Extended infrared ellipsometry method

Abstract

To provide methods and systems for performing simultaneous spectroscopic measurement of semiconductor structures at ultraviolet, visible and infrared wavelengths.SOLUTION: Wavelength errors are reduced by orienting a direction of wavelength dispersion on a detector 141 surface perpendicularly to the projection of a plane of incidence onto the detector 141 surface. A broad range of infrared wavelengths are detected by the detector 141 that includes multiple photosensitive areas having different sensitivity characteristics. Collected light is linearly dispersed on the detector 141 surface according to the wavelength. Each different photosensitive area is arranged on the detector 141 to sense a different range of incident wavelengths. In this manner, a broad range of infrared wavelengths are detected with a high signal-to-noise ratio by a single detector. These features enable high throughput measurement of high aspect ratio structures with high throughput, precision and accuracy.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The described embodiments relate to metrology systems and methods, more particularly to excellent measurement methods and systems for three-dimensional semiconductor structures.

Background Art

[0002] (Cross-reference to Related Applications) This patent application claims priority under 35 U.S.C. § 119 based on U.S. Provisional Patent Application No. 62 / 279,469, filed on January 15, 2016, entitled "Apparatus and Methods of Extended Infrared Ellipsometry", and incorporates the subject matter of the provisional patent application herein by reference in its entirety.

[0003] Semiconductor devices, such as logic devices and memory devices, are typically manufactured by applying a series of processing steps to a specimen. The features and structural hierarchies of those semiconductor devices are formed by those processing steps. For example, lithography among them is one of the semiconductor manufacturing processes that involves pattern generation on a semiconductor wafer. Other examples of semiconductor manufacturing processes include, but are not limited to, chemical mechanical polishing, etching, deposition, and ion implantation. It is advisable to fabricate a plurality of semiconductor devices on a single semiconductor wafer and then divide them into individual semiconductor devices thereon.

[0004] The metrology process is a process used in various steps during the semiconductor manufacturing process, by which defects on the wafer can be detected and yield improvement can be promoted. Optical metrology techniques have the potential to obtain high throughput without the risk of sample destruction. A number of optical metrology-dependent techniques, such as scatterometry (scattering measurement) and reflectometry (reflection measurement) devices and their related analysis algorithms, are widely used to elucidate the critical dimensions, film thickness, composition, overlay, and other parameters of nanostructures.

[0005] Flash memory architectures are shifting from two-dimensional floating-gate architectures to full three-dimensional geometry. In some examples, film stacks and etched structures are becoming extremely deep (for example, reaching depths of 6 μm). Such high aspect ratio structures present challenges in film measurement and CD measurement. The ability to measure the limit dimensions and determine the pore and trench shapes of these structures is crucial for achieving desired performance levels and device yields.

[0006] Many optical techniques suffer from low signal-to-noise ratios (SNRs), and this is because only a small portion of the illumination light can reach the bottom of high-aspect-ratio features and reflect upward to the detector. In other words, despite the many high-throughput metrology techniques available, reliable CD and film measurements of high-aspect-ratio structures remain difficult. Limit-size small-angle X-ray scatterometry (CD-SAXS), normal incidence reflectometry, and scatterometry are being explored as measurement solutions for high-aspect-ratio structures, but development is still ongoing.

[0007] Cross-sectional scanning electron microscopy (SEM) is a low-throughput disruptive technique and unsuitable for in-line quantization. Atomic force microscopy (AFM) has poor high-aspect-ratio structure measurement capabilities and relatively low throughput. It is still unclear whether CD-SAXS can achieve the high throughput capabilities required by the semiconductor industry. Model-based infrared reflectometry (MBIR) is used for quantizing high-aspect-ratio DRAM structures, but this technique does not achieve the resolution available at shorter wavelengths, and the measurement spot size is too large to be suitable for semiconductor quantization. Please refer to Non-Patent Literature 1, which is incorporated into this application as if it were a complete explanation.

[0008] Optical CD metricing currently lacks the ability to measure detailed profiles of structures with depth and lateral dimensions on the μm scale at high throughput using relatively small spots (e.g., less than 50 μm, more preferably less than 30 μm). Patent Document 1, which is incorporated into this application as if it were a complete explanation by reference, describes infrared spectroscopic ellipsometry (polarization analysis) techniques suitable for characterizing high aspect ratio structures. However, the techniques described therein have problems such as requiring long measurement times for measurements across ultraviolet and infrared wavelengths, low wavelength stability, and a narrow infrared wavelength range during operation. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] U.S. Patent No. 8,860,937 [Patent Document 2] U.S. Patent Application Publication No. 2013 / 0114085 [Non-patent literature]

[0010] [Non-Patent Document 1] "Measuring deep-trench structures with model-based IR," by Gostein et al., Solid State Technology, vol. 49, no. 3, Mar. 1, 2006 [Overview of the project] [Problems that the invention aims to solve]

[0011] In summary, the shrinking feature size and increasing depth of structural features are imposing challenging conditions on optical metrology systems. Without meeting high precision and accuracy requirements, it becomes impossible to weigh increasingly complex targets at high throughput while maintaining cost efficiency. In this context, broadband illumination and data acquisition speed, focusing error, and the infrared wavelength range are significant performance constraints when designing optical metrology systems suitable for high aspect ratio structures. Therefore, there is a need for superior metrology systems and methods that can overcome these constraints. [Means for solving the problem]

[0012] This invention presents a method and system for performing simultaneous spectroscopic measurements of semiconductor structures at ultraviolet, visible, and infrared wavelengths. Spectra including ultraviolet, visible, and infrared wavelengths are measured with high throughput under the same alignment conditions. In this configuration, machine errors, such as wavelength errors, are uniformly corrected across all measurement wavelengths. Simultaneous measurement of a target with infrared, visible, and ultraviolet light within a single system enables precise characterization of complex three-dimensional structures. Generally, relatively long wavelengths penetrate deeply into the structure, thereby suppressing higher-order diffraction and allowing measurement of structures with relatively long pitches. Relatively short wavelengths provide precise dimensional information for structures accessible at relatively short wavelengths (i.e., higher layers), as well as for relatively small CD and roughness features. Longer wavelengths have lower sensitivity to roughness, so by using longer wavelengths, as in certain examples, it becomes possible to measure the dimensional characteristics of targets with relatively rough surfaces or interfaces.

[0013] In one embodiment, a fine focus sensor (FFS) is incorporated into the detection subsystem to provide a measurement input for correcting focusing errors during measurement.

[0014] In one embodiment, a broadband spectrometer system is configured such that the measurement spot is imaged on the detector, and the direction in which the incident plane is aligned on the wafer surface is perpendicular to the wavelength dispersion direction on the detector surface. In this arrangement, the sensitivity of the metering system to focusing errors is greatly reduced. Because the sensitivity to focusing errors is low, precise measurement results can be obtained in a shorter MAM time, and consequently, with higher throughput.

[0015] In one embodiment, a multizone infrared detector is employed in the metric system described herein, which combines several sensitivity bands located at different points on a single detector package. This detector is configured to provide a continuous spectrum of data with different sensitivities depending on the incident point. The focused light is linearly dispersed on the detector surface according to its wavelength. Several photosensitive areas are arranged on the detector to be sensitive to different incident wavelength ranges. In this configuration, a wide range of infrared wavelengths is detected by a single detector with a high signal-to-noise ratio.

