System and method for performing characterization of a sample

Abstract

The optical metrology device may include a selectable pump arm used to generate a transient response in the target sample and a probe arm, and may be configured to perform static magneto-optical Kerr effect (MOKE) or ellipsometry measurements when the pump arm is not selected, and time-resolved (TR) MOKE or ellipsometry measurements when the pump arm is selected. The optical metrology device may be further configured to perform photoacoustic measurements when the pump arm is selected. A pulse shaper in the pump arm may be used to pulse the duration, phase, or both of the incident pump beam to enable measurements of the dependence of magnetodynamics on pump pulse characteristics. The optical metrology device may be configured to operate at a single selectable wavelength, or at multiple wavelengths in a continuous or discontinuous spectrum.

Description

[Technical Field]

[0001] Embodiments of the subject matter described herein generally relate to non-destructive measurement of samples, and more specifically to the characterization of samples using optical measurement. [Background technology]

[0002] In the semiconductor and other similar industries, optical measurement devices are often used to non-contact evaluate substrates during processing. In optical measurement, the sample under test is irradiated with light of, for example, a single wavelength or multiple wavelengths. After interaction with the sample, the resulting light is detected and analyzed to determine the desired properties of the sample.

[0003] There are many different techniques for measuring the properties of samples, such as semiconductors. One such technique relies on the magneto-optical Kerr effect (MOKE), where the polarization change of incident light polarized by a magnetic field from the sample is measured from the reflected light. For example, the polarization change due to MOKE can be useful for monitoring the electrical and magnetic properties of a sample. Another technique is polarization analysis, in which the polarization change of incident light polarized by the sample material and geometric shape is measured from the reflected light. The polarization change is then associated with the properties of the sample. Another technique is photoacoustic measurement, in which acoustic waves generated by a pump beam are reflected off a portion of the probe beam, and this portion of the probe beam interferes with another portion of the reflected probe beam from the surface interface. Interferometric measurements produced using photoacoustic measurement can provide information about the properties of the sample.

[0004] Optical measurement techniques such as MOKE, polarization analysis, and photoacoustic measurement are useful for sample analysis, and the optical measurement devices that use such techniques can be improved. [Overview of the Initiative]

[0005] The optical measurement device includes a selectable pump arm and a probe arm used to generate a transient response in a target sample, and may be configured to perform static magneto-optical Kerr effect (MOKE) measurements when the pump arm is not selected and time-resolved (TR) MOKE measurements when the pump arm is selected. The optical measurement device may similarly perform polarization analysis measurements when the pump arm is not selected and time-resolved (TR) polarization analysis measurements when the pump arm is selected. The optical measurement device may be further configured to perform photoacoustic measurements when the pump arm is selected. A pulse shaper within the pump arm can be used to pulse the duration, phase, or both of the incident pump beam, enabling the measurement of the magnetodynamic dependence of the pump pulse characteristics. The optical measurement device may be configured to operate at a single selectable wavelength or at multiple wavelengths in a continuous or discontinuous spectrum.

[0006] In one implementation, an apparatus for measuring at least one property, including the magnetic properties of a target sample, using at least one of the static magneto-optical Kerr effect (MOKE), time-resolved MOKE (TR MOKE), or a combination thereof, may include a pulsed light source for generating a pulsed light beam. A selectable pump arm may be configured to receive at least a portion of the pulsed light beam and irradiate the target sample with one or more pump pulses to induce transient perturbations within the target material when the pump arm is selected, and not irradiate the target sample when the pump arm is not selected. A probe arm may be configured to receive at least a portion of the pulsed light beam and irradiate the target sample with one or more polarized probe pulses to generate a reflected probe pulse having a polarization state influenced by the magnetic properties of the target sample, which is modulated based on transient perturbations within the target material when the pump arm is selected. One or more detectors may be configured to receive the reflected probe pulses from the target sample. At least one processor coupled to one or more detectors may be configured to measure at least one property, including the magnetic properties of the target sample, based on static MOKE when the pump arm is not selected, and based on TR MOKE when the pump arm is selected.

[0007] In one implementation, a method for measuring at least one property, including the magnetic properties of a target sample, using at least one of the static magneto-optical Kerr effect (MOKE), time-resolved MOKE (TR MOKE), or a combination thereof, includes generating a pulsed light beam using a pulsed light source. The method may further include receiving at least a portion of the pulsed light beam and selecting a pump arm to irradiate the target sample with one or more pump pulses to induce transient perturbations in the target material, or not selecting a pump arm so that the target sample is not irradiated with one or more pump pulses. The method may further include receiving at least a portion of the pulsed light beam in a probe arm and irradiating the target sample with one or more polarized probe pulses to generate reflected probe pulses having a polarization state influenced by the magnetic properties of the target sample, which, if a pump arm is selected, is modulated based on transient perturbations in the target material. The method may further include detecting reflected probe pulses from the target sample using one or more detectors. This method may further include determining at least one property, including the magnetic properties of the target sample, based on the reflected probe pulse and static MOKE measurement when the pump arm is not selected, and based on the reflected probe pulse and TR MOKE when the pump arm is selected.

[0008] In one implementation, an apparatus for measuring at least one property, including the magnetic properties of a target sample, using at least one of the static magneto-optical Kerr effect (MOKE), time-resolved MOKE (TR MOKE), or a combination thereof, includes means for generating a pulsed light beam. The apparatus further includes means for receiving at least a portion of the pulsed light beam and selecting a pump arm to irradiate the target sample with one or more pump pulses to cause transient perturbations in the target material, or means for not selecting a pump arm so that the target sample is not irradiated with one or more pump pulses. The apparatus further includes means for receiving at least a portion of the pulsed light beam in a probe arm and irradiating the target sample with one or more polarized probe pulses to generate a reflected probe pulse having a polarization state influenced by the magnetic properties of the target sample and modulated based on transient perturbations in the target material when a pump arm is selected, and means for detecting the reflected probe pulse from the target sample. The apparatus includes means for determining at least one property, including the magnetic properties of the target sample, based on the reflected probe pulse and static MOKE measurement when a pump arm is not selected, and based on the reflected probe pulse and TR MOKE when a pump arm is selected.

[0009] In one implementation, an apparatus for measuring at least one property of a target sample, including the magnetic properties, using at least one of time-resolved magneto-optical Kerr effect (MOKE) measurements, photoacoustic measurements, or a combination thereof, includes a pulsed light source for generating a pulsed light beam. A pump arm may be configured to receive at least a portion of the pulsed light beam and irradiate the target sample with one or more pump pulses to induce transient perturbations within the target material. A probe arm may be configured to receive at least a portion of the pulsed light beam and irradiate the target sample with one or more polarized probe pulses to generate reflected probe pulses, and the probe arm may include a phase modulator configured to periodically phase-modulate one or more polarized probe pulses for time-resolved MOKE measurements and to not phase-modulate one or more pulses for photoacoustic measurements. One or more detectors may be configured to receive reflected probe pulses from the target sample. At least one processor coupled to one or more detectors may be configured to measure the effect of the magnetic properties of the target sample on the polarization state of the probe pulses for time-resolved MOKE measurements when the phase modulator periodically phase-modulates one or more probe pulses, and to measure the change in reflectivity of the probe beam as a function of the time delay between each pump pulse and probe pulse for photoacoustic measurements when the phase modulator does not phase-modulate one or more pulses.

[0010] In one implementation, a method for measuring at least one property of a target sample, including the magnetic properties, using at least one of time-resolved magneto-optical Kerr effect (MOKE) measurements, photoacoustic measurements, or a combination thereof, may include generating a pulsed light beam using a pulsed light source. This method may include receiving at least a portion of the pulsed light beam in a pump arm and irradiating the target sample with one or more pump pulses to induce transient perturbations within the target material. This method may include receiving at least a portion of the pulsed light beam in a probe arm and irradiating the target sample with one or more polarized probe pulses to generate reflected probe pulses, wherein the probe arm comprises a phase modulator configured to periodically phase-modulate one or more polarized probe pulses for time-resolved MOKE measurements and to not phase-modulate one or more pulses for photoacoustic measurements. This method may include detecting reflected probe pulses from the target sample using one or more detectors. This method may include, when a phase modulator periodically phase-modulates one or more probe pulses, determining the effect of the reflected probe pulse on the polarization state of the probe pulse for time-resolved MOKE measurement based on the magnetic properties of the target sample, and when the phase modulator does not phase-modulate one or more pulses, determining the change in the reflectivity of the probe beam as a function of the time delay between each pump pulse and probe pulse for photoacoustic measurement based on the reflected probe pulse.

[0011] In one implementation, the apparatus is for measuring at least one property of a target sample, including the magnetic properties, using at least one of time-resolved magneto-optical Kerr effect (MOKE) measurement, photoacoustic measurement, or a combination thereof, the apparatus including means for generating a pulsed light beam. The apparatus may include means for receiving at least a portion of the pulsed light beam with a pump arm and irradiating the target sample with one or more pump pulses to induce transient perturbations in the target material, and means for receiving at least a portion of the pulsed light beam with a probe arm and irradiating the target sample with one or more polarized probe pulses to generate reflected probe pulses, the probe arm comprising a phase modulator configured to periodically phase-modulate one or more polarized probe pulses for time-resolved MOKE measurement and to not phase-modulate one or more pulses for photoacoustic measurement. The apparatus may further include means for detecting reflected probe pulses from a target sample, and means for determining the effect on the polarization state of the probe pulses based on the reflected probe pulses due to the magnetic properties of the target sample for time-resolved MOKE measurements, when a phase modulator periodically phase-modulates one or more probe pulses, and for determining the change in reflectance of the probe beam as a function of the time delay between each pump pulse and probe pulse for photoacoustic measurements, when the phase modulator does not phase-modulate one or more pulses.

[0012] In one implementation, an apparatus for measuring at least one property of a target sample, including the magnetic properties, using at least one of time-resolved magneto-optical Kerr effect (MOKE) measurement, polarization analysis measurement, or a combination thereof, includes a pulsed light source for generating a pulsed light beam. A selectable pump arm may be configured to receive at least a portion of the pulsed light beam and irradiate the target sample with one or more pump pulses to induce transient perturbations within the target material when the pump arm is selected, and not irradiate the target sample when the pump arm is not selected. A probe arm may be configured to receive at least a portion of the pulsed light beam and irradiate the target sample with one or more polarized probe pulses to generate reflected probe pulses, and the probe arm includes a phase modulator configured to periodically phase-modulate one or more polarized probe pulses. One or more detectors may be for receiving reflected probe pulses from the target sample. At least one processor coupled to one or more detectors may be configured to measure the effect of the magnetic properties of the target sample on the polarization state of the probe pulses for time-resolved MOKE measurement when the pump arm is selected, and to measure the effect of the non-magnetic properties of the target sample on the polarization state of the probe pulses for polarization analysis measurement when the pump arm is not selected.

[0013] In one implementation, a method for measuring at least one property of a target sample, including the magnetic properties, using at least one of time-resolved magneto-optical Kerr effect (MOKE) measurements, polarization analysis measurements, or a combination thereof, may include generating a pulsed light beam using a pulsed light source. This method may include selecting a pump arm to receive at least a portion of the pulsed light beam and irradiate the target sample with one or more pump pulses to induce transient perturbations in the target material, and not selecting a pump arm so that the target sample is not irradiated with one or more pump pulses. This method may include receiving at least a portion of the pulsed light beam in a probe arm and irradiating the target sample with one or more polarized probe pulses to generate reflected probe pulses, wherein the probe arm comprises a phase modulator configured to periodically phase-modulate one or more polarized probe pulses. This method may include detecting the reflected probe pulses from the target sample using one or more detectors. This method may include, when a pump arm is selected, determining the effect of the probe pulse on the polarization state based on the reflected probe pulse due to the magnetic properties of the target sample for time-resolved MOKE measurement, and when a pump arm is not selected, determining the effect of the probe pulse on the polarization state based on the reflected probe pulse due to the non-magnetic properties of the target sample for polarization analysis measurement.

[0014] In one implementation, an apparatus for measuring at least one property, including the magnetic properties of a target sample, using at least one of time-resolved magneto-optical Kerr effect (MOKE) measurement, polarization analysis measurement, or a combination thereof, includes means for generating a pulsed light beam. The apparatus includes means for receiving at least a portion of the pulsed light beam and selecting a pump arm to irradiate the target sample with one or more pump pulses to produce transient perturbations in the target material, and / or not selecting a pump arm so that the target sample is not irradiated with one or more pump pulses. The apparatus includes means for receiving at least a portion of the pulsed light beam in a probe arm and irradiating the target sample with one or more polarized probe pulses to generate reflected probe pulses, the probe arm comprising a phase modulator configured to periodically phase-modulate one or more polarized probe pulses. The apparatus may further include means for detecting reflected probe pulses from the target sample, and, if a pump arm is selected, means for determining the effect of the probe pulses on the polarization state based on the reflected probe pulses due to the magnetic properties of the target sample for time-resolved MOKE measurement, and, if a pump arm is not selected, means for determining the effect of the probe pulses on the polarization state based on the reflected probe pulses due to the non-magnetic properties of the target sample for polarization analysis measurement. [Brief explanation of the drawing]

[0015] [Figure 1A] A schematic diagram of an optical measurement device is shown, which can use a variety of measurement techniques, including one or more of the following, or any combination thereof: static MOKE measurement, time-resolved MOKE measurement, photoacoustic measurement, static polarization analysis measurement, and dynamic time-resolved polarization analysis measurement. [Figure 1B] Figure 1A shows a side view of a part of a magnetic random access memory (MRAM) device, which is an example of a target sample that can be measured by the optical measurement device. [Figure 2A] This shows the MOKE geometric shape and Kerr rotation θk that occur in reflected light. [Figure 2B] The geometry of the Kerr rotation θk and ellipticity εk is shown. [Figure 3]This graph shows the change in reflectance with respect to time delay in photoacoustic measurements. [Figure 4] A more detailed schematic diagram of the optical measuring device in one implementation configuration shown in Figure 1A is provided. [Figure 5] Figure 4 shows the optical measurement device operating in static MOKE measurement mode. [Figure 6] Figure 4 shows the optical measurement device operating in TR MOKE measurement mode. [Figure 7] Figure 4 shows the optical measurement device operating in static polarization analysis measurement mode. [Figure 8] Figure 4 shows the optical measurement device operating in TR polarization analysis measurement mode. [Figure 9] Figure 4 shows the optical measurement device operating in photoacoustic measurement mode. [Figure 10] This flowchart shows a method for selectively performing MOKE and TR MOKE measurements. [Figure 11] This flowchart shows the operation method of an optical measurement device for performing optical measurement on a target sample. [Figure 12] This flowchart shows the operation method of an optical measurement device for performing optical measurement on a target sample. [Modes for carrying out the invention]

[0016] During the manufacturing of semiconductors and similar devices, it may be necessary to monitor the manufacturing process by non-destructively measuring the device. Optical measurement may be employed for non-contact evaluation of samples during processing. For example, recent developments in magnetic random-access memory (MRAM) technology have necessitated the need for efficient measurement techniques for characterizing magnetic tunnel junctions (MTJs). Monitoring the electrical and magnetic properties of MTJs is crucial for process control. One technique that can be employed for such purposes is the magneto-optical Kerr effect (MOKE). When polarized light is reflected by a sample exposed to a magnetic field, the reflected light undergoes rotation in the polarization direction or the addition of ellipticity. The behavior of an incident laser beam reflected from an MRAM stack changes as the applied magnetic field changes. MOKE testing can determine the orientation, coercivity, and thermal stability of individual layers or combined stacks. Furthermore, if a magnetic layer cannot realign itself in response to a magnetic field, it also cannot be electronically switched. Therefore, MOKE can be used to test the switching capability of a sample.

