Method and system for detecting and / or quantifying manufacturing errors

Abstract

The present disclosure relates to a method for detecting and / or quantifying manufacturing errors resulting from a lithography process. The method comprises providing at least one design for fabricating a structure on a substrate using a set of lithography processes, wherein the fabricated structure defines an array of measurement sensors, each measurement sensor being adapted to generate one of a set of different physical phenomena that are known and finite when a physical process is applied, the resulting physical phenomenon being unknown prior to the application of the physical process and depending on a manufacturing error generated by at least one of the set of lithography processes, the displacement state of the fabricated structure, or having one or more physical objects associated with the fabricated structure that did not exist prior to the application of the physical process; applying the set of lithography processes; applying the physical process; and reading out the resulting physical phenomena of all the measurement sensors. The present disclosure further relates to a measurement system.

Description

Technical Field

[0001] The present disclosure relates to a method for detecting and / or quantifying manufacturing errors resulting from a lithography process. The present disclosure further relates to a metrology sensor assembly and a metrology system.

Background Art

[0002] A lithography apparatus is generally used in the manufacture of integrated circuits and applies a designed pattern onto a substrate. A typical substrate is a semiconductor substrate such as Si. The transfer of the pattern is performed by irradiating a radiation-sensitive layer of a material (resist) uniformly deposited on the substrate.

[0003] Known lithography apparatuses include electron beam writers, laser beam writers, steppers, and scanners. Each of these tools converts computer-aided design (CAD) into a pattern on a resist on a substrate, which is an important part of the manufacture of semiconductor devices. An electron beam writer uses the rastering of an electron beam focused into a single spot of several nanometers to expose a part of the resist where the feature of interest is to be formed, and a scanner uses a wide-area light beam modulated by a mask to achieve selective exposure of the resist. The image of the mask projected onto the substrate is reduced by optical components such as deep ultraviolet (DUV) lenses or extreme ultraviolet (EUV) mirrors. In the case of DUV, the light transmitted through the mask is important. On the other hand, in EUV, the mask is a mirror and the light reflected by the mask is important. In the semiconductor industry, electron beam lithography is mainly used to pattern the shape on the mask. A scanner uses a mask to perform a photolithography process at high speed and with high wafer throughput. The mask is also a typical substrate on which writing-type lithography is performed to transfer the design to the pattern on the substrate on which the device is to be manufactured. There are multi-beam type beam writers.

[0004] All lithography apparatuses suffer from a wide range of errors that result in minute differences between what is designed in CAD files and the patterns on the substrate. These errors affect the placement, shape, dimensions, and roughness of the patterns generated on the wafer and ultimately impact the performance and yield of semiconductor devices. Some of these types of errors are called edge placement errors (EPE) and include overlay (OV, measurement of displacement between patterns between layers), critical dimension (CD, including local critical dimension (LCD) and critical dimension uniformity (CDU)), registration (REG, pattern position relative to an absolute grid), any roughness type (including line edge roughness (LER) and line width roughness (LWR)), and stochastic factors.

[0005] Any EPE present at any level from sub-device level, device level, system level, die level to wafer and batch level, induced by any mask, lithography apparatus, lithography process, and other process steps involved in the creation of devices or structures, accumulates after several masks and can potentially induce a large mismatch between the intended design and the actual design on the substrate, which can strongly affect the yield of the manufactured devices. Defects are defined as any physical, electrical, or parametric deviation that can affect the yield. As the number of individual process steps and masks increases and higher density shapes are required, a more stringent EPE budget is needed to keep the number of defects low, and precise measurement, control, and mitigation of EPE are required at all process steps and levels of all masks and lithography apparatuses.

[0006] Electron beam lithography is troubled by various error sources that result in EPE. The sources of error include incomplete beam focus and aberration, diffraction, spherical and chromatic aberration, beam deflection hysteresis, stage errors (including stitching, non - orthogonality, and calibration errors), overlay misalignment, registration error, proximity effect, charging effect, fogging effect, heating effect, etc. Also included are drifts in several beam characteristics that occur during exposure, such as focus, aberration, XY positioning, and calibration of beam deflection.

[0007] Apart from EPE caused by writing the mask, mask - based lithography using a scanner has additional sources of error that can affect EPE. These sources of error include shot noise, overlay misalignment, optical proximity effect, phase - shift effect, source - mask optimization error, illumination error, pupil error, flare effect, shadowing effect, incomplete focusing, wafer and reticle curvature and thermal expansion, wafer clamp, reticle clamp, distortion due to pellicle, dose error, incomplete rastering, stage (reticle and wafer stage) errors, tool matching, and others.

