JP5149874B2 - Thermophysical property analysis apparatus and thermophysical property analysis method - Google Patents

Description

  The present invention irradiates and heats the measurement site on the surface of the object to be measured, reflects the detection light to the measurement site, receives the reflected light, and changes the temperature of the measurement site from the change in the received light intensity. The present invention relates to a thermophysical analysis apparatus and a thermophysical analysis method for detecting thermophysical properties and analyzing thermophysical properties.

  2. Description of the Related Art Conventionally, a method described in Patent Document 1 is known as a measurement method for analyzing and evaluating the thermal properties of an object to be measured, for example, a thin film sample. This method uses a common short pulse laser as heating light (heating pulse light) for heating a measurement site of a thin film sample and detection light (detection pulse light) for detecting a temperature change of the measurement site. This is a so-called thermoreflectance method that performs thermal diffusion measurement by irradiating the front and back surfaces of the measurement site in a thin film sample formed on a transparent substrate by branching and irradiating these heating light and detection light. When a thin film sample is irradiated with heating light and detection light in this measurement method, the detection light is focused so as to focus on the measurement site in order to ensure the intensity of light at the measurement site in order to detect temperature changes with high accuracy. In order to efficiently perform heating, the heating light is irradiated so as to focus on the measurement site in order to ensure the intensity of light at the measurement site.

  In this thermoreflectance method, if the substrate disposed on the back side of the thin film sample (opposite to the surface irradiated with detection light) is not a material that transmits the heating light, the heating light is the back side of the thin film sample. The thin film sample cannot be heated. That is, the thermoreflectance method has a problem that the measurement necessary for the analysis of the thermal properties of the thin film sample formed on the surface of the opaque substrate cannot be performed.

  Therefore, a method has been considered in which the surface of the thin film sample, that is, the same surface is irradiated with the heating light and the detection light, and the temperature change of the measurement site is detected from the reflected light of the detection light. In this way, both the heating light and the detection light are irradiated on the surface of the thin film sample, so that even if the substrate disposed on the back side of the thin film sample is made of an opaque material, the thin film sample is irradiated with the heating light. Can be heated.

JP 2001-83113 A

  However, in this method, since the heating light and the detection light are reflected on the same surface (surface) of the thin film sample, the reflected light of the heating light may enter the measurement system that measures the reflected light intensity of the detection light. is there. Moreover, since the heating light is irradiated so as to focus on the measurement site, the intensity of the reflected light of the heating light reflected at this focal position is high. Since the reflected light of the heating light directed to the measurement system is measured by the measurement system with the same intensity, it is easy to enter the measurement result of the reflected light intensity of the detection light measured by the measurement system as noise. Thus, if noise is mixed in the measurement result of the reflected light intensity of the detection light, the analysis and evaluation of the thermal properties of the object to be measured cannot be performed with high accuracy.

  Therefore, in view of the above problems, the present invention is not limited to the heating light in the measurement of the reflected light intensity of the detection light, even if the thermal property of the sample is analyzed by irradiating the same surface of the measurement object with the heating light and the detection light. It is an object of the present invention to provide a thermophysical property analysis apparatus and a thermophysical property analysis method that are not easily affected by reflected light.

Accordingly, in order to solve the above problems, the present invention is a thermophysical property analyzer that irradiates a measurement site on the surface of an object to be measured and analyzes the thermophysical properties of the object to be measured based on the reflected light. A heating light emitting means for emitting heating light for heating the measurement site, a first optical system for guiding the heating light to the measurement site, and a temperature change for detecting the temperature of the measurement site A detection light emitting means for emitting detection light; a second optical system for guiding the detection light to the measurement site; and a light receiving unit for receiving reflected light of the detection light from the measurement site. Detection light measuring means for measuring the intensity of reflected light of the detection light incident on the light receiving section, and third optical for guiding reflected light of the detection light from the measurement site to the light receiving section of the detection light measuring means And the second optical system is focused on the measurement site The detection light have a detection light for condensing member for condensing so as to connect the first optical system, the third compared with the case where the heating light at the measurement site is condensed to focus The measurement part is defocused and heated so that the irradiation range of the detection light is included in the measurement region so that the intensity of the reflected light of the heating light that is guided to the optical system and reaches the light receiving unit is reduced. light while have a heating condensing member for condensing the heating for condensing heating light condensed by the member irradiating the measurement site, the heating condensing member, said from the measurement site The reflected light of the heating light is configured to focus on the upstream side of the light receiving unit in the third optical system, or the reflected light of the heating light from the measurement site is reflected by the third optical system. Focusing on the upstream side and in the third optical system Characterized in that configured to diverge toward the light receiving portion. In the present invention, focusing means not only the case where light is focused at a single point (focal point), but also a light beam that spreads as the light travels so that the light beam diverges so that the light irradiation range becomes constant. This includes the case where it is not to be performed.

  Compared with the case where the detection light is irradiated so as to focus on the measurement site on the surface of the object to be measured and the heating light is focused so as to focus on the measurement site, the light receiving unit is guided to the third optical system. The focused light is blurred so that the intensity of the reflected light (reflected heating light) of the heating light that reaches the light beam is reduced and the measurement site is focused so that the irradiation range includes the detection light irradiation range. When the detection light and the heating light are respectively collected on the measurement site by the member, the reflected heating light mixed in the reflected light (reflected detection light) of the detection light guided to the third optical system is one of them. Only the portion can enter the light receiving portion of the detection light measuring means, and thereby the influence (noise) of the reflected heating light hardly enters the result of measuring the intensity of the reflected detection light in the detection light measuring means.

