SYSTEM AND METHOD FOR PERFORMING CHARACTERIZATION OF A SAMPLE - Patent application

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] FIELD OF THE DISCLOSURE Embodiments of the subject matter described herein relate generally to non-destructive measurement of a sample, and more particularly to characterization of a sample using optical metrology. [Background technology]

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

[0003] There are many different techniques for measuring the properties of a sample, for example a semiconductor. One such technique relies on the magneto-optical Kerr effect (MOKE), where the change in polarization of polarized incident light due to a magnetic field from the sample is measured from the reflected light. For example, the change in polarization due to MOKE can be useful to monitor the electrical and magnetic properties of a sample. Another technique is ellipsometry, where the change in polarization of polarized incident light due to the sample material and geometry is measured from the reflected light. The change in polarization is then related to the properties of the sample. Another technique is photoacoustic metrology, where an acoustic wave generated in a pump beam reflects a portion of a probe beam, and this portion of the probe beam interferes with another portion of the reflected probe beam from a surface interface. Interferometric measurements generated using photoacoustic metrology can provide information about the properties of the sample.

[0004] Optical metrology techniques such as MOKE, ellipsometry, and photoacoustic metrology are useful for analyzing samples, but optical metrology instruments that use such techniques can be improved. Summary of the Invention

[0005] 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) measurements when the pump arm is not selected and time-resolved (TR) MOKE measurements when the pump arm is selected. The optical metrology device may similarly perform ellipsometry measurements when the pump arm is not selected and time-resolved (TR) 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.

[0006] In one implementation, an apparatus for measuring at least one property, including a magnetic property, of a target sample using at least one of a static magneto-optical Kerr effect (MOKE), a 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 a transient perturbation in 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 affected by the magnetic property of the target sample, which is modulated based on the transient perturbation in the target material when the pump arm is selected. One or more detectors may be configured to receive a reflected probe pulse from the target sample. At least one processor coupled to the one or more detectors may be configured to measure at least one property, including a magnetic property, of the target sample based on a static MOKE when the pump arm is not selected, and based on a TR MOKE when the pump arm is selected.

[0007] In one implementation, a method for measuring at least one property including a magnetic property 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 with a pulsed light source. The method can 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 cause a transient perturbation in the target material, or not selecting a pump arm such that the target sample is not irradiated with one or more pump pulses. The method can further include receiving at least a portion of the pulsed light beam at 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 affected by the magnetic property of the target sample, and modulated based on the transient perturbation in the target material when the pump arm is selected. The method can further include detecting the reflected probe pulse from the target sample with one or more detectors. The method may further include determining at least one property, including a magnetic property, of the target sample based on the reflected probe pulse and static MOKE measurements 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 a magnetic property, of a target sample using at least one of a static magneto-optical Kerr effect (MOKE), a time-resolved MOKE (TR MOKE), or a combination thereof includes a means for generating a pulsed light beam. The apparatus further includes a 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 a transient perturbation in the target material, or a means for not selecting a pump arm such that the target sample is not irradiated with one or more pump pulses. The apparatus further includes a 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 affected by the magnetic property of the target sample and modulated based on the transient perturbation in the target material when the pump arm is selected, and a means for detecting the reflected probe pulse from the target sample. The apparatus includes a means for determining at least one property, including a magnetic property, of the target sample based on the reflected probe pulse and a 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.

[0009] In one implementation, an apparatus for measuring at least one property including a magnetic property of a target sample using at least one of a time-resolved magneto-optical Kerr effect (MOKE) measurement, a photoacoustic measurement, 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 a transient perturbation in 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 a reflected probe pulse, the probe arm comprising a phase modulator configured to periodically phase modulate the one or more polarized probe pulses for the time-resolved MOKE measurement and configured to not phase modulate the one or more pulses for the photoacoustic measurement. One or more detectors may be configured to receive the reflected probe pulses from the target sample. At least one processor coupled to the one or more detectors may be configured to measure an effect on the polarization state of the probe pulse due to magnetic properties of the target sample for time-resolved MOKE measurements when the phase modulator periodically phase-modulates the one or more probe pulses, and to measure a change in reflectivity of the probe beam as a function of a time delay between each pump pulse and the probe pulse for photoacoustic measurements when the phase modulator does not phase-modulate the one or more pulses.

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

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

[0012] In one implementation, an apparatus for measuring at least one property including a magnetic property of a target sample using at least one of a time-resolved magneto-optical Kerr effect (MOKE) measurement, an ellipsometry 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 a transient perturbation in 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, the probe arm comprising a phase modulator configured to periodically phase modulate the one or more polarized probe pulses. The one or more detectors may be for receiving the reflected probe pulse from the target sample. At least one processor coupled to the one or more detectors may be configured to measure an effect on a polarization state of the probe pulse due to a magnetic property of the target sample for a time-resolved MOKE measurement when the pump arm is selected, and to measure an effect on a polarization state of the probe pulse due to a non-magnetic property of the target sample for an ellipsometry measurement when the pump arm is not selected.

[0013] In one implementation, a method for measuring at least one property including a magnetic property of a target sample using at least one of a time-resolved magneto-optical Kerr effect (MOKE) measurement, an ellipsometry measurement, or a combination thereof can include generating a pulsed light beam with a pulsed light source. The method can 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 cause a transient perturbation in the target material, and not selecting a pump arm such that the target sample is not irradiated with the one or more pump pulses. The method can 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 a reflected probe pulse, the probe arm comprising a phase modulator configured to periodically phase modulate the one or more polarized probe pulses. The method can include detecting the reflected probe pulse from the target sample with one or more detectors. The method may include determining an effect on the polarization state of the probe pulse based on a reflected probe pulse due to a magnetic property of the target sample for a time-resolved MOKE measurement when the pump arm is selected, and determining an effect on the polarization state of the probe pulse based on a reflected probe pulse due to a non-magnetic property of the target sample for an ellipsometry measurement when the pump arm is not selected.

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

[0015] [Figure 1A] FIG. 1 shows a schematic diagram of an optical metrology setup capable of using a variety of metrology techniques, including one or more of static MOKE measurements, time-resolved MOKE measurements, photoacoustic measurements, static ellipsometry measurements, dynamic time-resolved ellipsometry measurements, or any combination thereof. [Figure 1B] FIG. 1B shows a side view of a portion of a magnetic random access memory (MRAM) device, which is an example of a target sample that may be measured by the optical metrology apparatus of FIG. 1A. [Figure 2A] The MOKE geometry and Kerr rotation θk that occurs in the reflected light are shown. [Figure 2B] The geometry of the Kerr rotation θk and the ellipticity εk are shown. [Diagram 3]1 shows a graph illustrating the change in reflectance versus time delay in photoacoustic measurements. [Figure 4] 1B shows a more detailed schematic diagram of an optical metrology device in one implementation of the optical metrology device shown in FIG. 1A. [Diagram 5] FIG. 5 shows the optical metrology setup of FIG. 4 operated in static MOKE measurement mode. [Figure 6] The optical measurement setup of Figure 4 is shown operating in the TR MOKE measurement mode. [Figure 7] 5 shows the optical metrology setup of FIG. 4 operated in a static ellipsometry measurement mode. [Figure 8] FIG. 5 shows the optical metrology setup of FIG. 4 operated in TR ellipsometry measurement mode. [Figure 9] 5 shows the optical measurement apparatus of FIG. 4 operating in a photoacoustic measurement mode. [Figure 10] 1 is a flow chart illustrating a method for selectively performing MOKE and TR MOKE measurements. [Figure 11] 1 is a flow chart illustrating a method of operating an optical metrology device to perform optical metrology measurements on a target sample. [Figure 12] 1 is a flow chart illustrating a method of operating an optical metrology device to perform optical metrology measurements on a target sample. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] During the manufacture of semiconductors and similar devices, it may be necessary to monitor the manufacturing process by measuring the devices non-destructively. Optical metrology may be employed for non-contact evaluation of samples during processing. As an example, recent developments in magnetic random access memory (MRAM) technology have prompted the need for efficient metrology techniques for characterization of magnetic tunnel junctions (MTJs). Monitoring the electrical and magnetic properties of magnetic tunnel junctions (MTJs) is important for process control. One technique that may 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 an addition of rotation or ellipticity to the polarization direction. The behavior of an incident laser beam reflected from an MRAM stack changes as the applied magnetic field is changed. MOKE testing can determine the orientation, coercivity, and thermal stability of individual layers or combined stacks. Furthermore, if the magnetic layer cannot realign itself in response to a magnetic field, it also cannot be electronically switched. Thus, MOKE may be used to test the switching capabilities of a sample.

[0017] As described herein, an optical metrology instrument can use MOKE to test a sample using linearly polarized light that is periodically (at a frequency f) phase modulated. The reflected light intensity at the detector is determined by the dc component of the modulation frequency (I dc ), the fundamental 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 a measurement. Thus, as described herein, an optical metrology device may be configured to obtain multiple types of optical metrology measurements, including static MOKE measurements, time-resolved MOKE measurements, photoacoustic measurements, static ellipsometry measurements, dynamic time-resolved ellipsometry measurements, or any combination thereof.

[0019] For example, the optical metrology apparatus can be configured for multiple types of MOKE measurements, including static MOKE measurements as well as transient (e.g., sometimes referred to as "time-resolved (TR)") MOKE measurements. In some implementations, the optical metrology apparatus can be configured for TR MOKE measurements, e.g., with a resolution of about 20 fs, thereby enabling the study of spin dynamics in magnetic media samples. For example, the optical metrology apparatus can include a magnetic field generator at or near the sample, e.g., in a chuck that holds the sample, to generate a magnetic field while the sample, e.g., an MRAM wafer, is loaded and undergoing testing.

[0020] The optical metrology device may perform TR MOK measurements to study the interaction of ultrafast lasers with ferromagnetic metals. For example, the optical metrology device may induce magnetization dynamics using, for example, femtosecond pump laser pulses. The optical metrology device may optionally include a pulse shaper that varies 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-optical modulator (AOM), may vary the shape of the pump pulse, thereby enabling the study of the dependence of the magnetodynamics on the pump pulse characteristics. Furthermore, the optimal pulse shape that results in the desired control over the magnetodynamics in the sample under consideration may be adaptively determined using the pulse shaper.

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

[0022] In another example, the optical metrology instrument may be configured for ellipsometric measurements along with one or more types of MOKE and / or photoacoustic measurements. For example, an EOM (or other type of modulator, such as an AOM, PEM, or rotating compensator) may be configured to act as a phase modulator for ellipsometric measurements. The optical metrology instrument may be configured to perform, for example, static ellipsometric measurements and / or time-resolved ellipsometric measurements.

