Phase-resolved optical metrology for substrates

Abstract

The present method and apparatus provides phase-resolved optical metrology for determining the quality of a substrate and a film thereon. To improve the metrology information obtained from a film layer on a substrate, transmitted and reflected signals are combined using both amplitude and phase information.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION

[0001] Embodiments of the present principles relate generally to semiconductor processing of semiconductor substrates. [Background technology]

[0002] During semiconductor processing, various materials are deposited or grown on a substrate, forming various structures. Metrology is performed on the processed substrate to ensure that the necessary parameters for achieving high-quality semiconductors are met. Metrology systems can be used, for example, to check the quality and composition of films using optical metrology techniques and to determine the absorption curve of a substrate over a range of wavelengths. Traditionally, reflection and transmission absorption curves are obtained by detecting the amplitude of various wavelengths reflected from and transmitted through the substrate surface, respectively. In order to subtract substrate properties from the data, information about the substrate must be known prior to metrology processing. However, the inventors have recognized that such metrology systems reduce throughput and even limit metrology testing in situations where substrate information is unavailable. Furthermore, the inventors have recognized that as layer thickness and composition variations require increasingly higher resolution, amplitude-based metrology systems are unable to meet these increasing demands.

[0003]

[0003] Accordingly, the present inventors have provided a method and apparatus for significantly increasing the resolution capabilities of optical metrology systems while increasing test throughput and reducing costs. Summary of the Invention

[0004] A method and apparatus for phase-resolved optical metrology is provided.

[0005]

[0005] In some embodiments, a method for determining an absorption profile for a film on a substrate includes irradiating the substrate with a broadband spectrum, obtaining an amplitude and phase for a reflected beam from a first surface of the substrate, obtaining an amplitude and phase for a transmitted beam that passes through the substrate and propagates beyond a second surface of the substrate, forming a model of the substrate by concatenating the amplitude and phase of the reflected beam and the amplitude and phase of the transmitted beam to form a phase-resolved signal including a first sub-signal at a first end of a standing wave ratio (SWR) envelope that resolves information about the top layer and a second sub-signal at a second end of the SWR envelope that resolves information about the substrate bulk, determining an absorption profile of the film on the substrate and the substrate based on the model of the substrate, and using the absorption profile to perform corrective measures during processing of the film or the substrate.

[0006]

[0006] In some embodiments, the method may further include a film that is an epitaxial layer; film or substrate processing including physical vapor deposition, chemical vapor deposition, or resist layer deposition; a film having a thickness of one atomic layer; a film that is a stack of two or more film layers; a substrate that is silicon, silicon carbide, quartz, or sapphire; a broadband spectrum including wavelengths from about 2 microns to about 20 microns; a single light source used to irradiate the substrate; obtaining the amplitude and phase of the transmitted beam and the amplitude and phase of the reflected beam, including scanning at a speed that resolves the amplitude and phase fringes; the method being performed without prior substrate pre-measurement; and / or a film composed of an unknown material.

[0007] In some embodiments, a non-transitory computer-readable storage medium is provided having instructions stored thereon that, when executed, cause a method for determining an absorption profile for a film on a substrate to be performed, the method may include illuminating the substrate with a broadband spectrum, acquiring an amplitude and phase for a reflected beam from a first surface of the substrate, acquiring an amplitude and phase transmitted through the substrate and propagating beyond a second surface of the substrate, forming a model of the substrate by concatenating the amplitude and phase of the reflected beam and the amplitude and phase of the transmitted beam to form a phase-resolved signal including a first sub-signal at a first end of a standing wave ratio (SWR) envelope that resolves information about a top layer and a second sub-signal at a second end of the SWR envelope that resolves information about the substrate bulk, and determining an absorption profile of the film on the substrate and the substrate based on the model of the substrate.