[0017] As described herein, the optical measuring device can use MOKE to test a sample using linearly polarized light that is periodically phase-modulated (at frequency f). The reflected light intensity at the detector is the dc component (I) of the modulation frequency. dc The signal has contributions from the fundamental wave component (f) and the second harmonic component (2f). The reflected signal can be demodulated using lock-in detection techniques to calculate the polarization rotation and ellipticity from the dc,f and 2f components.

[0018] It may be desirable to obtain multiple types of information from a sample during measurement. Therefore, as described herein, an optical measurement device may be configured to obtain multiple types of optical measurement, including static MOKE measurement, time-resolved MOKE measurement, photoacoustic measurement, static polarization analysis measurement, dynamic time-resolved polarization analysis measurement, or any combination thereof.

[0019] For example, an optical measuring device can be configured for multiple types of MOKE measurements, including static MOKE measurements and transient (sometimes called "time-resolved (TR)") MOKE measurements. In some implementations, the optical measuring device may be configured for TR MOKE measurements with a resolution of, for example, about 20 fs, thereby enabling the study of spin dynamics in magnetic medium samples. For example, the optical measuring device may include a magnetic field generator in or near the sample, for example, in a chuck holding the sample, to generate a magnetic field while the sample, such as an MRAM wafer, is loaded and being tested.

[0020] The optical instrument may perform TR MOK measurements to study the interaction between an ultrafast laser and a ferromagnetic metal. For example, the optical instrument can induce magnetodynamics using, for instance, a femtosecond pump laser pulse. The optical instrument may optionally include a pulse shaper that changes the pulse duration, phase, or both of the incident pump beam. The pulse shaper, which may be a spatial light modulator (SLM) or an acousto-optic modulator (AOM), may change the shape of the pump pulse, thereby enabling the study of the dependence of magnetodynamics on the pump pulse characteristics. Furthermore, the optimal pulse shape that yields desired control over magnetodynamics in the sample under consideration can be adaptively determined using the pulse shaper.

[0021] In some implementations, an optical measuring device may be configured for one or more types of MOKE measurements, along with one or more other types of measurements. For example, an optical measuring device may be configured for photoacoustic measurements, such as time-resolved picosecond acoustic measurements. For example, an optical measuring device may use one or more electro-optic modulators (EOMs) to modulate the amplitude (i.e., intensity) of the pump beam and probe beam for photoacoustic measurements and one or more types of MOKE measurements. In some implementations, other types of modulators may be used, such as acousto-optic modulators (AOMs), photoelastic modulators (PEMs), or rotational compensators.

[0022] In another example, an optical measuring device may be configured for polarization analysis measurements, along with one or more types of MOKE measurements and / or photoacoustic measurements. For example, an EOM (or other types of modulators such as an AOM, PEM, or rotational compensator) may be configured to operate as a phase modulator for polarization analysis measurements. The optical measuring device may be configured to perform, for example, static polarization analysis measurements and / or time-resolved polarization analysis measurements.

[0023] The use of EOM, AOM, or PEM for amplitude or phase modulation in optical measuring devices can be advantageous because it provides the ability to perform measurements with high sensitivity, low noise, and high speed. Furthermore, EOMs, AOMs, and PEMs can be readily configured to perform measurements including one or more of the following, or any combination thereof: photoacoustic measurements, static polarization analysis measurements, dynamic time-resolved polarization analysis measurements, static MOKE measurements, and time-resolved MOKE measurements.

[0024] In some implementations, the optical measuring device can use an optical geometric shape that modulates both the pump beam and the probe beam individually, for example, by physically separating the beam paths of the pump beam and the probe beam so that the pump beam is incident perpendicularly to the sample and the probe beam is incident obliquely to the sample. Beam path separation and individual modulation of the pump beam and probe beam can be beneficial for signal-to-noise enhancement and may enable the ability to easily switch between different types of measurements.

[0025] In some implementations, optical measuring instruments can be configured to operate at a single (narrowband) wavelength or at multiple (broadband) wavelengths. For example, an optical measuring instrument may include a supercontinuum generator in the probe beam to enable multi-wavelength measurements, including MOKE measurements, photoacoustic measurements, and polarization analysis measurements. By enabling the ability to vary the probe wavelength, for example, from the visible spectral range to the near-infrared spectral range, a wide range of materials can be measured. In some implementations, acousto-optic filters can be used to select specific wavelengths for studying different types of materials.

[0026] Figure 1A shows a schematic diagram of an optical measurement device 100 that can use a variety of measurement techniques, including one or more of the following, or any combination thereof: static MOKE measurement, time-resolved MOKE measurement, photoacoustic measurement, static polarization analysis measurement, and dynamic time-resolved polarization analysis measurement. The optical measurement device 100 may be further configured to use a pulse shaper for pulses in the pump beam and a supercontinuum generator for extending or selecting wavelengths for one or more types of measurement techniques. Figure 1A shows a simplified diagram of the optical measurement device 100, and it should be understood that additional optical components, such as lenses, polarizers, waveplates, etc., may be included.

[0027] The optical measuring device 100 includes a pulsed light source 110 that generates a pulsed light beam 111. The pulsed light source 110 may be, for example, a single-wavelength or narrow-band laser. In some implementations, the pulsed light source 110 may be a pulsed laser that generates the pulsed light beam 111. In some configurations, the pulsed light source 110 can generate pulse widths ranging from several hundred femtoseconds to several hundred picoseconds.

[0028] The beam splitter 115 receives the pulsed light beam 111 and directs a first portion to the probe arm 130 and a second portion to a selectable pump arm 120. The beam selection element 117 may be positioned between the beam splitter 115 and the target sample 102 (e.g., in front of or in the pump arm 120) and is used to select or not select, i.e., exclude, the pump arm 120 during measurement of the target sample 102. The beam selection element 117 may be a movable element such as a shutter or flip mirror, or it may be fixed and electrically controlled such as an electrochromic light switch. In another implementation, as shown by the dotted line, the beam selection element 117 may be in front of the beam splitter 115. For example, the beam selection element 117 may be a polarizer 117', and the beam splitter 115 may be a polarizing beam splitter that splits and directs light based on its polarization state. The beam selection element 117 may be configured such that the polarizing beam splitter 115 directs a portion of the pulsed light beam 111 toward the probe arm 130 and the other portion toward the pump arm 120 (e.g., 50% toward the probe arm 130 and 50% toward the pump arm 120) (e.g., by rotating the polarizer), or the polarizing beam splitter 115 may be configured to direct all of the pulsed light beam 111 toward the probe arm 130 (e.g., 100% toward the probe arm 130 and 0% toward the pump arm 120) (e.g., by rotating the polarizer). Other arrangements and types of beam selection elements 117 may be used if desired.

[0029] The pump arm 120 may be selectable, for example, using a selection element 117, for use during the measurement of the target sample 102. When selected, the pump arm 120 receives at least a portion of the pulsed light beam 111 and directs the pulsed pump beam 121 toward the target sample 102. As shown in Figure 1A, the pump beam 121 can be directed (e.g., focused) by one or more lenses (not shown) so as to be incident perpendicular to the target sample 102, but non-perpendicular incidence angles, including but not limited to, perpendicular incidence angles of ~70°, can be used as needed. When the pump arm 120 is selected, the pump beam 121 generated by the pump arm 120 irradiates the target sample 102 and causes transient perturbations within the material of the target sample 102; when the pump arm 120 is not selected, the pump beam 121 does not irradiate the target sample 102.

[0030] In some implementations, the pump arm 120 may include a delay stage 122 for controlling the delay of pulses in the pump beam 121 by increasing or decreasing the length of the optical path between the pulsed light source 110 and the target sample 102. The delay stage 122 can change the optical path length to control the time delay between irradiating the target sample 102 with each pulse in the pump beam 121 and irradiating the target sample 102 with the corresponding pulse in the probe beam 123.

[0031] The pump arm 120 may further include a pulse shaper 124 that receives a portion of the pulsed light beam 111 and generates the pump beam 121 by changing the duration, phase, or at least one of the pulses in the pulsed light beam. The pulse shaper 124 may be, for example, a spatial light modulator or an acousto-optic modulator. As an example, all-optical switching (AOS) of magnetic materials is a field of interest due to the requirement to control magnetization in a device in a faster and more efficient way. The study of the interaction between ultrafast lasers and ferromagnetic metals may lead to greater advances in future magnetic data storage devices. The pump beam 121 may be configured to induce magnetodynamics, for example, using femtosecond pump laser pulses. The optical measuring device 100 may be used to study optically induced magnetodynamics. Controlling the shape of the pulses of the pump beam 121 by changing the pulse duration and / or phase of the incident pump beam 121 using the pulse shaper 124 may be advantageously used to determine the dependence of magnetodynamics in a target sample 102 on the pump pulse characteristics. Furthermore, by using an adaptive algorithm to define and utilize the optimal pulse shape of the pump beam 121, desired control over the magnetodynamics within the target sample 102 under consideration can be achieved.

[0032] The pump arm 120 may further include a modulator 126 for modulating the amplitude (intensity) of the pump beam 121. For example, the modulator 126 can modulate the amplitude (intensity) of the polarization probe pulses in the pump beam 121. The modulator 126 can be an electro-optic modulator (EOM), acousto-optic modulator (AOM), photoelastic modulator (PEM), or rotational compensator capable of modulating the amplitude (intensity) of the pump beam 121, which is advantageous as it enables high sensitivity, low noise, and high-speed measurements.

[0033] Many other alternative configurations of the pump arm 120 are possible. For example, the pump arm 120 may include only the delay stage 122, the modulator 126, or the pulse shaper 124, or any combination thereof. Further additional optical elements may be present within the pump arm 120. It should be understood that the diagram of the pump arm 120 in Figure 1A is not intended to be limiting, but rather to show one of several exemplary configurations.

[0034] The probe arm 130 receives at least a portion of the pulsed light beam 111 and directs the probe beam 131, which may include, for example, one or more polarization pulses, to irradiate the target sample 102. The probe beam 131 may be directed (e.g., focused) by a lens (not shown) so as to be obliquely incident on the target sample 102 at any angle from 5 to 85 degrees from the normal.

[0035] The probe arm 130 may include, for example, one or more polarization elements 138 (e.g., polarizers and / or waveplates) that generate one or more polarization states and arbitrary phase shifts, and these may be configurable, for example, rotatable, to generate desired polarization states in the probe beam 131. In some implementations, the probe arm 130 may include a delay stage 132 for controlling the delay of pulses in the probe beam 131 by increasing or decreasing the length of the optical path between the pulse light source 110 and the target sample 102.

[0036] The probe arm 130 may further include a wavelength selector 133 that can receive at least a portion of the pulsed light beam 111 and be used to select one or more wavelengths to be used in the probe beam 131. The wavelength selector may include a multiwavelength generator 134 that can receive, for example, a single wavelength or narrowband generated by a laser in the pulsed light beam 111 and spectrally broaden at least a portion of the pulsed light beam 111. The multiwavelength generator 134 may be, for example, a supercontinuum generator that spectrally broadens light. In some implementations, the multiwavelength generator 134 may be a multiple harmonic generator, such as a frequency doubling crystal (DBO), that receives a narrowband wavelength and generates a widerband wavelength. In some implementations, the multiwavelength generator 134 may be a photonic crystal fiber that receives a narrowband wavelength and generates a widerband wavelength. In some implementations, the multiwavelength generator 134 spectrally broadens the pulsed light beam 111 to produce a continuous light spectrum. In some implementations, the multi-wavelength generator 134 spectrally expands the pulsed light beam 111 to generate multiple discontinuous light spectral bands. The multi-wavelength generator 134 enables the ability to increase the wavelength of the probe beam 131, for example, from the visible to the near-infrared spectral range. These wavelengths may be continuous or discontinuous and may be used for spectroscopic measurements of the target sample 102, or may be filtered to select specific wavelengths or a narrow band of wavelengths for measurement of the target sample 102. For example, in some implementations, the wavelength selector 133 may further include a filter 136, such as an acousto-optic filter, which, when used with the multi-wavelength generator 134, enables the ability to select one or more specific wavelengths in the probe beam 131, for example, from the visible spectral range to the near-infrared spectral range used for measuring the target sample 102. For example, some sample materials are opaque to some wavelengths and transparent to other wavelengths.By using the multi-wavelength generator 134 and filter 136 in the wavelength selector 133, the wavelength(s) included in the probe beam 131 may be specifically selected by the optical measuring device 100 based on the type of material of the target sample 102, which enables measurement of a wide range of different materials.