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

[0024] In some implementations, the optical metrology device can use optical geometries that modulate both the pump and probe beams individually, for example, the beam paths of the pump and probe beams can be physically separated such that the pump beam is incident on the sample normally and the probe beam is incident on the sample obliquely. The separation of the beam paths and the individual modulation of the pump and probe beams can be beneficial for signal-to-noise enhancement as well as allowing the ability to easily switch between different types of measurements.

[0025] In some implementations, the optical metrology device can be configured to operate at a single (narrowband) wavelength or at multiple (broadband) wavelengths. For example, the optical metrology device can include a supercontinuum generator in the probe beam to enable multi-wavelength measurements including MOKE, photoacoustic, and ellipsometric 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] FIG. 1A shows a schematic diagram of an optical metrology device 100 that can use various metrology techniques, including one or more of static MOKE measurements, time-resolved MOKE measurements, photoacoustic measurements, static ellipsometry measurements, dynamic time-resolved ellipsometry measurements, or any combination thereof. The optical metrology device 100 may be further configured to use a pulse shaper for the pulses in the pump beam and a supercontinuum generator to expand or select wavelengths for one or more types of metrology techniques. It should be understood that FIG. 1A shows a simplified diagram of the optical metrology device 100 and that additional optical components, such as lenses, polarizers, wave plates, etc., may be included.

[0027] The optical metrology 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 narrowband 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 may generate pulse widths ranging from hundreds of femtoseconds to hundreds of 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 the selectable pump arm 120. The beam selection element 117 may be disposed between the beam splitter 115 and the target sample 102 (e.g., before or in the pump arm 120) and is used to select or not select, i.e., exclude, the pump arm 120 during the measurement of the target sample 102. The beam selection element 117 may be a movable element such as a shutter or flip mirror, or may be fixed and electrically controlled such as an electrochromic light switch. In another implementation, the beam selection element 117 may be in front of the beam splitter 115, as shown by the dotted line. 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 the polarization state. The beam selection element 117 may be configured (e.g., by rotating a polarizer) to generate a polarization state in the pulsed light beam 111 such that the polarizing beam splitter 115 directs a portion of the pulsed light beam 111 to the probe arm 130 and another portion to the pump arm 120 (e.g., 50% to the probe arm 130 and 50% to the pump arm 120), or may be configured (e.g., by rotating a polarizer) to generate a polarization state in the pulsed light beam 111 such that the polarizing beam splitter 115 directs all of the pulsed light beam 111 to the probe arm 130 (e.g., 100% to the probe arm 130 and 0% to the pump arm 120). Other arrangements and types of beam selection element 117 may be used if desired.

[0029] The pump arm 120 may be selectable, for example using the selection element 117, for use during measurement of the target sample 102. Once selected, the pump arm 120 receives at least a portion of the pulsed light beam 111 and directs a pulsed pump beam 121 to the target sample 102. As shown in FIG. 1A, the pump beam 121 may be directed (e.g., focused) by one or more lenses (not shown) to be perpendicularly incident on the target sample 102, although non-perpendicular angles of incidence may be used if desired, including, for example, but not limited to, angles of incidence from normal to 70°. The pump beam 121 generated by the pump arm 120 when the pump arm 120 is selected irradiates the target sample 102 and induces a transient perturbation in the material of the target sample 102, and 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 can include a delay stage 122 to increase or decrease the length of the optical path between the pulsed light source 110 and the target sample 102 to control the delay of the pulses in the pump beam 121. The delay stage 122 can vary the optical path length, for example, 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 a 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 varies at least one of the duration, phase, or both of the pulses in the pulsed light beam to generate the pump beam 121. 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 an area of ​​interest due to the demand to control magnetization in devices in a faster and more efficient manner. Studying the interaction of ultrafast lasers with ferromagnetic metals may lead to greater advances in future magnetic data storage devices. The pump beam 121 may be configured to induce magnetization dynamics, for example, using femtosecond pump laser pulses. The optical metrology device 100 may be used to study optically induced magnetodynamics. Controlling the shape of the pulses of the pump beam 121 by varying 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 the target sample 102 on the pump pulse characteristics. Furthermore, adaptive algorithms can be used to define and use optimal pulse shapes for the pump beam 121 to provide the desired control over the magnetic dynamics within the target sample 102 under study.

[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 may modulate the amplitude (intensity) of a polarized probe pulse in the pump beam 121. The modulator 126 may be an electro-optical modulator (EOM), an acousto-optical modulator (AOM), a photoelastic modulator (PEM), or a rotating compensator that may modulate the amplitude (intensity) of the pump beam 121, which is advantageous because it allows for measurements with high sensitivity, low noise, and high speed.

[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. Additional optical elements may also be present in the pump arm 120. It should be understood that the illustration of the pump arm 120 in FIG. 1A is not intended to be limiting, but rather illustrates one of several exemplary configurations.

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

[0035] The probe arm 130 may include one or more polarizing elements 138 (e.g., polarizers and / or wave plates) for generating, for example, one or more polarization states and any phase shifts, which may be configurable, e.g., rotatable, to generate a desired polarization state in the probe beam 131. In some implementations, the probe arm 130 may include a delay stage 132 to increase or decrease the length of the optical path between the pulsed light source 110 and the target sample 102 to control the delay of the pulses in the probe beam 131.

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

[0037] The probe arm 130 may include, for example, one or more polarizing elements 138 (e.g., polarizers and / or wave plates) that generate one or more polarization states and any phase shifts, which may be configurable, e.g., rotatable, to generate a desired polarization state 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 may modulate the amplitude (intensity) of a polarized probe pulse in the probe beam 131. The modulator 139 may periodically phase modulate the polarized probe pulse in the probe beam 131. The modulator 139 may be an EOM, an AOM, a PEM, or a rotating compensator that may modulate the amplitude and / or phase of the probe beam 131. For example, the use of an EOM may be advantageous as it allows for measurements with high sensitivity, low noise, and high speed.

[0039] Many other alternative configurations of the probe arm 130 are possible. For example, the probe arm 130 may include only the polarizing element 138, the delay stage 132, the wavelength selector 133 (including one or more of the multi-wavelength generator 134 and the filter 136), the modulator 139, or any combination thereof. Further additional optical elements may be present in the probe arm 130. It should be understood that the illustration of the probe arm 130 in FIG. 1A is not intended to be limiting, but rather illustrates 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 polarizing elements 142 that can be used to analyze the polarization state of the reflected beam 141. The one or more polarizing elements 142 may be, for example, a polarizing beam splitter, a polarizer, etc. that 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 the reflected probe pulse in the reflected beam 141 from the target sample 102. When 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, the detector 144 can detect the P state polarization of the reflected probe pulse in the reflected beam 141, and the 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 the detectors 144 and / or 146 generated based on reflected probe pulses received in the reflected beam 141 from the target sample 102.

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

[0042] The pulsed light source 110, the pump arm 120, the probe arm 130, and the detector arm 140 are connected to and controlled by a controller 150. The controller 150 can further be connected to and control a stage 104 that includes an actuator for holding the target sample 102 and for 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 allow horizontal motion in either Cartesian (i.e., X and Y) or polar (i.e., R and θ) coordinates, or some combination of the two. The stage 104 may also be capable of vertical motion along a Z coordinate.

[0043] The optical metrology device 100 may further include a magnetic element 106, e.g., an electromagnet, which may be within the stage 104 or external to the stage 104, to apply a magnetic field to the target sample 102 during measurements. The application of the magnetic field may be controlled by a controller 150.

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

[0045] 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. It should be understood that controller 150 may include a single processor, multiple individual processors, or multiple linked processors that may be used together, all of which may be referred to interchangeably herein as controller 150, processor 150, at least one processor 150, or one or more processors 150. Controller 150 is preferably included in, connected to, or otherwise associated with optical metrology device 100.

[0046] The controller 150 may also control the operation of the optical metrology 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 metrology device 100 may be controlled by the controller 150 to use various metrology techniques. For example, the optical metrology device 100 may be configured by the controller 150 to perform static MOKE measurements or time-resolved (TR) MOKE measurements (sometimes referred to as transient MOKE measurements). In MOKE measurements, linearly polarized light becomes elliptically polarized upon reflection from 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 the multi-wavelength generator 134 and the filter 136) in the probe arm 130 may be used to select a particular wavelength used for the MOKE measurement and / or to use multiple wavelengths for the MOKE measurement, e.g., 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 either, and thus the measurements can be used to detect defective devices.

[0049] Figure 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 an incident plane. k Figure 2B shows the geometry of the Kerr rotation θ k and ellipticity ε k , which are related to each other by the relationship θ k + iε k = k / r in the limit of 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. Figure 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 EThe effect of the reflected light 206 on the magnetization M of the material in the sample 202 can be explained based on the interaction of the electric field E of the material in the sample 202 with the electric field of the light. For linearly polarized incident light 204, the electrons in the sample 202 oscillate along the electric field of the light. For example, for p-polarized light as shown in FIG. 2A, the electrons oscillate in the plane of incidence of the beam and also in the plane of the sample 202. The reflected light 206 undergoes a phase change of π with respect to the incident light 204. Thus, the direction of the electric field E in the reflected light 206 is opposite to that of the electric field E in the incident light 204. For the magnetization M of the material in the sample 202, the Lorentz force (F Lor ) generates an additional small vibration 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). FIG. 2A shows the vector sum of the reflected light 206, where the resulting electric field E of the reflected light 206 is driven by the magnetization M of the sample 202, k For s-polarized light, where the electric field E is perpendicular to the plane of incidence, a similar Kerr rotation is produced due to polar effects.

[0052] 1A may be used to perform static MOKE measurements, for example, using only the probe arm 130. For example, the controller 150 can cause the selection element 117 to not select the pump arm 120, i.e., to prevent the pump arm 120 from generating a pump beam 121 incident on the target sample 102. The polarizing element 138 in the probe arm 130 can be configured to generate one or more desired polarization states of a probe pulse in the probe beam 131.

[0053] A modulator 139 in the probe arm 130 operates at a frequency f probe The probe beam 131 can be phase modulated by the polarizing element 142 and the magnetization in the target sample 102 changes the polarization state of the incident light, as described above. In some implementations, the magnetic element 106 can be used to modify the magnetization of the target sample 102 during testing. The polarizing element 142 and one or more detectors 144 and 146 are used to detect the polarization state of the reflected beam 141 and to measure the Kerr rotation (θ kFor example, polarizing element 142 and one or more detectors 144 and 146 can be used to detect S and P polarizations. A lock-in amplifier 148 can couple signals from detectors 144 and 146 to, for example, a fundamental probe frequency and a second harmonic probe frequency, e.g., f probe , 2F probe , which can be used to demodulate the signal.

[0054] Thus, the optical metrology device 100 periodically (e.g., at a frequency f probe Static MOKE can be performed using linearly polarized light that is phase modulated at the modulation frequency (I dc ), fundamental wave component (f probe ) and the second harmonic component (2f probe The reflected signal has a contribution from the polarization rotation (Kerr rotation angle) θ k and ellipticity ε k DC, F probe and 2f probe The components are demodulated using a lock-in amplifier 148 for calculation.