  Specifically, the detection light is condensed so that the detection light is focused on the surface of the object to be measured (measurement site), and the heating light is defocused on the surface of the object to be measured by the heating light condensing member. By condensing in this way, each reflected light at the measurement site of the detection light and the heating light has a different beam divergence angle. In the third optical system, the reflected heating light is diverged at the position of the light receiving part (including a state where it is once converged on the upstream side of the light receiving part and then diverged) due to the difference in the beam divergence angle. Only a part of the light can enter the light receiving portion. As a result, the intensity of the reflected heating light incident on the light receiving portion is reduced, and this reflected heating light is less likely to enter the measurement result as noise.

  In addition, since the detection light is irradiated so as to focus on the measurement site, the intensity of the detection light at the measurement site is ensured, thereby ensuring the measurement accuracy of the temperature change at the site.

  In the thermophysical property analyzing apparatus according to the present invention, the first optical system is configured such that the heating light condensed by the heating condensing member is coaxial or substantially coaxial with the detection light condensed by the detecting condensing member. It is preferable to irradiate the measurement site by joining together.

  The intensity of the reflected heating light incident on the third optical system since the reflected heating light passes through the same optical path as the reflected detection light by making the heating light and the detection light irradiated on the measurement site coaxial or substantially coaxial in this way. However, it is possible to suppress the influence of the reflected heating light on the measurement result of the reflected detection light by blurring the focus of the heating light applied to the measurement site as in the apparatus.

  In addition, when the thickness of the object to be measured is changed by irradiating the measurement site with the heating light and the detection light coaxially or substantially coaxially, that is, the distance between the surface of the object to be measured and each condensing member changes. In this case, although the heating light and the detection light are condensed toward the measurement site by different condensing members, adjustment of each irradiation position becomes unnecessary.

Before Symbol third optical system includes a light shielding portion for shielding the progress of the reflected light focused on the focal position of the reflected light of the heating light the heating light, the periphery thereof to support the light shielding part of light can pass It is preferable to provide a light-shielding member having a proper light passing portion.

  According to such a configuration, in the third optical system, the reflection heating light guided toward the light receiving unit is blocked by the light blocking unit of the light blocking member from traveling while the reflection detection is guided toward the light receiving unit. Since the light is collected by the light receiving portion on the downstream side of the light shielding member, the light can reach the light receiving portion on the downstream side through the periphery of the light shielding portion (that is, the light passage portion). As a result, the reflected heating light is less likely to enter the light receiving portion, and thereby the influence of the reflected heating light is less likely to enter the result of measuring the intensity of the reflected detection light in the detection light measuring unit.

  The first optical system has a first polarization unit that polarizes the heating light in a first polarization direction, and the second optical system has a first light direction different from the first polarization direction. A second polarization unit that polarizes in the second polarization direction, and the third optical system allows the light polarized in the second polarization direction to travel downstream in the third optical system. In addition, it is preferable to have selection means for preventing the light polarized in the first polarization direction from proceeding downstream.

  According to such a configuration, the selection unit prevents the reflected heating light from entering the third optical system and traveling toward the light receiving unit and allows the reflected detection light to travel. As a result, the influence of the reflected heating light is less likely to enter the measurement result of the intensity of the reflected detection light in the detection light measuring means. That is, in the third optical system, since the reflected heating light is reflected light of the heating light polarized in the first polarization direction by the first polarizing means, the light receiving section is selected by the selecting means while being guided to the light receiving section. While the reflected detection light is the reflected light of the detection light polarized in the second polarization direction by the second polarizing means, the selection means allows the light to travel to the light receiving section, and the light receiving section Can be reached.

  Further, the heating light emitting means and the detection light emitting means are constituted by a common light emitting means for emitting both the heating light and the detection light, and the light emitting means emits pulsed light having a predetermined cycle. A pulsed light radiating part, and the pulsed light emitted from the radiating part is branched into the heating light and the detection light, and the branched heating light is incident on the first optical system and the branched detection light. It is preferable to have branching means for making the light incident on the second optical system.

  According to such a configuration, it is not necessary to separately arrange the pulse light emitting means for emitting the heating light and the detection light, thereby reducing the cost and the size of the apparatus, and further, from different pulse light emitting means. Difficult adjustment work such as synchronization of emitted pulsed light, complicated adjustment circuit, and the like are not required.

Further, in order to solve the above problems, the present invention is a thermophysical property analysis method for irradiating light to a measurement site of a measurement object and analyzing the thermal property of the measurement object based on the reflected light. Irradiating the measurement region with detection light for measuring the temperature change of the measurement region, condensing and irradiating the measurement region with the detection light, and heating the measurement region with heating light. A light guide step of guiding reflected light of the detection light from the measurement site to a measurement position different from the measurement site, and reflection of the detection light guided to the measurement position in the light guide step Ru and a measurement step of measuring the intensity of light. In the irradiation step, the intensity of the reflected light of the heating light that is guided in the light guiding step and reaches the measurement position is smaller than that in the case where the heating light is focused so as to be focused at the measurement site. The measurement region is defocused so that the irradiation range includes the detection light irradiation range , and the heating light reflected by the measurement unit is reflected together with the detection light reflection light in the light guiding step. When the light is guided toward the measurement position , the heating light is condensed so as to focus on the upstream side from the measurement position , and the condensed heating light is irradiated to the measurement site. To do.