[0008] In addition to errors that occur during exposure of the resist on the substrate, other errors and defects are often found in the resist as a result of baking and developing the resist, erosion of the resist during dry etching, and local stochastic defects such as micro - bridges, open circuits, missing contacts, damaged contacts, stochastic effects, and material quality. Dry etching also causes errors that affect overlay, CD, and LCDU, etc., such as re - deposition, resist hardening, micro - loading, pitch - walk, etching bias, as well as non - uniformities and drifts in the wafer edge effect, etching rate, and etching direction. Furthermore, when many layers are stacked on top of each other, 3D effects also affect EPE.

[0009] All of these error sources accumulate after each processing step, resulting in various EPEs in the final device, which affects the manufacturing yield and the density at which the devices are manufactured and which need to be detected, investigated, and minimized in order to improve the manufacturing yield and the performance of the overall device.

[0010] Measurement tools that can detect and quantify any of these EPEs play an important role in process control and risk reduction in the manufacture of semiconductor devices. The measurement tools also play an important role in research and development activities and production ramp-ups aimed at optimizing the operating conditions of lithography and other equipment involved in the manufacture of semiconductor devices to maximize yield, reduce costs, increase device density, and improve performance. As the density of nanometer-processed features increases and the feature size decreases, the development of measurement tools that can detect and quantify these errors at the single-digit nanometer and sub-nanometer levels is important for determining whether the tool functions as expected (monitoring), and, if not, what the cause of the error or deviation is (problem solving).

[0011] The technologies related to this context fall into two main categories, namely inspection and measurement. In inspection technology, optical microscopy is usually used to detect defects (such as particles) at the nanoscale, micron scale or above, while in measurement technology, the critical dimensions and coordinates (absolute and relative values) of specific features or sub-features on a patterned substrate are measured in order to evaluate the fidelity of pattern transfer or to ensure proper overlay of subsequent patterns onto existing patterns. As semiconductor manufacturing technology continues to evolve towards ever-smaller critical dimensions, measurement needs to be performed on nanometer features and must achieve very high resolution and accuracy at high throughput. Otherwise, important causes of patterning variations may be detected too late in the production process, leading to possible chip defects. What is important for the semiconductor industry is the ability to measure EPE in order to perform process control or to utilize any possible process corrections in any tool or process step, such as higher-order scanner corrections that can improve the final yield and performance of the manufactured devices.

[0012] Currently, two broad categories of technologies are being used to perform critical dimension and overlay measurements: (1) imaging-based (optical or scanning electron microscopy) and (2) scatterometry-based (scatterometry, OCD).

[0013] Light scattering-based measurement methods, called scatterometry, derive information on shape, dimensions, and composition from the scattering patterns observed in light that has interacted with a sample. This requires a regular array of similar features, which can be features within a circuit such as a line array, or specially designed measurement targets (also known as scribe lines) typically placed in the areas between dies on a wafer. Scatterometry is usually performed using a dedicated grating structure (an array of lines and spaces at regular intervals) as the measurement target, and analyzing the interference pattern of monochromatic light interacting with the grating to derive information on critical dimensions and overlay with sub-nanometer accuracy. Typical metrology applications include performing a series of scatterometry measurements with light excitation at different wavelengths.

[0014] Critical dimension scanning electron microscopy (CD-SEM) is a direct measurement technique that functions by performing measurements using image processing of a scanned electron microscopy (SEM) image of a pattern (typical examples include the width and pitch of an array of lines, or the diameter and pitch of an array of holes). This technique, which operates in a vacuum, is typically used not only to measure the critical dimensions of a pattern, but also to quantify other types of important lithography defects such as stochastic errors (missing holes, broken lines, etc.) and LER. Optical microscopy using a wavelength-tunable light source for specially designed targets is used in a technique known as image-based overlay to perform overlay measurements.

[0015] Scattering measurements and other OCD techniques require special optical equipment including a coherent wavelength tunable light source and a spectrometer. They typically operate on a single spot at a time rather than over an area. Also, some of these techniques require a special type of grating structure of a particular micrometer size to operate, which limits their usefulness in device metrology. CD-SEM is typically performed on capital-intensive equipment and has very low throughput because it requires very high magnification to resolve sub-nanometric features. Furthermore, each of these techniques suffers from inherent noise, errors or mistakes due to the imaging and detection components of the tool, tool calibration, and the calculations leading to the final measurement data such as image processing, modeling, and fitting.