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

number

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

number

[0057] Advantageously, the optical metrology apparatus 100 may also be used to perform TR MOKE measurements using a selectable pump arm 120 in conjunction with the probe arm 130. For example, the controller 150 may cause the selection element 117 to select the pump arm 120, i.e., 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 pulse can be amplitude (intensity) modulated using a modulator 126 at 100 .mu.m. The transient measurements can be performed with a resolution of, for example, about 20 fs due to the pulse duration and delay state resolution, which can be used, for example, to study spin dynamics in a magnetic medium within the target sample 102.

[0058] Additionally, a pulse shaper 124 in the pump arm 120 can be used to vary the pulse duration and / or phase of the incident pump beam 121 to determine the dependence of the magnetic dynamics in the target sample 102 on the pump pulse characteristics. Additionally, an adaptive algorithm can be used to define and use an optimal pulse shape of the pump beam 121 to provide the desired control over the magnetic dynamics in the target sample 102 under consideration.

[0059] A polarizing element 138 in the probe arm 130 can be configured to generate one or more desired polarization states of a probe pulse in the probe beam 131. A modulator 139 in the probe arm 130 is configured to modulate the polarizing element 138 at a frequency f probe The phase of the probe beam 131 can be modulated by the pump pulse. 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 the delay stage 122 in the pump arm 120 and / or the 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, the magnetic element 106 can be used to modify the magnetization of the target sample 102 during testing.

[0060] A polarizing element 142 and one or more detectors 144 and 146 are used to detect the polarization state of the reflected beam 141 and to calculate the Kerr rotation (θ k For example, polarizing element 142 and one or more detectors 144 and 146 can be used to detect S and P polarizations. A lock-in amplifier 148 can be used to, for example, modulate the pump and pump ±f probe , f pump ±2f probe , etc., may be used to demodulate the signals from the detectors 144 and 146 as a function of some combination of various harmonics of the probe frequency.

[0061] Thus, the optical metrology device 100 detects f via the modulator 126 in the pump arm 120. pump Also linearly polarized and periodically (e.g., at a frequency f probe TRMOKE can be performed using a probe light that is phase modulated with a 100 Hz frequency (I pump ), pump frequency (f pump ), and the fundamental of the probe modulation frequency (f probe ) and the second harmonic (2f probe The reflected signal is demodulated using a lock-in amplifier 148 to obtain the polarization rotation (Kerr rotation angle) θ k and ellipticity ε k is calculated, and Equation 3 is given as an example and not a limitation.

number

[0062] In some implementations, the optical metrology device 100 may be controlled by the controller 150 to perform ellipsometric measurements. In ellipsometric 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 metrology device 100 may measure at least a partial Mueller matrix, e.g., off-diagonal elements, and / or ellipsometric parameters, Ψ and Δ, by measuring the change in polarization state in the reflected beam 141. In some implementations, the change in polarization may be compared to a model or library to determine the properties of the target sample 102. For example, ellipsometry may be used to determine properties of the target sample 102, such as composition, roughness, thickness (depth), crystallinity, doping concentration, conductivity, etc. A wavelength selector 133 (including one or more of the multi-wavelength generator 134 and the filter 136) in the probe arm 130 may be used to select a particular wavelength used for the ellipsometric measurement and / or to use multiple wavelengths for the ellipsometric measurement, e.g., spectroscopic ellipsometry.

[0063] The optical metrology apparatus 100 may be used to perform static ellipsometry measurements, for example, using only the probe arm 130, e.g., by having the controller 150 not cause the selection element 117 to select the pump arm 120, i.e., the pump arm 120 does not generate a pump beam 121 that is incident on the target sample 102. The polarizing element 138 in the probe arm 130 may be configured to generate one or more desired polarization states of a probe pulse in the probe beam 131.

[0064] A modulator 139 in the probe arm 130 operates at a frequency f probeThe probe beam 131 can modulate the phase of the linearly polarized probe beam 131 with a polarizer. 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. The polarizing element 142 and one or more detectors 144 and 146 can be used to detect the polarization state of the reflected beam 141 and determine the ellipsometric parameters Ψ and Δ, and / or adapt the Mueller matrix form, such as looking for off-diagonal elements in some applications. For example, the polarizing element 142 and one or more detectors 144 and 146 can be used to detect S-polarized and P-polarized light. The lock-in amplifier 148 converts the signals from the detectors 144 and 146 into a signal that can be, for example, a fundamental, second harmonic or higher harmonic of the probe frequency, such as f probe , 2F probe etc., can be used to demodulate at various harmonics, including

[0065] Thus, optical metrology system 100 can perform static ellipsometry using linearly polarized light that is phase modulated periodically (e.g., with a frequency f) via modulator 139 in probe arm 130. The reflected light intensity at detectors 144 and 146 is proportional to the dc component of the modulation frequency (I dc ), a fundamental component (f), and a second harmonic component (2f). The reflected signal is demodulated using a lock-in amplifier 148 to calculate at least a partial Mueller matrix, e.g., off-diagonal elements, and / or the ellipsometric parameters Ψ and Δ from the dc, f, and 2f components. The ellipsometric parameters can be, for example, the following:

number

number

[0066] The optical metrology device 100 may further be used to perform time-resolved (TR) ellipsometry measurements using a selectable pump arm 120 in conjunction with the probe arm 130. For example, the controller 150 may cause the selection element 117 to select the pump arm 120, i.e., 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 signal may be amplitude (intensity) modulated using a modulator 126 at

[0067] A polarizing element 138 in the probe arm 130 can be configured to generate one or more desired polarization states of a probe pulse in the probe beam 131. A modulator 139 in the probe arm 130 is configured to modulate the polarizing element 138 at a frequency f probe The phase of the probe beam 131 can be modulated with a pump pulse, which interacts with the target sample 102 after each pump pulse. TR ellipsometry 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 the delay stage 122 in the pump arm 120 and / or the 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. A polarizing element 142 and one or more detectors 144 and 146 can be used to detect the polarization state of the reflected beam 141 and determine at least a partial Mueller matrix, e.g., off-diagonal elements, and / or ellipsometric parameters Ψ and Δ. For example, the polarizing element 142 and one or more detectors 144 and 146 can be used to detect S-polarized light and P-polarized light. A lock-in amplifier 148 couples the signals from the detectors 144 and 146, e.g., to the pump frequency and the fundamental, second harmonic and higher probe frequencies, e.g., f pump ±f probe , f pump ±2f probe , etc., as a function of some combination of harmonics of the probe frequency.

[0069] Thus, the optical metrology device 100 receives a frequency f via the modulator 126 in the pump arm 120. pump Using a pump beam 121 that is intensity modulated at , also linearly polarized and periodically (e.g., f probe The reflected light intensity at detectors 144 and 146 can be calculated by multiplying the pump intensity (I pump ), pump frequency (f pump ), as well as components at the fundamental (f) and second harmonic (2f) of the probe modulation frequency. The reflected signal is demodulated using a lock-in amplifier 148 and at least partial Mueller matrices, such as the off-diagonal elements and / or ellipsometric parameters Ψ and Δ, are calculated, for example:

number

number

[0070] In some implementations, the optical metrology device 100 may be controlled by the controller 150 to perform photoacoustic measurements. Photoacoustic measurements may be picosecond ultrasonic measurements that may be used to measure, for example, depth-resolved measurements of inhomogeneities in the target sample 102. Photoacoustic measurements use, for example, a pump beam 121 to generate a transient response in the target sample 102, where a transducer layer, for example, a metal layer in the target sample 102, absorbs the pump pulse energy and launches an acoustic wave vertically into the target sample 102. The propagating acoustic wave interacts with and is reflected by the probe beam 131 via a piezo reflection response. Light reflected from the propagating acoustic wave interferes with light reflecting from the top surface of the target sample 102, resulting in a characteristic vibration time-evolution signal, i.e., coherent Brillouin scattering. The period of the vibrations reveals information about the speed of sound and elastic modulus in the target sample 102. The depth-resolved vibration period may be used to extract the sound speed 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 inhomogeneities or thickness measurements of opaque films.

[0071] The optical metrology device 100 can perform photoacoustic measurements using a selectable pump arm 120 in conjunction with a probe arm 130. For example, the controller 150 can cause the selection element 117 to select the pump arm 120, i.e., 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 signal may be amplitude (intensity) modulated using a modulator 126 at

[0072] The probe arm 130 generates a probe pulse in the probe beam 131, which may be, but need not be, polarized by a polarizing element 138 in the probe arm 130. Furthermore, the probe beam 131 does not need to be phase modulated by the 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 may be collected as a function of the time delay between the pump beam 121 and the probe beam 131, controlled, for example, by the delay stage 122 in the pump arm 120 and / or the delay stage 132 in the probe arm 130.

[0073] Material properties including material type, thickness, and non-uniformity within the target sample 102 can be measured based on the reflected beam 141 by varying the propagation time of the acoustic wave. The detector arm 140 can detect changes in the reflection or surface deformation of the reflected beam 141 using detector 144, for example, with respect to the time delay. FIG. 3 shows, by way of example, a graph illustrating the change in reflectivity ΔR in arbitrary units versus time delay (psec) that may be measured by the optical metrology device 100 operating in a photoacoustic measurement mode. By way of example, the thickness of the target sample 102 may be measured based on the following:

number

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

[0075] 1B shows a side view of a portion of an MRAM device 180, which is an example of a target sample 102 that may be measured by optical metrology tool 100. By way of example, MRAM device 180 may include a [Co(x) / Pt(y)] hard mask layer 181, a cap layer (top electrode) 182, CoFeB layers 183 and 185 with an intervening MgO layer 184, a Ta spacer 186, and an intervening Ru or Ir layer 188. nIt may include multilayers 187 and 189, a seed layer 190, and a bottom electrode 191. For example, acoustic and ellipsometric 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 may be used, for example, to measure the magnetic stack deposition, annealing, and magnetization. Subtle changes in the free and pinned layers can be measured to obtain the optimal magnetization state. For example, in tunneling magnetoresistance (TMR), the resistance of the MTJ depends on the relative orientation of the magnetic layers, which is important for reading. In another example, with spin transfer torque (STT), the spin angular momentum transfer between the magnetic layers results in a torque on the free layer, which is important for writing. Static MOKE may be used to measure the magnetization to achieve these properties. On the other hand, transient MOKE may be used for characterization of magnetization dynamics, for example, to study the speed of magnetic writing and reading. For example, magnetic switching may occur on the picosecond time scale. Transient MOKE may be used to study the control of individual bits on the sub-ns time scale in high density magnetic memories. Optical metrology tool 100 can be used to measure a variety of properties, such as those discussed above.