  In this way, the detection light is irradiated so as to be focused on the measurement site on the surface of the object to be measured, and is guided in the light guide process to reach the measurement position as compared with the case where the light is focused so as to focus on the measurement site. The reflected detection light is reflected in the light guide step by focusing the heating light so that the focus of the measurement site is defocused so that the intensity of the reflected light of the heating light is reduced and the irradiation range of the detection light is included in the irradiation range. In addition, only a part of the reflected heating light that is guided is measured at the measurement position, so that the influence of the reflected heating light does not easily enter the result of measuring the intensity of the reflected detection light at the measurement position.

  That is, the heating light and the detection light are irradiated on the measurement site so as to be in different focal positions, so that the reflected heating light and the reflected detection light have different beam divergence angles. Then, the reflected heating light guided in the light guiding step is diverged at the measurement position, and only a part thereof is measured.

  In addition, since the detection light is irradiated so as to focus on the measurement site, the intensity of the detection light at the measurement site is ensured, thereby ensuring the measurement accuracy of the temperature change at the site.

  As described above, according to the present invention, even if the thermal properties of the sample are analyzed by irradiating the same surface of the object to be measured with the heating light and the detection light, the reflected light of the heating light is measured in the measurement of the reflected light intensity of the detection light. It is possible to provide a thermophysical property analysis apparatus and a thermophysical property analysis method that are not easily affected by the above.

It is a schematic block diagram of the thermophysical property analyzer which concerns on this embodiment. It is an expanded block diagram around the 3rd optical system of the said thermophysical-characteristic analyzer. It is a block diagram of the photodetector in the thermophysical property analyzer which concerns on other embodiment. It is an enlarged block diagram around the 3rd optical system in the thermophysical property analyzer which concerns on other embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1 and FIG. 2, a thermophysical property analyzer (hereinafter also simply referred to as “analyzer”) 10 according to the present embodiment is periodically emitted (radiated) from one pulse laser 21. The main pulse laser (main pulse light) B0 is branched into two, one of which is a heating pulse light (hereinafter also simply referred to as “heating light”) B1, and the other is a detection pulse light (hereinafter simply referred to as “detection light”). Also referred to as B). Then, the measurement light 11a on the surface of the thin film sample (object to be measured) 11 is irradiated with the heating light B1 and the detection light B2, and the detection light (reflected detection light) B2a reflected by the measurement part 11a is received. It is a device that performs thermophysical analysis based on the thermoreflectance method that measures the temperature change of the measurement site 11a (performs thermal diffusion measurement) by measuring the strength. The thin film sample 11 according to the present embodiment is formed on the substrate 12.

  Specifically, the analyzing apparatus 10 includes a light emitting means 20 that emits both the heating light B1 and the detection light B2, and the heating light B1 is also referred to as a measurement site 11a (hereinafter simply referred to as “measurement site 11a”) of the thin film sample 11. ), The second optical system 40 for guiding the detection light B2 to the measurement site 11a, and the detection light measurement means for measuring the intensity of the reflected detection light B2a from the measurement site 11a. 50, a third optical system 60 for guiding the reflected detection light B2a from the measurement site 11a to the detection light measurement means 50, and the stage 13.

  The light emitting means 20 is a first laser beam that divides the pulsed light emitted from the pulsed laser 21 into a heating light B1 and a detection light B2 and a pulsed laser (pulsed light emitting part) 21 that emits pulsed light of a predetermined period. And a splitter (branching means) 22.

  The pulse laser 21 is a light source that emits basic pulsed light (basic pulsed beam) B0 composed of unit pulsed light PL having a width of about several picoseconds to ten picoseconds intermittent at a predetermined cycle. For example, the pulse laser 21 according to this embodiment outputs pulsed light (pulsed beam) B0 having a wavelength of 532 nm and a pulse width of 12 ps at a repetition frequency of 80 MHz.

  The first beam splitter 22 branches the basic pulsed light B0 output from the pulse laser 21, and splits it into heating light (heating pulsed light) B1 and detection light (detecting pulsed light) B2. The first beam splitter 22 divides the basic pulse light B 0, and then makes the heating light B 1 incident on the first optical system 30 and makes the detection light B 2 incident on the second optical system 40. The first beam splitter 22 of the present embodiment is a polarization beam splitter, and polarization adjustment wavelength plates 101 and 102 are disposed on the downstream side. The first beam splitter 22 passes the branched light (heating light B1 and detection light B2) through the polarization adjusting wavelength plates 101 and 102, thereby polarizing the heating light B1 in the first polarization direction and the detection light B2. Polarizes in the second polarization direction. That is, the first beam splitter 22 having the polarization adjusting wavelength plates 101 and 102 of the present embodiment includes a branching unit that branches the basic pulse light B0 into the heating light B1 and the detection light B2, and the heating light B1 and the detection light B2. Also serves as a polarization means for making the polarization states different from each other. Note that the first polarization direction and the second polarization direction are different polarization directions.

  The first optical system 30 has a mirror 31, a heating condensing lens (heating condensing member) 32, and a second beam splitter 33, and measures the heating light B1 emitted from the light emitting means 20. The light is guided to the part 11a. Further, the first optical system 30 includes a modulation unit 34 for modulating the intensity of the heating light B1.