[0016] In a further embodiment, the dimensions of the illumination field projected onto the wafer plane along the direction perpendicular to the incident plane are adjusted based on the properties of the target under measurement so that the resulting measurement accuracy and speed are optimized.

[0017] The above is a summary and therefore contains simplifications, generalizations, and omissions of details; and as will be apparent to those skilled in the art, this summary is purely illustrative and not limiting in any way. Other aspects, original features, and advantages of the apparatus and / or process described herein will become apparent in the non-limiting detailed descriptions provided herein. [Brief explanation of the drawing]

[0018] [Figure 1] This figure shows an example 100 of a weighing system according to one embodiment that performs simultaneous spectroscopic measurement of one or more structures at ultraviolet, visible, and infrared wavelengths. [Figure 2]FIG. 200 is a diagram showing an example 200 of a metrology system that performs simultaneous spectroscopic measurement of one or more structures at ultraviolet, visible, and infrared wavelengths according to another embodiment. [Figure 3] FIG. 300 is a diagram showing an example 300 of a metrology system that performs simultaneous spectroscopic measurement of one or more structures at ultraviolet, visible, and infrared wavelengths according to yet another embodiment. [Figure 4] FIG. 400 is a diagram showing an example 400 of a metrology system that performs simultaneous spectroscopic measurement of one or more structures at ultraviolet, visible, and infrared wavelengths according to yet another embodiment. [Figure 5A] FIG. is a top view of a wafer 120 including an illustration of a measurement spot 116 illuminated by an illumination light beam 117 of FIG. 1. [Figure 5B] FIG. is a direct view of the surface of a detector 23 in a conventional metrology system configuration. [Figure 6] FIG. is a diagram showing the occurrence of a focus position error due to a wafer 120. [Figure 7] FIG. is a diagram showing a focused light beam wavelength-dispersed and imaged on the surface of a detector 23 in a conventional configuration. [Figure 8] FIG. is a direct view of the surface of a detector 141 shown in FIG. 1. [Figure 9] FIG. is a direct view of the surface of a detector 150 shown in FIG. 1 according to one embodiment. [Figure 10] FIG. is a diagram showing typical photosensitivity curves of four available indium gallium arsenide (InGaAs) sensors. [Figure 11] FIG. 500 is a diagram showing a method 500 for performing simultaneous spectroscopic measurement of one or more structures at ultraviolet, visible, and infrared wavelengths according to at least one aspect described in the present application. [Figure 12] FIG. 600 is a diagram showing an example 600 of a high aspect ratio NAND structure where the low transmittance to the measurement target structure (s) is a problem.

BEST MODE FOR CARRYING OUT THE INVENTION

[0019] Hereinafter, a background example and certain embodiments of the present invention, in which examples are depicted in the accompanying drawings, will be referred to in more detail.

[0020] This invention presents a method and system for performing simultaneous spectroscopic measurements of semiconductor structures at ultraviolet, visible, and infrared wavelengths. Spectra including ultraviolet, visible, and infrared wavelengths are measured with high throughput under the same alignment conditions. In this configuration, machine errors, such as wavelength errors, are uniformly corrected across all measurement wavelengths. In one embodiment, wavelength errors are reduced by aligning the wavelength dispersion direction on the detector surface to a direction perpendicular to the projection of the incident surface onto the detector surface. In another embodiment, a wide range of infrared wavelengths is detected by a detector having multiple photosensitive areas exhibiting different sensitivity characteristics. Focused light is linearly dispersed on the detector surface according to wavelength. Several photosensitive areas are arranged on the detector to be sensitive to different incident wavelength ranges. In this configuration, a wide range of infrared wavelengths is detected with a high signal-to-noise ratio by a single detector. Each of these features, or a combination thereof, makes it possible to perform high-throughput measurements of high-aspect-ratio structures (e.g., structures with a depth of 1 μm or more) with high throughput, accuracy, and precision.

[0021] By simultaneously measuring a target with infrared, visible, and ultraviolet light within a single system, precise characterization of complex three-dimensional structures becomes possible. Generally, relatively long wavelengths penetrate deeply into the structure, thereby suppressing higher-order diffraction and allowing measurement of structures with relatively long pitches. Relatively short wavelengths provide precise dimensional information for structures accessible at relatively short wavelengths (i.e., higher layers), as well as for relatively small CD and roughness features. Longer wavelengths have lower sensitivity to roughness, so by using longer wavelengths, as in certain examples, it becomes possible to measure the dimensional characteristics of targets with relatively rough surfaces or interfaces.

[0022] In certain embodiments, the semiconductor device spectrometering method and system described herein are applicable to the measurement of high aspect ratio (HAR) structures, large lateral dimension structures, or both. In these embodiments, it is possible to measure the optical limit dimension (CD), film, and composition of semiconductor devices having HAR structures (e.g., NAND, VNAND, TCAT, DRAM, etc.), and more generally, complex devices where low light transmittance into the structure(s) to be measured is a problem. HAR structures often have a hard mask layer for performing etching processes for HAR. The term "HAR structure" as used herein refers to any structure characterized by an aspect ratio greater than 10:1 and potentially having a height of 100:1 or more.

[0023] Figure 1 shows an example 100 of a metering system that performs simultaneous spectroscopic measurements of one or more structures in ultraviolet, visible, and infrared wavelengths. The one or more structures include, for example, at least one HAR structure or at least one large transverse structure. The metering system 100 shown in Figure 1 is configured as a broadband spectroscopic ellipsometer. However, generally, the metering system 100 can be configured as a spectroscopic reflectometer, a scatterometer, an ellipsometer, or any combination thereof.

[0024] The weighing system 100 has an illumination source 110 that generates an illumination light beam 117 incident on the wafer 120. The illumination source 110 is a broadband illumination source that emits illumination light comprising ultraviolet, visible, and infrared spectra. In one embodiment, the illumination source 110 is a laser-sustained plasma (LSP) light source (a so-called laser-driven plasma light source). The pump laser of this LSP light source can be continuous wave or pulsed. A laser-driven plasma light source can supply a considerably larger number of photons than a xenon lamp across the entire wavelength range of 150 nm to 2000 nm. The illumination source 110 can be a single light source or a combination of multiple broadband or discrete wavelength light sources. The light generated by the illumination source 110 includes a continuous spectrum from ultraviolet to infrared (e.g., from vacuum ultraviolet to mid-infrared) or several parts of a continuous spectrum. In general, the illumination light source 110 can be any suitable light source, such as a supercontinuous laser light source, an infrared helium-neon laser light source, an arc lamp, or the like.

[0025] In a further embodiment, the illumination light group is broadband illumination light having a wavelength range with a width of at least 500 nm. Examples of broadband illumination light include wavelengths less than 250 nm and wavelengths greater than 750 nm. Generally, broadband illumination light includes wavelengths from 120 nm to 3000 nm. Depending on the embodiment, broadband illumination light including wavelengths greater than 3000 nm may be used.