[0076] FIG. 4 shows a schematic diagram of an optical metrology apparatus 400 illustrating one embodiment of the optical metrology apparatus 100 shown in FIG. 1A. It should be understood that the optical metrology apparatus 400 may include components and subsystems such as beam management and conditioning components such as beam expanders, collimators, polarizers, half-wave plates, and beam power detectors, and focus sensors, in addition to those shown in FIG. 4. Those skilled in the art will appreciate variations of the optical metrology apparatus 400 of FIG. 4 that are still suitable for performing the metrology techniques described herein. Additionally, it should be understood that certain components shown in FIG. 4 may not be included in the optical metrology apparatus 400 if the particular component is not necessary to perform the desired metrology techniques described herein. For example, in some implementations, the pump arm 420 may be omitted from the optical metrology apparatus 400 if transient or time-resolved measurements are not desired, and in other implementations, the shutter 410 (or pump arm 420 selection components) may be omitted from the optical metrology apparatus 400 if static measurements, e.g., 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., one or both of a multi-wavelength generator 434 and a filter 436, such as a dichroic mirror, laser line filter, notch filter, etc.), or other components may be omitted from the optical metrology device 400 if they are not necessary for the desired measurement, as would be understood by one of ordinary skill in the art.

[0077] As shown, 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 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 may 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) may be used as the pulsed light source 110 shown in FIG. 1A.

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

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

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

[0081] The pulse shaper 424 receives the pulsed light beam and varies at least one of the duration, phase, or both of the pulses in the pulsed light beam in the pump beam. The pulse shaper 424 may be, for example, a spatial light modulator or an acousto-optical modulator. For example, a spatial light modulator such as a liquid crystal SLM manufactured by Jenoptik may be used, or an acousto-optical 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 may further pass through a polarizer P2 and a half-wave plate HWP2, and is directed to the target sample 412 via mirrors M6, M7, M8, a beam splitter 428, and a lens L1. Lens L1 may include one or more reflective or refractive lenses, or a combination thereof. Lens L1 may direct the pump beam to be normally incident on the target sample 412. In some implementations, the pump beam may have a non-normal angle of incidence, for example, an angle of incidence between normal and 70°.

[0083] The vision system 429 can be focused 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 a motorized half-wave plate HWP3 preceded by a variable delay stage 432, shown as including a number of mirrors M9, M10, M11, and M12, where mirror M11 is movable via a piezoelectric motor to change the length of the optical path to control the delay of the pulses in the probe beam generated by the probe arm 430 to vary 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 may be used to select one or more wavelengths to be used in the probe beam for the measurement of the target sample 412. The wavelength selector 433 may include a multi-wavelength generator 434 that receives the pulsed light beam 111, which may be, for example, a narrow band, and spectrally broadens the pulsed light beam to generate the probe beam. The multi-wavelength generator 434 may be, for example, a supercontinuum generator, such as a multi-harmonic generator, for example, a DBO or photonic crystal fiber that receives a single or narrow band of wavelengths and generates multiple wavelengths in a continuous or non-continuous spectral wavelength for the probe beam. For example, a DBO or photonic crystal fiber may be used. The multi-wavelength generator 434 allows the ability to increase the wavelength of the probe beam, for example, from the visible spectral range to the near infrared spectral range. This 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 a narrow band of wavelengths for the measurement of the target sample 412. The wavelength selector 433, in some implementations, can further include a filter 436, such as an acousto-optic filter, which, when used in conjunction with the multi-wavelength generator 434, enables the ability to select one or more specific wavelengths to be included 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 one or more polarizing elements 438 (e.g., polarizers and / or waveplates) that, for example, generate one or more polarization states and optional phase shifts, 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 may modulate the amplitude (intensity) of the polarized probe pulse in the probe beam. For example, the EOM 439 may be a KD*P crystal-based EOM manufactured by Conoptics. The EOM 439 may periodically phase modulate the polarized probe pulse in the probe beam.

[0087] The probe beam generated by the probe arm 430 is directed to 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 to be obliquely incident on the target sample 412.

[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 of the reflected light to a second detector 446. For example, the detectors 444 and 446 may be a single photodetector, such as a Si-based photodetector manufactured by Thorlabs. In some implementations, one or more polarizing elements may be disposed in the detector arm 440 that may act as an analyzer to select the polarization state of the reflected light to be detected. The first detector 444 and the second detector 446 may receive orthogonal polarization states of the reflected light. For example, in some implementations, the beam splitter 442 may be a polarizing beam splitter and may direct the reflected light to the detectors 444 and 446 based on the polarization state of the reflected light, e.g., the first detector 444 receives the S polarization state of the reflected light and the second detector 446 receives the P polarization state of the reflected light. In some implementations, the beam splitter 442 may be non-polarizing and one or more polarizing elements may be disposed in the detector arm 440 to select the polarization state of the reflected light received by the detectors 444 and 446. The polarizing elements may be rotatable, for example, to allow multiple polarization states to be detected as needed. Additionally, in some implementations, a shutter 443 (or other selection element such as a flip mirror or other movable element, or an electrically controlled element such as an electrochromic light switch) may be disposed in front of the detector 444 to prevent detection of the reflected light by the 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 which receives signals from detectors 444 and 446 generated based on the reflected probe pulses received 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 and the modulation frequency generated by the EOM 439 in the probe arm 430 and, if used, the EOM 426 in the pump arm 420.

[0090] As shown, the optical metrology device 400 may further include a stage 414 including 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 movement in either Cartesian (i.e., X and Y) or polar (i.e., R and θ) coordinates, or some combination of the two. The stage may also allow vertical movement along a Z coordinate. Additionally, one or more magnetic elements 416, e.g., electromagnets, may be included within the stage 414 or external to 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] The detectors 444, 446, e.g., lock-in amplifier 448, as well as other components of the optical metrology device 400, such as the light source 402, shutter 410, pump variable delay stage 422, pulse shaper 424, EOM 426, probe variable delay stage 432, wavelength selector 433, polarizer 438, EOM 439, shutter 443 (if present), stage 414, and one or more magnetic elements 416, may be coupled to at least one controller 450, such as a workstation, personal computer, central processing unit or other suitable computer system, or multiple systems. It should be understood that the controller 450 includes one or more processing units 452, which may be separate or linked processors, and 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 metrology 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 can further control the operation of the chuck 414 to hold or release the target sample 412. The controller 450 can also collect and analyze data obtained from the 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, ellipsometry, TR ellipsometry, spectroscopic ellipsometry, photoacoustic measurements, etc., as described herein. In some implementations, measured data can be acquired and compared to modeled data, which can be stored in a library or acquired in real time. The parameters of the model can be varied and the modeled data and measured data 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 properties of the target sample 412.

[0092] The controller 450 includes at least one processing unit 452 and memory 454, as well as user interfaces such as a display 456 and input devices 458. A non-transitory computer usable storage medium 459 having computer readable program code embodied therein may be used by the at least one processor 452 to cause the at least one processor 452 to control the optical metrology device 400 and perform the measurement functions and analyses described herein. Data structures and software code for automatically implementing one or more operations described in this detailed description may be implemented by one of ordinary skill in the art in view of this disclosure and may be stored, for example, on a 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, disk drives, magnetic tapes, compact disks, and flash drives, magnetic storage devices, such as DVDs (digital versatile disks or digital video disks), and optical storage devices. The communication port 457 may also be used to receive instructions that may be stored in the memory 454 and used to program the 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 network. The communication port 457 may further export signals with the 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 a manufacturing process step of the specimen 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 a programmable logic device (PLD), and the functions may be embodied in a computer understandable description language that may be used to create an ASIC or PLD that operates as described herein.Analysis of the data may be stored, for example, in a memory 454 associated with the sample and / or provided to a user, for example, via a display 456, alarm, or other output device. Additionally, the analysis may be fed back to the process tool to adjust the appropriate patterning steps to compensate for detected processing variations.

[0093] 5 shows, by way of example, an optical metrology apparatus 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 to deselect the pump arm 420, preventing it from generating a pump beam. The wavelength selector 433 can 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. A 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, for example, at a frequency f probe In some implementations, the magnetic element 416 may be used to change the magnetization of the target sample 102 during testing, for example, by changing the magnetization before some measurements. The shutter 443 is configured to enable 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 For example, the S and P polarization states may be detected by detectors 444 and 446, and a lock-in amplifier 448 may be used to convert signals from the detectors 444 and 446 into, for example, fundamental, second harmonic and higher probe frequencies, e.g., f pump ±f probe , f pump ±2f probe The optical metrology device 400 may be used to demodulate at any combination of harmonics of the probe frequency, such as dc(I dc), fundamental wave (f probe ) and the second harmonic (2f probe ) is used to obtain the detection intensity having the components dc, f, as shown in Eq. probe , and 2f probe Polarization rotation (Kerr rotation angle) θ from the component k and the ellipticity ε may be determined.

[0094] FIG. 6 shows, by way of example, an optical metrology device 400 configured to perform TR MOKE measurements, e.g., using both pump arm 420 and probe arm 430. For example, as shown, a shutter 410 is configured to select pump arm 420 to generate a pump beam incident on a target sample 412 and generate a transient response in the target sample 412. The pump beam may be configured to induce magnetization dynamics in the target sample 412, e.g., using a femtosecond pump laser pulse. A pulse shaper 424 may be used to vary the pulse duration and / or phase of the incident pump beam to determine the dependence of the magnetic dynamics in the target sample 112 on the pump pulse characteristics. Additionally, an adaptive algorithm may be used to define and use an optimal pulse shape of the pump beam to provide the desired control over the magnetic dynamics in the target sample 112 under consideration, e.g., by changing the pulse shape of the pump beam until the strongest response is detected. The EOM 426 is configured to generate a pulse shape of the pump beam at a frequency f pump The amplitude (intensity) of the pump beam may be modulated by

[0095] A wavelength selector 433 in the probe arm 430 can 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. A 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, for example, at a frequency f probeIn some implementations, the magnetic element 416 can be used to modify the magnetization of the target sample 112 during testing, for example by varying the magnetization before some measurements, and / or to induce the magnetization of the target sample 112 with a pump pulse. The shutter 443 is configured to enable 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 detect the Kerr rotation (θ ) as described above. k For example, the S and P polarization states may be detected by detectors 444 and 446, and a lock-in amplifier 448 may be used to convert signals from the detectors 444 and 446 into, for example, fundamental, second harmonic and higher probe frequencies, e.g., f pump ±f probe , f pump ±2f probe The optical metrology setup 400 may be used to demodulate the components of the pump intensity (I pump ), pump frequency (f pump ), and the fundamental of the probe modulation frequency (f probe ) and the second harmonic (2f probe ) is used to calculate the polarization rotation (Kerr rotation angle) θ k and ellipticity ε k may be determined from the dc, f and 2f components as shown in Equation 3:

[0096] FIG. 7 illustrates, as an example, an optical metrology device 400 configured to perform ellipsometric measurements using, for example, only the probe arm 430. For example, as shown, the shutter 410 is configured to not select the pump arm 420, preventing it from generating a pump beam. The wavelength selector 433 can 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. A 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. In some implementations, the polarizer 438 can be rotated to generate different polarization states. The linearly polarized light from the polarizer 438 is polarized by the EOM 439, for example, at a frequency f probe The reflected light is phase modulated at f. A shutter 443 can be configured to prevent the reflected light from being received by a detector 444. A polarizing beam splitter 442 (or one or more polarizers, if used) acts as an analyzer and directs the reflected light from the target sample 412 to a detector 446, which detects the intensity of the reflected light at a selected polarization state. A lock-in amplifier 448 amplifies the signal from the detector 444 at, for example, the fundamental, second harmonic, and higher probe frequencies, e.g., f probe , 2F probe The optical metrology device 400 demodulates the dc (I dc ), fundamental wave (f probe ) and the second harmonic (2f probe ) is used to calculate at least a partial Mueller matrix, e.g., off-diagonal elements and / or ellipsometric parameters Ψ and Δ, as shown in Equations 4 and 5, probe and 2f probe It can be determined from the ingredients.