[0008]

[0008] In some embodiments, the non-transitory computer-readable storage medium may further include a method involving obtaining the amplitude and phase of a transmitted beam and the amplitude and phase of a reflected beam, including scanning a broadband spectrum including wavelengths from about 2 microns to about 20 microns, a film that is a stack of two or more film layers, at a speed that resolves amplitude and phase fringes, and / or a method that is performed without prior substrate pre-measurement.

[0009]

[0009] In some embodiments, a metrology device for determining an absorption profile for a film on a substrate may include a broadband illumination source configured to generate an infrared (IR) illumination band beam, a beam splitter configured to split the IR illumination band beam, a fixed mirror configured to receive the IR illumination band beam, a movable mirror configured to receive the IR illumination band beam and move to change the resolution of the metrology device, a reflection detector configured to obtain the amplitude and phase of the reflection of the IR illumination band beam, a transmission detector configured to obtain the amplitude and phase of the transmission of the IR illumination band beam through the film and substrate, and a controller configured to change the step distance of the movable mirror to less than the shortest wavelength in the IR illumination band beam or to change the speed of the movable mirror to the lowest possible continuous speed, wherein the reflection detector and transmission detector are configured to detect at a sampling rate greater than the rate divided by the shortest wavelength of the illumination band beam.

[0010] In some embodiments, the metrology device may further include an IR radiation band beam comprising wavelengths between about 2 microns and about 25 microns, a step distance of less than about 2 microns, and / or a sampling rate that is about 100 Hz.

[0011]

[0011] Other and further embodiments are disclosed below.

[0012]

[0012] Embodiments of the present principles, briefly summarized above and described in detail below, can be understood by reference to exemplary embodiments of the present principles as illustrated in the accompanying drawings. However, since the present principles are susceptible to other equally effective embodiments, the accompanying drawings illustrate only typical embodiments of the present principles and therefore should not be considered limiting in scope. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view of a metrology device that detects only amplitude data, in accordance with some embodiments of the present principles; [Figure 2] 10 shows a spectral plot based on amplitude only in accordance with some embodiments of the present principles; [Figure 3] 1 is a cross-sectional view of a metrology device for detecting amplitude and phase data, in accordance with some embodiments of the present principles; [Figure 4] 10 shows a spectral plot based on amplitude and phase data, according to some embodiments of the present principles; [Figure 5] 10 shows maximum and minimum envelopes of a spectral plot, according to some embodiments of the present principles; [Figure 6] 10 shows a spectral plot of amplitude and phase test data, in accordance with some embodiments of the present principles; [Figure 7] 1A-1C are cross-sectional views of reflective and transmissive variations of a substrate and a film, according to some embodiments of the present principles; [Figure 8] 1 is a cross-sectional view of a metrology device based on FTIR (Fourier Transform Infrared) analysis, in accordance with some embodiments of the present principles; DETAILED DESCRIPTION OF THE INVENTION

[0014]

[0021] To facilitate understanding, identical elements common to the figures have been designated using the same reference numerals where possible. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further description.

[0015]

[0022] The method and apparatus provide phase-resolved optical metrology for determining substrate quality. Transmitted and reflected signals are combined using both amplitude and phase information to improve metrology information obtained from film layers on a substrate. Using this principle, improvements in throughput, cost, sensitivity, and accuracy over conventional methods can potentially be achieved by a factor of 10 or more. Furthermore, the need to measure a bare substrate prior to metrology testing is completely eliminated, expanding testing scenarios, reducing metrology costs, and creating "on-demand" metrology testing not previously possible. This principle may further have the advantage of improving the accuracy of metrology measurements to detect subtle substrate changes caused by processes such as, but not limited to, epitaxial growth, annealing, and diffusion. The method can be used with films deposited by physical or chemical vapor deposition, epitaxially grown films, and / or resists, etc.