[0026] The weighing system 100 shown in Figure 1 has an illumination subsystem configured to direct illumination light 117 to one or more structures formed on a wafer 120. The illumination subsystem in the figure includes a light source 110, one or more optical filters 111, a polarizing member 112, a field diaphragm 113, an aperture diaphragm 114, and an illumination optical system 115. By using one or more optical filters 111, the amount of light emitted to the illumination subsystem, the spectral output, or both can be controlled. In certain examples, one or more multizone filters are used as optical filters 111. The polarizing member 112 generates a desired polarization state, which is emitted from the illumination subsystem. In certain embodiments, the polarizing member is a polarizer, a compensator, or both, and can include any suitable commercially available polarizing member. The polarizing member may be fixed, rotatable with several fixed positions, or continuously rotatable. The illumination subsystem shown in Figure 1 has one polarizing member, but the illumination subsystem may have multiple polarizing members. The field diaphragm 113 controls the field of view (FOV) of the illumination subsystem and may include any suitable commercially available field diaphragm. The aperture diaphragm 114 controls the numerical aperture (NA) of the illumination subsystem and may include any suitable commercially available aperture diaphragm. Light from the illumination source 110 is directed into the illumination optical system 115 and is focused by the illumination optical system onto one or more structures (not shown in Figure 1) on the wafer 120. The illumination subsystem may have any type and arrangement of optical filters 111, polarizer 112, field diaphragm 113, aperture diaphragm 114 and illumination optical system 115 known in the fields of spectroscopic ellipsometry, reflectometry and scatterometry.

[0027] As shown in Figure 1, the illumination light beam 117 passes through the optical filter(group) 111, polarizing member 112, field diaphragm 113, aperture diaphragm 114, and illumination optical system 115, and propagates as a beam from the illumination source 110 to the wafer 120. The beam 117 illuminates the portion of the wafer 120 above the measurement spot 116.

[0028] In certain cases, the beam size of the illumination light group 117 projected onto the surface of the wafer 120 becomes smaller than the size of the measurement target measured on the surface of the specimen. An example of beam shaping technology is described in detail in Patent Document 2 by Wang et al., and the entire details will be incorporated into this application by reference to this document.

[0029] The metering system 100 also includes a focusing optical system subsystem configured to collect light generated by the interaction between one or more structures and the incident illumination beam 117. The focused light beam 127 is focused from the measurement spot 116 by the focusing optical system 122. The focused light 127 passes through the focusing aperture diaphragm 123, polarizing element 124, and field diaphragm 125 of this focusing optical system subsystem.

[0030] The focusing optical system 122 has some focusing element suitable for focusing light from one or more structures formed on the wafer 120. The focusing aperture diaphragm 123 controls the NA of the focusing optical system subsystem. The polarizing element 124 detects the desired polarization state. The polarizing element 124 is a polarizer or compensator. The polarizing element 124 may be fixed, rotatable to several fixed positions, or continuously rotatable. The focusing subsystem shown in Figure 1 has one polarizing element, but the focusing subsystem may have multiple polarizing elements. The focusing field diaphragm 125 controls the FOV of the focusing subsystem. The focusing subsystem captures light from the wafer 120 and directs that light into the focusing optical system 122 and polarizing element 124, focusing it onto the focusing field diaphragm 125. In certain embodiments, the focusing field diaphragm 125 is used as a spectrometer slit in place of the spectrometer of the detection subsystem. However, the focusing aperture 125 may be placed in or near the spectrometer slit 126 of the spectrometer in the detection subsystem.

[0031] The focusing subsystem may have any type and arrangement of focusing optical system 122, aperture diaphragm 123, polarizing element 124, and field diaphragm 125 known in the fields of spectroscopic ellipsometry, reflectometry, and scatterometry.

[0032] In the embodiment shown in Figure 1, the focusing optical system subsystem directs light to multiple spectrometers provided in the detection subsystem. The detection subsystem generates an output in response to the light focused from one or more structures illuminated by the illumination subsystem.

[0033] A detector subsystem according to one embodiment has two or more detectors, each configured to simultaneously detect focused light across several wavelength ranges, including infrared.

[0034] In the embodiment shown in Figure 1, focused light 127 passes through the spectrometer slit 126 and is incident on the diffraction element 128. The diffraction element 128 is configured to diffract one group of wavelengths of the incident light by ±1 order, while diffracting another group of wavelengths of the incident light by 0 order. The portion 129 shown in Figure 1 is the portion of the incident light that includes the ultraviolet spectrum, and is dispersed by the diffraction element 128 with diffraction orders of ±1 and directed toward the detector 141. In addition, the diffraction element 128 is configured to reflect the portion 140 of the incident light that includes infrared wavelengths toward the grating 147 with diffraction order 0. Light 140 is incident on the diffraction element 147, and the diffraction element 147 disperses the portion 148 of the incident light 140 that includes infrared wavelengths with diffraction orders of ±1 and directs it toward the detector 150.

[0035] In the embodiment shown in Figure 1, the diffraction element 128 is a reflective grating element. However, generally, the diffraction element 128 only needs to be configured to subdivide the incident light into several wavelength bands, propagate these wavelength bands along different directions, and then disperse one of these wavelength bands of light so that it is directed onto the detector in some suitable form. In one example, the diffraction element 128 is configured as a transmission grating. In another example, the diffraction element 128 has a beam splitting element that subdivides the beam into several wavelength bands, and a reflective or transmission grating structure that disperses one of these wavelength bands so that it is directed onto the detector 141.

[0036] The reason for adopting the 128 reflection grating is that it exhibits high ±1st-order diffraction efficiency in the ultraviolet spectral region and high 0th-order diffraction efficiency in the infrared spectral region. By employing a reflection grating, losses associated with beam splitting elements (e.g., dichroic beam splitting elements) are avoided.

[0037] The diffracting elements 128 and 147 linearly disperse the first-order diffracted light according to wavelength along the one-dimensional direction of the corresponding two-dimensional detector (i.e., the wavelength dispersion direction noted in Figure 1 for each corresponding detector). For illustrative purposes, light detected at two different wavelengths is shown on the surface of detector 141. The diffracting element 128 creates spatial separation between these two wavelengths of light projected onto the surface of detector 141. In this way, light with a specific wavelength focused from measurement spot 116 is projected onto detector 141 to form spot 142A, and light with a different wavelength focused from measurement spot 116 is projected onto detector 141 to form spot 142B.

[0038] One example detector 141 is a charge-coupled device (CCD) that is sensitive to ultraviolet and visible light (e.g., light with wavelengths from 190 nm to 860 nm). Another example detector 150 is a photodetector array (PDA) that is sensitive to infrared light (e.g., light with wavelengths from 950 nm to 2500 nm). However, other two-dimensional detector technologies can generally be envisioned (e.g., position-sensing detectors (PSDs), infrared detectors, photovoltaic detectors, etc.). Each detector converts incident light into an electrical signal that indicates the spectral intensity of that incident light. For example, the UV detector 141 generates an output signal 154A indicating incident light 129, and the IR detector 150 generates an output signal 154B indicating incident light 148.