  The heating condensing lens 32 condenses the heating light B1 guided by the first optical system 30 toward the measurement site 11a. The focal position of the heating condenser lens 32 is set to a position different from that of the measurement site 11a. Therefore, the heating light B1 collected by the heating condenser lens 32 is irradiated so that the irradiation range s is widened without being focused at one point in the measurement site 11a (see FIG. 2). That is, the heating light B1 is irradiated in a state where the focal point is blurred at the measurement site 11a. This heating condensing lens 32 is reflected and heated by the third optical system 60 and reaches the detection light measuring means 50 as compared with the case where the heating light B1 is focused so as to be focused at the measurement site 11a. The focal point is set so that the focal point is blurred in the measurement region 11a so that the intensity of the light B1a is reduced and the irradiation range s of the irradiation range of the detection light B2 is included in the irradiation range s. By setting the focal position of the heating condensing lens 32 in this way, the reflected heating light B1a reflected by the measurement site 11a and entering the third optical system 60 is detected by the photodetector of the detection light measuring means 50. The focus is set on the upstream side of 51 (specifically, the light receiving portion 51a of the photodetector 51). Specifically, a convex lens having a focal length (focal position) of 40 mm is used for the heating condensing lens 32 of the present embodiment. The heating light B1 that has passed through the heating condensing lens 32 is once focused before reaching the measurement site 11a, and then reaches the measurement site 11a in a divergent state (see FIG. 2).

  The second beam splitter 33 is a polarization beam splitter, and transmits light polarized in the second polarization direction and reflects light polarized in a polarization direction different from the second polarization direction. That is, in the second beam splitter 33 of the present embodiment, the detection light B2 polarized in the second polarization direction is transmitted, but the heating light B1 polarized in the first polarization direction is reflected. The second beam splitter 33 merges the heating light B1 reflected by the second beam splitter 33 with the detection light B2 after passing through the beam splitter 33 so as to be coaxial or substantially coaxial. Note that the second beam splitter 33 of the present embodiment also constitutes a part of the third optical system 60. The operation of the second beam splitter 33 in the third optical system 60 will be described later.

  The modulation means 34 has a modulator 35 and an oscillator 36, and the modulator 35 modulates the intensity of the heating light B1 at a predetermined frequency based on the modulation signal from the oscillator 36. In the present embodiment, an acousto-optic modulator is used as the modulator 35, and the intensity of the heating light B1 is modulated at 100 kHz.

  The second optical system 40 includes a mirror 41, an optical path delay device 42, and a detection condensing lens (detection condensing member) 43, and irradiates the measurement site 11a with the detection light B2 from the vertical direction. To guide the light.

  The optical path delay device 42 generates a time difference in the arrival of the pulsed light at the measurement site 11a between the heating light B1 and the detection light B2, and the time difference can be adjusted (variable) with an accuracy of, for example, picosecond order. . The optical path delay device 42 includes an optical device and its moving mechanism. The optical path delay device 42 of the present embodiment is a device that generates a time difference in arrival of pulsed light at the measurement site 11a between the heating light B1 and the detection light B2 by adjusting the optical path length of the detection light B2. Specifically, the optical path delay device 42 controls from the computer 53 a pair of mirrors 42a, a moving stage 42b that moves the pair of mirrors 42a in the optical axis direction of the detection light B2, and an operation of the moving stage 42b. A control circuit (not shown) for controlling according to the command is provided.

  The detection condensing lens 43 condenses the detection light B2 guided by the second optical system 40 toward the measurement site 11a. The focal position of the detection condensing lens 43 is set to coincide with or substantially coincide with the measurement site 11a. Therefore, the detection light B2 collected by the detection condenser lens 43 is focused at one point in the measurement site 11a. That is, the detection light B2 is irradiated so as to focus on the measurement site 11a (see FIG. 2). By setting the focal position of the condensing lens 43 for detection in this way, the reflected detection light B2a reflected by the measurement site 11a and entering the third optical system 60 is detected by the photodetector of the detection light measuring means 50. 51 (specifically, the light receiving unit 51a of the photodetector 51) is focused. Specifically, a convex lens having a focal length (focal position) of 60 mm is used for the detection condensing lens 43 of the present embodiment. Note that the detection condensing lens 43 of this embodiment also constitutes a part of the third optical system 60. The operation of the detection condensing lens 43 in the third optical system 60 will be described later.

  The detection light measuring means 50 includes a photodetector 51 to which the reflected detection light B2a from the measurement site 11a is incident, a lock-in amplifier 52 to which the photodetector 51 and the oscillator 36 are connected, and the lock-in amplifier 52. And a computer 53 to be connected.

  The photodetector 51 has a light receiving portion 51a on which the reflected detection light B2a is incident, and outputs the intensity of the reflected detection light B2a incident on the light receiving portion 51a as an intensity signal. The light receiving unit 51a only needs to have a size with which the reflected detection light B2a guided by the third optical system 60 can enter. In the present embodiment, since the reflected detection light B2a is guided by the third optical system 60 so as to converge at the position of the light receiving unit 51a, a small light receiving element is used for the light receiving unit 51a. Specifically, a silicon photodiode (length 0.5 mm, width 0.5 mm, light receiving diameter φ 0.5 mm) is used as the light receiving portion 51a.

  The specific configuration of the photodetector 51 is not limited. For example, in the present embodiment, a light receiving element is arranged as the light receiving unit 51a, but the present invention is not limited to this, and as shown in FIG. 3, the photodetector 151 is arranged in the detector main body 152 and the inside thereof. And the reflected detection light B2a incident on the pinhole 151a provided in the detector main body 152 as a light receiving portion (that is, passed through the pinhole 154) is disposed inside the detector main body 152. The light receiving element 153 may receive light and be configured to detect the received light intensity. In this light detector 151, the reflected detection light B2a is focused toward the pinhole (light receiving portion) 151a in a condensed state and once converged when passing through the pinhole 151a, and then diverges through the pinhole 151a. And reaches the light receiving element 153. Therefore, this photodetector 151 can use a light receiving element 153 larger than the light receiving element 51a of the present embodiment.

  The lock-in amplifier 52 detects (extracts) the frequency component modulated by the modulation means 34 from the intensity signal output from the photodetector 51.