[0097] 8 illustrates, by way of example, an optical metrology apparatus 400 configured to perform TR ellipsometry measurements, e.g., using both pump arm 420 and probe arm 430. For example, as shown, shutter 410 is configured to select pump arm 420 to generate a pump beam that is incident on target sample 412 and generates a transient response in target sample 412. EOM 426 is configured to receive a pulsed laser beam at frequency f pump The amplitude (intensity) of the pump beam may be modulated by

[0098] A wavelength selector 433 in the probe arm 430 can 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. A 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. In some implementations, the polarizer 438 can be rotated to generate different polarization states. The linearly polarized light from the polarizer 438 is polarized by an EOM 439, for example, at a frequency f probe The reflected light is phase modulated at f. A shutter 443 can be configured to prevent the reflected light from being received by detector 444. A polarizing beam splitter 442 (or one or more polarizers, if used) acts as an analyzer and directs the reflected light from the target sample 412 to a detector 446, which detects the intensity of the reflected light at a selected polarization state. A lock-in amplifier 448 amplifies the signals from detectors 444 and 446 at, for example, the fundamental, second harmonic, and higher probe frequencies, e.g., f pump ±f probe , f pump ±2f probe The optical metrology setup 400 can be used to demodulate the components of the pump intensity (I pump ), the pump frequency component (f pump ), and the fundamental component of the probe modulation frequency (f probe ) and the second harmonic component (2f probe) can be used to determine at least a partial Mueller matrix, e.g., off-diagonal elements, and / or the ellipsometric parameters Ψ and Δ, as shown in Equation 6 and Equation 7.

[0099] 9 illustrates, by way of example, an optical metrology device 400 configured to perform photoacoustic measurements, e.g., using both pump arm 420 and probe arm 430. For example, as shown, shutter 410 is configured to select pump arm 420 to generate a pump beam that is incident on target sample 412 and generates a transient response in target sample 412. Variable delay stage 422 can be controlled to generate a variety of delays between the pump and probe beams such that photoacoustic measurements can be collected as a function of the time delay between the pump and probe beams. EOM 426 is configured to generate a frequency f pump The amplitude (intensity) of the pump beam may be modulated by

[0100] A wavelength selector 433 in the probe arm 430 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. A polarizer 438 in the probe arm 430 may be configured to generate a desired polarization state, for example, 0° in the probe pulse in the probe beam. A shutter 443 may be configured to prevent reflected light from being received by a detector 444. A beam splitter 442 directs reflected light from the target sample 412 to a detector 446 to detect changes in reflectance of the reflected beam versus time delay. The changes in reflectance versus time delay may be used to determine various properties of the target sample 412, such as thickness as shown in Equation 8.

[0101] 10 is a flow chart 1000 illustrating a method of operating an optical metrology device, such as optical metrology device 100 or 400, as described herein, to perform optical metrology measurements on a target sample. For example, the method of operation may be for measuring at least one property, including a magnetic property, of the target sample using at least one of the following, or a combination: static magneto-optical Kerr effect (MOKE), time-resolved MOKE (TR MOKE).

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

[0103] In block 1004, the optical metrology device selects 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 a transient perturbation in the target material, as shown, for example, by beam selection element 117 and pump arm 120 generating pump beam 121 as shown in FIG. 1A, or shutter 410 and pump arm 420 as shown in FIGS. 4-8, or does not select a pump arm such that the target sample is not irradiated with one or more pump pulses. Means for receiving at least a portion of the pulsed light beam and selecting a pump arm to irradiate a target sample with one or more pump pulses to cause a transient perturbation in the target material, or for not selecting a pump arm so that the target sample is not irradiated with one or more pump pulses, may include, for example, beam selection element 117 of FIG. 1A (which may be polarizer 117' and beam splitter 115), 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 application of current or voltage, or beam splitter 408, which may be a polarizing element (e.g., polarizer P1) and a polarizing beam splitter, and pump arm 420 as described with reference to FIGS. 4 to 8.

[0104] In block 1006, the optical metrology device can receive at least a portion of the pulsed light beam in a probe arm and irradiate the target sample with one or more polarized probe pulses to generate a reflected probe pulse having a polarization state that is affected by the magnetic properties of the target sample, and is modulated based on a transient perturbation in the target material when the pump arm is selected, as shown, for example, by probe arm 130 generating probe beam 131 in FIG. 1A or probe arm 430 in FIG. 4-8. The 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 that is affected by the magnetic properties of the target sample, and is modulated based on a transient perturbation in the target material when the pump arm is selected, can include probe arm 130 in FIG. 1A or probe arm 430 in FIG. 4-8.

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

[0106] In block 1010, the optical metrology device determines at least one property including a magnetic property 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, for example, as described with reference to controller 150 of Figure 1A or controller 450 of Figures 4-8. The means for determining at least one property including a magnetic property 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 controller 150 of Figure 1A or controller 450 of Figures 4-8.

[0107] In one implementation, the optical metrology device can determine the at least one characteristic by determining at least one or a combination of magnetic stack deposition, annealing, or magnetization characteristics based on static MOKE when the pump arm is not selected, and determining at least one or a combination of magnetization dynamics, magnetic switching, or control of individual bits based on TR MOKE when the pump arm is selected, as described with reference to Figures 1A and 1B. The means for determining at least one or a combination of magnetic stack deposition, annealing, or magnetization characteristics based on static MOKE when the pump arm is not selected, and determining at least one or a combination of magnetization dynamics, magnetic switching, or control of individual bits based on TR MOKE when the pump arm is selected, can include controller 150 of Figure 1A or controller 450 of Figures 4-8.

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

[0109] In one implementation, the optical metrology 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 pulsed light source 110 in FIG. 1A.

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

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

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

[0113] As an example, the optical metrology device can perform ellipsometric measurements of a target sample by phase modulating one or more polarized probe pulses with a phase modulator in a probe arm, or intensity modulating one or more pump pulses with an amplitude modulator in a selectable pump arm, as described in FIG. 1A and 4-8. For example, the pump arm may be selectable to produce a transient perturbation 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 is selected for a time-resolved MOKE measurement or a time-resolved ellipsometric measurement, the pump arm is not selected, and the phase modulator periodically phase modulates one or more probe pulses for the ellipsometric measurement, as described in FIG. 1A and 4-8. In some implementations, the optical metrology device can periodically modulate the intensity of one or more pump pulses with an amplitude modulator in a pump arm, for a time-resolved MOKE measurement or a time-resolved ellipsometric measurement, as described in FIG. 1A and 4-8. In some implementations, the 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, where both the first detector and the second detector are used for the time-resolved MOKE measurement and only one of the first detector and the second detector is used for the ellipsometry measurement, as described in FIG. 1A and FIG. 4-FIG. 8. For example, the optical metrology device may demodulate the signals from the first detector and the second detector generated based on the reflected probe pulse received from the target sample using a lock-in amplifier coupled to the first detector and the second detector, as described with reference to the lock-in amplifier 148 of FIG. 1A or the lock-in amplifier 448 of FIG. 4-FIG. 8. The means for demodulating the signals from the first detector and the second detector generated based on the reflected probe pulse received from the target sample may include the lock-in amplifier 148 of FIG. 1A or the lock-in amplifier 448 of FIG. 4-FIG. 8.

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

[0115] 11 is a flow chart 1100 illustrating a method of operation of an optical metrology device, such as optical metrology device 100 or 400, to perform optical metrology measurements on a target sample, as described herein. For example, the method of operation may be for measuring at least one property, including a magnetic property, of the target sample using at least one of a time-resolved magneto-optical Kerr effect (MOKE) measurement, an optoacoustic measurement, or a combination thereof.

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

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

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

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

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

[0121] In one implementation, the optical metrology device can determine the effect on the polarization state of the probe pulse by determining at least one of the characteristics of magnetization dynamics, magnetic switching, or control of individual bits, or a combination thereof, for time-resolved MOKE measurements when the phase modulator periodically phase-modulates one or more pulses, or by determining at least one of the characteristics of bottom electrode thickness or metal layer thickness, magnetic random access memory (MRAM), or a combination thereof, for photoacoustic measurements when the phase modulator does not phase-modulate one or more pulses. When the phase modulator periodically phase-modulates one or more probe pulses, the means for determining at least one of the characteristics of magnetization dynamics, magnetic switching, or control of individual bits, or a combination thereof, for time-resolved MOKE measurements can include the controller 150 of FIG. 1A or the controller 450 of FIG. 4-8. In the case where the phase modulator does not phase modulate the one or more pulses, for photoacoustic measurements, the means for determining at least one of the bottom electrode thickness measurement or the metal layer thickness magnetic random access memory (MRAM), or a combination thereof, may include controller 150 of FIG. 1A or controller 450 of FIGS. 4-8.

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

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

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

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

[0126] In one implementation, the optical metrology 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 pulsed light source 110 in FIG. 1A.