[0039] The detection subsystem shown in Figure 1 is arranged so that the focused light propagates simultaneously to all detectors of the weighing system 100. The weighing system 100 also includes an information processing system 130 configured to receive a detection signal 154 containing both UV and IR signals and to estimate the parameters of interest of the structure(s) under measurement based on both UV and IR signals. Simultaneous focusing of UV and IR spectra shortens the measurement time, and all spectra are measured under the same alignment conditions. This allows for the application of a common correction to the entire spectral dataset, making it easier to correct wavelength errors.

[0040] In a further embodiment, a fine focus sensor (FFS) is incorporated into the detection subsystem to provide a measurement input for correcting focusing errors during measurement.

[0041] Figure 2 shows another embodiment 200 of the weighing system, which includes an FFS 146. Among the elements shown in Figure 2, those configured similarly to the weighing system 100 shown in Figure 1 are indicated using the same reference numerals. The zero-order diffracted light 140 shown in Figure 2 is diffracted by the diffracting element 128 and incident on the beam splitting element 143. The beam splitting element 143 can be either transmissive or reflective. The beam splitting element 143 directs the portion of the light in the IR region 145 to the IR grating 147, and the portion of the light below the IR region (i.e., UV to visible region) 144 to the FFS 146. In this way, the UV to visible light diffracted by the diffracting element 128 is detected by the FFS 146. In certain embodiments, the FFS 146 is a photodiode array, and the beam splitting element 143 is a dichroic beam splitter capable of high-efficiency reflection of IR and high-efficiency transmission of UV. In other embodiments, the beam splitting element 143 is a neutral density filter, a partial reflector, an uncoated substrate, or any other focusing element suitable for splitting the beam into two or more lower-intensity beams for individual channels.

[0042] The output (not shown) generated by the FFS146 is sent to the information processing system 130. The information processing system 130 determines the change in the focal position (z position) of the wafer 120 based on the output of the FFS146. All desirable changes in the focal position of the wafer 120 are sent to a wafer positioning system (not shown) that adjusts the z position of the wafer 120 accordingly.

[0043] Figure 3 shows another embodiment 300 of the weighing system, which includes an FFS 146. Among the elements shown in Figure 3, those configured similarly to the weighing system 100 shown in Figure 1 are indicated using the same reference numerals. The zero-order diffracted light 149 shown in Figure 3 is diffracted by the diffracting element 147 and incident on the FFS 146, while the first-order diffracted light 148 incident on the IR detector 150.

[0044] The output (not shown) generated by the FFS146 is sent to the information processing system 130. The information processing system 130 determines the change in the focal position (z position) of the wafer 120 based on the output of the FFS146. All desirable changes in the focal position of the wafer 120 are sent to a wafer positioning system (not shown) that adjusts the z position of the wafer 120 accordingly.

[0045] A further embodiment of the metering system has two or more detectors configured to simultaneously detect light in separate IR spectrum ranges.

[0046] Figure 4 shows another embodiment 400 of the weighing system, which has multiple cascaded IR detectors. Elements shown in Figure 4 that are configured similarly to those in the weighing system 100 shown in Figure 1 are indicated by the same reference numerals. As shown in Figure 4, light 145 is incident on the IR grating 147. The IR grating 147 is configured to first-order diffract a portion 148 of the incident light 145. This first-order diffracted light 148 includes a portion of the IR wavelength range of the incident light 145. Furthermore, the IR grating 147 is configured to zero-order diffract a portion 149 of the incident light 145. This zero-order diffracted light 149 includes IR wavelengths outside the IR wavelength range that constitutes the first-order diffracted light 148. The zero-order diffracted light 149 propagates to the IR grating 151, which first-order diffracts the incident light and directs it toward the IR detector 153. In the embodiment shown in Figure 4, the first-order diffracted light 152 includes the entire IR wavelength of the incident light 149. On the other hand, in other embodiments, the IR grating 151 is configured to diffract only a portion of the incident light in the first order, and the remaining zero-order light is directed to another IR grating. In this way, any number of IR detectors can be cascaded together to detect individual IR wavelength ranges of the focused light 127.

[0047] The embodiments described with reference to Figures 1 to 4 are presented as non-limiting examples, and many other configurations for simultaneously detecting UV, visible, and IR wavelengths can be envisioned. In one example, the metering system can be configured such that the IR wavelength of the focused light 127 is dispersed by first-order diffraction, and the UV wavelength of the focused light 127 is diffracted by zero-order diffraction and directed toward the UV grating and detector. By employing a beam splitting element as in certain examples, the entire spectrum of the focused light can be subdivided into two or more subspectrums. However, employing a diffraction element as described in this application can be beneficial, as it avoids losses associated with beam splitting elements such as dichroic beam splitters, neutral concentration filters, partial reflectors, or uncoated substrates.

[0048] The illumination beam 117 shown in Figure 1 is supplied to the surface of the wafer 120 at a certain oblique angle. In general, illumination light can be supplied to the surface of the wafer 120 at any oblique angle, or any number of oblique angles. In certain embodiments, the illumination light group is supplied to the surface not only with oblique illumination but also with perpendicular incidence (i.e., aligned with the surface normal).

[0049] As shown in Figure 1, the Z-axis is oriented perpendicular to the surface of the wafer 120. The X-axis and Y-axis are in the same plane as the surface of the wafer 120 and are therefore perpendicular to the Z-axis. The incident plane is determined by the principal ray 118 of the illumination beam 117 and the principal ray 121 of the focusing beam 127. The X-axis is aligned with the incident plane, and the Y-axis is perpendicular to that incident plane. In this configuration, the incident plane lies in the XZ plane. The illumination beam 117 is incident on the surface of the wafer 120, its incident angle with respect to the Z-axis is α, and it lies within the incident plane. Because the shape projection of the illumination beam onto the sample surface is performed at an oblique angle, the illumination beam cross-section is elongated along the direction aligned with the incident plane. To give a non-limiting example, if a circular illumination beam is projected onto the wafer surface, the illumination area is elliptical. Thus, generally, oblique illumination of the surface results in a longer projected illumination area compared to the illumination cross-section, and the direction of this elongation is aligned with the direction of the incident plane. Furthermore, the degree of lengthening increases with increasing incidence angle. More specifically, the beam shape is inversely proportional to the cosine value of the incidence angle along the direction of incidence plane. In the absence of diffraction and aberration effects, the projected illumination light remains distortion-free along the direction perpendicular to the illumination plane (e.g., the Y direction).

[0050] Figure 5A is a top view of the wafer 120, including an illustration of the measurement spot 116 illuminated by the illumination beam 117 of Figure 1. In the embodiment shown in Figure 1, the cross-section of the illumination beam 117 is circular (e.g., at the illumination aperture 113). In the case of a circular illumination beam, the measurement spot 116 projected onto the surface of the wafer 120 becomes elliptical, as shown in Figure 5A.

[0051] The measurement spot 116 shown in Figure 1 is projected onto the surfaces of detectors 141 and 150 in a wavelength-dispersive manner. In one embodiment, the spectroscopic component of the metering system described herein is configured such that the plane of light dispersion onto each detector is perpendicular to the projection of the incident plane onto each detector. In this configuration, the measurement spot 116 is imaged onto each detector such that the direction aligned with the incident plane on the wafer surface is perpendicular to the wavelength dispersion direction on the detector surface. In this arrangement, the sensitivity of the metering system to focusing errors is greatly reduced. Due to the low sensitivity to focusing errors, precise measurement results can be obtained with shorter MAM times and consequently higher throughput. A notable advantage of this architecture is its ability to measure thick films and multilayer stacks without introducing wavelength errors.