  The computer 53 derives the temperature change of the measurement site 11 a from the frequency component detected by the lock-in amplifier 52. Further, the computer 53 analyzes the thermophysical property of the thin film sample 11 from the temperature change of the measurement site 11a according to a predetermined analysis rule and outputs the analysis result (writing to the storage unit, display on the display unit, other devices) To send to).

  The third optical system 60 includes a second beam splitter 33, a detection condensing lens 43, a third beam splitter 61, a light blocking member 62, and a condensing lens 63, and is reflected by the measurement site 11a. The reflected reflection light B2a is guided to the light receiving portion 51a of the photodetector 51.

  The second beam splitter 33 condenses the reflected heating light B1a polarized in the first polarization direction among the reflected lights of the heating light B1 and the detection light B2 incident from the vertical direction with respect to the measurement site 11a. The reflected detection light B2a that is reflected toward the lens 32 and polarized in the second polarization direction is allowed to pass. At this time, the second beam splitter 33 cannot reflect all the reflected heating light B1a, and a small amount of reflected heating light B1a passes through the second beam splitter 33 together with the reflected detection light B2a.

  The detection condensing lens 43 converts the reflected detection light B2a that has been reflected by the measurement site 11a and has reached the detection condensing lens 43 in a divergent state into parallel light by passing through the inside thereof. Further, the detection condensing lens 43 is reflected by the measurement site 11a and is reflected and diverged (a beam divergence angle different from that of the reflected detection light B2a) and reaches the detection condensing lens 43 in the reflected heating light B1a (second beam splitter 33). The reflected heating light B1a) that has been transmitted without being reflected by the light passes through the inside thereof to be brought into a condensed state.

  The third beam splitter 61 is disposed on the optical path of the detection light B2 guided by the second optical system 40. The third beam splitter 61 of the present embodiment is configured by a half mirror, and allows the detection light B2 traveling from the vertical direction toward the measurement site 11a to pass through the measurement site 11a and returns coaxially from the measurement site 11a. The reflected detection light B2a is reflected to the photodetector 51 side.

  In the third optical system 60, the light blocking member 62 allows the reflected detection light B2a to travel downstream and blocks the reflected heating light B1a from traveling downstream. The light shielding member 62 is disposed at the focal position of the reflected heating light B1a in the third optical system 60, and includes a light shielding portion 62a and a light passage portion 62b. In the light shielding member 62, the light shielding part 62a is a part for blocking the progress of the reflected heating light B1a collected at the focal position of the reflected heating light B1a, and the light passage part 62b supports the light shielding part 62a at the focal position. This is a part configured to allow light (reflection detection light B2a) to pass therethrough. In the present embodiment, a plate-like glass (light) arranged in a posture orthogonal to the optical path of the light guided by the optical system 60 at the focal position of the reflected heating light B1a in the light guiding direction of the third optical system 60. (Passing part) 62b and aluminum (light-shielding part) 62a deposited at the focal position on the surface of the glass 62b. That is, the reflected heating light B1a collected at the focal position is reflected by the deposited aluminum 62a to block its progress, and the reflected detection light B2a passes through the surrounding glass portion 62b.

  The condenser lens 63 receives the reflected detection light B2a, which has become parallel light by passing through the detection condenser lens 43, and the light receiving unit of the photodetector 51 when the reflected detection light B2a passes through the condenser lens 63. The light is focused so as to be focused at 51a.

  The stage 13 supports the substrate 12 on which the thin film sample 11 is formed, and moves the position of the thin film sample 11 in a two-dimensional direction (perpendicular to the irradiation direction of the heating light B1 and the detection light B2) according to a control command from the computer 53. Alternatively, it is a so-called XY stage that is movable in the direction of a substantially vertical plane). That is, by controlling the stage 13 with the computer 53, the desired measurement site 11a on the surface of the thin film sample 11 can be aligned with the irradiation position of the heating light B1 and the detection light B2.

  In the analysis apparatus 10 configured as described above, the thermal properties of the thin film sample 11 are analyzed as follows.

  A substrate 12 on which a thin film sample 11 is formed is placed on a stage 13. The stage 13 is controlled by the computer 53 so that the measurement site 11a on the surface of the thin film sample 11 is positioned at the irradiation position of the heating light B1 and the detection light B2.

  Next, the heating light B1 and the detection light B2 are emitted by the light emitting means 20. The heating light B1 is guided by the first optical system 30 and applied to the measurement site 11a, while the detection light B2 is guided by the second optical system 40 and applied to the measurement site 11a. Specifically, the basic pulse light B0 emitted by the pulse laser 21 is branched into the heating light B1 and the detection light B2 by the first beam splitter 22. At this time, the heating light B1 and the detection light B2 branched by the first beam splitter 22 pass through the polarization adjusting wave plates 101 and 102, so that the heating light B1 is polarized in the first polarization direction, and the detection light B2 is Polarized in the second polarization direction. The intensity of the heating light B1 is modulated at a predetermined period by the modulation means 34, and then condensed by the heating condenser lens 32 and applied to the measurement site 11a. On the other hand, the detection light B2 is condensed by the detection condenser lens 43 after the optical path length is adjusted by the optical path delay device 42 so as to reach the measurement site 11a with a predetermined pulse light arrival time difference with respect to the heating light B1. Then, the measurement site 11a is irradiated. At this time, the detection light B2 is irradiated so as to focus on the measurement site 11a, while the heating light B1 is irradiated so as to defocus, that is, the focus position is different from the measurement site 11a.