[0016]

[0023] The methods and apparatus of the present principles utilize phase-resolved optical metrology techniques, such as, but not limited to, Raman spectroscopy or Fourier transform infrared (FTIR) spectroscopy. The techniques provided herein are not limited to infrared wavelengths and can be applied to other wavelengths. For simplicity's sake, the examples herein are based on FTIR spectroscopy, but this is not meant to be limited to FTIR-based spectroscopy alone. Due to the reduced sensitivity of FTIR in highly processed ultrathin films, conventional FTIR methods are unusable for processing and device development. Conventional FTIR methods require substrate pre-measurement, which increases costs and reduces throughput. Furthermore, conventional FTIR methods use two independent channels: a reflectance channel containing only amplitude signals and a transmission channel. The inventors have discovered that using only amplitude signals in two separate channels introduces errors and results in incomplete FTIR measurements.

[0017]

[0024] In some embodiments, the phase signal of the FTIR measurement of the substrate's reflected and also transmitted signals is used to improve signal accuracy and / or sensitivity. The amplitude and phase signals of the reflected and transmitted signals are combined together, enabling use with ultra-thin films and advanced processes, enabling "on-demand" FTIR-based metrology without the need for prior measurement of the bare substrate. The phase of the FTIR signal is measured by setting test parameters that spectrally resolve the phase of the transmitted and reflected signals. The phase-resolved signal generates two sub-signals at either end of the standing wave ratio (SWR) envelope, one sub-signal resolving the film layer on top of the substrate, and the other sub-signal containing additional substrate bulk information. In doing so, FTIR workflow issues are resolved (e.g., significantly improving FTIR sensitivity, throughput, and cost by eliminating the need for bare substrate pre-measurement; enabling applications that were previously prohibited by a lack of substrate pre-processing information and creating an on-demand FTIR solution that is particularly important in high volume manufacturing and production; improving the accuracy of FTIR measurements as substrates can change with processing; and / or coupling reflection and transmission channels through the bulk substrate, further enhancing the value of FTIR analysis).

[0018]

[0025] The method and apparatus of the present principles can be used to perform metrology on substrates with known or unknown films thereon. The substrate can be, for example, silicon, silicon carbide, quartz, sapphire, and the like. The substrate provides reflection from both sides (top and bottom) and can be treated as an etalon (described in more detail below). The substrate is exposed to a single illumination source and does not require additional external forces, probes, or effects to generate the response that needs to be measured. The present principles simultaneously detect reflected and transmitted emissions from the illumination source and utilize analytical / numerical co-optimization of the captured reflected and transmitted data. All diffraction orders used in the analysis are in the frequency domain. The metrology data is used to identify intrinsic properties (non-transient properties) of the temporally static substrate (and film layer). In some embodiments, existing hardware can be used without hardware modifications, improving the sensitivity of the metrology device without expensive modifications. The resulting absorption profiles obtained by the metrology techniques herein can be used to analyze film or substrate materials to detect properties not obtainable by conventional metrology techniques, such as doping levels, the presence of specific molecular bonds, annealing effects, etc. The resulting absorption profiles can also be used to perform corrective actions during film and substrate processing for quality control, such as thickness, composition, and / or purity.

[0019]

[0026] The diagram 100 of FIG. 1 illustrates a metrology device 102, such as, but not limited to, an FTIR-based metrology system, that uses an illumination source device 104, a reflectance detector 106, and a transmission detector 108. In some embodiments, the illumination source device 104 can be a broadband illumination source. An illumination beam 112 is directed toward a substrate 122 having a film layer 124. In some embodiments, the film layer 124 can include two or more film stacks. A first reflected beam 114 is detected by the reflectance detector 106. A first transmitted beam 116 propagates through the substrate 122 and the film layer 124, generating a first reflected-transmitted beam 120 and a second reflected-transmitted beam 118. The second reflected-transmitted beam 118 is detected by the transmission detector 108. The first reflected-transmitted beam 120 forms a second reflected beam 126 and a third transmitted beam 128. The second reflected beam 126 is detected by the reflectance detector 106. The third transmitted beam 128 forms a fourth transmitted beam 130 that is detected by the transmission detector 108. Although only a limited number of reflected and transmitted beams are shown in Figure 1, many more transmitted and reflected beams are formed and detected as the substrate 122 and film layer 124 are illuminated by the illumination source device 104.