[0052] Conventionally, the metering system was configured such that the projection of the measurement spot in the longitudinal direction aligned with the wavelength dispersion direction on the detector surface. Figure 5B shows the conventional configuration. As shown in Figure 5B, the projection of the measurement spot 116 in the longitudinal direction (i.e., the X-axis on the wafer and the X'-axis on the detector) onto the detector 23 is aligned with the wavelength dispersion direction on the surface of the detector 23. For example, the longitudinal directions of spots 24A and 24B are aligned with the wavelength dispersion direction. By integrating these wavelength-dependent images on the surface of the detector 23 (e.g., spots 24A and 24B) along a direction perpendicular to the wavelength dispersion direction, a spectrum, i.e., intensity as a function of wavelength along the wavelength dispersion axis, is obtained. In the case of a CCD type detector, the spectrum is obtained by integrating the charge along a direction perpendicular to the wavelength dispersion.

[0053] When a measurement spot is imaged onto a detector such that the direction aligned with the incident plane on the wafer surface aligns with the wavelength dispersion direction on the detector surface, the resulting point broadening function (PSF) exhibits a strong wavelength dependence. The resulting PSF shows a high peak because the image intensity fluctuates significantly along the long-length direction related to a given wavelength. To accurately capture this high-peak PSD, spectral data must be captured with high resolution using a spectrometer. This increases measurement time and reduces throughput.

[0054] Furthermore, for example, if a long-scale image and its corresponding long-scale intensity distribution are aligned in the direction of spectral dispersion, the resulting PSF for a specific wavelength depends on the angle of incidence. The resulting PSF will broaden or narrow depending on the angle of incidence.

[0055] Furthermore, for example, the resulting PSF exhibits high sensitivity to focusing errors. As the measurement target on the wafer moves and comes into and out of focus, changes in size and positional shifts occur in the detected image of the measurement spot on the wafer. In addition, the position of the measurement spot on the wafer shifts. As shown in Figure 6, when the wafer 120 is in focus, part A of the wafer is illuminated by the illumination light beam 117. In the conventional configuration, when the focused light beam 127 is wavelength-dispersed and imaged on the detector 23, the image appears at spots 24A and 24B as shown in Figure 7. When the wafer 120 moves upward along the z direction and is defocused by an amount greater than 0 ΔZ, part C of the wafer is illuminated by the illumination light beam 117. In the conventional configuration, when the focused light beam 127' is wavelength-dispersed and imaged on the detector 23, the image appears at spots 24A' and 24B'. The appearing image becomes larger as the wafer moves away from the focusing plane of the optical system, and the center position of the image shifts along the direction aligned in the wavelength dispersion direction. This shift along the wavelength dispersion direction causes a change in wavelength-to-pixel mapping, resulting in spectral measurement errors. When the wafer 120 moves downward along the z-direction and defocuses by an amount ΔZ less than 0, the illumination beam 117 illuminates part B of the wafer. In the conventional configuration, when the focused beam 127" is wavelength-dispersed and imaged onto the detector 23, the image appears in spots 24A" and 24B". Even then, as the wafer moves away from the focal plane of the optical system, the resulting image becomes larger, and the center position of the image shifts along the direction aligned in the wavelength dispersion direction.

[0056] In this situation, the shift of the measurement spot on the wafer 120, caused by a focusing error where ΔZ≠0, results in image shift along the spectrometer dispersion axis, which is a function of wavelength. Since wavelength calibration is performed at the focal plane, i.e., Z=0, any image shift along the spectrometer dispersion direction caused by a focusing error makes the measurement spectrum extremely sensitive to deviations from the wavelength calibration.

[0057] In contrast, as described in this application, by projecting the incident plane onto the detector perpendicular to the wavelength dispersion direction, the dispersion plane is separated from the incident plane, and therefore the focusing error no longer affects the spectral position on the detector.

[0058] As shown in Figure 1, the measurement spot 116 is projected onto the surfaces of detectors 141 and 150 in a wavelength-dispersive manner. The weighing system 100 is configured such that the longitudinal projection of the measurement spot 116 is oriented perpendicular to the wavelength-dispersive direction on the surfaces of detectors 141 and 150. The X' axis shown in Figure 1 represents the longitudinal projection (i.e., X-axis) of the measurement spot 116 onto detectors 141 and 150. The X' axis shown in Figure 1 is oriented perpendicular to the wavelength-dispersive direction on the surfaces of detectors 141 and 150.

[0059] In some cases, by imaging the measurement spot onto the detector such that the direction aligned with the incident plane on the wafer surface is perpendicular to the wavelength dispersion direction on the detector surface, a 20-fold reduction in sensitivity to the focal position can be achieved. This reduction in focusing error sensitivity allows for relaxation of focusing accuracy and repeatability requirements, faster focusing time, and reduced sensitivity to wavelength errors without compromising measurement accuracy. These effects are particularly evident in large-aperture optical metricing systems.

[0060] Figure 8 is a direct view of the surface of detector 141. As shown in Figure 8, the longitudinal projection (i.e., the X' axis) of the measurement spot 116 is oriented perpendicular to the wavelength dispersion direction on the surface of detector 141. For example, the longitudinal directions of spots 142A and 142B are oriented perpendicular to the wavelength dispersion direction. By integrating these wavelength-dependent images on the surface of detector 141 (e.g., spots 142A and 142B) along the direction perpendicular to the wavelength dispersion direction, a spectrum, i.e., intensity as a function of wavelength along the wavelength dispersion axis, is obtained. In the case of a CCD type detector, the spectrum is obtained by integrating the charge along the direction perpendicular to the wavelength dispersion.

[0061] The measurement spectrum is obtained by integrating the image projected onto the surface of the detector (e.g., CCD141) along a direction perpendicular to the wavelength dispersion axis of the spectrometer at each wavelength. The individual spectral shape at each wavelength is the point spreading function (PSF) of this system at that particular wavelength.

[0062] When a measurement spot is imaged onto a detector such that the direction aligned with the incident plane on the wafer surface is perpendicular to the wavelength dispersion direction on the detector surface, the resulting point spreading function (PSF) is considerably less dependent on wavelength compared to conventional configurations. The resulting PSF exhibits a low peak because the image intensity does not fluctuate significantly along the direction perpendicular to the longitudinal direction related to a given wavelength (e.g., along the minor axis of an ellipse). Furthermore, although the image intensity fluctuates significantly along the longitudinal direction (e.g., along the major axis of an ellipse), these fluctuations are integrally smoothed because the longitudinal direction is aligned with the charge integration direction of the CCD. With this configuration, it is not necessary to capture spectral data with high resolution using a spectrometer and accurately construct the PSF. Therefore, measurement time is reduced and throughput is increased.

[0063] Furthermore, for example, if a long-scale image is oriented perpendicular to the direction of spectral dispersion, the PSF obtained for a specific wavelength becomes independent of the incident angle. The image and the corresponding intensity distribution along the direction perpendicular to the long-scale direction (i.e., along the minor axis of the ellipse) are largely invariant with respect to the incident angle. That is, the image and its corresponding intensity distribution, which are due to projection along the direction of spectral dispersion, are largely invariant with respect to the incident angle. Therefore, the calculated PSF shows almost no dependence on the incident angle.