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

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

[0129] As an example, the optical metrology device can perform ellipsometric measurements of a target sample by phase modulating one or more polarized probe pulses with a phase modulator in the probe arm, as described in FIG. 1A and 4-8. For example, the pump arm may be selectable to produce a transient perturbation 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 is selected for a time-resolved MOKE measurement or a time-resolved ellipsometric measurement, the pump arm is not selected, and the phase modulator periodically phase modulates one or more probe pulses for the ellipsometric measurement, as described in FIG. 1A and 4-8. In some implementations, the optical metrology device can periodically modulate the intensity of one or more pump pulses with an amplitude modulator in the pump arm, as described in FIG. 1A and 4-8, for a time-resolved MOKE measurement or a time-resolved ellipsometric measurement. In some implementations, the 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, where both the first detector and the second detector are used for the time-resolved MOKE measurement and only one of the first detector and the second detector is used for the ellipsometry measurement, as described in FIG. 1A and FIG. 4-FIG. 8. For example, the optical metrology device may demodulate the signals from the first detector and the second detector generated based on the reflected probe pulse received from the target sample using a lock-in amplifier coupled to the first detector and the second detector, as described with reference to the lock-in amplifier 148 of FIG. 1A or the lock-in amplifier 448 of FIG. 4-FIG. 8. The means for demodulating the signals from the first detector and the second detector generated based on the reflected probe pulse received from the target sample may include the lock-in amplifier 148 of FIG. 1A or the lock-in amplifier 448 of FIG. 4-FIG. 8.

[0130] 12 is a flow chart 1200 illustrating a method of operating an optical metrology device, such as optical metrology device 100 or 400, to perform optical metrology measurements on a target sample, as described herein. For example, the method of operation may be for measuring at least one property, including a magnetic property, of the target sample using at least one of a time-resolved magneto-optical Kerr effect (MOKE) measurement, an ellipsometry measurement, or a combination thereof.

[0131] In block 1202, the optical metrology device generates a pulsed light beam using a pulsed light source, for example, as shown by pulsed light source 110 generating pulsed light beam 111 in Fig. 1A, or light source 402, intensity control 403, beam expander 404, and chopper 406 shown in Fig. 4-8. The means for generating a pulsed light beam may include, for example, pulsed light source 110 in Fig. 1A, or light source 402, intensity control 403, beam expander 404, and chopper 406 shown in Fig. 4-8.

[0132] In block 1204, the optical metrology device selects 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 a transient perturbation in the target material, as shown, for example, by beam selection element 117 and pump arm 120 generating pump beam 121 as shown in FIG. 1A, or shutter 410 and pump arm 420 as shown in FIGS. 4-8, or does not select a pump arm such that the target sample is not irradiated with one or more pump pulses. Means for receiving at least a portion of the pulsed light beam and selecting a pump arm to irradiate a target sample with one or more pump pulses to cause a transient perturbation in the target material, or for not selecting a pump arm so that the target sample is not irradiated with one or more pump pulses, may include, for example, beam selection element 117 of FIG. 1A (which may be polarizer 117' and beam splitter 115), 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 application of current or voltage, or beam splitter 408, which may be a polarizing element (e.g., polarizer P1) and a polarizing beam splitter, and pump arm 420 as described with reference to FIGS. 4 to 8.

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

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

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

[0136] In one implementation, the optical metrology device can determine the effect of the probe pulse on the polarization state by determining at least one or a combination of the properties of magnetization dynamics, magnetic switching, or control of individual bits for time-resolved MOKE measurements when the pump arm is selected, or at least one or a combination of bottom electrode thickness measurements or metal layer thickness magnetic random access memory (MRAM) for ellipsometry measurements when the pump arm is not selected, as described with reference to Figures 1A and 1B. The means for determining at least one or a combination of the properties of magnetization dynamics, magnetic switching, or control of individual bits for time-resolved MOKE measurements when the pump arm is selected, or at least one or a combination of the properties of bottom electrode thickness measurements or metal layer thickness magnetic random access memory (MRAM) for ellipsometry measurements when the pump arm is not selected, can include the controller 150 of Figure 1A or the controller 450 of Figures 4-8.

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

[0138] In one implementation, the optical metrology 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 ellipsometry measurements when the pump arm is selected as described in Figures 1A and 4-8. 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 ellipsometry measurements can include controller 150 of Figure 1A or controller 450 of Figures 4-8.

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

[0140] In some implementations, the 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, where both the first detector and the second detector are used for the time-resolved MOKE measurement, and only one of the first detector and the second detector is used for the photoacoustic measurement and the ellipsometric measurement, as described with reference to FIG. 1A and FIG. 4-FIG. 8. For example, the optical metrology device may demodulate the signals from the first detector and the second detector generated based on the reflected probe pulse received from the target sample using a lock-in amplifier coupled to the first detector and the second detector, as described with reference to the lock-in amplifier 148 of FIG. 1A or the lock-in amplifier 448 of FIG. 4-FIG. 8. The means for demodulating the signals from the first detector and the second detector generated based on the reflected probe pulse received from the target sample may include the lock-in amplifier 148 of FIG. 1A or the lock-in amplifier 448 of FIG. 4-FIG. 8.

[0141] In one implementation, the optical metrology device can deselect a pump arm such that the target sample is not illuminated with one or more pump pulses, and periodically phase modulate one or more probe pulses using a phase modulator for static MOKE measurement, and the optical metrology device can determine the magnetic properties of the target sample based on the static MOKE 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 the pump arm 120 and the controller 150 in FIG. 1A, or the shutter 410 and the pump arm 420 and the controller 450 in FIG. 4-8. The means for deselecting the pump arm such that the target sample is not illuminated with one or more pump pulses can be the beam selection element 117 and the controller 150 in FIG. 1A, or the shutter 410 and the controller 450 in FIG. 4-8. The means for periodically phase modulating one or more probe pulses for static MOKE measurements may include the modulator 139 of Figure 1A (which may be, for example, an EOM, an AOM, a PEM, or a rotating compensator) or the EOM 439 of Figures 4-8. The means for determining the magnetic properties of the target sample based on the 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 of Figure 1A or the controller 450 of Figures 4-8.

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

[0143] In one implementation, the optical metrology 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 pulsed light source 110 in FIG. 1A.

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

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

[0146] Although the present invention has been illustrated in connection with specific embodiments for purposes of illustration, the present invention is not limited thereto. Various adaptations and modifications may be made without departing from the scope of the invention. Therefore, the spirit and scope of the appended claims should not be limited to the foregoing description.

Claims

1. 1. An apparatus for measuring at least one property, including a magnetic property, of a target sample using at least one of a static magneto-optical Kerr effect (MOKE), a time-resolved MOKE (TR MOKE), or a combination thereof, the apparatus comprising: 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 induce a transient perturbation in the target material when the pump arm is selected, to irradiate the target sample with one or more pump pulses, and to 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 irradiate the target sample with one or more polarized probe pulses to generate a reflected probe pulse having a polarization state affected by the magnetic property of the target sample, the probe arm being modulated based on the transient perturbation in the target material when the pump arm is selected; one or more detectors for receiving reflected probe pulses from the target sample; and at least one processor coupled to the one or more detectors and configured to measure the at least one property including the magnetic property of the target sample based on a static MOKE when the pump arm is not selected and based on a TR MOKE when the pump arm is selected.

2. 2. The apparatus of claim 1, wherein the at least one processor is configured to measure at least one of a magnetic stack deposition, annealing, or magnetization characteristic, or a combination thereof, as the at least one characteristic based on static MOKE when the pump arm is not selected, and to measure at least one of a magnetization dynamics, magnetic switching, or individual bit control characteristic, or a combination thereof, as the at least one characteristic based on TR MOKE when the pump arm is selected.

3. The apparatus of claim 1 further comprising a movable element for selecting the pump arm.

4. The apparatus of claim 1 , wherein the pulsed light source for generating the pulsed light beam comprises a pulsed laser.

5. 10. The apparatus of claim 1, further comprising a variable delay operative with the pulsed light beam to control a time delay between illumination of the target sample by each pump pulse and illumination of the target sample by a corresponding probe pulse.

6. The apparatus of claim 5 , wherein the variable delay is in the selectable pump arm and operates on the pulsed light beam in the selectable pump arm.

7. a phase modulator in the probe arm that periodically phase modulates the one or more polarized probe pulses to measure the at least one property, including the magnetic property, of the target sample based on a static MOKE when the pump arm is not selected; 13. The apparatus of claim 1, further comprising: an amplitude modulator in the selectable pump arm that periodically modulates an intensity of the one or more pump pulses when the pump arm is selected to measure the at least one property of the target sample including the magnetic property based on TR MOKE.

8. The apparatus of claim 7 , wherein the amplitude modulator in the selectable pump arm modulates the intensity of the one or more pump pulses to perform photoacoustic measurements on the target sample.

9. The apparatus of claim 8 , wherein the phase modulator in the probe arm modulates the intensity of the one or more probe pulses to perform the photoacoustic measurement of the target sample.

10. 8. The apparatus of claim 7, wherein the phase modulator in the probe arm phase modulates the one or more polarized probe pulses or the amplitude modulator in the selectable pump arm intensity modulates the one or more pump pulses to perform an ellipsometric measurement of the target sample.

11. 11. The apparatus of claim 10, wherein the pump arm is selectable to induce the transient perturbation in the target material when the pump arm is selected and to not irradiate the target sample when the pump arm is not selected, the pump arm is selected for the time-resolved MOKE measurement or time-resolved ellipsometry measurement and the pump arm is not selected, and the phase modulator periodically phase modulates the one or more probe pulses for the ellipsometry measurement.

12. The apparatus of claim 11 , wherein the amplitude modulator periodically modulates the intensity of the one or more pump pulses for the time-resolved MOKE or time-resolved ellipsometry measurements.

13. 11. The apparatus of claim 10, wherein the one or more detectors comprise a first detector for detecting a P-state polarization of the reflected probe pulse and a second detector for detecting an S-state polarization of the reflected probe pulse, both the first detector and the second detector being used for the time-resolved MOKE measurement and only one of the first detector and the second detector being used for the ellipsometry measurement.

14. 14. The apparatus of claim 13, wherein the first detector and the second detector are coupled to a lock-in amplifier for demodulating signals from the first detector and the second detector generated based on the received reflected probe pulse from the target sample.

15. a first set of optical elements configured to irradiate the one or more pump pulses onto the target sample at normal incidence; 10. The apparatus of claim 1, further comprising: a second set of optical elements configured to irradiate the one or more probe pulses onto the target sample at oblique incidence.

16. 1. A method for measuring at least one property, including a magnetic property, of a target sample using at least one of a static magneto-optical Kerr effect (MOKE), a time-resolved MOKE (TR MOKE), or a combination thereof, the method comprising: 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 produce a transient perturbation in the target material, or not selecting the pump arm such that the target sample is not irradiated with the one or more pump pulses; receiving at least a portion of the pulsed light beam at 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 affected by the magnetic property of the target sample, the reflected probe pulse having a polarization state modulated based on the transient perturbation in the target material when a pump arm is selected; detecting reflected probe pulses from the target sample with one or more detectors; determining the at least one property including the magnetic property of the target sample based on the reflected probe pulse and a 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.

17. 17. The method of claim 16, wherein determining the at least one characteristic comprises: determining at least one of a magnetic stack deposition, annealing, or magnetization characteristic, or a combination thereof, based on a static MOKE if a pump arm is not selected; and determining at least one of a magnetization dynamics, magnetic switching, or individual bit control characteristic, or a combination thereof, based on a TR MOKE if the pump arm is selected.