[0020]

[0027] The controller 150 controls the operation of the metrology device 102, either through direct control of the metrology device 102 or, alternatively, by controlling a computer (or controller) associated with the metrology device 102. During operation, the controller 150 enables data collection and feedback from each system to optimize the performance of the metrology device 102 in detecting the absorption properties of the substrate 122 and film layer 124. The controller 150 generally includes a central processing unit (CPU) 152, memory 154, and support circuits 156. The CPU 152 may be any form of general-purpose computer processor usable in an industrial environment. The support circuits 156 are conventionally coupled to the CPU 152 and may include cache, clock circuits, input / output subsystems, power supplies, etc. Software routines (e.g., methods described herein) may be stored in the memory 154 and, when executed by the CPU 152, may transform the CPU 152 into a special-purpose computer (controller 150). The software routines may be further stored and / or executed by a second controller (not shown) located remotely from the metrology device 102.

[0021]

[0028] Memory 154 is in the form of a computer-readable storage medium containing instructions that, when executed by CPU 152, facilitate semiconductor process and device operation. The instructions in memory 154 are in the form of a program product (e.g., a program implementing the methods of the present principles). The program code may conform to any one of numerous different programming languages. In one embodiment, the present disclosure may be implemented as a program product stored on a computer-readable storage medium for use with a computer system. One or more programs in the program product define the functions of aspects (including the methods described herein). Exemplary computer-readable storage media include, but are not limited to, non-writable storage media on which information is permanently stored (e.g., a read-only memory device in a computer such as a CD-ROM disk readable by a CD-ROM drive, flash memory, a ROM chip, or any type of solid-state nonvolatile semiconductor memory), and writable storage media on which changeable information is stored (e.g., a floppy disk in a diskette drive or hard disk drive, or any type of solid-state random-access semiconductor memory). Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, constitute aspects of the present principles.

[0022]

[0029] If the metrology device 102 is configured to detect only the amplitude of the transmitted and reflected beams, the spectral plot 200 shown in FIG. 2 can be obtained for either the transmitted or reflected beam. For example, an amplitude-only reflectance curve 206 can be obtained by plotting the detected amplitude reflectance data (from the reflectance detector 106) as spectrum 202 versus amplitude 204. Generally, the amplitude-only reflectance curve 206 shows an average value over a spectral range. In a similar manner, a transmission curve (not shown) can also be obtained by plotting the detected transmission data (from the transmission detector 108) as spectrum 202 versus amplitude 204. The transmission curve also shows an average value over a spectral range.

[0023]

[0030] In diagram 300 of Figure 3, metrology system 102 has been modified to incorporate the method of the present principles. Illumination source apparatus 104A has been modified to enable reflection detector 106 and transmission detector 108 to have higher detection resolution so that they can obtain phase information as well as amplitude information of the transmitted and reflected signals. First reflected beam 114A and second reflected beam 126A now contain phase information that can be detected by reflection detector 106. Similarly, second reflected transmitted beam 118A and fourth transmitted beam 130a now contain phase information that can be detected by transmission detector 108.

[0024]

[0031] If the metrology device 102 is configured to detect the amplitudes of the transmitted and reflected beams, the spectral plot 400 shown in FIG. 4 can be obtained for either the transmitted or reflected beam. For example, an amplitude and phase reflectance curve 402 can be obtained by plotting the detected amplitude and phase reflectance data (from the reflectance detector 106) as spectrum 202 versus amplitude 204. Generally, the amplitude and phase reflectance curve 402 exhibits substantially more detail (e.g., additional peak and valley detail) than the amplitude-only reflectance curve 206 of FIG. 2 . A similar spectral plot can be constructed for the amplitude and phase transmission data obtained from the transmission detector 108. A standalone analyzer or an integrated analyzer (e.g., the controller 150) can be used to further process the amplitude and phase reflectance curve 402, as shown in the spectral plot 500 of FIG. 5 . A best-fit process can be used to obtain maximum amplitude and phase reflectance curves 502 and minimum amplitude and phase reflectance curves 504. The maximum amplitude and phase reflectance curves and minimum amplitude and phase reflectance curves can also be calculated based on data points from the amplitude and phase reflectance curve 402. Similar processing is performed on the amplitude and phase transmission curves to determine the maximum amplitude and phase transmission curves and the minimum amplitude and phase transmission curves (not shown).