[0064] Furthermore, for example, the resulting PSF exhibits significantly lower sensitivity to focusing errors compared to conventional configurations. As the measurement target on the wafer moves and comes into and out of focus, a positional shift occurs in the detected image of the measurement spot on the wafer. As shown in Figure 6, when the wafer 120 is in focus, the illumination beam 117 illuminates part A of the wafer. The focused beam 127 is wavelength-dispersed and, as shown in Figure 8, forms spots 142A and 142B which are imaged on the detector 141. When the wafer 120 moves upward along the z-direction and is defocused by an amount greater than 0 ΔZ, the illumination beam 117 illuminates part C of the wafer. The focused beam 127' is wavelength-dispersed and, as shown in Figure 8, forms spots 142A' and 142B' which are imaged on the detector 141. In this image position shift perpendicular to the direction of wavelength dispersion, the wavelength-to-pixel mapping does not change, thus reducing the spectral measurement error induced by focusing errors. When the wafer 120 moves downward along the z-direction and defocuses by an amount ΔZ less than 0, the illumination beam 117 illuminates part B of the wafer. The focused beam 127" is wavelength-dispersed and forms spots 142A" and 142B" which are imaged on the detector 141. Even at this time, since the image position shift is perpendicular to the wavelength dispersion direction, the spectral measurement error induced by the focusing error is reduced.

[0065] In this configuration, focusing error causes the image on the detector to shift along a direction perpendicular to the wavelength dispersion axis. Since the calculated spectrum is obtained by integrating the image perpendicular to the spectrometer dispersion axis, the image shift induced by focusing error is integrally smoothed and does not induce any substantial spectral measurement error. This reduction in sensitivity to focusing error eliminates the need to track and correct the focusing error based on atomic beam emission. In this configuration, a broadband light source, such as a high-brightness laser-driven light source (LDLS), can be used as the light source within the spectrometer system, for example, system 100, under loose focusing conditions.

[0066] As mentioned above, the PSF obtained by projection using a spectrometer is largely determined by the light distribution along the direction perpendicular to the incident plane (i.e., the XZ plane). For this reason, the PSF is independent of the oblique incident angle. In other words, the wavelength dependence of the PSF is considerably less than in conventional configurations.

[0067] As described in this application, any vertical or oblique incidence broadband optical metric system can be configured such that the direction in which the measurement spot is aligned with the incident plane on the wafer surface is perpendicular to the wavelength dispersion direction on the detector surface, so that the measurement spot is imaged on the surface of the detector. By orienting the spectrometer dispersion axis perpendicular to the wafer focusing axis (e.g., the z-axis in Figures 1 to 4) according to certain embodiments, the system sensitivity to focusing errors can be further reduced.

[0068] In another embodiment, a multizone infrared detector combining several sensitivity bands located at different points on a single detector package is employed in the metering system described in this application. This detector is configured to provide continuous spectrum data with different sensitivities depending on the incident point.

[0069] Figure 10 shows typical photosensitivity curves for available indium gallium arsenide (InGaAs) sensors. As shown in Figure 10, none of the available InGaAs sensors can provide adequate photosensitivity across the wavelength range of 1 μm to 2.5 μm. In other words, individually, available sensors are only capable of sensing over a narrow wavelength range. Some embodiments arrange the individual sensors in a cascaded configuration, as shown in Figure 4. However, in this case, it is necessary to subdivide the focused light into individual spectral ranges and disperse each spectral range onto separate detectors, either through individual lattice structures or a combination of beam splitting elements and lattice structures. As a result, unnecessary optical loss and optical system complexity occur.

[0070] In one embodiment, multiple sensor chips, each sensitive to a different wave band, are combined to form a single detector package. Furthermore, this multi-zone detector is mounted within the weighing system described in this application.

[0071] Figure 9 shows the four sensor chips 150A to D, each originating from four different wavebands, that constitute the multizone infrared detector 150. As shown in Figure 10, these four sensor chips each have different material compositions that exhibit different photosensitivity characteristics. As shown in Figure 10, sensor chip 150A exhibits high sensitivity in waveband A, sensor chip 150B exhibits high sensitivity in waveband B, sensor chip 150C exhibits high sensitivity in waveband C, and sensor chip 150D exhibits high sensitivity in waveband D. The weighing system into which the detector 150 is incorporated is configured to disperse wavelengths in waveband A onto sensor chip 150A, wavelengths in waveband B onto sensor chip 150B, wavelengths in waveband C onto sensor chip 150C, and wavelengths in waveband D onto sensor chip 150D. In this way, high optical sensitivity (i.e., high SNR) is achieved with a single detector across an integrated waveband including wavebands A to D.

[0072] A multizone detector, in certain cases, has InGaAs sensors that are sensitive to different spectral regions, which are assembled into a single sensor package, thereby obtaining a single and continuous spectrum covering wavelengths from 750 nm to 3000 nm or even further out.

[0073] In general, a continuous spectrum can be obtained from a multizone detector regardless of how many individual sensors are assembled along the wavelength dispersion direction. However, typically, a multizone detector, such as detector 150, employs 2 to 4 individual sensors.

[0074] In another further embodiment, the measurement accuracy and speed obtained can be optimized based on the properties of the target being measured by adjusting the dimensions of the illumination field aperture along the direction perpendicular to the incident plane of the wafer plane projection.

[0075] By adjusting the projection of the illumination field aperture onto the wafer plane along the direction perpendicular to the incident plane, the PSF can be shaped for each measurement application to achieve a flat-top profile that is virtually insensitive to wavelength. In addition, by adjusting the spectral resolution, measurement accuracy and speed can be optimized based on that flat-top profile.

[0076] In some cases, for example, when the sample is an extremely thick film or has a lattice structure, adjusting the projection of the illumination field aperture onto the wafer plane along the direction perpendicular to the incident plane can reduce the field of view size and improve spectral resolution. In some cases, for example, when the sample is a thin film, adjusting the projection of the illumination field aperture onto the wafer plane along the direction perpendicular to the incident plane can widen the field of view size and shorten the measurement time without loss of spectral resolution.

[0077] In the embodiments shown in Figures 1 to 4, the information processing system 130 is configured to receive a signal 154 indicating the spectral response detected by detectors 141, 150, and 153 (if applicable). The information processing system 130 is further configured to determine a control signal 119 and send it to the programmable illumination field aperture 113. The programmable illumination field aperture 113 receives the control signal 119 and adjusts the size of the illumination aperture so that the desired illumination field size is achieved.

[0078] In some cases, adjusting the illumination field aperture can optimize measurement accuracy and speed, as described above. In other cases, adjusting the illumination field aperture can prevent image clipping by the spectrometer slit and the corresponding degradation of measurement results. In this case, the illumination field size is adjusted so that the spectrometer slit is not filled with the image of the measurement target. In one example, the illumination field aperture is adjusted so that the spectrometer slit of the metering system is not filled with the projection of the polarizer slit of the illumination optical system.