18. The method of claim 16 further comprising moving a movable element to select the pump arm.

19. 17. The method of claim 16, wherein generating the pulsed light beam with the pulsed light source comprises generating the pulsed light beam with a pulsed laser.

20. 17. The method of claim 16, further comprising controlling a time delay between illumination of the target sample with each pump pulse and illumination of the target sample with a corresponding probe pulse having a variable delay operating on the pulsed light beam.

21. The method of claim 20 , wherein the variable delay is in the selectable pump arm and operates on the pulsed light beam in the selectable pump arm.

22. when the pump arm is not selected, periodically phase modulating the one or more polarized probe pulses with a first phase modulator in the probe arm to measure the at least one property of the target sample, including the magnetic property, based on static MOKE; 17. The method of claim 16, further comprising: when the pump arm is selected, periodically modulating an intensity of the one or more pump pulses using an amplitude modulator in the selectable pump arm to measure the at least one property of the target sample including the magnetic property based on TR MOKE.

23. 23. The method of claim 22, wherein the amplitude modulator in the selectable pump arm modulates the intensity of the one or more pump pulses to perform photoacoustic measurements on the target sample.

24. 24. The method of claim 23, wherein the phase modulator in the probe arm modulates the intensity of the one or more probe pulses to perform the photoacoustic measurement of the target sample.

25. 23. The method of claim 22, further comprising performing an ellipsometric measurement of the target sample by phase modulating the one or more polarized probe pulses with the phase modulator in the probe arm or intensity modulating the one or more pump pulses with the amplitude modulator in the selectable pump arm.

26. 26. The method of claim 25, wherein the pump arm is selectable to induce the transient perturbation in the target material when the pump arm is selected and to not irradiate the target sample when the pump arm is not selected, the pump arm is selected for the time-resolved MOKE measurement or time-resolved ellipsometry measurement, the pump arm is not selected, and the phase modulator periodically phase modulates the one or more probe pulses for the ellipsometry measurement.

27. 27. The method of claim 26, further comprising periodically modulating the intensity of the one or more pump pulses with the amplitude modulator in the pump arm for the time-resolved MOKE or time-resolved ellipsometry measurements.

28. 26. The method of claim 25, wherein the one or more detectors comprise a first detector for detecting a P-state polarization of the reflected probe pulse and a second detector for detecting an S-state polarization of the reflected probe pulse, both the first detector and the second detector being used for the time-resolved MOKE measurement, and only one of the first detector and the second detector being used for the ellipsometry measurement.

29. 30. The method of claim 28, further comprising demodulating signals from the first detector and the second detector generated based on the received reflected probe pulse from the target sample using a lock-in amplifier coupled to the first detector and the second detector.

30. irradiating the target sample with the one or more pump pulses at normal incidence using a first set of optical elements; 17. The method of claim 16, further comprising irradiating the one or more probe pulses at oblique incidence to the target sample using a second set of optical elements.

31. 1. An apparatus for measuring at least one property, including a magnetic property, of a target sample using at least one of a static magneto-optical Kerr effect (MOKE), a time-resolved MOKE (TR MOKE), or a combination thereof, the apparatus comprising: means for generating a pulsed light beam; means for receiving at least a portion of the pulsed light beam and for selecting a pump arm to irradiate the target sample with one or more pump pulses to induce a transient perturbation in the target material, or for not selecting the pump arm such that the target sample is not irradiated with the one or more pump pulses; means for receiving at least a portion of the pulsed light beam in a probe arm and illuminating the target sample with one or more polarized probe pulses to generate a reflected probe pulse having a polarization state affected by the magnetic property of the target sample, the ... means for detecting a reflected probe pulse from the target sample; and means for determining the at least one property including the magnetic property of the target sample based on the reflected probe pulse and a 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.

32. 1. An apparatus for measuring at least one property including a magnetic property of a target sample using at least one of a time-resolved magneto-optical Kerr effect (MOKE) measurement, an ellipsometry measurement, or a combination thereof, the apparatus comprising: 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 induce a transient perturbation in the target material when the pump arm is selected, to irradiate the target sample with one or more pump pulses, and to 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 irradiate 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 the one or more polarized probe pulses; one or more detectors for receiving reflected probe pulses from the target sample; and at least one processor coupled to the one or more detectors and configured to measure an effect of 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 an effect of non-magnetic properties of the target sample on the polarization state of the probe pulse for the ellipsometry measurement when the pump arm is not selected.

33. 33. The apparatus of claim 32, wherein the at least one processor is configured to measure at least one of, or a combination of, magnetization dynamics, magnetic switching, or control of individual bits for the time-resolved MOKE measurement if the pump arm is selected, or to measure at least one of, or a combination of, bottom electrode thickness or metal layer thickness magnetic random access memory (MRAM) for the ellipsometry measurement if the pump arm is not selected.

34. 33. The apparatus of claim 32, wherein the pump arm comprises an amplitude modulator that periodically modulates the intensity of the one or more pump pulses for the time-resolved MOKE measurement.

35. 35. The apparatus of claim 34, wherein the at least one processor is further configured to measure, when the pump arm is selected, a time-resolved effect on the polarization state of the probe pulse due to non-magnetic properties of the target sample for time-resolved ellipsometry measurements.

36. 35. The apparatus of claim 34, wherein the phase modulator in the probe arm is configured not to phase modulate the one or more pulses for the photoacoustic measurement, and the at least one processor is further configured to measure a change in reflectivity of the probe beam as a function of a time delay between each pump pulse and a probe pulse for the photoacoustic measurement when the phase modulator does not phase modulate the one or more pulses.

37. 37. The apparatus of claim 36, wherein the one or more detectors comprise a first detector for detecting a P-state polarization of the reflected probe pulse and a second detector for detecting an S-state polarization of the reflected probe pulse, both the first detector and the second detector being used for the time-resolved MOKE measurements, and only one of the first detector and the second detector being used for the photoacoustic measurements and the ellipsometry measurements.

38. 38. The apparatus of claim 37, wherein the first detector and the second detector are coupled to a lock-in amplifier to demodulate signals from the first detector and the second detector generated based on the received reflected probe pulse from the target sample.

39. 33. The apparatus of claim 32, wherein the pump arm is not selected and the phase modulator periodically phase modulates the one or more probe pulses for a static MOKE measurement, and the 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 the one or more probe pulses.

40. 33. The apparatus of claim 32, further comprising a movable element for selecting the pump arm.

41. 33. The apparatus of claim 32, wherein the pulsed light source for generating the pulsed light beam comprises a pulsed laser.

42. 33. The apparatus of claim 32, further comprising a variable delay operating on the pulsed light beam to control a time delay between illuminating the target sample with each pump pulse and illuminating the target sample with a corresponding probe pulse.

43. 43. The apparatus of claim 42, wherein the variable delay is in the selectable pump arm and operates on the pulsed light beam in the selectable pump arm.

44. a first set of optical elements configured to irradiate the one or more pump pulses onto the target sample at normal incidence; 33. The apparatus of claim 32, further comprising: a second set of optical elements configured to irradiate the one or more probe pulses onto the target sample at oblique incidence.

45. 1. A method for measuring at least one property, including a magnetic property, of a target sample using at least one of a time-resolved magneto-optical Kerr effect (MOKE) measurement, an ellipsometry measurement, or a combination thereof, the method comprising: 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 produce a transient perturbation in the target material, or not selecting the pump arm such that the target sample is not irradiated with the one or more pump pulses; receiving at least a portion of the pulsed light beam in a probe arm and illuminating 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 the one or more polarized probe pulses; detecting reflected probe pulses from the target sample with one or more detectors; determining an effect on the polarization state of the probe pulse based on the reflected probe pulse due to magnetic properties of the target sample for the time-resolved MOKE measurement when the pump arm is selected, and determining an effect on the polarization state of the probe pulse based on the reflected probe pulse due to non-magnetic properties of the target sample for the ellipsometry measurement when the pump arm is not selected.

46. 46. ​​The method of claim 45, wherein determining the effect on the polarization state of the probe pulse comprises determining at least one or a combination of properties of magnetization dynamics, magnetic switching, or control of individual bits for the time-resolved MOKE measurement if the pump arm is selected, or determining at least one or a combination of properties of bottom electrode thickness or metal layer thickness magnetic random access memory (MRAM) for the ellipsometry measurement if the pump arm is not selected.

47. 46. ​​The method of claim 45, further comprising periodically modulating the intensity of the one or more pump pulses for the time-resolved MOKE measurement using an amplitude modulator in the pump arm.

48. 48. The method of claim 47, further comprising determining a time-resolved effect on the polarization state of the probe pulse due to non-magnetic properties of the target sample for time-resolved ellipsometry measurements when the pump arm is selected.

49. 48. The method of claim 47, wherein the phase modulator in the probe arm is configured not to phase modulate the one or more pulses for the photoacoustic measurement, and further comprising determining a change in reflectivity of the probe beam as a function of a time delay between each pump pulse and a probe pulse for the photoacoustic measurement when the phase modulator does not phase modulate the one or more pulses.

50. 50. The method of claim 49, wherein the one or more detectors comprise a first detector for detecting a P-state polarization of the reflected probe pulse and a second detector for detecting an S-state polarization of the reflected probe pulse, both the first detector and the second detector being used for the time-resolved MOKE measurements, and only one of the first detector and the second detector being used for the photoacoustic measurements and the ellipsometric measurements.

51. 51. The method of claim 50, further comprising demodulating signals from the first detector and the second detector generated based on the received reflected probe pulse from the target sample using a lock-in amplifier coupled to the first detector and the second detector.

52. 46. ​​The method of claim 45, further comprising: not selecting the pump arm such that the target sample is not irradiated with the one or more pump pulses, and periodically phase-modulating the one or more probe pulses using the phase modulator for a static MOKE measurement; and determining 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 the one or more probe pulses.

53. 46. ​​The method of claim 45, further comprising moving a movable element to select the pump arm.

54. 46. ​​The method of claim 45, wherein generating the pulsed light beam with the pulsed light source comprises generating the pulsed light beam with a pulsed laser.

55. 46. ​​The method of claim 45, further comprising controlling a time delay between illumination of the target sample with each pump pulse and illumination of the target sample with a corresponding probe pulse with a variable delay operating on the pulsed light beam.

56. 56. The method of claim 55, wherein the variable delay is in the pump arm and operates on the pulsed light beam in the selectable pump arm.

57. irradiating the target sample with the one or more pump pulses at normal incidence using a first set of optical elements; 46. ​​The method of claim 45, further comprising: irradiating the one or more probe pulses at oblique incidence to the target sample using a second set of optical elements.