[0025]

[0032] In the spectral plot 600 of FIG. 6 , actual data samples are shown for amplitude and phase reflectance data forming an amplitude and phase reflectance curve 608. For comparison, an amplitude-only reflectance curve 606 is also shown. The data is plotted as amplitude 604 versus spectrum 602. As described above and in more detail below, a maximum amplitude and phase reflectance curve 610 and a minimum amplitude and phase reflectance curve 612 are determined. As shown in FIG. 6 , the amplitude-only reflectance curve 606 provides less detailed information than the amplitude and phase reflectance curve 608 (the amplitude-only reflectance curve 606 is less sensitive). For example, peak 614 of the amplitude and phase reflectance curve 608 is nearly removed from peak 616 of the amplitude-only reflectance curve 606. Similar minimum data is also not available from the amplitude-only reflectance curve 606.

[0026]

[0033] To obtain the absorption properties of any film layer on a substrate and the substrate without prior information (e.g., the properties of the bare substrate, which are typically required for FTIR processing), the substrate and film layers are modeled as an asymmetric, lossy Fabry-Perot etalon. The substrate is asymmetric because only one side of the substrate has a film layer that affects the optical properties of the substrate. The substrate is lossy (light-absorbing). This is desirable for determining the properties of the substrate and film. The substrate is treated as a resonator or fixed etalon based on the principle of Fabry-Perot interferometry (an optical resonator with two parallel reflective surfaces). The substrate reflects infinitely within the substrate, but the internal reflections ultimately converge to a single beam with a single phase, which can be determined as a converging infinite series. Based on this modeling, the values ​​of the absorption parameters of the film and substrate can be determined using the following equations. See diagram 700 in Figure 7 for the variable definitions in the equations. The amplitude of the transmitted beam 706 formed from the incident beam 702 is given by Equation 1: where R1 710 is the reflection coefficient of the surface of the substrate with a film, R2 712 is the reflectance of the surface of the substrate without a film, α (alpha) is the absorption, l (length) 708 is the thickness of the film and substrate, Φ (phi) is the combined phase of the film phase and the substrate phase, prop is the propagation through the substrate and film, f is the film, and sub is the substrate. The amplitude of the transmitted beam 704 formed from the incident beam 702 is given by Equation 2: TIFF2025540345000003.tif44170The total absorption or loss for propagation through the substrate and film is given by Equation 3, where d is the distance or thickness and k is a given value of the spectrum. formula 3 TIFF2025540345000004.tif28170The phase is found by Equation 4 for a given spectral value. TIFF2025540345000005.tif30170The upper limit (maximum value) and lower limit (minimum value) envelope can be calculated using Equation 5. TIFF2025540345000006.tif31170 The minimum and maximum phase values ​​for a given vector value can be determined by Equation 6. TIFF2025540345000007.tif30170The phase delta between adjacent peaks in the phase can be calculated using Equation 7. TIFF2025540345000008.tif45170

[0027]

[0034] To determine the absorption values ​​of the substrate and film, the maximum and minimum envelopes determined from the amplitude and phase data from reflection are used along with the maximum and minimum envelopes determined from the amplitude and phase data from transmission. The reflection data generates two equations (maximum and minimum envelope curves) and the transmission data generates two equations (maximum and minimum envelope curves), for a total of four equations. Thus, Equation 1 and Equation 2, respectively, are: For TIFF2025540345000009.tif9170 (from Equation 6), generate two equations (four in total): A'trans and A' refl @ TIFF2025540345000010.tif9170 can be obtained from the raw FTIR spectrum. The four equations are solved in four unknowns that can be numerically optimized. Generated using TIFF2025540345000011.tif9170. TIFF2025540345000012.tif9170, so using Equation 7, Further optimization of TIFF2025540345000013.tif8170, followed by Optimize the absorption profiles of both the substrate and the film. The resulting file is TIFF2025540345000015.tif9170.