[0079] Figure 11 shows a spectroscopic measurement execution method 500 according to at least one embodiment. Method 500 is suitable for execution in a weighing system, for example, the weighing systems 100, 200, 300, and 400 of the present invention shown in Figures 1 to 4. In one embodiment, as can be seen, the data processing blocks of Method 500 can be executed by executing a pre-programmed algorithm using one or more processors in the information processing system 130 or any other general-purpose information processing system. As recognized herein, the specific structural aspects of the weighing systems 100, 200, 300, and 400 are not limiting and should be interpreted solely as illustrative.

[0080] In block 501, a broadband illumination beam from the illumination source is directed to the measurement spot on the surface of the specimen under measurement at one or more incident angles within the incident plane.

[0081] In block 502, a group of light is collected from a measurement spot on the surface of the specimen.

[0082] In block 503, the first portion of the focused light group within the first wavelength range is directed towards the surface of the first detector, and the second portion of the focused light group within the second wavelength range is directed towards the surface of the second detector.

[0083] In block 504, the sample's response to a group of illumination lights within the first wavelength range is detected.

[0084] In block 505, the sample's response to the illumination light group in the second wavelength range is detected simultaneously with the detection of the sample's response to the illumination light group in the first wavelength range.

[0085] Examples of measurement techniques that can be configured as described in this application include, but are not limited to, spectroscopic ellipsometry (SE), such as Müller matrix ellipsometry (MMSE), rotational polarizer SE (RPSE), rotational polarizer-rotational compensator SE (RPRC), rotational compensator-rotational compensator SE (RCRC), spectroscopic reflectometry (SR), such as polarized SR, unpolarized SR, spectroscopic scatterometry, scatterometry overlay, beam profile reflectometry, angle-resolved or polarization-resolved beam profile ellipsometry, single or multiple discrete wavelength ellipsometry, and so on. In general, any metric techniques that incorporate illumination with UV and IR wavelengths can be envisioned individually or in any combination. For example, any SR or SE techniques applicable to characterizing semiconductor structures, including image-based metric techniques, can be envisioned individually or in any combination.

[0086] Systems 100, 200, 300, and 400 according to further embodiments utilize one or more information processing systems 130 to perform measurements of the actual device structure based on spectroscopic measurement data collected in accordance with the method described in this application. The one or more information processing systems 130 may be communicate-coupled to a spectrometer. In one embodiment, the one or more information processing systems 130 are configured to receive measurement data 154 related to the measurement of the structure of the sample 120.

[0087] It should be noted that one or more steps described throughout this disclosure may be performed by a single computer system 130, or by multiple computer systems 130. Furthermore, various subsystems of systems 100, 200, 300, and 400 may include computer systems suitable for performing at least some of the steps described herein. Accordingly, the above descriptions should be understood as illustrative examples only, and not as limitations on the present invention.

[0088] In addition, the computer system 130 may be communicate-coupled to the spectrometer in any form known in the present art. For example, one or more information processing systems 130 can be coupled to the information processing system related to the spectrometer. Alternatively, for example, these spectrometers can be directly controlled by a single computer system coupled to the computer system 130.

[0089] The computer system 130 of the weighing systems 100, 200, 300, and 400 may be configured to have a transmission medium, such as a wired section and / or a wireless section, thereby enabling it to receive and / or capture data or information from subsystems of the system (e.g., a spectrometer). In this configuration, the transmission medium can function as a data link between the computer system 130 and other subsystems of systems 100, 200, 300, and 400.

[0090] The computer system 130 of the weighing systems 100, 200, 300, and 400 may be configured to receive and / or capture data or information (e.g., measurement results, modeling inputs, modeling results, reference measurement results, etc.) from other systems by having a transmission medium such as a wired section and / or a wireless section. In this configuration, the transmission medium can act as a data link between the computer system 130 and other systems (e.g., onboard memory of weighing systems 100, 200, 300, and 400, external memory, or other external systems). For example, the information processing system 130 may be configured to receive measurement data from a storage medium (i.e., memory 132 or external memory) via the data link. For example, spectral results acquired using the spectrometer described in this application may be stored in a permanent or semi-permanent storage device (e.g., memory 132 or external memory). With this configuration, spectral results can be imported from onboard memory or from an external memory system. Furthermore, it is preferable to configure the computer system 130 to send data to other systems via a transmission medium. For example, the measurement model and estimated parameter values ​​obtained by the computer system 130 can be sent and stored in external memory. With this configuration, the measurement results can be exported to other systems.

[0091] Information processing system 130 may include, but is not limited to, personal computer systems, mainframe computer systems, workstations, image computers, parallel processors, and any other devices known in the art. Generally, the term "information processing system" can be broadly defined to include all devices having one or more processors that execute instructions obtained from a storage medium.

[0092] For example, the program instructions 134 for executing the method described herein may be transmitted over a transmission medium such as a wire, cable, or wireless transmission link. For example, as shown in Figure 1, the program instructions 134 stored in memory 132 are transmitted to the processor 131 over bus 133. The program instructions 134 are stored in a computer-readable medium (e.g., memory 132). Examples of computer-readable media include read-only memory, random-access memory, magnetic or optical disks, and magnetic tapes.

[0093] In certain cases, the measurement model is implemented as a component of the SpectraShape (trade name) optical limiting dimensional metrology system, available from KLA-Tencor Corporation in Milpitas, California, USA. In this configuration, the model is generated and prepared for use immediately after the spectrum is collected by the system.

[0094] In other examples, the measurement model is implemented offline by running AcuShape® software, available, for example, from KLA-Tencor Corporation in Milpitas, California, on an information processing system. The resulting trained model can be incorporated as a component of the AcuShape® library, which is accessible by the metrology system performing the measurements.

[0095] Furthermore, in certain embodiments, the semiconductor device spectrometry method and system described herein can be applied to the measurement of high aspect ratio (HAR) structures, large lateral dimension structures, or both. Examples of structures suitable for measurement by the system and method described herein include three-dimensional NAND structures such as vertical NAND (V-NAND®) structures and dynamic random access memory (DRAM), which are manufactured by various semiconductor manufacturers such as Samsung Inc. (South Korea), SK Hynix Inc. (South Korea), Toshiba Corporation (Japan), and Micron Technology, Inc. (USA). Such complex devices have the problem of low light transmittance into the structure(s) to be measured. Figure 12 shows an example 600 of a high aspect ratio NAND structure that has the problem of low light transmittance into the structure(s) to be measured. A spectroscopic ellipsometer that has broadband capability extending to infrared and performs simultaneous spectral band detection using a multizone sensor as described herein is suitable for measuring such high aspect ratio structures.

[0096] In yet another embodiment, the measurement results described herein can be used to provide active feedback to processing tools (e.g., lithography tools, etching tools, deposition tools, etc.). For example, measurement parameter values ​​derived based on the measurement method described herein can be sent to a lithography tool to adjust the lithography system to obtain the desired output. Similarly, etching parameters (e.g., etching time, diffusivity, etc.) and deposition parameters (e.g., time, concentration, etc.) can be incorporated into the measurement model and provided active feedback to the etching tool or deposition tool, respectively. In one example, corrections to processing parameters obtained based on a trained measurement model and device parameter measurements can be sent to the lithography tool, etching tool, or deposition tool.