[0037] The probe arm 130 may include, for example, one or more polarization elements 138 (e.g., polarizers and / or waveplates) that generate one or more polarization states and arbitrary phase shifts, and these may be configurable, for example, rotatable, to generate desired polarization states in the probe beam 131.

[0038] The probe arm 130 may further include a modulator 139 that modulates the amplitude and / or phase of the probe beam 131. For example, the modulator 139 can modulate the amplitude (intensity) of polarized probe pulses in the probe beam 131. The modulator 139 can periodically phase-modulate the polarized probe pulses in the probe beam 131. The modulator 139 can be an EOM, AOM, PEM, or rotational compensator that can modulate the amplitude and / or phase of the probe beam 131. For example, the use of an EOM may be advantageous because it enables high sensitivity, low noise, and high-speed measurements.

[0039] Many other alternative configurations of the probe arm 130 are possible. For example, the probe arm 130 may include only the polarization element 138, the delay stage 132, the wavelength selector 133 (including one or more of the multi-wavelength generator 134 and the filter 136), and the modulator 139, or any combination thereof. Further additional optical elements may be present within the probe arm 130. It should be understood that the diagram of the probe arm 130 in Figure 1A is not intended to be limiting, but rather to show one of several exemplary configurations.

[0040] The pump beam 121 (if used) and the probe beam 131 interact with the target sample 102, and the probe beam 131 is reflected from the target sample 102 as a reflected beam 141 to the detector arm 140. The detector arm 140 includes one or more polarization elements 142 that can be used to analyze the polarization state of the reflected beam 141. The one or more polarization elements 142 may be, for example, a polarization beam splitter, polarizer, etc., which can be used to determine the polarization state of the reflected beam 141. The detector arm 140 further includes one or more detectors, for example detectors 144 and / or 146, that receive reflected probe pulses in the reflected beam 141 from the target sample 102. If two detectors 144 and 146 are used in the detector arm 140, they can detect different polarization states, for example, orthogonal polarization states. For example, detector 144 can detect the P-state polarization of the reflected probe pulse in the reflected beam 141, and detector 146 can detect the S-state polarization of the reflected probe pulse. One or more detectors 144 and / or 146 may be connected to a lock-in amplifier 148 that demodulates signals from detectors 144 and / or 146, which are generated based on the received reflected probe pulses in the reflected beam 141 from the target sample 102.

[0041] Many other alternative configurations of the detector arm 140 are also possible. For example, the detector arm 140 may include a detector 144, a detector 146, a lock-in amplifier 148, or any combination thereof. Further additional optical elements may be present within the detector arm 140. It should be understood that the diagram of the detector arm 140 in Figure 1A is not intended to be limiting, but rather to show one of several exemplary configurations.

[0042] The pulse light source 110, pump arm 120, probe arm 130, and detector arm 140 are connected to and controlled by a controller 150. Furthermore, the controller 150 can be connected to and controlled a stage 104 which includes an actuator for holding the target sample 102 and moving the target sample 102 based on control signals from the controller 150 to position the target sample 102 at a desired measurement position. For example, the stage 104 can be configured to move horizontally in Cartesian (i.e., X and Y) coordinates, or polar (i.e., R and θ) coordinates, or any combination of the two. The stage 104 may also be configured to move vertically along the Z coordinate.

[0043] The optical measuring device 100 may further include a magnetic element 106, such as an electromagnet, which may be located inside or outside the stage 104, in order to apply a magnetic field to the target sample 102 during measurement. The application of the magnetic field can be controlled by the controller 150.

[0044] The controller 150 can further control the operation of the chuck on the stage 104 used to hold or release the target sample 102. It should be understood that the controller 150 may be an embedded or distributed computing device capable of performing necessary calculations, receiving and transmitting instructions or commands, and receiving, storing, and transmitting information related to the system's measurement functions.

[0045] The controller 150 includes one or more processors and may be a workstation, personal computer, central processing unit, or other suitable computer system, or multiple systems. The controller 150 may include one processor, multiple individual processors, or multiple linked processors that can be used together, and it should be understood that all of these can be interchangeably referred to herein as controller 150, processor 150, at least one processor 150, or one or more processors 150. The controller 150 is preferably included in, connected to, or otherwise associated with, an optical measuring device 100.

[0046] The controller 150 may also control the operation of the optical measuring device 100 and collect and analyze data obtained from the detector arm 140. Based on the acquired data, the controller 150 can analyze the data to determine one or more physical properties of the target sample 102.

[0047] In some implementations, the optical measuring device 100 may be controlled by a controller 150 to employ various measurement techniques. For example, the optical measuring device 100 may be configured by the controller 150 to perform static MOKE measurements or time-resolved (TR) MOKE measurements (sometimes called transient MOKE measurements). In a MOKE measurement, linearly polarized light is elliptically polarized when reflected from the magnetized material in the target sample 102. MOKE measurements of the target sample 102 may be useful with or without an external magnetic field generated by the magnetic element 106. A wavelength selector 133 (including one or more of a multi-wavelength generator 134 and a filter 136) in the probe arm 130 may be used to select a specific wavelength to be used for a MOKE measurement and / or to use multiple wavelengths for a MOKE measurement, e.g., a spectroscopic MOKE.

[0048] For example, the behavior of an incident laser beam reflected from a target sample 102 that can be an MRAM stack changes as the applied magnetic field within the target sample 102 changes. A MOKE test can determine the orientation, coercivity, and thermal stability of the target sample 102, including individual layers or combined layer stacks within the target sample 102. For example, if the magnetic layers within the target sample 102 do not reorient themselves in response to the application of a magnetic field (e.g., from magnetic element 106), those magnetic layers do not electronically switch, and thus, the measurements can be used to detect defective devices.

[0049] FIG. 2A shows the MOKE geometry and Kerr rotation (θ iinc ) generated by the reflected light 206 from the p-polarized incident light 204 incident at an angle φ with respect to the normal to the surface of the sample 202 to generate the plane of incidence. k FIG. 2B shows the geometry of the Kerr rotation θ k and ellipticity ε k , which in the limit of k << r are related to each other by the relationship θ k + iε k = k / r, where k is the Lorentz field vector and r is the electric field vector r of the incident light.

[0050] The MOKE geometry depends on the orientation of the magnetization vector M with respect to the surface of the sample 202, the plane of incidence of the light with respect to the sample surface, and the plane of incidence of the incident light 204. FIG. 2A shows, as an example, the polar geometry where the magnetization M is positioned perpendicular to the surface of the sample 202. Other types of MOKE geometries exist, including a longitudinal direction where the magnetization M is parallel to the sample surface and parallel to the plane of incidence of the incident light 204, and a transverse direction where the magnetization M is parallel to the sample surface and perpendicular to the plane of incidence of the incident light 204.

[0051] The Kerr rotation (θ k ) is the electric field of the light 204 EThis can be explained based on the interaction between the Lorentz force (F) on the magnetization M of the material in sample 202. With linearly polarized incident light 204, the electrons in sample 202 vibrate along the electric field of the light. For example, in the case of p polarization as shown in Figure 2A, the electrons vibrate in the plane of incidence of the beam and also in the plane of sample 202. The reflected light 206 undergoes a phase shift of π with respect to the incident light 204. Therefore, the direction of the electric field E in the reflected light 206 is opposite to the direction of the electric field E in the incident light 204. With respect to the magnetization M of the material in sample 202, the Lorentz force (F) on the vibrating electrons Lor ) generates an additional small vibrational component perpendicular to the plane of incidence. Thus, the electric field E of the reflected light 206 is the vector sum of the original electric field vector (r) and the Lorentz field vector (k). Figure 2A shows the vector sum of the reflected light 206, and the resulting electric field E of the reflected light 206 is due to the magnetization M of sample 202 θ k This indicates that it is rotating by only a certain amount. In the case of s-polarized light where the electric field E is perpendicular to the plane of incidence, a similar Kerr rotation is produced due to the polarity effect.

[0052] The optical measuring device 100 shown in Figure 1A may be used to perform static MOKE measurements using, for example, only the probe arm 130. For example, the controller 150 may prevent the selection element 117 from selecting the pump arm 120, i.e., prevent the pump arm 120 from generating a pump beam 121 that is incident on the target sample 102. The polarization element 138 in the probe arm 130 may be configured to generate one or more desired polarization states of the probe pulses in the probe beam 131.

[0053] The modulator 139 in the probe arm 130 controls the frequency f probe The phase of the probe beam 131 can be modulated. The probe beam 131 interacts with the target sample 102, and as described above, the magnetization within the target sample 102 changes the polarization state of the incident light. In some implementations, the magnetic element 106 may be used to change the magnetization of the target sample 102 during the test. The polarization state of the reflected beam 141 is detected using the polarization element 142 and one or more detectors 144 and 146, and the Kerr rotation (θ) is determined. k) can be determined. For example, S-polarized and P-polarized signals can be detected using the polarization element 142 and one or more detectors 144 and 146. The lock-in amplifier 148 takes the signals from detectors 144 and 146 and determines, for example, the fundamental probe frequency and the second harmonic probe frequency, for example, f probe , 2f probe It can be used to restore function.

[0054] Therefore, the optical measuring device 100 periodically (for example, at frequency f) via the modulator 139 in the probe arm 130. probe Static MOKE can be performed using phase-modulated linear polarization. The reflected light intensity at detectors 144 and 146 is the dc component (I) of the modulation frequency. dc ), fundamental wave component (f probe ) and the second harmonic component (2f probe ) has a contribution from. The reflected signal has polarization rotation (Kerr rotation angle) θ k and ellipticity ε k to dc, f probe and 2f probe The signal is demodulated using lock-in amplifier 148 for calculation from its components.

[0055] The formula for static MOKE measurement can be written, for example, as follows:

number

[0056] Here ω is 2πf (modulation frequency), and J n is the nth Bessel function, and ε k θ is the ellipticity, k θ is the Kerr rotation angle. k and ellipticity ε k It can be written as follows:

number

[0057] Advantageously, the optical measuring device 100 may also be used to perform TR MOKE measurements using a selectable pump arm 120 together with the probe arm 130. For example, the controller 150 may cause the selection element 117 to select the pump arm 120, i.e., to generate a pump beam 121 that is incident on the target sample 102 and generates a transient response in the target sample 102. The pump beam 121 has a frequency f pump The amplitude (intensity) can be modulated using modulator 126. Transient measurements may be performed with a resolution of, for example, about 20 fs, due to the pulse duration and delayed state resolution, which may be used, for example, to study the spin dynamics in the magnetic medium within a target sample 102.

[0058] Furthermore, the pulse shaper 124 within the pump arm 120 can be used to change the pulse duration and / or phase of the incident pump beam 121 to determine the dependence of the magnetodynamics within the target sample 102 on the pump pulse characteristics. Additionally, an adaptive algorithm can be used to define and utilize the optimal pulse shape of the pump beam 121 to achieve desired control over the magnetodynamics within the target sample 102 under consideration.

[0059] A polarization element 138 within the probe arm 130 may be configured to generate one or more desired polarization states of the probe pulse in the probe beam 131. A modulator 139 within the probe arm 130 controls the frequency f probe The phase of the probe beam 131 can be modulated. The probe beam 131 interacts with the target sample 102 after each pump pulse. TRMOKE measurements can be collected as a function of the time delay between the pump beam 121 and the probe beam 131, controlled, for example, by a delay stage 122 in the pump arm 120 and / or a delay stage 132 in the probe arm 130. The magnetization of the target sample 102 changes the polarization state of the incident light. In some implementations, a magnetic element 106 may be used to change the magnetization of the target sample 102 during the test.

[0060] The polarization state of the reflected beam 141 is detected using the polarization element 142 and one or more detectors 144 and 146, and the Kerr rotation (θ) is determined. k ) can be determined. For example, S-polarized and P-polarized can be detected using the polarization element 142 and one or more detectors 144 and 146. The lock-in amplifier 148 can, for example, pump modulation and f pump ±f probe ,f pump ±2f probe The signals from detectors 144 and 146 can be used to demodulate the signals as a function of some combination of various harmonics of the probe frequency, such as the following.

[0061] Therefore, the optical measuring device 100 uses the modulator 126 in the pump arm 120 to measure f pump Using the intensity-modulated pump beam 121, and also linearly polarized via the modulator 139 in the probe arm 130, periodically (for example, at frequency f probe TRMOKE can be performed using phase-modulated probe light. The reflected light intensity at detectors 144 and 146 is the pump intensity (I pump ), pump frequency (f pump ), as well as the fundamental frequency (f) of the probe modulation frequency. probe ) and the second harmonic (2f probe The reflected signal has a contribution from the component of ). The reflected signal is demodulated using the lock-in amplifier 148 and the polarization rotation (Kerr rotation angle) θ k and ellipticity ε k The calculation is performed, and Equation 3 is shown as an example and is not a limitation.

number

[0062] In some implementations, the optical measuring device 100 may be controlled by a controller 150 to perform polarization analysis measurements. In polarization analysis measurements, linearly polarized light becomes elliptically polarized upon reflection from the target sample 102 due to the dielectric properties (e.g., complex refractive index or dielectric function) of the material in the target sample 102. The optical measuring device 100 can measure at least a partial Müller matrix, e.g., off-diagonal elements, and / or polarization analysis parameters, by measuring the changes in polarization state in the reflected beam 141, Ψ and Δ. In some implementations, the changes in polarization can be compared with a model or library to determine the properties of the target sample 102. For example, polarization analysis may be used to determine properties of the target sample 102 such as composition, roughness, thickness (depth), crystallinity, doping concentration, and conductivity. A wavelength selector 133 (including one or more of a multi-wavelength generator 134 and a filter 136) in the probe arm 130 may be used to select a specific wavelength to be used for polarization analysis measurements and / or to use multiple wavelengths for polarization analysis measurements, e.g., spectral polarization analysis.

[0063] The optical measuring device 100 may be used to perform static polarization analysis measurements, for example, by using only the probe arm 130, and by preventing the controller 150 from causing the selection element 117 to select the pump arm 120, i.e., by preventing the pump arm 120 from generating the pump beam 121 incident on the target sample 102. The polarization element 138 in the probe arm 130 may be configured to generate one or more desired polarization states of the probe pulses in the probe beam 131.