  The detection light (reflection detection light) B2a reflected by the measurement site 11a is guided to the detection light measurement means 50 by the third optical system 60, while the reflected heating light (reflection heating light) B1a is The progress is prevented in the middle of the third optical system 60. Specifically, the reflected detection light B2a passes through the second beam splitter 33, and the detection condenser lens 43, the third beam splitter 61, the light shielding member 62 (specifically, the light passage part 62b), and the condenser lens 63. The light reaches the light receiving part 51a of the photodetector 51 through the above. On the other hand, most of the reflected heating light B <b> 1 a is reflected by the second beam splitter 33 toward the heating condenser lens 32, and only a part thereof passes through the second beam splitter 33. That is, a part of the reflected heating light B <b> 2 a enters the third optical system 60. The reflected heating light B1a that has passed through the second beam splitter 33 passes through the detection condensing lens 43 and the third beam splitter 61 in order, and is focused at the position of the light shielding portion 62a of the light shielding member 62, and reflected by this light shielding portion 62a. Is prevented from proceeding. That is, the reflected heating light B1a that has entered the third optical system 60 is prevented from reaching the light receiving portion 51a by the second beam splitter 33 and the light shielding member 62.

  In the detection light measuring means 50, the intensity of the guided reflected detection light B2a is measured, and the thermophysical property of the thin film sample 11 (measurement site 11a) is analyzed based on the intensity. Specifically, the intensity of the reflected detection light B2a incident on the light receiving unit 51a of the photodetector 51 is output from the photodetector 51 as an intensity signal. In the lock-in amplifier 52 that has received this intensity signal, the periodic component of the intensity modulation in the modulation means 34 is detected from the intensity signal, and the computer 53 analyzes the thermal physical properties of the thin film sample 11 based on this periodic component and analyzes the analysis. Output the result.

  As described above, in the analysis apparatus 10 of the present embodiment, the detection light B2 is condensed so as to be focused at the measurement site 11a, and the reflected heating light B1a that has entered the third optical system 60 is the optical system 60. In FIG. 5, the heating light B1 is focused at the measurement site 11a so as to focus on the upstream side of the light receiving portion 51a, and is condensed so that the irradiation range s includes the irradiation range (focus position) of the detection light B2. As described above, since the heating light B1 and the detection light B2 are respectively condensed on the measurement site 11a by the different condensing lenses 32 and 43, the reflection mixed in the reflection detection light B2a guided to the third optical system 60. Since the heating light B1a once converges at the focal position and then reaches the light receiving unit 51a in a diverging state, the intensity of the reflected heating light B1a incident on the light receiving unit 51a is small. Therefore, the influence (noise) of the reflected heating light B1a does not easily enter the result of measuring the intensity of the reflected detection light B2a in the detection light measuring means 50.

  Moreover, in the present embodiment, in the third optical system 60, the light shielding member 62 is disposed at a position where the reflected heating light B1a is focused, and the reflected heating light B1a focused at the focal position is reflected to reflect the reflected light. By preventing the heating light B1a from proceeding, the reflected heating light B1a reaching the light receiving portion 51a is further reduced, and the result of measuring the intensity of the reflected detection light B2a in the detection light measuring means 50 is influenced by the influence of the reflected heating light B1a. (Noise) is more suppressed.

  Specifically, since the focal length of the heating condenser lens 32 is set so that the reflected heating light B1a is focused on the upstream side of the light receiving portion 51a in the third optical system 60, the third optical system. The reflected heating light B1a that has entered 60 is once converged on the upstream side of the light receiving portion 51a and then diverges, and only a part thereof enters the light receiving portion 51a. Therefore, the intensity of the reflected heating light B1a incident on the light receiving portion 51a is smaller than that when entering the light receiving portion 51a in a focused state. Therefore, the influence of the reflected heating light B1a is less likely to enter the measurement result of the reflected detection light B2a.

  In addition, in the analysis apparatus 10 of the present embodiment, the light shielding member 62 is disposed at the focal position, so that the reflected heating light that passes through the second beam splitter 33 and travels toward the light receiving unit 51a in the third optical system 60. Since the progress of B1a is blocked by the light shielding portion 62a of the light shielding member 62, the influence of the reflected heating light B1a is further less likely to enter the measurement result of the reflected detection light B2a. On the other hand, the reflection detection light B2a passes through the light shielding member 62 in the state of parallel light and is condensed by the condenser lens 63 on the downstream side of the light shielding member 62. Therefore, at the position of the light shielding member 62, the reflection detecting light B2a It can pass through the surroundings (that is, the light passage part 62b) and reach the light receiving part 51a on the downstream side.

  Further, in the analysis apparatus 10 of the present embodiment, the second beam splitter 33 that is a polarization beam splitter is disposed in the third optical system 60, so that the second beam splitter 33 enters the third optical system 60. In order to prevent much of the reflected heating light B1a from traveling toward the light receiving portion 51a and to allow the reflected detection light B2a to travel, the intensity of the reflected detection light B2a reaching the light receiving portion 51a can be sufficiently secured. The amount of the reflected heating light B1a that enters the third optical system 60 can be reduced. As a result, the influence of the reflected heating light B1a is less likely to enter the measurement result of the intensity of the reflected detection light B2a in the detection light measuring means 50.