[0016] In summary, the available measurement techniques have low throughput, require complex and expensive tools, and rely on sophisticated data analysis, thus limiting the frequency and density of measurements performed for process control and monitoring. SUMMARY OF THE INVENTION

[0017] In a lithography system, errors, i.e., edge placement errors (EPE), inevitably occur in the location and manner in which the edges of a pattern are placed on a substrate. EPE has an undesirable impact on all micro and nano manufacturing structures and has historically been a major yield problem in the semiconductor industry, so the detection and quantification of EPE is very important. In the present disclosure, a new metrology approach is described that binarizes EPE into discretely identifiable physical phenomena on the substrate on which lithography is performed. This method is compatible with all lithography systems and independent of all other existing metrology techniques, expanding the toolbox available to sense and quantify lithography-originated errors in parallel with SEM, TEM, AFM, and diffraction-based techniques.

[0018] The present disclosure relates to methods and systems for addressing at least some of the aforementioned limitations.

[0019] According to a first embodiment, the present disclosure relates to a method for detecting and / or quantifying manufacturing errors made by a lithography process, the method comprising providing at least one design for fabricating a structure on a substrate using a set of lithography processes, the fabricated structure defining an array of measurement sensors, each measurement sensor being adapted to generate one of a set of different physical phenomena that are known and finite and can occur when a physical process is applied, including providing at least one design, the resulting physical phenomenon being unknown before application of the physical process, dependent on manufacturing errors generated by at least one of the set of lithography processes, having a displacement state of the fabricated structure or one or more physical objects associated with the fabricated structure that did not exist before application of the physical process, applying a set of lithography processes to obtain the fabricated structure, applying a physical process to cause each measurement sensor to generate one of a set of different physical phenomena that are known and finite and can occur, reading out the resulting physical phenomena of all measurement sensors, and processing the resulting physical phenomena of all measurement sensors to detect and / or quantify manufacturing errors caused by the lithography process.

[0020] Those skilled in the art are proficient in lithography systems and processes and will be able to implement examples of such processes referred to in the present disclosure.

[0021] The present disclosure further relates to a method for detecting and / or quantifying manufacturing errors made by a lithography apparatus, Providing at least one pattern for fabricating a structure on a substrate, wherein the at least one pattern defines an array of measurement sensors, each measurement sensor being configured in a stationary state and including a displaceable material distributed over a local region, the displaceable material being adapted to reach a displaced state towards predetermined discrete positions within the local region in a displacement process upon application of a physical stressor; Obtaining a structure fabricated on a substrate from a lithographic apparatus, wherein the displaceable material of the measurement sensors is in a stationary state; Applying a physical stressor to each measurement sensor for at least a predetermined period; Reading out the measurement sensors to detect and / or quantify manufacturing errors caused by the lithographic apparatus.

[0022] By imaging measurement sensors as described in the last step of the method disclosed above, it is possible to perform measurements related to semiconductor manufacturing with nanometer resolution using basic optical microscopy. This is a cost-effective method compared to the existing measurement techniques described above. The disclosed method may be further configured to generate a new stream of measurement data independent of all the other measurement techniques described above, and use it to efficiently detect, investigate, control, and minimize any of the above-described causes of EPE due to masks, lithographic apparatuses, etching and deposition processes and tools.

[0023] The disclosed method can be used in a scanner qualification process. It can further be used in a pattern control process.

[0024] Advantageously, in this method, nanoscale experiments are carried out, and each result can be said to be the displacement of an object (liquid or solid) from its displacement state, or the generation of one or more physical objects whose number or arrangement is sensitive to the lithography pattern and its errors. The shape and size of the lithography pattern can be considered as an analog signal containing the EPE processed by the experiment for detecting the EPE. The displacement of the substance, or the number or arrangement of the physical objects, constitutes the result of the experiment in the form of a binary (when the set of all possible physical phenomena is equal to 2) or discrete (when the set of all possible physical phenomena is more than 2) signal generated by each measurement sensor and depending on the deviation from the lithography pattern and its ideal design. After performing different steps of the method, each measurement sensor contains data regarding the error brought about by the entire lithography process, including the contribution of the lithography apparatus, in a binary or discretized form comparable to an analog-to-digital converter. If one of these lithography processes has a major contribution to the measurement sensor, the measurement sensor contains data regarding that particular lithography process. By manufacturing at least one pattern as described and applying a physical process, the method can be said to replace computer-based data processing with several parallel physical processes that perform analog-to-digital conversion on the substrate. This method allows the option of using imaging to collect the data generated by the measurement sensors into a computer. As long as the resolution and signal-to-noise ratio of the imaging system (determined, among other things, by the magnification, illumination, camera, and exposure settings used) are sufficient to detect the discretized data generated by the measurement sensors on the substrate, i.e., the measurement data is independent of the imaging technique, the associated calibration, and computer-based data processing.