[0028]

[0035] As an exemplary implementation, although not intended to be limited to FTIR measurements, a metrology device 802 usable as an in-line FTIR assembly is shown in diagram 800 of FIG. 8. The metrology device 802 includes an illumination source device 804. The illumination source device 804 includes a broadband infrared source 810 that provides an illumination beam 820 to a beam splitter 818. The beam splitter 818 splits the illumination beam 820 to a fixed mirror 812 and to a movable mirror 814 that can move 816 a distance X for a given step. The metrology device 802 further includes a reflection detector 806 and a transmission detector 808 that detect reflection and transmission, respectively, through the substrate 122 and the film layer 124. The metrology device 802 includes a controller 150 that is used to control the metrology device 802 and to perform metrology processing and analysis of the substrate 122 and the film layer 124. To obtain transmission or reflection phase information, metrology tool 802 uses one of two exemplary techniques with the FTIR process recipe set to a low setting for spectral resolution. The first exemplary technique is to set the interferometer arm (not shown) on movable mirror 814 to a step size (X distance) that is smaller than the shortest wavelength in the illumination band of broadband infrared light source 810. For example, if the wavelength of the illumination band is between 2 μm and 25 μm, the step size would be less than 2 μm (e.g., 1 μm).

[0029]

[0036] A second exemplary technique is to use the shortest wavelength of the illumination band (e.g., v / λ shortest The key is to set the interferometer arm on the movable mirror 814 at the lowest possible continuous velocity v (e.g., 1 μm / s) using a high-speed detector with a sampling rate greater than the velocity multiplied by (μ = 100 μm / s / 1 μm = 100 Hz). Spectral data should be collected simultaneously with minimal noise for both the reflected and transmitted channels. For each reflected / transmitted channel, the controller 150 or other analyzer can create two spectra from interpolation of the minimum and maximum values, resulting in a total of four spectra. For each of the four new spectra, TIFF2025540345000016.tif9170 as a variable parameter, and iteratively optimize equations (1) and (2) by minimizing the residual between the equations above in a numerical fit, until the residual is less than a reasonable value (e.g., less than 1% of the difference in the area under the curve). Any other numerically or analytically equivalent method can also be used, which allows for simultaneous optimization of equations (1) through (7). The solution for TIFF2025540345000017.tif9170 can be derived.

[0030]

[0037] Embodiments according to the present principles may be implemented in hardware, firmware, software, or any combination thereof. Embodiments may be implemented as instructions stored using one or more computer-readable media, which may be read and executed by one or more processors. A computer-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing platform or a "virtual machine" running on one or more computing platforms). For example, a computer-readable medium may include any suitable form of volatile or non-volatile memory. In some embodiments, a computer-readable medium may include a non-transitory computer-readable storage medium.

[0031]

[0038] While the forgoing is directed to embodiments of the present principles, other and further embodiments of the present principles may be devised without departing from the basic scope thereof.

Claims

1. 1. A method for determining an absorption profile for a film on a substrate, comprising: irradiating the substrate with a broadband spectrum; obtaining an amplitude and a phase of a reflected beam from a first surface of the substrate; obtaining an amplitude and phase for a transmitted beam that is transmitted through the substrate and propagates beyond a second surface of the substrate; forming a model of the substrate by concatenating the amplitude and phase of the reflected beam and the amplitude and phase of the transmitted beam to form a phase-resolved signal including a first sub-signal at a first end of a standing wave ratio (SWR) envelope that resolves information about a top layer, and a second sub-signal at a second end of the SWR envelope that resolves information about a substrate bulk; determining an absorption profile of the film on the substrate and the substrate based on the model of the substrate; using the absorption profile to take corrective action during processing of the film or substrate; A method comprising:

2. The method of claim 1 , wherein the film is an epitaxial layer.

3. The method of claim 1 , wherein the film or substrate treatment comprises physical vapor deposition, chemical vapor deposition, or resist layer deposition.