  Moreover, in the analysis apparatus 10 of this embodiment, since the heating light B1 and the detection light B2 irradiated on the measurement site 11a are coaxial or substantially coaxial, the reflected heating light B1a passes through the same optical path as the reflected detection light B2a. Although the intensity of the reflected heating light B1a toward the third optical system 60 increases, the reflected reflected light is reflected on the measurement result of the reflected detection light B2a by blurring the focus of the heating light B1 applied to the measurement site 11a as in the analysis apparatus 10. It is possible to suppress the influence of the heating light B1a. That is, in the analysis apparatus 10, even if the light blocking member 62 is not disposed, the intensity of the reflected heating light B1a incident on the light receiving unit 51a is more than that when the heating light B1 is irradiated so as to focus on the measurement site 11a. Therefore, the influence of the reflected heating light B1a on the measurement result of the reflected detection light B2a can be suppressed. If the light shielding member 62 is arranged as in the present embodiment, the light shielding member 62 receives light. It is possible to further prevent the influence of the reflected heating light B1a from entering the measurement result of the reflected detection light B2a by being prevented from reaching the portion 51a.

  Here, for example, when the analysis device 10 irradiates the measurement light 11 vertically with the detection light B2 and irradiates the heating light B1 with a large incident angle, the thin film sample 11 changes in thickness. Since the distance between the surface of the sample 11 and the condenser lens for heating 32 and the condenser lens for detection 43 changes, the irradiation position on the surface of the thin film sample 11 of the heating light B1 irradiated obliquely moves, and the heating light B1 and The irradiation position with the detection light B2 is shifted. Therefore, in such an analysis apparatus, it is necessary to adjust the irradiation position of the heating light B <b> 1 according to the thickness of the thin film sample 11. However, in the analysis apparatus 10 of the present embodiment, the heating light B1 and the detection light B2 are irradiated coaxially or substantially coaxially to the measurement site 11a, so that even if the thickness of the thin film sample 11 changes, that is, the thin film sample 11 Even if the distance between the surface of the lens and each of the condensing lenses 32 and 43 changes, the irradiation position of the heating light B1 and the detection light B2 does not shift. Therefore, adjustment of each irradiation position becomes unnecessary.

  Further, in the analysis apparatus 10 of the present embodiment, since one light emitting means 20 emits both the heating light B1 and the detection light B2, it is not necessary to separately arrange the pulse light emitting means, thereby reducing the cost. The size of the apparatus and the size of the apparatus can be reduced, and a complicated adjustment circuit or a complicated adjustment circuit for synchronizing the pulsed light emitted from different pulsed light emission means is not required.

  Moreover, in the analysis apparatus 10 of this embodiment, since the detection light B2 is irradiated so as to focus on the measurement site 11a, the intensity of the detection light B2 at the measurement site 11a is ensured, and thereby the temperature of the site 11a. The measurement accuracy of changes is ensured.

  In addition, the thermophysical property analysis apparatus and thermophysical property analysis method of the present invention are not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

  For example, in the above embodiment, the heating condensing lens 32 is configured so that the reflected heating light B1a that has entered the third optical system 60 is focused on the upstream side of the light receiving unit 51a (that is, the heating condensing lens 32). The focal length of the lens 32 is set), but is not limited to this configuration. That is, the measurement site is such that the intensity of the reflected heating light B1a that enters the third optical system 60 and reaches the light receiving portion 51a is smaller than when the heating light B1 is focused so as to be focused at the measurement site 11a. It is only necessary that the heating light B1 is condensed toward the measurement site 11a so that the focal point is blurred in 11a and the irradiation range s includes the detection light irradiation range.

  If comprised in this way, the reflection detection guided to the 3rd optical system 60 by condensing by heating light B1, detection light B2, and the measurement site | part 11a by the different condensing lenses 32 and 43, respectively. Only a part of the reflected heating light B1a mixed in the light B2a can enter the light receiving portion 51a of the detection light measuring means 50. As a result, the reflected heating light B2a is measured as a result of measuring the intensity of the reflected detection light B2a. The influence (noise) of B1a is difficult to enter.

  Therefore, as described above, even if the light shielding member 62 is removed in the third optical system 60 of the above embodiment, the reflected heating light B1a diverges after being focused once at the focal position (arrangement position of the light shielding member 62). Only a part of the light can enter the light receiving portion 51a, whereby the intensity of the reflected heating light B1a incident on the light receiving portion 51a becomes sufficiently small, and the measurement result of the reflected detection light B2a is less likely to be affected by the reflected heating light B1a.

  Further, as shown in FIG. 4, the beam diameter of the detection light B12 is reduced to the same level as the light receiving portion 51a, and the focal lengths of the detection condenser lens 143 and the heating condenser lens 132 are adjusted, respectively. The analysis apparatus 10 may be configured such that the reflected detection light B12a is incident on the light receiving unit 51a in the state of parallel light and the reflected heating light B11a continues to diverge toward the light receiving unit 51a. Even if comprised in this way, the intensity | strength of the reflected heating light B11a which injects into the light-receiving part 51a can be made small enough, and it becomes difficult to enter into the measurement result of the reflected detection light B12a by the reflected heating light B11a. it can.

  In the above embodiment, the second beam splitter 33 is configured by a polarization beam splitter. However, the present invention is not limited to this. The second beam splitter 33 is configured by a half mirror, and the third beam splitter 61 is configured by a polarization beam splitter. May be. That is, the third beam splitter 61 may be configured such that the reflected heating light B1a passes through the third beam splitter 61 and the reflected detection light B2a is reflected toward the light receiving portion 51a.

  In the above embodiment, the heating light B1 and the detection light B2 are irradiated on the measurement site 11a coaxially or substantially coaxially, but the measurement site 11a is not limited to this. For example, the detection light B2 may be irradiated perpendicularly to the measurement site 11a and the heating light B1 may be irradiated from an oblique direction. In this case, since there are microscopic irregularities on the surface of the thin film sample 11, the reflected heating light B1a irregularly reflected by the irregularities enters the third optical system 60 toward the photodetector 51, but the measurement site The intensity of the reflected heating light B1a measured by the photodetector 51 is weakened by irradiating the heating light obliquely so that the focal point is defocused at 11a, compared to the case where the measurement site 11a is irradiated obliquely so as to focus. can do.