[0025] In the method of the present disclosure, information regarding EPE is advantageously processed and binarized on a substrate by an experiment sensitive to patterns on the substrate defined by a lithography process and apparatus. Imaging may be used to collect data already discretized on the substrate for statistical analysis on a computer. Thus, it can be said that the described method performs the measurement of EPE before the digitization of the data in the computer.

[0026] Thus, in this method, it can be said that the data processing of EPE precedes imaging or the digitization of the data in the computer. This is in contrast to conventional measurement techniques where the data processing of EPE needs to be carried out algorithmically or using machine learning methods on a computer after digitizing the data into the computer, and thus continuing the imaging or inspection process. This method generates universally readable measurement data without further causing errors or inaccuracies in the measurement data introduced after a binarization experiment or the creation of a physical object containing displaceable substances is performed on the substrate. The only requirement is that the result of each binarization experiment can be correctly registered to the corresponding pattern of the original design. This is in stark contrast to conventional measurement techniques that are susceptible to a wide range of errors and inaccuracies introduced by the detection / imaging system as well as computational modeling and analysis. Thereby, the extracted final measurement value depends on the process including the creation of the measurement data starting from the arrangement of the excitation and imaging systems, and the digitization process to computer-based data processing such as individual components like lenses and detectors, calibration methods, measurement conditions and parameters, as well as models and algorithms. For example, unlike this method, in model-based measurement techniques such as interferometry and scattering methods, experimental data and simulations of fundamental physics are used to extract a quantitative estimate of the measured quantity of a sample based on a parametric model of the sample. This is based not only on the uncertainty of these estimates, but especially on the uncertainty of the experimental data, the sensitivity of that data to the model parameters, the parametric correlations between those parameters, and the fitting.

[0027] In the present disclosure, EPE measurement data written in a stable physical bitmap format on-chip can be collected by imaging with a spatial resolution much lower than the length scale of the errors. This is because it is encoded with much larger physical bits and binarized. Conceptually, this is similar to the principle of barcodes. That is, the data is encoded in a series of bits and presented in a simple visual form that is machine-readable. The method of the present disclosure is similar to printing a two-dimensional barcode (such as a QR code) on paper with ink, where the barcode is actually printed depending on the errors made by the printer and the ink appears only after a certain process (here, the stressor, or more generally, the physical process) is applied. The deviation of the barcode revealed from what was expected can be easily determined and used for the calculation of EPE. In this analogy, the printer is the lithography tool, the paper is the semiconductor substrate with one or more layers of patternable materials, and the encoded information of the ink pattern is the physical bits resulting from the binarization experiments at each measurement sensor. The type of EPE information (CDU, overlay, etc.) to be encoded is determined by the design of the specific type of pattern printed on the substrate, but the physical bit format remains the same for the same combination of the substrate and the physical process. In other words, the barcode encoding and printing process remains the same, but enables the encoding of different types of EPE information. The physical bits are larger than 200 nm and can thus be read with a basic optical microscope (such as those in some wafer inspection apparatuses), while the data stored in the bitmap can encode measurement data regarding EPE with an accuracy of 10 nm or better. (That is, even EPEs with a size of 10 nm or less can be detected and quantified using this method.) Furthermore, as long as the readout technique can identify individual physical bits and register those bits to the patterns in the design used to generate them, the entire measurement data can be acquired without error regardless of the imaging technique or microscope used. Also, the appropriate instructions are known or provided to correctly interpret the string of bits.Since the entire measurement data exists in the physical bits on the substrate, improving the calibration, magnification, or contrast when imaging the physical bits does not improve the accuracy and precision of the measurement. The measurement data is in a state without noise caused by photons and electron bias or the source of generation during image acquisition. Different microscopes imaging the same bitmap can read exactly the same measurement data. Thus, it can be said that the measurement of EPE is performed before imaging. Imaging is only necessary to read or digitize the already processed measurement data and process it into qualitative or quantitative measurement values.

[0028] The measurement data generated by this method is independent of many of the limitations that plague conventional optical techniques. For example, in the present invention, optical microscopy, whose resolution is usually limited by the wavelength of light and the lenses used, can sense local EPE at a level of less than 10 nm in a single isolated structure. This is because, although the measurement sensor was designed to anticipate a specific bit, if different bits are found after binarization, it can be seen that a patterning error has occurred in that specific measurement sensor.