[0064] The modulator 139 in the probe arm 130 controls the frequency f probeThe phase of the linearly polarized probe beam 131 can be modulated. The probe beam 131 interacts with the target sample 102, and the properties of the material in the target sample 102 change the polarization state of the incident light. Using the polarization element 142 and one or more detectors 144 and 146, the polarization state of the reflected beam 141 can be detected, the polarization analysis parameters Ψ and Δ can be determined, and / or a Müller matrix form can be adapted, such as searching for off-diagonal elements in some applications. For example, S-polarization and P-polarization can be detected using the polarization element 142 and one or more detectors 144 and 146. The lock-in amplifier 148 receives signals from detectors 144 and 146, for example, the fundamental wave, second harmonic, or higher harmonics of the probe frequency, for example, f probe , 2f probe It can be used to demodulate with various harmonics, including those mentioned above.

[0065] Therefore, the optical measuring device 100 can perform static polarization analysis using linearly polarized light that is periodically (e.g., at frequency f) phase-modulated via the modulator 139 in the probe arm 130. The reflected light intensity at detectors 144 and 146 is the dc component (I) of the modulation frequency. dc The signal has contributions from the fundamental wave component (f) and the second harmonic component (2f). The reflected signal is demodulated using a lock-in amplifier 148 to calculate at least a partial Müller matrix, e.g., off-diagonal elements, and / or polarization analysis parameters Ψ and Δ from the dc, f, and 2f components. The polarization analysis parameters are, for example, as follows:

number

number

[0066] The optical measuring device 100 may also be used to perform time-resolved (TR) polarization analysis measurements using a selectable pump arm 120 together with the probe arm 130. For example, the controller 150 may cause the selection element 117 to select the pump arm 120, i.e., to generate a pump beam 121 that is incident on the target sample 102 and generates a transient response in the target sample 102. The pump beam 121 has a frequency f pump The amplitude (intensity) can then be modulated using modulator 126.

[0067] A polarization element 138 within the probe arm 130 may be configured to generate one or more desired polarization states of the probe pulse in the probe beam 131. A modulator 139 within the probe arm 130 controls the frequency f probe The phase of the probe beam 131 can be modulated. The probe beam 131 interacts with the target sample 102 after each pump pulse. TR polarization analysis measurements can be collected as a function of the time delay between the pump beam 121 and the probe beam 131, controlled, for example, by a delay stage 122 in the pump arm 120 and / or a delay stage 132 in the probe arm 130.

[0068] The properties of the material in the target sample 102 change the polarization state of the incident light. Using the polarization element 142 and one or more detectors 144 and 146, the polarization state of the reflected beam 141 can be detected, and at least a partial Müller matrix, e.g., off-diagonal elements, and / or polarization analysis parameters Ψ and Δ can be determined. For example, S-polarization and P-polarization can be detected using the polarization element 142 and one or more detectors 144 and 146. The lock-in amplifier 148 takes the signals from detectors 144 and 146 and uses them to determine, for example, the pump frequency and the fundamental wave, second harmonic, and higher probe frequencies, e.g., f pump ±f probe ,f pump ±2f probe It can be used to demodulate as a function of some combination of harmonics of the probe frequency, such as [examples of probe frequencies].

[0069] Therefore, the optical measuring device 100 measures frequency f via the modulator 126 in the pump arm 120. pump Using the intensity-modulated pump beam 121, which is also linearly polarized, periodically (e.g., f) via the modulator 139 in the probe arm 130. probe TR polarization analysis can be performed using phase-modulated probe light (at the frequency of ). The reflected light intensity at detectors 144 and 146 is the pump intensity (I pump ), pump frequency (f pump ), as well as contributions from the fundamental (f) and second harmonic (2f) components of the probe modulation frequency. The reflected signal is demodulated using the lock-in amplifier 148, and at least a partial Müller matrix is ​​calculated, including off-diagonal elements and / or polarization analysis parameters Ψ and Δ, for example:

number

number

[0070] In some implementations, the optical measuring device 100 may be controlled by a controller 150 to perform photoacoustic measurements. The photoacoustic measurement may be a picosecond ultrasonic measurement, for example, which can be used to measure depth-resolved measurements of heterogeneity in a target sample 102. The photoacoustic measurement uses, for example, a pump beam 121 to generate a transient response within the target sample 102, where a transducer layer, such as a metal layer within the target sample 102, absorbs the pump pulse energy and emits sound waves perpendicularly into the target sample 102. The propagating sound waves interact with and are reflected by the probe beam 131 via a piezoelectric reflection response. The light reflected from the propagating sound waves interferes with the light reflected from the upper surface of the target sample 102, resulting in a characteristic vibration time evolution signal, i.e., coherent Brillouin scattering. The period of vibration reveals information about the sound velocity and modulus within the target sample 102. Depth-resolved vibration periods may be used to extract the sound velocity and Young's modulus at various depths within the target sample 102, which may be used to provide insight into the presence and location of heterogeneity or to measure the thickness of an opaque film.

[0071] The optical measuring device 100 can perform photoacoustic measurements using a selectable pump arm 120 together with the probe arm 130. For example, the controller 150 may cause the selection element 117 to select the pump arm 120, that is, to generate a pump beam 121 that is incident on the target sample 102 and generates a transient response in the target sample 102. The pump beam 121 has a frequency f pump The amplitude (intensity) can then be modulated using modulator 126.

[0072] The probe arm 130 generates probe pulses within the probe beam 131, which may, but do not need to be, polarized by a polarization element 138 within the probe arm 130. Furthermore, the probe beam 131 does not need to be phase-modulated by a modulator 139. In some implementations, the probe beam may be amplitude (intensity) modulated by the modulator 139. The probe beam 131 interacts with the target sample 102 after each pump pulse. Photoacoustic measurements can be collected as a function of the time delay between the pump beam 121 and the probe beam 131, controlled, for example, by a delay stage 122 in the pump arm 120 and / or a delay stage 132 in the probe arm 130.

[0073] The material properties within the target sample 102, including the type of material, thickness, and non-uniformity, can be measured based on the reflected beam 141 by varying the sound wave propagation time. The detector arm 140 can detect changes in the reflection or surface deformation of the reflected beam 141, for example, with respect to time delay using the detector 144. Figure 3 shows, as an example, a graph showing the change in reflectance ΔR with respect to time delay (psec) as possible, as measured by the optical measuring device 100 operating in photoacoustic measurement mode. As an example, the thickness of the target sample 102 may be measured based on the following:

number

[0074] Here, τ is the echo arrival time, and v sound This is the speed of sound in the material of target sample 102.

[0075] Figure 1B shows a partial side view of an MRAM apparatus 180, which is an example of a target sample 102 that can be measured by an optical measuring device 100. For example, the MRAM apparatus 180 has a hard mask layer 181, a cap layer (upper electrode) 182, CoFeB layers 183 and 185 with an interposed MgO layer 184, a Ta spacer 186, and an interposed Ru or Ir layer 188 [Co(x) / Pt(y)] nThe structure may include multilayers 187 and 189, a seed layer 190, and a bottom electrode 191. For example, acoustic and polarization analysis measurements may be used to measure the thickness of the bottom electrode 191 or the thickness of the metal in the MTJ stack. Static MOKE can be used, for example, to measure magnetic stack deposition, annealing, and magnetization. Subtle changes in the free and pinned layers can be measured to obtain an optimal magnetization state. For example, in tunnel magnetoresistance (TMR), the resistance of the MTJ depends on the relative orientation of the magnetic layers, which is important for reading. In another example, using spin transfer torque (STT), spin angular momentum transfer between magnetic layers results in a torque on the free layer, which is important for writing. Static MOKE can be used to measure magnetization to achieve these properties. Transient MOKE, on the other hand, can be used to characterize magnetodynamics, for example, to study the speed of magnetic writing and reading. For example, magnetic switching can occur on a picosecond timescale. Transient MOKE can be used to study the control of individual bits on a sub-ns timescale in high-density magnetic memory. The various characteristics described above can be measured using the optical measuring device 100.

[0076] Figure 4 shows a schematic diagram of an optical measuring device 400, which represents one embodiment of the optical measuring device 100 shown in Figure 1A. It should be understood that, in addition to those shown in Figure 4, the optical measuring device 400 may include beam management and adjustment components such as beam expanders, collimators, polarizers, and half-wave plates, as well as components and subsystems such as beam power detectors and focus sensors. Those skilled in the art will understand that variations of the optical measuring device 400 in Figure 4 are still suitable for performing the measurement techniques described herein. Furthermore, it should be understood that certain components shown in Figure 4 may not be included in the optical measuring device 400 if they are not necessary for performing the desired measurement techniques described herein. For example, in some implementations, the pump arm 420 can be excluded from the optical measuring device 400 if transient or time-resolved measurements are not desired, and in other implementations, the shutter 410 (or optional pump arm 420 component) can be excluded from the optical measuring device 400 if static measurements, such as non-transient or non-time-resolved measurements, are not desired. Similarly, one or more of the pump delay stage 422, pulse shaper 424, probe delay stage 432, wavelength selector 433 (e.g., a multi-wavelength generator 434 and one or both of the filters 436 such as a dichroic mirror, laser line filter, or notch filter), or other components may be excluded from the optical measuring device 400 if they are not necessary for the desired measurement, as will be understood by those skilled in the art.

[0077] As shown in the figure, the light may be generated from a light source 402, such as a 510-535 nm range 50-400 fs, 20-150 MHz laser that generates a pulsed light beam. The light may be directed through an intensity control 403, which includes a half-wave plate HWP1 and a polarizer P1. The light may pass through a beam expander 404, which may include a series of lenses that expand the beam. The light may pass through a chopper 406, which can be used for intensity control of the pulsed light beam. In some implementations, another intensity modulator, such as an EOM or AOM, may be used instead of the chopper 406. The light source 402, intensity control 403, beam expander 404, and chopper 406 (if present) can be used as a pulsed light source 110 as shown in Figure 1A.

[0078] The pulsed light beam is directed to the beam splitter 408 by the mirror M1. The beam splitter 408 can be used, for example, as the beam splitter 115 shown in Figure 1A. The beam splitter may also be an unpolarized beam splitter that separates the pulsed light beam, directing a portion (e.g., 50%) to a selectable pump arm 420 (which may be used as the pump arm 120 in Figure 1A) and another portion (e.g., 50%) to a probe arm 430 (which may be used as the probe arm 130 in Figure 1A).

[0079] The shutter 410 may be used to select or exclude the pump arm 120 from measurement, for example, by opening it to allow the pulsed light beam to pass through the pump arm 120, or by closing it to prevent the pulsed light beam from passing through the pump arm 120. The shutter 410 may, as an example, be used as the selection element 117 in Figure 1A. The shutter 410 may be replaced with a flip mirror or other movable element, or with an electrically controlled element such as an electrochromic optical switch that can be made opaque by the application of current or voltage. In some implementations, the shutter 410 may be replaced with a polarization element (e.g., polarizer P1) in front of the beam splitter 408, the beam splitter may be a polarizing beam splitter for selecting whether the pulsed light beam is supplied to the pump arm 120, and the polarizer P1 may be controlled to produce a polarization state in the pulsed light beam that is either directed to both the pump arm 420 and the probe arm 430, or directed only to the probe arm 430.

[0080] The pump arm 420 includes a variable delay stage 422, shown as including a plurality of mirrors M2, M3, M4, and M5, where mirror M4 is movable via a piezoelectric motor and changes the length of the optical path to control the delay of pulses in the pump beam generated by the pump arm 420, thereby changing the time delay between pulses in the pump beam and pulses in the probe beam.

[0081] The pulse shaper 424 receives a pulsed light beam and changes the duration, phase, or at least one of the pulses in the pulsed light beam within the pump beam. The pulse shaper 424 may be, for example, a spatial light modulator or an acousto-optic modulator. For example, a spatial light modulator such as a liquid crystal SLM manufactured by Jenoptik may be used, or an acousto-optic modulator such as a KD*P crystal-based EOM manufactured by Conoptics may be used.

[0082] The pump beam passes through an EOM 426, such as a KD*P crystal-based EOM manufactured by Conoptics. The pump beam can further pass through a polarizer P2 and a half-wave plate HWP2, and is directed towards the target sample 412 via mirrors M6, M7, M8, a beam splitter 428, and a lens L1. The lens L1 may include one or more reflective or refractive lenses, or a combination thereof. The lens L1 can direct the pump beam so that it is incident perpendicularly to the target sample 412. In some implementations, the pump beam may have a non-perpendicular incidence angle, for example, an incidence angle of ~70° perpendicular.

[0083] The visual system 429 can focus on the target sample 412 via the beam splitter 428 and lens L1, and can be used to position the target sample 412.

[0084] The probe arm 430 may include an electric half-wave plate HWP3 before a variable delay stage 432, which is shown as including a number of mirrors M9, M10, M11, and M12, and the mirror M11 is movable via a piezoelectric motor to change the length of the optical path in order to control the delay of pulses in the probe beam generated by the probe arm 430 and change the time delay between the pulses in the pump beam and the pulses in the probe beam.

[0085] The probe arm 430 may include a wavelength selector 433 that can be used to select one or more wavelengths to be used in the probe beam for measuring the target sample 412. The wavelength selector 433 may include, for example, a multiwavelength generator 434 that receives a narrowband pulsed light beam 111 and spectrally broadens the pulsed light beam to generate a probe beam. The multiwavelength generator 434 may be, for example, a supercontinuum generator such as a multiple harmonic generator, or a DBO or photonic crystal fiber that receives a single or narrowband wavelength and generates multiple wavelengths in a continuous or discontinuous spectral wavelength range for the probe beam. For example, a DBO or photonic crystal fiber can be used. The multiwavelength generator 434 enables the ability to increase the wavelength of the probe beam, for example, from the visible spectral range to the near-infrared spectral range. These may be continuous or discontinuous wavelengths and may be used for spectroscopic measurements of the target sample 412, or may be filtered to select a specific wavelength or narrowband wavelength for measuring the target sample 412. In some implementations, the wavelength selector 433 may further include a filter 436, such as an acousto-optic filter, which, when used with the multi-wavelength generator 434, enables the ability to select one or more specific wavelengths contained in the probe beam, for example, from the visible spectral range to the near-infrared spectral range used to measure the target sample 412.