  In the above embodiment, the analysis apparatus 10 irradiates the measurement site 11a with the intensity modulated with the heating light B1, but may be configured to irradiate the measurement site 11a with the heating light B1 that has not been intensity modulated. . Even if comprised in this way, the thermophysical property of the thin film sample 11 can be analyzed based on the intensity | strength of reflected detection light B2a.

  In the analysis apparatus 10 of the above embodiment, one pulse laser 21 is used, and the heating light B1 and the detection light B2 are derived by branching the basic pulse light B0 emitted from the pulse laser 21, Individual pulse lasers, that is, a heating pulse laser (heating light radiation means) and a detection pulse laser (detection light radiation means) may be used. In this case, it is necessary to synchronize the heating light (heating pulse light) emitted from the heating pulse laser and the detection light (detection pulse light) emitted from the detection pulse laser.

10 Analysis device (Thermophysical property analysis device)
11 Thin film sample (object to be measured)
11a Measurement site 20 Light emitting means 30 First optical system 32 Condensing lens for heating (condensing member for heating)
40 Second optical system 43 Condensing lens for detection (condensing member for detection)
50 Detection light measuring means 60 Third optical system B1 Heating light B1a Reflected heating light (reflected light of heating light)
B2 detection light B2a reflection detection light (reflection light of detection light)
s Irradiation range of the heating light at the measurement site

Claims (6)

A thermophysical property analyzing apparatus that irradiates light to a measurement site on the surface of the object to be measured and analyzes the thermophysical properties of the object to be measured based on the reflected light,
Heating light emitting means for emitting heating light for heating the measurement site;
A first optical system for guiding the heating light to the measurement site;
A detection light emitting means for emitting detection light for detecting a temperature change of the measurement site;
A second optical system for guiding the detection light to the measurement site;
A detection light measuring means for receiving reflected light of the detection light from the measurement site, and measuring the intensity of reflected light of the detection light incident on the light reception unit;
A third optical system for guiding reflected light of the detection light from the measurement site to a light receiving unit of the detection light measurement means;
It said second optical system, possess the detection light collecting light detecting optical light focusing member so as to focus at the measuring site,
The first optical system, wherein the heating light in the measurement site of the third heat of the reflected light reaching the light receiving portion is guided to the optical system than in the case of converging to focus strength while have a heating condensing member for condensing the heating light to include irradiation range of the detection light and the irradiation range defocused at said measurement site to be smaller, the heating condenser Irradiate the measurement site with heating light collected by the member,
The heating condensing member is configured such that the reflected light of the heating light from the measurement site is focused on the upstream side of the light receiving unit in the third optical system, or from the measurement site The thermal property analyzing apparatus characterized in that the reflected light of the heating light is focused on the upstream side of the third optical system and is diverged toward the light receiving unit in the third optical system. . In the thermophysical property analyzer according to claim 1,
The first optical system combines the heating light collected by the heating condensing member with the detection light condensed by the detecting condensing member so as to be coaxial or substantially coaxial with the measurement site. A thermophysical property analyzing apparatus characterized by irradiating a laser beam. In the thermophysical property analyzer according to claim 2,
Before Symbol third optical system includes a light shielding portion for shielding the progress of the reflected light focused on the focal position of the reflected light of the heating light the heating light, the periphery thereof to support the light shielding part of light can pass A thermophysical property analyzing apparatus comprising a light shielding member having a light passing portion. In the thermophysical property analyzer according to claim 2 or 3,
The first optical system includes a first polarization unit that polarizes the heating light in a first polarization direction,
The second optical system includes a second polarization unit that polarizes the detection light in a second polarization direction different from the first polarization direction,
The third optical system allows the light polarized in the second polarization direction to travel downstream in the third optical system and downstream of the light polarized in the first polarization direction. The thermophysical property analysis apparatus characterized by having a selection means for preventing the progress of the process. In the thermophysical property analyzer according to any one of claims 1 to 4,
The heating light emitting means and the detection light emitting means are constituted by a common light emitting means for emitting both the heating light and the detection light,
The light radiating means divides the pulsed light radiating part radiating pulsed light of a predetermined period, the pulsed light radiated from the radiating part into the heating light and the detection light, and the branched heating light is A thermophysical property analysis apparatus comprising: a branching unit that causes the detection light to be incident on the first optical system and the branched detection light to be incident on the second optical system. A thermophysical property analysis method for irradiating a measurement site of a measurement object with light and analyzing the thermal property of the measurement object based on the reflected light,
Irradiation step of condensing and irradiating detection light for measuring a temperature change of the measurement site so as to focus on the measurement site, and irradiating the measurement site with heating light for heating the measurement site When,
A light guide step for guiding reflected light of the detection light from the measurement site to a measurement position different from the measurement site;
A measurement step of measuring the intensity of reflected light of the detection light guided to the measurement position in this light guide step,
Wherein in the irradiating step, so that the intensity of the reflected light of the heating light to reach the measuring position is guided in the light guide step as compared with the case where the heating light at the measurement site is condensed to focus decreases And the measurement light is defocused , and the irradiation range of the detection light is included in the irradiation range , and the heating light reflected by the measurement unit is measured together with the reflected light of the detection light in the light guiding step. Heat is condensed so as to focus on the upstream side of the measurement position when guided toward the position, and the measurement site is irradiated with the condensed heating light. Physical property analysis method.

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