[0097] The term "limit dimension" as used in this application encompasses all limit dimensions of a structure (e.g., lower limit dimension, middle limit dimension, upper limit dimension, side wall angle, grid height, etc.), limit dimensions between any two or more structures (e.g., distance between two structures), and positional misalignment between two or more structures (e.g., overlay misalignment between overlapping grid structures, etc.). Examples of structures include three-dimensional structures, patterned structures, overlay structures, etc.

[0098] The terms "limit dimension application" and "limit dimension measurement application" as used in this application encompass all types of limit dimension measurement.

[0099] The term “measuring system” as used herein encompasses all systems employed at least partially in characterizing a specimen in any manner, including measurement applications such as limit dimensional weighing, overlay weighing, focus / irradiation dose weighing, and composition weighing. However, these technical terms do not limit the scope of the term “measuring system” as used herein. In addition, the weighing system 100 can be configured for measuring patterned wafers and / or unpatterned wafers. This weighing system can be configured as an LED inspection tool, edge inspection tool, back inspection tool, macro inspection tool, or multimode inspection tool (with simultaneous data acquisition from one or more platforms), or any other weighing or inspection tool that benefits from calibration of system parameters based on limit dimensional data.

[0100] This application describes various embodiments of semiconductor measurement systems that can be used to measure specimens within any semiconductor processing tool (e.g., inspection system or lithography system). In this application, the term "specimen" is used to mean any wafer, reticle, or other sample that can be processed (e.g., printed or inspected for defects) by means known in the art.

[0101] In this application, the term "wafer" generally refers to a substrate formed from a semiconductor or non-semiconductor material. Examples of such materials, but not limited to, include single-crystal silicon, gallium arsenide, and indium phosphide. Such substrates are often seen and / or processed in semiconductor manufacturing equipment. In some cases, a wafer may consist only of a substrate (a so-called bare wafer). Alternatively, a wafer may have one or more layers, which are formed from different materials on the substrate. The one or more layers formed on the wafer may be "patterned" or "unpatterned." For example, multiple dies with repeatable pattern features may exist within a wafer.

[0102] A “reticle” may be a reticle at any stage of the reticle manufacturing process or a finished reticle, and may or may not be released for use in semiconductor manufacturing equipment. A reticle or “mask” is generally defined as a substantially transparent substrate on which substantially opaque regions are formed, and these regions form a pattern. The substrate may, for example, contain a glass material such as amorphous SiO2. The pattern on the reticle can be transferred to the resist by placing the reticle on a resist-coated wafer and performing an exposure step in the lithography process.

[0103] One or more layers formed on the wafer may or may not be patterned. For example, repeatable pattern features can be provided on each of the multiple dies that make up the wafer. By forming and processing such material layers, a finished device can ultimately be obtained. Many types of devices can be formed on the wafer, and the term "wafer" in this application is intended to encompass wafers on which any type of device known in the art is fabricated.

[0104] According to one or more exemplary embodiments, the functions described above can be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, these functions are stored or transmitted on a computer-readable medium as one or more instructions or codes. The computer-readable medium includes both computer storage media and communication media, and all media that are useful for transferring computer programs from one place to another. The storage medium may be any available medium that is accessible by a general-purpose or dedicated computer. To give an example, rather than an limitation, such a computer-readable medium may consist of any other medium that can be used to transport or store desired program code means in the form of instructions or data structures, and that is accessible by a general-purpose or dedicated computer or general-purpose or dedicated processor, including RAM, ROM, EEPROM, CD-ROM and other optical disk storage, magnetic disk storage and other magnetic storage devices. Any connection may also be referred to as a computer-readable medium. For example, if coaxial cables, fiber optic cables, twisted pair cables, digital subscriber lines (DSL), or wireless technologies such as infrared, radio frequency, or microwave are used to transmit software from a website, server, or other remote source, then those coaxial cables, fiber optic cables, twisted pair cables, DSL, or wireless technologies such as infrared, radio frequency, or microwave fall within the definition of a medium. The term "disk" as used in this application encompasses both discs (disks) where data is typically reproduced magnetically and discs (discs) where data is reproduced optically by a laser, including compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs®), floppy disks, and Blu-ray® discs. Combinations of the above should also be included within the scope of computer-readable media.

[0105] While specific embodiments for teaching purposes have been described above, the teachings of this patent application have general applicability and are not limited to the specific embodiments described above. Therefore, various modifications, adaptations, and combinations can be made to the features of the above embodiments without deviating from the technical scope of the invention as defined in the claims.

Claims

1. The steps include directing a broadband illumination beam from an illumination source to a measurement spot on the surface of the specimen under measurement at one or more incidence angles within a certain incidence plane, The steps include: focusing the light beam from a measurement spot on the surface of the specimen, The steps include directing a first portion of the focused light group within the first wavelength range toward the surface of the first detector and directing a second portion of the focused light group within the second wavelength range toward the surface of the second detector, A step of detecting the response of a sample to a group of illumination lights within a first wavelength range, A step of detecting the sample's response to a group of illumination lights in the second wavelength range simultaneously with detecting the sample's response to a group of illumination lights in the first wavelength range, It has, The first portion within the first wavelength range is a portion that includes ultraviolet wavelengths and is dispersed by the diffraction grating with diffraction orders of ±1, and the second portion within the second wavelength range is a portion that includes infrared wavelengths and is reflected by the diffraction grating with diffraction orders of 0. The cross-sectional shape of the broadband illumination light group incident on the surface of the sample under measurement is elliptical. The method comprises the step of imaging the measurement spot onto the surfaces of the first and second detectors such that the alignment direction, which is the major axis of the ellipse of the incident surface projected onto the first detector, is perpendicular to the wavelength dispersion direction, which is the direction that spatially separates focused light having different wavelengths on the surfaces of the first and second detectors, wherein the wavelength dispersion direction on the surfaces of the first and second detectors is perpendicular to the focal axis of the sample under measurement, and the second detector is an infrared detector, configured as a single sensor package by arranging two or more sensor chips exhibiting different light sensitivities along the wavelength dispersion direction.

2. The method according to claim 1, The second detector comprises first to fourth sensor chips, each having a different material composition exhibiting different photosensitivity characteristics, wherein the first sensor chip exhibits high sensitivity in a first wavelength band, the second sensor chip exhibits high sensitivity in a second wavelength band, the third sensor chip exhibits high sensitivity in a third wavelength band, and the fourth sensor chip exhibits high sensitivity in a fourth wavelength band, and the wavelengths in the first wavelength band are dispersed onto the first sensor chip, the wavelengths in the second wavelength band are dispersed onto the second sensor chip, the wavelengths in the third wavelength band are dispersed onto the third sensor chip, and the wavelengths in the fourth wavelength band are dispersed onto the fourth sensor chip.

3. The method according to claim 1, further, The steps include directing the third portion of the collected light group within the third wavelength range toward the surface of the third detector, A step of detecting the sample's response to a group of illumination lights in the third wavelength range simultaneously with detecting the sample's response to a group of illumination lights in the first wavelength range, A method of having.

4. A method according to claim 1, wherein the sample under measurement is a three-dimensional NAND structure or a dynamic random access memory structure.

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