. Only placed. By adopting an optical system that minimizes the number of beam splitters while having the function of irradiating the sample SMP with observation light, it suppresses the attenuation of the measurement light and realizes high accuracy and high speed of measurement. it can.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is indicated by the scope of claims, not the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Optical measuring device, 2 Optical unit, 10 stages, 12 Lower cylinder, 14 Upper cylinder, 16 Light receiving probe, 18 Connector, 20 Imaging lens, 22 Main beam splitter, 24 Observation light source, 26 Secondary beam splitter, 28 macro lens, 30 imaging unit, 32 optical filter, 34 transmission optical member, 40 Y type fiber, 41, 42 branched fiber, 43 fiber coupler, 100 measurement unit, 110 measurement light source, 120 spectroscopic measurement unit, 121 slit, 122 Shutter, 123 cut filter, 124 collimating mirror, 125 diffraction grid, 126 focus mirror, 127 detector, 130 arithmetic unit, 140 interface, 200 display device, 302,310 image sensor, 304 color filter, 306 near infrared absorption filter, 308 Photoelectric converter, 312 microlens, 314 protective layer, 316 transparent electrode, 318 organic thin film for visible region, 320 organic thin film for near infrared region, 322 pixel electrode, 324 silicon substrate, 326 charge storage node, 328 power supply, 330 signal Charge, AX1, AX2, AX3 optical axis, FV field, ML1 measurement light, ML2, ML3, OL2 measurement light reflected light, OL1 observation light, OL2 observation light reflected light, SMP sample.

Claims (12)

A probe that irradiates the sample with measurement light having a wavelength range other than the visible region along the first optical axis and receives the reflected light of the measurement light generated in the sample.
With the first beam splitter arranged on the first optical axis,
A second beam splitter that directs the observation light to the first beam splitter so that the observation light including the visible region in the wavelength range is applied to the sample along the first optical axis.
Of the reflected light of the measurement light generated in the sample and the reflected light of the observation light generated in the sample, the light whose optical path is changed to the second optical axis by the first beam splitter is received, and the received light image. It is equipped with an imaging unit that outputs an captured image indicating
The imaging unit is an optical unit having sensitivity to at least a part of the wavelength range of the observation light and at least a part of the wavelength range of the measurement light. The wavelength range of the measurement light includes the near infrared region.
The optical unit according to claim 1, wherein the wavelength range of the observation light does not overlap with the wavelength range of the measurement light. The second beam splitter is arranged on the second optical axis.
The optical unit according to claim 1 or 2, wherein the observation light source that generates the observation light is arranged on a third optical axis associated with the second beam splitter. The second optical axis is orthogonal to the first optical axis and is orthogonal to the first optical axis.
The optical unit according to claim 3, wherein the third optical axis is orthogonal to the second optical axis and is non-parallel to the first optical axis. The optical unit according to any one of claims 1 to 4, wherein the first beam splitter is made of a pellicle film. The optical unit according to any one of claims 1 to 5, further comprising an intensity adjusting means for adjusting the intensity balance between the reflected light of the measurement light incident on the imaging unit and the reflected light of the observation light. The optical unit according to claim 6, wherein the intensity adjusting means includes an optical filter arranged in front of the imaging unit. The strength adjusting means
Means for changing the process of synthesizing the output signal from the imaging unit for the wavelength range of the measurement light and the output signal from the imaging unit for the wavelength range of the observation light.
The optical unit according to claim 6, further comprising any of means for changing the ratio of the sensitivity of the imaging unit to the wavelength range of the measurement light and the sensitivity of the imaging unit to the wavelength range of the observation light. The optical unit according to any one of claims 1 to 8.
An optical measuring device including a measuring unit that is optically connected to the probe of the optical unit, receives reflected light of the measurement light guided through the probe, and outputs a measurement result including optical characteristics. The measuring unit is
A means for calculating the reflectance spectrum of the sample based on the reflected light of the measurement light, and
A means for calculating a wavenumber conversion reflectance spectrum by a predetermined wavenumber conversion with respect to the reflectance spectrum, and
A means for calculating the power spectrum by Fourier transforming the wave number conversion reflectance spectrum with respect to the wave number,
The claim includes means for calculating at least one of the optical film thickness of the sample, the film thickness of the sample, and the distance to the sample as the optical characteristics based on the position of the peak appearing in the power spectrum. 9. The optical measuring device according to 9. The optical film thickness of the first beam splitter is determined to be less than the lower limit of the measurable optical film thickness determined based on the upper and lower limits of the measurement wavelength range of the measuring unit. Item 9. The optical measuring apparatus according to Item 9. The step of irradiating the sample with the measurement light generated by the measurement light source, which includes the wavelength range other than the visible region, along the first optical axis.
A step of irradiating the sample with observation light having a visible region in the wavelength range along the first optical axis.
A step of receiving the reflected light of the measurement light generated in the sample and outputting the measurement result including the optical characteristics.
Of the reflected light of the measurement light generated in the sample and the reflected light of the observation light generated in the sample, the optical path was changed to the second optical axis by the first beam splitter arranged on the first optical axis. It includes a step of receiving light at the imaging unit and outputting an captured image showing an image of the received light.
An optical measurement method in which the imaging unit has sensitivity to at least a part of the wavelength range of the observation light and at least a part of the wavelength range of the measurement light.