58. 1. An apparatus for measuring at least one property including a magnetic property of a target sample using at least one of a time-resolved magneto-optical Kerr effect (MOKE) measurement, an ellipsometry measurement, or a combination thereof, the apparatus comprising: means for generating a pulsed light beam; means for receiving at least a portion of the pulsed light beam and for selecting a pump arm to irradiate the target sample with one or more pump pulses to induce a transient perturbation in the target material, and / or for not selecting the pump arm such that the target sample is not irradiated with the one or more pump pulses; means for receiving at least a portion of the pulsed light beam at a probe arm and illuminating 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 the one or more polarized probe pulses; means for detecting a reflected probe pulse from the target sample; and means for determining an effect on the polarization state of the probe pulse based on the reflected probe pulse due to magnetic properties of the target sample for the time-resolved MOKE measurement when the pump arm is selected, and for determining an effect on the polarization state of the probe pulse based on the reflected probe pulse due to non-magnetic properties of the target sample for the ellipsometry measurement when the pump arm is not selected.

59. 1. An apparatus for measuring at least one property including a magnetic property of a target sample using at least one of a time-resolved magneto-optical Kerr effect (MOKE) measurement, a photoacoustic measurement, or a combination thereof, the apparatus comprising: a pulsed light source for generating a pulsed light beam; a pump arm configured to receive at least a portion of the pulsed light beam and to irradiate the target sample with one or more pump pulses to induce transient perturbations in the target material; a probe arm configured to receive at least a portion of the pulsed light beam and to illuminate 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 the one or more polarized probe pulses for the time-resolved MOKE measurement and configured not to phase modulate the one or more pulses for the photoacoustic measurement; one or more detectors for receiving reflected probe pulses from the target sample; and at least one processor coupled to the one or more detectors and configured to measure an effect on the polarization state of the probe pulse due to magnetic properties of the target sample for the time-resolved MOKE measurement when the phase modulator periodically phase-modulates the one or more probe pulses, and to measure a change in reflectivity of the probe beam as a function of a time delay between each pump pulse and a probe pulse for the photoacoustic measurement when the phase modulator does not phase-modulate the one or more pulses.

60. 60. The apparatus of claim 59, wherein the at least one processor is configured to measure at least one of the following characteristics, or a combination thereof: magnetization dynamics, magnetic switching, or control of individual bits, for the time-resolved MOKE measurement when the phase modulator periodically phase-modulates the one or more probe pulses, or to measure at least one of the following characteristics, or a combination thereof: bottom electrode thickness measurement, or metal layer thickness, magnetic random access memory (MRAM), for the photoacoustic measurement when the phase modulator does not phase-modulate the one or more pulses.

61. 60. The apparatus of claim 59, wherein the pump arm is selectable to cause the transient perturbation in the target material when the pump arm is selected and to not irradiate the target sample when the pump arm is not selected, the pump arm is selected for the time-resolved MOKE measurement or the photoacoustic measurement and the pump arm is not selected, the phase modulator periodically phase modulates the one or more probe pulses for a static MOKE measurement, and the 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 the one or more probe pulses.

62. 62. The apparatus of claim 61, further comprising a movable element for selecting the pump arm.

63. 60. The apparatus of claim 59, wherein the pump arm comprises an amplitude modulator that periodically modulates the intensity of the one or more pump pulses for the time-resolved MOKE or photoacoustic measurements.

64. 60. The apparatus of claim 59, wherein the phase modulator is configured to periodically modulate the intensity of the one or more polarized probe pulses for the photoacoustic measurement.

65. 60. The apparatus of claim 59, wherein the pulsed light source for generating the pulsed light beam comprises a pulsed laser.

66. 60. The apparatus of claim 59, further comprising a variable delay operative with the pulsed light beam to control a time delay between illumination of the target sample by each pump pulse and illumination of the target sample by a corresponding probe pulse.

67. 67. The apparatus of claim 66, wherein the variable delay is in the pump arm and operates on the pulsed light beam in the pump arm.

68. a first set of optical elements configured to irradiate the one or more pump pulses onto the target sample at normal incidence; 60. The apparatus of claim 59, further comprising: a second set of optical elements configured to irradiate the one or more probe pulses onto the target sample at oblique incidence.

69. 60. The apparatus of claim 59, wherein the phase modulator in the probe arm phase modulates the one or more polarized probe pulses for ellipsometric measurements of the target sample.

70. 70. The apparatus of claim 69, wherein the pump arm is selectable to cause the transient perturbation 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 is selected for the time-resolved MOKE measurement or the photoacoustic measurement or the time-resolved ellipsometry measurement, the pump arm is not selected, and the phase modulator periodically phase modulates the one or more probe pulses for the ellipsometry measurement.

71. 70. The apparatus of claim 69, wherein the pump arm comprises an amplitude modulator that periodically modulates the intensity of the one or more pump pulses for the time-resolved MOKE measurement, the photoacoustic measurement, or the time-resolved ellipsometry measurement.

72. 70. The apparatus of claim 69, wherein the one or more detectors comprise a first detector for detecting a P-state polarization of the reflected probe pulse and a second detector for detecting an S-state polarization of the reflected probe pulse, both the first detector and the second detector being used for the time-resolved MOKE measurements, and only one of the first detector and the second detector being used for the photoacoustic measurements and the ellipsometry measurements.

73. 73. The apparatus of claim 72, wherein the first detector and the second detector are coupled to a lock-in amplifier for demodulating signals from the first detector and the second detector generated based on the received reflected probe pulse from the target sample.

74. 1. A method for measuring at least one property, including a magnetic property, of a target sample using at least one of a time-resolved magneto-optical Kerr effect (MOKE) measurement, a photoacoustic measurement, or a combination thereof, the apparatus comprising: generating a pulsed light beam using a pulsed light source; receiving at least a portion of the pulsed light beam at a pump arm and irradiating the target sample with one or more pump pulses to induce a transient perturbation in the target material; 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 the one or more polarized probe pulses for the time-resolved MOKE measurement and configured to not phase modulate the one or more pulses for the photoacoustic measurement; detecting reflected probe pulses from the target sample with one or more detectors; determining an effect on the polarization state of the probe pulse based on the reflected probe pulse due to magnetic properties of the target sample for the time-resolved MOKE measurement when the phase modulator periodically phase-modulates the one or more probe pulses, and determining a change in reflectivity of the probe beam as a function of time delay between each pump pulse and probe pulse based on the reflected probe pulse for the photoacoustic measurement when the phase modulator does not phase-modulate the one or more pulses.

75. 75. The method of claim 74, wherein determining the effect on the polarization state of the probe pulse comprises determining at least one or a combination of properties of magnetization dynamics, magnetic switching, or control of individual bits for the time-resolved MOKE measurements when the phase modulator periodically phase-modulates the one or more probe pulses, and / or determining a change in reflectivity of the probe beam as a function of time delay between each pump pulse and probe pulse comprises determining at least one or a combination of properties of bottom electrode thickness or metal layer thickness magnetic random access memory (MRAM) for the photoacoustic measurements when the phase modulator does not phase-modulate the one or more pulses.

76. 75. The method of claim 74, further comprising selecting the pump arm to cause the transient perturbation in the target material and not selecting the pump arm so that the target sample is not irradiated with the one or more pump pulses, wherein the pump arm is selected for the time-resolved MOKE measurement or the photoacoustic measurement, the pump arm is not selected and the phase modulator periodically phase modulates the one or more probe pulses for a static MOKE measurement, and when the pump arm is not selected and the phase modulator periodically phase modulates the one or more probe pulses, the at least one processor is configured to measure the magnetic properties of the target sample based on static MOKE.

77. 77. The method of claim 76, further comprising moving a movable element to select the pump arm.

78. 75. The method of claim 74, further comprising periodically modulating the intensity of the one or more pump pulses using an amplitude modulator in the pump arm for the time-resolved MOKE or photoacoustic measurements.

79. 75. The method of claim 74, further comprising periodically modulating the intensity of the one or more polarized probe pulses with the phase modulator for the photoacoustic measurements.

80. 75. The method of claim 74, wherein generating the pulsed light beam with the pulsed light source comprises generating the pulsed light beam with a pulsed laser.

81. 75. The method of claim 74, further comprising controlling a time delay between illumination of the target sample with each pump pulse and illumination of the target sample with a corresponding probe pulse having a variable delay operating on the pulsed light beam.

82. 82. The method of claim 81, wherein the variable delay is in the pump arm and operates on the pulsed light beam in the pump arm.

83. irradiating the target sample with the one or more pump pulses at normal incidence using a first set of optical elements; 75. The method of claim 74, further comprising: irradiating the one or more probe pulses at oblique incidence to the target sample using a second set of optical elements.

84. 75. The method of claim 74, further comprising performing an ellipsometric measurement of the target sample by phase modulating the one or more polarized probe pulses with the phase modulator in the probe arm.

85. 85. The method of claim 84, wherein the pump arm is selectable to cause the transient perturbation 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 is selected for the time-resolved MOKE measurement or the photoacoustic measurement or the time-resolved ellipsometry measurement, the pump arm is not selected, and the phase modulator periodically phase modulates the one or more probe pulses for the ellipsometry measurement.

86. 85. The method of claim 84, further comprising periodically modulating the intensity of the one or more pump pulses using an amplitude modulator in the pump arm for the time-resolved MOKE measurement or the photoacoustic measurement or the time-resolved ellipsometry measurement.

87. 85. The method of claim 84, wherein the one or more detectors comprise a first detector for detecting a P-state polarization of the reflected probe pulse and a second detector for detecting an S-state polarization of the reflected probe pulse, both the first detector and the second detector being used for the time-resolved MOKE measurements, and only one of the first detector and the second detector being used for the photoacoustic measurements and the ellipsometric measurements.

88. 90. The method of claim 87, further comprising demodulating signals from the first detector and the second detector generated based on the received reflected probe pulse from the target sample using a lock-in amplifier coupled to the first detector and the second detector.

89. 1. An apparatus for measuring at least one property including a magnetic property of a target sample using at least one of a time-resolved magneto-optical Kerr effect (MOKE) measurement, a photoacoustic measurement, or a combination thereof, the apparatus comprising: means for generating a pulsed light beam; means for receiving at least a portion of the pulsed light beam at a pump arm and irradiating the target sample with one or more pump pulses to induce a transient perturbation in the target material; a 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 the one or more polarized probe pulses for the time-resolved MOKE measurements and configured to not phase modulate the one or more pulses for the photoacoustic measurements; means for detecting a reflected probe pulse from the target sample; and means for determining an effect on the polarization state of the probe pulse due to magnetic properties of the target sample based on the reflected probe pulse for the time-resolved MOKE measurement when the phase modulator periodically phase-modulates the one or more probe pulses, and for determining a change in reflectivity of the probe beam as a function of time delay between each pump pulse and probe pulse based on the reflected probe pulse for the photoacoustic measurement when the phase modulator does not phase-modulate the one or more pulses.

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