[0086] The probe arm 430 may include, for example, one or more polarization elements 438 (e.g., polarizers and / or waveplates) that generate one or more polarization states and an optional phase shift, which may be configurable, for example, rotatable, to generate a desired polarization state in the probe beam. The probe arm 430 may further include an EOM 439 for modulating the amplitude and / or phase of the probe beam. The EOM 439 can modulate the amplitude (intensity) of the polarization probe pulses in the probe beam. For example, the EOM 439 may be a KD*P crystal-based EOM manufactured by Conoptics. The EOM 439 can periodically phase-modulate the polarization probe pulses in the probe beam.

[0087] The probe beam generated by the probe arm 430 is directed towards the target sample 412 via mirrors M13, M7, M14 and lens L2. Lens L2 may include one or more reflective or refractive lenses, or a combination thereof. Lens L2 directs the probe beam so that it is incident on the target sample 412 at an oblique angle.

[0088] The detector arm 140 receives the beam reflected from the target sample 412 via lens L3 and mirrors M15 and M16. Lens L3 may include one or more reflective or refractive lenses, or a combination thereof. The detector arm 140 may include a beam splitter 442 that directs a portion of the reflected light to a first detector 444 and another portion to a second detector 446. For example, detectors 444 and 446 may be single photodetectors, such as Si-based photodetectors manufactured by Thorlabs. In some implementations, one or more polarization elements can be placed within the detector arm 440, which can act as an analyzer for selecting the polarization state of the reflected light to be detected. The first detector 444 and the second detector 446 can receive the orthogonal polarization state of the reflected light. For example, in some implementations, the beam splitter 442 may be a polarizing beam splitter, which may direct the reflected light to detectors 444 and 446 based on the polarization state of the reflected light, for example, the first detector 444 may receive the S-polarized state of the reflected light, and the second detector 446 may receive the P-polarized state of the reflected light. In some implementations, the beam splitter 442 may be unpolarized, and one or more polarizing elements may be arranged within the detector arm 440 to select the polarization state of the reflected light received by detectors 444 and 446. The polarizing elements may be rotatable, for example, to detect multiple polarization states as needed. Furthermore, in some implementations, a shutter 443 (or other selection elements such as a flip mirror or other movable element, or an electrically controlled element such as an electrochromic light switch) can be placed in front of detector 444 to prevent detection of reflected light by detector 446 when only a single detector 444 is desired for measurement.

[0089] One or more detectors 444 and / or 446 may be connected to a lock-in amplifier 448 that receives signals from detectors 444 and 446 generated based on the received reflected probe pulse in the reflected beam from the target sample 412 and demodulates the signal based on the DC frequency component generated by the light source 402, as well as the modulation frequencies generated by the EOM 439 in the probe arm 430 and, if used, the EOM 426 in the pump arm 420.

[0090] As shown in the figure, the optical measuring device 400 may further include a stage 414 which includes a chuck for holding the target sample 412 and an actuator for moving the target sample 412 to a desired positioning system. For example, the stage 414 may allow horizontal motion in Cartesian (i.e., X and Y) coordinates, or polar (i.e., R and θ) coordinates, or any combination of the two. The stage may also allow vertical motion along the Z coordinate. In addition, one or more magnetic elements 416, such as electromagnets, may be included within or outside the stage 414 and may be used to apply a magnetic field to the target sample 412 for measurements such as static MOKE and / or TR MOKE measurements.

[0091] Other components of the optical measuring device 400, such as detectors 444, 446, a lock-in amplifier 448, and a light source 402, a shutter 410, a pump variable delay stage 422, a pulse shaper 424, an EOM 426, a probe variable delay stage 432, a wavelength selector 433, a polarizer 438, an EOM 439, a shutter 443 (if present), a stage 414, and one or more magnetic elements 416, may be coupled to at least one controller 450, such as a workstation, a personal computer, a central processing unit or other suitable computer system, or multiple systems. The controller 450 includes one or more processing units 452, which may be separate or linked processors, and it should be understood that the controller 450 may be referred to herein as a processor 450, at least one processor 450, one or more processors 450, etc. The controller 450 is preferably included in, connected to, or otherwise associated with the optical measuring device 400. The controller 450 can control the positioning of the target sample 412, for example, by controlling the movement of the stage 414 on which the target sample 412 is held. The controller 450 may further control the movement of the chuck 414 to hold or release the target sample 412. The controller 450 may also collect and analyze data obtained from detectors 444, 446. The controller 450 can analyze the data to determine one or more physical properties of the sample based on static MOKE, TR MOKE, polarization analysis, TR polarization analysis, spectroscopic polarization analysis, photoacoustic measurements, etc., as described herein. In some implementations, measured data may be acquired and compared with modeled data, which may be stored in a library or acquired in real time. The model parameters may be varied until the modeled data and measured data are compared, for example, in a linear regression process, until a good fit is achieved between the modeled data and the measured data, at which point the modeled parameters are determined to be the properties of the target sample 412.

[0092] The controller 450 includes at least one processing unit 452 and memory 454, as well as a user interface such as a display 456 and an input device 458. A non-temporary computer-usable storage medium 459 incorporating computer-readable program code is used by at least one processor 452, which can control the optical measuring device 400 to perform the measurement functions and analyses described herein. Data structures and software code for automatically implementing one or more operations described in embodiments of this invention can be implemented by those skilled in the art in consideration of this disclosure, for example, stored on the computer-usable storage medium 459, which may be any device or medium capable of storing code and / or data for use by a computer system such as the processing unit 452. The computer-usable storage medium 459 may be, but is not limited to, a disk drive, magnetic tape, compact disc, and flash drive such as DVD (Digital Multipurpose Disc or Digital Video Disc), magnetic storage devices, and optical storage devices. Communication port 457 may also be used to receive instructions stored in memory 454 that can be used to program processor 450 to perform any one or more of the functions described herein, and may represent any type of communication connection, such as the Internet or other computer networks. Communication port 457 may, for example, further export signals with measurement results and / or instructions to another system, such as an external process tool, in a feedforward or feedback process, to adjust process parameters associated with the sample manufacturing process steps based on the measurement results. Furthermore, the functions described herein may be embodied in whole or in part within the circuitry of an application-specific integrated circuit (ASIC) or programmable logic device (PLD), and the functions may be embodied in a computer-understandable description language that can be used to create an ASIC or PLD that operates as described herein.The data analysis results may be stored, for example, in a memory 454 associated with the sample, and / or provided to the user, for example, via a display 456, an alarm, or other output device. Furthermore, the analysis results may be fed back to the process apparatus to adjust an appropriate patterning process to compensate for the detected processing variability.

[0093] Figure 5 shows, as an example, an optical measuring device 400 configured to perform a static MOKE measurement using, for example, only the probe arm 430. For example, as shown, the shutter 410 is configured not to select the pump arm 420, preventing the pump arm 420 from generating a pump beam. The wavelength selector 433 may be configured to generate a desired wavelength or multiple continuous or discontinuous wavelengths in the probe beam, for example, using a multi-wavelength generator 434 and a filter 436. The polarizer 438 in the probe arm 430 is configured to generate a desired polarization state, for example, 45° in the probe pulse in the probe beam. The EOM 439 is configured, for example, at frequency f probe The probe beam is configured to be phase-modulated. In some implementations, the magnetic element 416 may be used to change the magnetization of the target sample 102 during the test, for example, by changing the magnetization before some measurements. The shutter 443 is configured to allow the use of both detectors 444 and 446. The polarizing beam splitter 442 (or one or more polarizers, if used) and detectors 444 and 446 detect the polarization state of the reflected beam as described above and the Kerr rotation (θ k ) can be used to determine the S-polarization and P-polarization states. For example, the S-polarization and P-polarization states may be detected by detectors 444 and 446, and the lock-in amplifier 448 takes the signals from detectors 444 and 446 and, for example, the fundamental wave, the second harmonic and higher probe frequencies, for example, f pump ±f probe ,f pump ±2f probe It may be used to demodulate with any combination of harmonics of the probe frequency, such as dc(I dc), fundamental wave (f probe ) and the second harmonic (2f probe Using the detection intensity having the components of ), as shown in Equation 2, dc, f probe , and 2f probe Polarization rotation (Kerr rotation angle) θ from the components k The ellipticity ε may also be determined.

[0094] Figure 6 shows, as an example, an optical measurement device 400 configured to perform TR MOKE measurements using, for example, both a pump arm 420 and a probe arm 430. For example, as shown, the shutter 410 is configured to select the pump arm 420 to generate a pump beam that is incident on the target sample 412 and produces a transient response in the target sample 412. The pump beam may be configured to induce magnetodynamics within the target sample 412, for example, using femtosecond pump laser pulses. A pulse shaper 424 can be used to change the pulse duration and / or phase of the incident pump beam to determine the dependence of magnetodynamics within the target sample 112 on the pump pulse characteristics. Furthermore, an adaptive algorithm may be used to define and use the optimal pulse shape of the pump beam to bring about desired control over the magnetodynamics within the target sample 112 under consideration, for example, by changing the pulse shape of the pump beam until the strongest response is detected. EOM 426 is frequency f pump The amplitude (intensity) of the pump beam may be modulated.

[0095] The wavelength selector 433 in the probe arm 430 may be configured to generate a desired wavelength or a plurality of continuous or discontinuous wavelengths in the probe beam, for example, using a multi-wavelength generator 434 and a filter 436. The polarizer 438 in the probe arm 430 is configured to generate a desired polarization state, for example, 45° in the probe pulse in the probe beam. The EOM 439 is configured to generate a desired polarization state, for example, 45° in the probe pulse in the probe beam. probeThe probe beam is configured to be phase-modulated. In some implementations, the magnetization of the target sample 112 can be changed during the test, for example, by changing the magnetization before some measurements, using the magnetic element 416, and / or the magnetization of the target sample 112 can be induced by a pump pulse. The shutter 443 is configured to allow the use of both detectors 444 and 446. The polarizing beam splitter 442 (or one or more polarizers, if used) and detectors 444 and 446 detect the polarization state of the reflected beam and, as described above, the Kerr rotation (θ k ) can be used to determine the S-polarization and P-polarization states. For example, the S-polarization and P-polarization states may be detected by detectors 444 and 446, and the lock-in amplifier 448 takes the signals from detectors 444 and 446 and, for example, the fundamental wave, the second harmonic and higher probe frequencies, for example, f pump ±f probe ,f pump ±2f probe It may be used to demodulate with any combination of harmonics of the probe frequency, such as the following. The optical measuring device 400 is a component of the pump intensity (I pump ), pump frequency (f pump ), as well as the fundamental frequency (f) of the probe modulation frequency. probe ) and the second harmonic (2f probe Using the detection intensity having the component of ), polarization rotation (Kerr rotation angle) θ k and ellipticity ε k The dc, f, and 2f components may be determined as shown in Equation 3.

[0096] FIG. 7 shows, as an example, an optical measurement device 400 configured to perform polarization analysis measurement using, for example, only the probe arm 430. For example, as shown, the shutter 410 is configured not to select the pump arm 420, preventing the pump arm 420 from generating a pump beam. The wavelength selector 433 may be configured to generate a desired wavelength or a plurality of continuous or discontinuous wavelengths in the probe beam, for example, using a multi-wavelength generator 434 and a filter 436. The polarizer 438 in the probe arm 430 is configured to generate 45° within a desired polarization state, for example, within a probe pulse in the probe beam. In some implementations, the polarizer 438 can be rotated to generate different polarization states. The linearly polarized light from the polarizer 438 is phase-modulated by the EOM 439, for example, at a frequency f probe The shutter 443 may be configured to prevent the reflected light from being received by the detector 444. The polarization beam splitter 442 (or, if used, one or more polarizers) operates as an analyzer, directing the reflected light from the target sample 412 to the detector 446, which detects the intensity of the reflected light in the selected polarization state. The lock-in amplifier 448 demodulates the signal from the detector 444, for example, in some combination of harmonics of the fundamental wave, the second harmonic, and higher probe frequencies, such as f probe , 2f probe and so on. The optical measurement device 400 uses the detected intensity having components of the modulation frequency dc (I dc ), the fundamental wave (f probe ) and the second harmonic (2f probe ) to determine at least a partial Mueller matrix, for example, the off-diagonal components and / or the polarization analysis parameters Ψ and Δ from the dc, f probe and 2f probe components shown in Equations 4 and 5.

[0097] FIG. 8 shows, by way of example, an optical measurement device 400 configured to perform TR polarization analysis measurements using, for example, both a pump arm 420 and a probe arm 430. For example, as illustrated, the shutter 410 is configured to select the pump arm 420 to generate a pump beam that is incident on the target sample 412 and generates a transient response in the target sample 412. The EOM 426 may modulate the amplitude (intensity) of the pump beam at a frequency f pump Thereby modulating the amplitude (intensity) of the pump beam.

[0098] The wavelength selector 433 within the probe arm 430 may be configured to generate a desired wavelength or a plurality of continuous or discontinuous wavelengths within the probe beam using, for example, a multi-wavelength generator 434 and a filter 436. The polarizer 438 within the probe arm 430 is configured to generate, for example, 45° within a probe pulse within the probe beam in a desired polarization state. In some implementations, the polarizer 438 can be rotated to generate different polarization states. The linearly polarized light from the polarizer 438 is phase-modulated by the EOM 439, for example, at a frequency f probe . The shutter 443 may be configured to prevent the reflected light from being received by the detector 444. The polarization beam splitter 442 (or, if used, one or more polarizers) operates as an analyzer, directing the reflected light from the target sample 412 to the detector 446, which detects the intensity of the reflected light in the selected polarization state. The lock-in amplifier 448 demodulates the signals from the detectors 444 and 446, for example, in some combination of harmonics of the fundamental wave, the second harmonic, and higher probe frequencies, such as f pump ±f probe , f pump ±2f probe and so on. The optical measurement device 400 includes components of the pump intensity (I pump ), components of the pump frequency (f pump ), and components of the fundamental wave (f probe ) and the second harmonic (2f probeUsing the detection intensity having ), at least a partial Müller matrix, e.g., the off-diagonal components, and / or the polarization analysis parameters Ψ and Δ can be determined as shown in Equations 6 and 7.