4. The method of claim 1 , wherein the film has a thickness of one atomic layer.

5. The method of claim 1 , wherein the film is a stack of two or more film layers.

6. The method of claim 1 , wherein the substrate is silicon, silicon carbide, quartz, or sapphire.

7. The method of claim 1 , wherein the broadband spectrum includes wavelengths from about 2 microns to about 20 microns.

8. The method of claim 1 , wherein a single light source is used to illuminate the substrate.

9. The method of claim 1 , wherein acquiring the amplitude and phase of the transmitted beam and the amplitude and phase of the reflected beam comprises scanning at a rate that resolves amplitude and phase fringes.

10. The method of claim 1 , wherein the method is performed without prior substrate pre-measurement.

11. The method of claim 1 , wherein the membrane is composed of an unknown material.

12. 1. A non-transitory computer readable storage medium having instructions stored thereon that, when executed, cause a method for determining an absorption profile for a film on a substrate to be performed, the method comprising: irradiating the substrate with a broadband spectrum; obtaining an amplitude and a phase of a reflected beam from a first surface of the substrate; acquiring amplitude and phase transmitted through the substrate and propagated beyond a second surface of the substrate; forming a model of the substrate by concatenating the amplitude and phase of the reflected beam and the amplitude and phase of the transmitted beam to form a phase-resolved signal including a first sub-signal at a first end of a standing wave ratio (SWR) envelope that resolves information about a top layer, and a second sub-signal at a second end of the SWR envelope that resolves information about a substrate bulk; determining an absorption profile of the film on the substrate and the substrate based on the model of the substrate; 1. A non-transitory computer-readable storage medium comprising:

13. 13. The non-transitory computer-readable storage medium of claim 12, wherein the broadband spectrum includes wavelengths from about 2 microns to about 20 microns.

14. 13. The non-transitory computer-readable storage medium of claim 12, wherein the film is a stack of two or more film layers.

15. 13. The non-transitory computer-readable storage medium of claim 12, wherein acquiring the amplitude and phase of the transmitted beam and the amplitude and phase of the reflected beam comprises scanning at a rate that resolves amplitude and phase fringes.

16. The non-transitory computer-readable storage medium of claim 12 , wherein the method is performed without prior substrate pre-measurement.

17. 1. A metrology apparatus for determining an absorption profile for a film on a substrate, comprising: a broadband illumination source configured to generate a band beam of infrared (IR) illumination; a beam splitter configured to split the IR radiation band beam; a fixed mirror configured to receive the IR radiation band beam; a movable mirror configured to receive the IR radiation band beam and to move to change the resolution of the metrology device; a reflectance detector configured to acquire the amplitude and phase of a reflection of the IR radiation band beam; a transmission detector configured to acquire the amplitude and phase of the transmission of the IR radiation band beam through the film and the substrate; and a controller configured to change the step distance of the movable mirror to less than the shortest wavelength in the IR radiation band beam or change the speed of the movable mirror to the slowest possible continuous speed, and the reflection detector and the transmission detector are configured to detect at a sampling rate greater than the rate divided by the shortest wavelength of the radiation band beam. A measuring device equipped with:

18. 18. The metrology device of claim 17, wherein the IR radiation band beam comprises a wavelength between about 2 microns and about 25 microns.

19. 20. The metrology device of claim 17, wherein the step distance is less than about 2 microns.

20. 18. The measurement device of claim 17, wherein the sampling rate is about 100 Hz.

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