[0099] Figure 9 shows, as an example, an optical measurement device 400 configured to perform photoacoustic measurements using, for example, both a pump arm 420 and a probe arm 430. For example, as shown, the shutter 410 is configured to select the pump arm 420 to generate a pump beam that is incident on the target sample 412 and produces a transient response in the target sample 412. A variable delay stage 422 can be controlled to generate various delays between the pump beam and the probe beam so that the photoacoustic measurements can be collected as a function of the time delay between the pump beam and the probe beam. EOM 426 controls the frequency f pump The amplitude (intensity) of the pump beam may be modulated.

[0100] A wavelength selector 433 within the probe arm 430 may be configured to generate a desired wavelength or a plurality of continuous or discontinuous wavelengths in the probe beam, for example, using a multi-wavelength generator 434 and a filter 436. A polarizer 438 within the probe arm 430 is configured to generate a desired polarization state, for example, 0° in the probe pulse within the probe beam. A shutter 443 may be configured to prevent reflected light from being received by the detector 444. A beam splitter 442 directs the reflected light from the target sample 412 to the detector 446 and detects the change in reflectivity of the reflected beam with respect to time delay. The change in reflectivity with respect to time delay can be used to determine various properties of the target sample 412, such as thickness, as shown in Equation 8.

[0101] Figure 10 is a flowchart 1000 illustrating how to operate an optical measuring device, such as optical measuring device 100 or 400, for performing optical measuring measurements on a target sample, as described herein. For example, the operation method may involve measuring at least one property, including the magnetic properties, of the target sample using at least one of the static magneto-optical Kerr effect (MOKE), time-resolved MOKE (TR MOKE), or a combination thereof.

[0102] In block 1002, the optical measuring device generates a pulsed light beam using a pulsed light source, for example, a pulsed light source 110 that generates the pulsed light beam 111 shown in Figure 1A, or a light source 402, intensity control 403, beam expander 404, and chopper 406 shown in Figures 4 to 8. Means for generating a pulsed light beam may include, for example, the pulsed light source 110 shown in Figure 1A, or the light source 402, intensity control 403, beam expander 404, and chopper 406 shown in Figures 4 to 8.

[0103] In block 1004, the optical measuring device receives at least a portion of the pulsed light beam and selects a pump arm to irradiate the target sample with one or more pump pulses to cause transient perturbations in the target material, as shown by, for example, the beam selection element 117 and pump arm 120 that generate the pump beam 121 shown in Figure 1A, or the shutter 410 and pump arm 420 shown in Figures 4 to 8, or does not select a pump arm so that the target sample is not irradiated with one or more pump pulses. Means for receiving at least a portion of a pulsed light beam and selecting a pump arm to irradiate a target sample with one or more pump pulses to cause transient perturbations in the target material, or means for not selecting a pump arm so that the target sample is not irradiated with one or more pump pulses, may include, for example, a beam selection element 117 (which may be a polarizer 117' and a beam splitter 115) as shown in Figure 1A, a shutter 410, a flip mirror or other movable element, or an electrically controlled element such as an electrochromic light switch that can be made opaque by the application of current or voltage, or a beam splitter 408 which may be a polarizing element (e.g., a polarizer P1) and a polarizing beam splitter, and a pump arm 420 as described with reference to Figures 4 to 8.

[0104] In block 1006, the optical measuring device can receive at least a portion of a pulsed light beam in a probe arm and irradiate a target sample with one or more polarized probe pulses to generate a reflected probe pulse having a polarization state influenced by the magnetic properties of the target sample, which is modulated based on transient perturbations in the target material when a pump arm is selected, for example, as shown by the probe arm 130 that generates the probe beam 131 in Figure 1A or the probe arm 430 in Figures 4 to 8. The means of receiving at least a portion of a pulsed light beam in a probe arm and irradiating a target sample with one or more polarized probe pulses to generate a reflected probe pulse having a polarization state influenced by the magnetic properties of the target sample, which is modulated based on transient perturbations in the target material when a pump arm is selected, may include the probe arm 130 in Figure 1A or the probe arm 430 in Figures 4 to 8.

[0105] In block 1008, the optical measuring device detects reflected probe pulses from a target sample using one or more detectors, as shown, for example, by a detector arm 140 having detectors 144 and / or 146 in Figure 1A, or by a detector arm 440 having a first detector 444 and a second detector 446 in Figures 4 to 8. Means for detecting reflected probe pulses from a target sample may include detectors 144 and / or 146 in Figure 1A, or the first detector 444 and second detector 446 in Figures 4 to 8.

[0106] In block 1010, the optical measuring device determines at least one property, including the magnetic properties of the target sample, based on the reflected probe pulse and static MOKE measurement when the pump arm is not selected, and based on the reflected probe pulse and TR MOKE when the pump arm is selected, as described with reference to, for example, the controller 150 in Figure 1A or the controller 450 in Figures 4 to 8. The means for determining at least one property, including the magnetic properties of the target sample, based on the reflected probe pulse and static MOKE measurement when the pump arm is not selected, and based on the reflected probe pulse and TR MOKE when the pump arm is selected, may include the controller 150 in Figure 1A or the controller 450 in Figures 4 to 8.

[0107] In one implementation, the optical measuring device can determine at least one characteristic by determining at least one of the characteristics of magnetic stack deposition, annealing, or magnetization, or a combination thereof, based on static MOKE when the pump arm is not selected, and by determining at least one of the characteristics of magnetodynamics, magnetic switching, or individual bit control, or a combination thereof, based on TR MOKE when the pump arm is selected. Means for determining at least one of the characteristics of magnetic stack deposition, annealing, or magnetization, or a combination thereof, based on static MOKE when the pump arm is not selected, and for determining at least one of the characteristics of magnetodynamics, magnetic switching, or individual bit control, or a combination thereof, based on TR MOKE when the pump arm is selected, may include the controller 150 in Figure 1A or the controllers 450 in Figures 4 to 8.

[0108] In one implementation, the optical measuring device can select a pump arm by moving a movable element, as described with reference to, for example, the beam selection element 117 in Figure 1A or the shutter 410 in Figures 4 to 8. Means for moving the movable element to select a pump arm may include, for example, the beam selection element 117 and controller 150 in Figure 1A, or the shutter 410, flip mirror or other movable element and controller 450 in Figures 4 to 8.

[0109] In one implementation, the optical measuring device may generate a pulsed light beam using a pulsed light source, for example, by generating a pulsed light beam using a pulsed laser, as described with reference to the pulsed light source 110 in Figure 1A.

[0110] In one implementation, the optical measuring device can control the time delay between the irradiation of the target sample with each pump pulse and the irradiation of the target sample with the corresponding probe pulse having a variable delay operating with a pulsed light beam, as described with reference to, for example, the pump arm 120, delay stage 122, probe arm 130, and delay stage 132 in Figure 1A, or the pump arm 420, delay stage 422, probe arm 430, and delay stage 432 in Figures 4 to 8. Means for controlling the time delay between irradiating the target sample with each pump pulse and irradiating the target sample with the corresponding probe pulse having a variable delay operating with a pulsed light beam may include, for example, the delay stage 122 and / or delay stage 132 and controller 150 in Figure 1A, or the delay stage 422 and / or delay stage 432 and controller 450 in Figures 4 to 8. For example, the variable delay may be located within a selectable pump arm and may operate on a pulsed light beam within a selectable pump arm, as described with reference to, for example, the delay stage 122 in pump arm 120 in Figure 1A or the delay stage 422 in pump arm 420 in Figures 4 to 8.

[0111] In one implementation, the optical measuring device periodically phase-modulates one or more polarized probe pulses with a phase modulator in the probe arm to measure at least one characteristic, including the magnetic properties of the target sample, based on static MOKE, when a pump arm is not selected, for example, as described with reference to modulator 139 in the probe arm 130 of Figure 1A (which may be, for example, an EOM, AOM, PEM, or rotational compensator) or EOM 439 in the probe arm 430 of Figures 4 to 8. When a pump arm is selected, for example, as described with reference to modulator 126 in the pump arm 120 of Figure 1A (which may be, for example, an EOM, AOM, PEM, or chopper) or EOM 426 in the pump arm 420 of Figure 408, the optical measuring device may further periodically modulate the intensity of one or more pump pulses using amplitude modulators in a selectable pump arm to measure at least one characteristic, including the magnetic properties of the target sample, based on TR MOKE. When a pump arm is not selected, means for periodically phase-modulating one or more polarization probe pulses to measure at least one property, including the magnetic properties of a target sample, based on static MOKE, may include modulator 139 in Figure 1A (which may be, for example, an EOM, AOM, PEM, or rotational compensator) or EOM 439 in Figures 4 to 8. When a pump arm is selected, means for periodically modulating the intensity of one or more pump pulses to measure at least one property, including the magnetic properties of a target sample, based on TR MOKE, may include modulator 126 in Figure 1A (which may be, for example, an EOM, AOM, PEM, or rotational compensator) or EOM 426 in Figure 408.

[0112] For example, an amplitude modulator in a selectable pump arm can modulate the intensity of one or more pump pulses to perform photoacoustic measurements of a target sample, as described in Figures 1A and 4-8. A phase modulator in a probe arm can, for example, modulate the intensity of one or more probe pulses to perform photoacoustic measurements of a target sample, as described in Figures 1A and 4-8.

[0113] As an example, the optical measuring device can perform polarization analysis measurements of a target sample by phase-modulating one or more polarization probe pulses using a phase modulator in a probe arm, or by intensity-modulating one or more pump pulses using an amplitude modulator in a selectable pump arm, as described in Figures 1A and 4-8. For example, the pump arm may be selectable to generate transient perturbations in the target material when the pump arm is selected, and not irradiate the target sample when the pump arm is not selected, the pump arm may be selected for time-resolved MOKE measurement or time-resolved polarization analysis measurement, the pump arm may not be selected, and the phase modulator periodically phase-modulates one or more probe pulses for polarization analysis measurement, as described in Figures 1A and 4-8. In some implementations, the optical measuring device can periodically modulate the intensity of one or more pump pulses using an amplitude modulator in a pump arm for time-resolved MOKE measurement or time-resolved polarization analysis measurement, as described in Figures 1A and 4-8. In some implementations, one or more detectors may include a first detector for detecting the P-state polarization of the reflected probe pulse and a second detector for detecting the S-state polarization of the reflected probe pulse, and both the first and second detectors may be used for time-resolved MOKE measurements, as illustrated in Figures 1A and 4-8, while only one of the first or second detectors may be used for polarization analysis measurements. For example, the optical measuring instrument may demodulate the signals from the first and second detectors generated based on the reflected probe pulses received from the target sample using a lock-in amplifier coupled to the first and second detectors, as illustrated with reference to the lock-in amplifier 148 in Figure 1A or the lock-in amplifier 448 in Figures 4-8. The means for demodulating the signals from the first and second detectors generated based on the reflected probe pulses received from the target sample may include the lock-in amplifier 148 in Figure 1A or the lock-in amplifier 448 in Figures 4-8.

[0114] In one implementation, the optical measuring device can irradiate a target sample with one or more pump pulses in a perpendicular incidence manner using a first set of optical elements such as the pump arm 120 in Figure 1A or the pump arm 420 and lens L1 in Figures 4 to 8. In another implementation, the optical measuring device can irradiate a target sample with one or more pump pulses at a non-perpendicular incidence angle, for example, between a perpendicular incidence angle and an incidence angle of 70°. The optical measuring device may irradiate a target sample with one or more probe pulses in an oblique incidence manner using a second set of optical elements such as the probe arm 130 in Figure 1A or the probe arm 430 and lens L2 in Figures 4 to 8. Means for irradiating a target sample with one or more pump pulses in a perpendicular incidence manner may include the lens L1 in Figures 4 to 8. Means for irradiating a target sample with one or more pump pulses in a non-perpendicular incidence angle may include the lens L1 in Figures 4 to 8. Means for irradiating a target sample with one or more probe pulses in an oblique incidence manner may include the lens L2 in Figures 4 to 8.

[0115] Figure 11 is a flowchart 1100 illustrating how to operate an optical measuring device, such as an optical measuring device 100 or 400, for performing optical measuring measurements on a target sample, as described herein. For example, the operation may involve measuring at least one property, including the magnetic properties, of the target sample using at least one of time-resolved magneto-optical Kerr effect (MOKE) measurements, photoacoustic measurements, or a combination thereof.

[0116] In block 1102, the optical measuring device generates a pulsed light beam using a pulsed light source, for example, a pulsed light source 110 that generates the pulsed light beam 111 shown in Figure 1A, or as shown by the light source 402, intensity control 403, beam expander 404, and chopper 406 shown in Figures 4 to 8. Means for generating a pulsed light beam may include, for example, the pulsed light source 110 shown in Figure 1A, or the light source 402, intensity control 403, beam expander 404, and chopper 406 shown in Figures 4 to 8.

[0117] In block 1104, the optical measuring device receives at least a portion of the pulsed light beam in a pump arm, as shown by, for example, a pump arm 120 that generates the pump beam 121 shown in Figure 1A, or a pump arm 420 shown in Figures 4 to 8, and irradiates the target sample with one or more pump pulses to induce transient perturbations in the target material. Means for receiving at least a portion of the pulsed light beam in a pump arm and irradiating the target sample with one or more pump pulses to induce transient perturbations in the target material may include, for example, a beam selection element 117 (which may be a polarizer 117' and a beam splitter 115) and a pump arm 120 as shown in Figure 1A, or a shutter 410, a flip mirror or other movable element, or an electrically controlled element such as an electrochromic optical switch that can be made opaque by the application of current or voltage, or a beam splitter 408 which may be a polarizing element (e.g., a polarizer P1) and a polarizing beam splitter, and a pump arm 420, as well as a lens L1 as described with reference to Figures 4 to 8.

[0118] In block 1106, the optical measuring device can receive at least a portion of a pulsed light beam in a probe arm and generate reflected probe pulses by irradiating a target sample with one or more polarized probe pulses. The probe arm includes, for example, a probe arm 130 and a modulator 139 (which may be, for example, an EOM, AOM, PEM, or rotational compensator) that generate the probe beam 131 in Figure 1A, or a phase modulator configured to periodically phase-modulate one or more polarized probe pulses for time-resolved MOKE measurements and to not phase-modulate one or more pulses for photoacoustic measurements, as shown by the probe arm 430 and EOM 439 in Figures 4 to 8. A means for receiving at least a portion of a pulsed light beam in a probe arm equipped with a phase modulator configured to periodically phase-modulate one or more polarized probe pulses for time-resolved MOKE measurements and one or more pulses not to be phase-modulated for photoacoustic measurements, and irradiating a target sample with one or more polarized probe pulses to generate reflected probe pulses may include the probe arm 130 and modulator 139 (which may be, for example, an EOM, AOM, PEM, or rotational compensator) in Figure 1A, or the probe arm 430, EOM 439, and lens L2 in Figures 4 to 8.

[0119] In block 1108, the optical measuring device detects reflected probe pulses from a target sample using one or more detectors, as shown, for example, by a detector arm 140 having detectors 144 and / or 146 in Figure 1A, or by a detector arm 440 having a first detector 444 and a second detector 446 in Figures 4 to 8. Means for detecting reflected probe pulses from a target sample may include detectors 144 and / or 146 in Figure 1A, or the first detector 444 and second detector 446 in Figures 4 to 8.

[0120] In block 1110, the optical measuring device, for example, as described with reference to controller 150 in Figure 1A or controller 450 in Figures 4-8, determines the effect on the polarization state of the probe pulses based on the reflected probe pulses due to the magnetic properties of the target sample for time-resolved MOKE measurements when the phase modulator periodically phase-modulates one or more probe pulses, and determines the change in reflectivity of the probe beam as a function of the time delay between each pump pulse and probe pulse based on the reflected probe pulses for photoacoustic measurements when the phase modulator does not phase-modulate one or more pulses. The means for determining the effect on the polarization state of the probe pulses based on the reflected probe pulses due to the magnetic properties of the target sample for time-resolved MOKE measurements when the phase modulator periodically phase-modulates one or more probe pulses, and for determining the change in reflectivity of the probe beam as a function of the time delay between each pump pulse and probe pulse based on the reflected probe pulses for photoacoustic measurements when the phase modulator periodically phase-modulates one or more probe pulses, may include controller 150 in Figure 1A or controller 450 in Figures 4-8.

[0121] In one implementation, the optical measuring device can determine the effect on the polarization state of the probe pulse by, for example, determining at least one of the characteristics of magnetodynamics, magnetic switching, or individual bit control, or a combination thereof, for time-resolved MOKE measurements when the phase modulator periodically phase-modulates one or more pulses, or by determining the change in reflectivity of the probe beam as a function of the time delay between each pump pulse and probe pulse, or by determining at least one of the lower electrode thickness measurement or metal layer thickness magnetic random access memory (MRAM), or a combination thereof, when the phase modulator does not phase-modulate one or more pulses, for photoacoustic measurements. When the phase modulator periodically phase-modulates one or more probe pulses, the means for determining at least one of the characteristics of magnetodynamics, magnetic switching, or individual bit control, or a combination thereof, for time-resolved MOKE measurements may include the controller 150 in Figure 1A or the controller 450 in Figures 4 to 8. If the phase modulator does not phase modulate one or more pulses, means for determining at least one of the following for photoacoustic measurement: measuring the thickness of the lower electrode, or the thickness of the metal layer magnetic random access memory (MRAM), or a combination thereof, may include the controller 150 in Figure 1A or the controllers 450 in Figures 4 to 8.

[0122] In one implementation, the optical measuring device can select a pump arm to cause transient perturbations in the target material, or deselect a pump arm so that the target sample is not irradiated with one or more pump pulses, the pump arm can be selected for time-resolved MOKE measurement or photoacoustic measurement, the pump arm can be deselected and a phase modulator periodically phase-modulates one or more probe pulses for static MOKE measurement, and at least one processor is configured to measure the magnetic properties of the target sample based on static MOKE when the pump arm is deselected and a phase modulator periodically phase-modulates one or more probe pulses, as described with reference to, for example, the beam selection element 117 and pump arm 120 and controller 150 in Figure 1A, or the shutter 410 and pump arm 420 and controller 450 in Figures 4 to 8. A means for selecting a pump arm to cause transient perturbations in a target material, and for not selecting a pump arm so that the target sample is not irradiated with one or more pump pulses, wherein when a pump arm is selected for time-resolved MOKE measurement or photoacoustic measurement, and when a pump arm is not selected and a phase modulator periodically phase-modulates one or more probe pulses for static MOKE measurement, at least one processor is configured to measure the magnetic properties of the target sample based on static MOKE, which may be the beam selection element 117 and pump arm 120 and controller 150 in Figure 1A, or the shutter 410 and pump arm 420 and controller 450 in Figures 4 to 8.

[0123] In one implementation, the optical measuring device can select a pump arm by moving a movable element, as described with reference to, for example, the beam selection element 117 in Figure 1A or the shutter 410 in Figures 4 to 8. Means for moving the movable element to select a pump arm may include, for example, the beam selection element 117 and controller 150 in Figure 1A, or the shutter 410, flip mirror or other movable element and controller 450 in Figures 4 to 8.

[0124] In one implementation, the optical measuring device periodically modulates the intensity of one or more pump pulses using an amplitude modulator in the pump arm for time-resolved MOKE measurement or photoacoustic measurement, as described with reference to, for example, the modulator 126 in the pump arm 120 in Figure 1A (which may be, for example, an EOM, AOM, PEM, or chopper) or the EOM 426 in the pump arm 420 in Figure 408. Means for periodically modulating the intensity of one or more pump pulses using an amplitude modulator in the pump arm for time-resolved MOKE measurement or photoacoustic measurement may include the modulator 126 in Figure 1A (which may be, for example, an EOM, AOM, PEM, or chopper) or the EOM 426 in Figure 408.

[0125] In one implementation, the optical measuring device can periodically modulate the intensity of one or more polarization probe pulses using an amplitude modulator for photoacoustic measurement, as described in Figures 1A and 4-8. The means for periodically modulating the intensity of one or more polarization probe pulses for photoacoustic measurement may include the modulator 139 in Figure 1A (which may be, for example, an EOM, AOM, PEM, or chopper) or the EOM 439 in Figures 4-8.

[0126] In one implementation, the optical measuring device may generate a pulsed light beam using a pulsed light source, for example, by generating a pulsed light beam using a pulsed laser, as described with reference to the pulsed light source 110 in Figure 1A.

[0127] In one implementation, the optical measuring device can control the time delay between the irradiation of the target sample with each pump pulse and the irradiation of the target sample with the corresponding probe pulse having a variable delay operating with a pulsed light beam, as described with reference to, for example, the pump arm 120, delay stage 122, probe arm 130, and delay stage 132 in Figure 1A, or the pump arm 420, delay stage 422, probe arm 430, and delay stage 432 in Figures 4 to 8. Means for controlling the time delay between irradiating the target sample with each pump pulse and irradiating the target sample with the corresponding probe pulse having a variable delay operating with a pulsed light beam may include, for example, the delay stage 122 and / or delay stage 132 and controller 150 in Figure 1A, or the delay stage 422 and / or delay stage 432 and controller 450 in Figures 4 to 8. For example, the variable delay may be located within a selectable pump arm and may operate on a pulsed light beam within a selectable pump arm, as described with reference to, for example, the delay stage 122 in pump arm 120 in Figure 1A or the delay stage 422 in pump arm 420 in Figures 4 to 8.

[0128] In one implementation, the optical measuring device can irradiate a target sample with one or more pump pulses at a perpendicular incidence using a first set of optical elements, such as the pump arm 120 in Figure 1A or the pump arm 420 and lens L1 in Figures 4 to 8. In another implementation, the optical measuring device can irradiate a target sample with one or more pump pulses at a non-perpendicular incidence angle, for example, between a perpendicular incidence angle and an incidence angle of 70°. The optical measuring device may also irradiate a target sample with one or more probe pulses at an oblique incidence using a second set of optical elements, such as the probe arm 130 in Figure 1A or the probe arm 430 and lens L2 in Figures 4 to 8. Means for irradiating a target sample with one or more pump pulses at a perpendicular incidence may include the lens L1 in Figures 4 to 8. Means for irradiating a target sample with one or more pump pulses at a non-perpendicular incidence angle Za may include the lens L1 in Figures 4 to 8. Means for irradiating a target sample with one or more probe pulses at an oblique incidence may include the lens L2 in Figures 4 to 8.

[0129] As an example, the optical measuring device can perform polarization analysis measurements of a target sample by phase-modulating one or more polarization probe pulses using a phase modulator in the probe arm, as described in Figures 1A and 4-8. For example, the pump arm may be selectable to generate transient perturbations in the target material when the pump arm is selected, and not irradiate the target sample when the pump arm is not selected. The pump arm may be selected for time-resolved MOKE measurement or time-resolved polarization analysis measurement, or the pump arm may not be selected, and the phase modulator periodically phase-modulates one or more probe pulses for polarization analysis measurement, as described in Figures 1A and 4-8. In some implementations, the optical measuring device can periodically modulate the intensity of one or more pump pulses using an amplitude modulator in the pump arm for time-resolved MOKE measurement or time-resolved polarization analysis measurement, as described in Figures 1A and 4-8. In some implementations, one or more detectors may include a first detector for detecting the P-state polarization of the reflected probe pulse and a second detector for detecting the S-state polarization of the reflected probe pulse, and both the first and second detectors may be used for time-resolved MOKE measurements, as illustrated in Figures 1A and 4-8, while only one of the first or second detectors may be used for polarization analysis measurements. For example, the optical measuring instrument may demodulate the signals from the first and second detectors generated based on the reflected probe pulses received from the target sample using a lock-in amplifier coupled to the first and second detectors, as illustrated with reference to the lock-in amplifier 148 in Figure 1A or the lock-in amplifier 448 in Figures 4-8. The means for demodulating the signals from the first and second detectors generated based on the reflected probe pulses received from the target sample may include the lock-in amplifier 148 in Figure 1A or the lock-in amplifier 448 in Figures 4-8.

[0130] Figure 12 is a flowchart 1200 illustrating how to operate an optical measuring device, such as an optical measuring device 100 or 400, for performing optical measuring measurements on a target sample, as described herein. For example, the operation may involve measuring at least one property, including the magnetic properties, of the target sample using at least one of time-resolved magneto-optical Kerr effect (MOKE) measurements, polarization analysis measurements, or a combination thereof.

[0131] In block 1202, the optical measuring device generates a pulsed light beam using a pulsed light source, for example, a pulsed light source 110 that generates the pulsed light beam 111 shown in Figure 1A, or a light source 402, intensity control 403, beam expander 404, and chopper 406 shown in Figures 4 to 8. Means for generating a pulsed light beam may include, for example, the pulsed light source 110 shown in Figure 1A, or the light source 402, intensity control 403, beam expander 404, and chopper 406 shown in Figures 4 to 8.

[0132] In block 1204, the optical measuring device receives at least a portion of the pulsed light beam and selects a pump arm to irradiate the target sample with one or more pump pulses to cause transient perturbations in the target material, as shown by, for example, the beam selection element 117 and pump arm 120 that generate the pump beam 121 shown in Figure 1A, or the shutter 410 and pump arm 420 shown in Figures 4 to 8, or does not select a pump arm so that the target sample is not irradiated with one or more pump pulses. Means for receiving at least a portion of a pulsed light beam and selecting a pump arm to irradiate a target sample with one or more pump pulses to cause transient perturbations in the target material, or means for not selecting a pump arm so that the target sample is not irradiated with one or more pump pulses, may include, for example, a beam selection element 117 (which may be a polarizer 117' and a beam splitter 115) as shown in Figure 1A, a shutter 410, a flip mirror or other movable element, or an electrically controlled element such as an electrochromic light switch that can be made opaque by the application of current or voltage, or a beam splitter 408 which may be a polarizing element (e.g., a polarizer P1) and a polarizing beam splitter, and a pump arm 420 as described with reference to Figures 4 to 8.

[0133] In block 1206, the optical measuring device can receive at least a portion of a pulsed light beam in a probe arm and generate reflected probe pulses by irradiating a target sample with one or more polarized probe pulses, the probe arm comprising, for example, a probe arm 130 and modulator 139 (which may be, for example, an EOM, AOM, PEM, or rotational compensator) that generates the probe beam 131 in Figure 1A, or a phase modulator configured to periodically phase-modulate one or more polarized probe pulses, as shown by the probe arm 430 and modulator 439 in Figures 4 to 8. The means for receiving at least a portion of a pulsed light beam in a probe arm and generating reflected probe pulses by irradiating a target sample with one or more polarized probe pulses, wherein the probe arm comprises a phase modulator configured to periodically phase-modulate one or more polarized probe pulses, may include the probe arm 130 and modulator 139 in Figure 1A (which may be, for example, an EOM, AOM, PEM, or rotational compensator), or the probe arm 430 and EOM 439 in Figures 4 to 8.

[0134] In block 1208, the optical measuring device detects reflected probe pulses from a target sample using one or more detectors, as shown, for example, by a detector arm 140 having detectors 144 and / or 146 in Figure 1A, or by a detector arm 440 having a first detector 444 and a second detector 446 in Figures 4-8. Means for detecting reflected probe pulses from a target sample may include detectors 144 and / or 146 in Figure 1A, or the first detector 444 and second detector 446 in Figures 4-8.

[0135] In block 1210, the optical measuring device, as described with reference to, for example, the controller 150 in Figure 1A or the controller 450 in Figures 4 to 8, determines the effect of the probe pulse on the polarization state of the probe pulse based on the reflected probe pulse due to the magnetic properties of the target sample for time-resolved MOKE measurement when the pump arm is selected, and determines the effect of the probe pulse on the polarization state of the probe pulse based on the reflected probe pulse due to the non-magnetic properties of the target sample for polarization analysis measurement when the pump arm is not selected. Means for determining the effect of the probe pulse on the polarization state of the probe pulse based on the reflected probe pulse due to the magnetic properties of the target sample for time-resolved MOKE measurement when the pump arm is selected, and for determining the effect of the probe pulse on the polarization state of the probe pulse based on the reflected probe pulse due to the non-magnetic properties of the target sample for polarization analysis measurement when the pump arm is not selected, may include the controller 150 in Figure 1A or the controller 450 in Figures 4 to 8.

[0136] In one implementation, the optical measuring device can determine the effect on the polarization state of the probe pulse by determining at least one of the characteristics of magnetodynamics, magnetic switching, or individual bit control, or a combination thereof, for time-resolved MOKE measurement when a pump arm is selected, or by determining at least one of the thickness measurement of the lower electrode or metal layer thickness magnetic random access memory (MRAM), or a combination thereof, for polarization analysis measurement when a pump arm is not selected. The means for determining at least one of the characteristics of magnetodynamics, magnetic switching, or individual bit control, or a combination thereof, for time-resolved MOKE measurement when a pump arm is selected, or the means for determining at least one of the thickness measurement of the lower electrode or metal layer thickness magnetic random access memory (MRAM), or a combination thereof, for polarization analysis measurement when a pump arm is not selected, may include the controller 150 in Figure 1A or the controller 450 in Figures 4 to 8.

[0137] In one implementation, the optical measuring device may periodically modulate the intensity of one or more pump pulses for time-resolved MOKE measurement using an amplitude modulator, as described with reference to the modulator 126 in the pump arm 120 of Figure 1A (which may be, for example, an EOM, AOM, PEM, or chopper) or the EOM 426 in the pump arm 420 of Figure 408. Means for periodically modulating the intensity of one or more pump pulses for time-resolved MOKE measurement may include the modulator 126 in Figure 1A (which may be, for example, an EOM, AOM, PEM, or chopper) or the EOM 426 in Figure 408.

[0138] In one implementation configuration, when the pump arm is selected as described in Figures 1A and 4-8, the optical measuring device can determine the time-resolved effect on the polarization state of the probe pulse due to the non-magnetic properties of the target sample for time-resolved polarization analysis measurement. When the pump arm is selected, the means for determining the time-resolved effect on the polarization state of the probe pulse due to the non-magnetic properties of the target sample for time-resolved polarization analysis measurement may include the controller 150 in Figure 1A or the controller 450 in Figures 4-8.

[0139] In one implementation, the phase modulator in the probe arm may be configured not to phase modulate one or more pulses for photoacoustic measurement, and the optical measuring device can determine the change in reflectivity of the probe beam as a function of the time delay between each pump pulse and probe pulse for photoacoustic measurement when the phase modulator does not phase modulate one or more pulses, as described in Figures 1A and 4 to 8. When the phase modulator does not phase modulate one or more pulses, means for determining the change in reflectivity of the probe beam as a function of the time delay between each pump pulse and probe pulse for photoacoustic measurement may include the controller 150 in Figure 1A or the controller 450 in Figures 4 to 8.

[0140] In some implementations, one or more detectors may include a first detector for detecting the P-state polarization of the reflected probe pulse and a second detector for detecting the S-state polarization of the reflected probe pulse, as illustrated in Figures 1A and 4-8, where both the first and second detectors are used for time-resolved MOKE measurements, and only one of the first or second detectors is used for photoacoustic and polarization analysis measurements. For example, the optical measuring device can demodulate the signals from the first and second detectors generated based on the reflected probe pulses received from the target sample using a lock-in amplifier coupled to the first and second detectors, as illustrated with reference to the lock-in amplifier 148 in Figure 1A or the lock-in amplifier 448 in Figures 4-8. The means for demodulating the signals from the first and second detectors generated based on the reflected probe pulses received from the target sample may include the lock-in amplifier 148 in Figure 1A or the lock-in amplifier 448 in Figures 4-8.

[0141] In one implementation, the optical measuring device does not select the pump arm so that the target sample is not irradiated by one or more pump pulses, and can periodically phase-modulate one or more probe pulses using a phase modulator for static MOKE measurement. When the pump arm is not selected and the phase modulator periodically phase-modulates one or more probe pulses, as described with reference to, for example, the beam selection element 117 and pump arm 120 and controller 150 in Figure 1A, or the shutter 410 and pump arm 420 and controller 450 in Figures 4 to 8, the optical measuring device can determine the magnetic properties of the target sample based on static MOKE. Means for not selecting the pump arm so that the target sample is not irradiated by one or more pump pulses may be the beam selection element 117 and controller 150 in Figure 1A, or the shutter 410 and controller 450 in Figures 4 to 8. Means for periodically phase-modulating one or more probe pulses for static MOKE measurement may include the modulator 139 in Figure 1A (which may be, for example, an EOM, AOM, PEM, or rotational compensator) or the EOM 439 in Figures 4-8. Means for determining the magnetic properties of a target sample based on static MOKE when the pump arm is not selected and the phase modulator periodically phase-modulates one or more probe pulses may include the controller 150 in Figure 1A or the controller 450 in Figures 4-8.

[0142] In one implementation, the optical measuring device can select a pump arm by moving a movable element, as described with reference to, for example, the beam selection element 117 in Figure 1A or the shutter 410 in Figures 4 to 8. Means for moving the movable element to select a pump arm may include, for example, the beam selection element 117 and controller 150 in Figure 1A, or the shutter 410, flip mirror or other movable element and controller 450 in Figures 4 to 8.

[0143] In one implementation, the optical measuring device may generate a pulsed light beam using a pulsed light source, for example, by generating a pulsed light beam using a pulsed laser, as described with reference to the pulsed light source 110 in Figure 1A.

[0144] In one implementation, the optical measuring device can control the time delay between the irradiation of the target sample with each pump pulse and the irradiation of the target sample with the corresponding probe pulse having a variable delay operating with a pulsed light beam, as described with reference to, for example, the pump arm 120, delay stage 122, probe arm 130, and delay stage 132 in Figure 1A, or the pump arm 420, delay stage 422, probe arm 430, and delay stage 432 in Figures 4 to 8. Means for controlling the time delay between irradiating the target sample with each pump pulse and irradiating the target sample with the corresponding probe pulse having a variable delay operating with a pulsed light beam may include, for example, the delay stage 122 and / or delay stage 132 and controller 150 in Figure 1A, or the delay stage 422 and / or delay stage 432 and controller 450 in Figures 4 to 8. For example, the variable delay may be located within the pump arm and operate in a pulsed light beam within a selectable pump arm, as described with reference to, for example, the delay stage 122 in the pump arm 120 in Figure 1A or the delay stage 422 in the pump arm 420 in Figures 4 to 8.

[0145] In one implementation, the optical measuring device can irradiate a target sample with one or more pump pulses in a perpendicular incidence manner using a first set of optical elements such as the pump arm 120 in Figure 1A or the pump arm 420 and lens L1 in Figures 4 to 8. In another implementation, the optical measuring device can irradiate a target sample with one or more pump pulses at a non-perpendicular incidence angle, for example, between a perpendicular incidence angle and an incidence angle of 70°. The optical measuring device may irradiate a target sample with one or more probe pulses in an oblique incidence manner using a second set of optical elements such as the probe arm 130 in Figure 1A or the probe arm 430 and lens L2 in Figures 4 to 8. Means for irradiating a target sample with one or more pump pulses in a perpendicular incidence manner may include the lens L1 in Figures 4 to 8. Means for irradiating a target sample with one or more pump pulses in a non-perpendicular incidence angle may include the lens L1 in Figures 4 to 8. Means for irradiating a target sample with one or more probe pulses in an oblique incidence manner may include the lens L2 in Figures 4 to 8.

[0146] While the present invention is illustrated in relation to specific embodiments for illustrative purposes, it is not limited thereto. Various adaptations and modifications may be made without departing from the scope of the invention. Accordingly, the spirit and scope of the appended claims should not be limited to the foregoing description.

Claims

1. An apparatus for measuring at least one property, including the magnetic properties, of a target sample using at least one of time-resolved magneto-optical Kerr effect (MOKE) measurement, polarization analysis measurement, or a combination thereof, A pulsed light source for generating a pulsed light beam, A selectable pump arm, configured to receive at least a portion of the pulsed light beam to cause transient perturbations in the target sample when the pump arm is selected, and to irradiate the target sample with one or more pump pulses, and not irradiate the target sample when the pump arm is not selected, A probe arm configured to receive at least a portion of the pulsed light beam and to generate a reflected probe pulse by irradiating the target sample with one or more polarizing probe pulses, the probe arm comprising a phase modulator configured to periodically phase modulate the one or more polarizing probe pulses, One or more detectors for receiving probe pulses reflected from the target sample, Apparatus comprising: at least one processor coupled to one or more detectors, configured to measure the effect of the magnetic properties of the target sample on the polarization state of the probe pulse for the time-resolved MOKE measurement when the pump arm is selected, and to measure the effect of the non-magnetic properties of the target sample on the polarization state of the probe pulse for the polarization analysis measurement when the pump arm is not selected.

2. The apparatus according to claim 1, wherein the at least one processor is configured to, when the pump arm is selected, measure at least one of the characteristics of magnetodynamics, magnetic switching, or the control of individual bits, or a combination thereof, for the time-resolved MOKE measurement, or, when the pump arm is not selected, measure the thickness of at least one of the lower electrodes or metal layers of the magnetic random access memory (MRAM), or a combination thereof, for the polarization analysis measurement.

3. The apparatus according to claim 1, wherein the pump arm comprises an amplitude modulator that periodically modulates the intensity of one or more pump pulses for the time-resolved MOKE measurement, and the at least one processor is further configured, when the pump arm is selected, to measure the time-resolved effect on the polarization state of the probe pulse due to the non-magnetic properties of the target sample for time-resolved polarization analysis measurement.

4. The apparatus according to claim 1, wherein the pump arm comprises an amplitude modulator that periodically modulates the intensity of one or more pump pulses for the time-resolved MOKE measurement, the phase modulator in the probe arm is configured not to phase modulate the one or more pulses for photoacoustic measurement, and the at least one processor is further configured to measure the change in reflectivity of a probe beam as a function of the time delay between each pump pulse and a probe pulse for photoacoustic measurement when the phase modulator does not phase modulate the one or more pulses.

5. The apparatus according to claim 1, wherein the pump arm is not selected, the phase modulator periodically phase modulates one or more probe pulses for static moke measurement, and at least one processor is configured to measure the magnetic properties of the target sample based on static moke when the pump arm is not selected and the phase modulator periodically phase modulates one or more probe pulses.

6. The apparatus according to claim 1, further comprising a movable element for selecting the pump arm.

7. The apparatus according to claim 1, wherein the pulsed light source for generating the pulsed light beam comprises a pulsed laser.

8. The apparatus according to claim 1, further comprising a variable delay that operates with the pulsed light beam and controls the time delay between the irradiation of the target sample by each pump pulse and the irradiation of the target sample by the corresponding probe pulse.

9. A method for measuring at least one property of a target sample, including the magnetic properties, using at least one of time-resolved magneto-optical Kerr effect (MOKE) measurement, polarization analysis measurement, or a combination thereof, wherein the method is: Generating a pulsed light beam using a pulsed light source, Selecting a pump arm to receive at least a portion of the pulsed light beam and irradiate the target sample with one or more pump pulses to cause transient perturbations in the target sample, or not selecting a pump arm so that the target sample is not irradiated with one or more pump pulses, The method involves receiving at least a portion of the pulsed light beam within a probe arm and irradiating the target sample with one or more polarized probe pulses to generate reflected probe pulses, wherein the probe arm includes a phase modulator configured to periodically phase-modulate the one or more polarized probe pulses. The probe pulse reflected from the target sample is detected by one or more detectors, A method comprising: if the pump arm is selected, determining the effect of the probe pulse on the polarization state based on the reflected probe pulse due to the magnetic properties of the target sample for the time-resolved MOKE measurement; and if the pump arm is not selected, determining the effect of the probe pulse on the polarization state based on the reflected probe pulse due to the non-magnetic properties of the target sample for the polarization analysis measurement.

10. The method according to claim 9, wherein determining the effect of the probe pulse on the polarization state includes, if the pump arm is selected, determining at least one of the characteristics of magnetodynamics, magnetic switching, or individual bit control, or a combination thereof, for the time-resolved MOKE measurement, or, if the pump arm is not selected, determining at least one of the thicknesses of the lower electrode or metal layer of the magnetic random access memory (MRAM), or a combination thereof, for the polarization analysis measurement.

11. The method according to claim 9, further comprising periodically modulating the intensity of one or more pump pulses for time-resolved MOKE measurement using an amplitude modulator in the pump arm, and if the pump arm is selected, further comprising determining the time-resolved effect on the polarization state of the probe pulses due to the non-magnetic properties of the target sample for time-resolved polarization analysis measurement.

12. The method according to claim 9, further comprising periodically modulating the intensity of one or more pump pulses for the time-resolved MOKE measurement using an amplitude modulator in the pump arm, wherein the phase modulator in the probe arm is configured not to phase modulate the one or more pulses for the photoacoustic measurement, and if the phase modulator does not phase modulate the one or more pulses, further comprising determining the change in reflectivity of the probe beam as a function of the time delay between each pump pulse and probe pulse for the photoacoustic measurement.

13. The method according to claim 9, further comprising: not selecting the pump arm so that the target sample is not irradiated by the one or more pump pulses; periodically phase-modulating the one or more probe pulses using the phase modulator for static MOKE measurement; and, when the pump arm is not selected and the phase modulator periodically phase-modulates the one or more probe pulses, determining the magnetic properties of the target sample based on static MOKE.

14. The method according to claim 9, further comprising moving a movable element to select the pump arm.

15. The method according to claim 9, wherein generating the pulsed light beam using the pulsed light source includes generating the pulsed light beam using a pulsed laser.

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