[0029] The measurement data generated by this method is independent of many of the limitations that usually hinder CD-SEM and CD-AFM. For example, in the present invention, unlike in the case of CD-SEM and CD-AFM, there is no need to perform complex image processing to obtain information on the size and shape of patterns from images. In the present invention, only simple image processing that can detect binary data or discrete data of a known format from a measurement sensor is required. Furthermore, in the present invention, the size of the pixels for imaging only needs to be large enough to resolve the binary data or individual data from the measurement sensor, and can be orders of magnitude larger than the pixels in CD-SEM and CD-AFM. This requires resolving the target nanometric features. Therefore, in this case, the effective physical size of each imaged pixel may be orders of magnitude larger than the length scale at which the EPE information is resolved. This leads to significant savings in data acquisition throughput, data storage, and data processing. Furthermore, the detection and measurement of nanometric or sub-nanometric EPE can be performed at the wafer scale, thanks to compatibility with high-throughput inspection optical microscopes or wafer inspection tools used in semiconductor foundries. Therefore, it is possible to capture the wafer-level signature of nanometric EPE with high wafer throughput using this method. Furthermore, with the method described herein, different imaging systems can read the same measurement data from the same EPE measurement without adding noise or bias. This is in stark contrast to all other measurement techniques where the measurement data is necessarily sensitive to all other downstream hardware components involved in the digitization of pattern information containing EPE and the software layer that calculates the measurement data from the digitized data. Such hardware may include a light source, filters, lenses, beam rastering systems, mechanical stages, CMOS sensors, etc., and the software may include physical equations, physical constants, CAD, meshing, edge detection algorithms, parameterization, fitting, etc.In other measurement techniques, any systematic or random errors introduced by any of these components or processes may affect the accuracy and precision of the final measurement data. As a result, two different measurement tools may yield significantly different measurements of the same error if not properly calibrated. Two different image processing algorithms or physical models may yield different measurements from the same raw digitized data. Aberrations caused by the optical system of the tool are perhaps the main cause of systematic errors in image-based measurements, and the method of the present invention is less susceptible to its effects in much the same way as a barcode reader.

[0030] The ability to generate data independent of other measurement techniques and their inherent errors strongly supports hybrid measurement and may be used to enhance, monitor, or calibrate the performance of any existing measurement techniques used in lithography patterning and lithography processes.

[0031] In one embodiment, the measurement sensor comprises a plurality of mechanical actuators connected by at least one connecting element in a tension state representing a stationary state, each mechanical actuator being adapted to trigger a mechanical actuation to reach a final state at a predetermined time at the start of an etching process. The step of reaching a non-restrained state representing a displaced state when one of the mechanical actuators reaches its final state for each connecting element and applying a physical stress to each measurement sensor for at least a predetermined period of time to simultaneously apply the physical actuators includes simultaneously etching an array of measurement sensors for at least a predetermined period of time.

[0032] In this embodiment, since the actuator is designed to operate in a specific manner, the expected results of the operation of the mechanical actuator are known. The mechanical actuator can be considered as a timer. When the first timer reaches its final state, it can trigger a mechanical operation, whereby the connecting element remains in a displaced state. When the mechanical operation is triggered, the connecting element can be physically displaced towards one of the mechanical actuators while the other is not operating or is operating more slowly than the other. In this state, the optical microscope can provide an image of the entire area covering several measurement sensors, thereby instantaneously obtaining detailed information regarding manufacturing errors caused by the lithography apparatus by analyzing the deviation from the expected results.

[0033] The present disclosure further relates to a measurement sensor assembly, the measurement sensor assembly comprising a substrate, and an array of measurement sensors, each measurement sensor comprising a plurality of mechanical actuators connected by at least one connecting element in a tensioned state, each mechanical actuator being adapted to trigger a mechanical operation and reach a final state within a predetermined period at the start of an etching process, and each connecting element reaching an unconstrained state when one of the mechanical actuators reaches the final state.

[0034] As will be appreciated by those skilled in the art, any embodiment of the measurement sensor assembly of the present disclosure may be used in any embodiment of the method of the present disclosure to detect and / or quantify manufacturing errors caused by a lithography apparatus, and vice versa.

[0035] The present disclosure is a measurement system, comprising A lithographic apparatus configured to pattern a radiation-sensitive resist, such as a polymer, on a substrate in order to fabricate a structure using a design that includes an array of measurement sensors, wherein each measurement sensor is adapted to generate one of a set of known and finite different physical phenomena when a physical process is applied, and the resulting physical phenomenon is unknown prior to the application of the physical process, depends on manufacturing errors generated by the lithographic apparatus, a lithographic apparatus having a displacement state of the fabricated structure or one or more physical objects associated with the fabricated structure that did not exist prior to the application of the physical process, and further relates to a measurement system comprising a system adapted to apply a physical process to each measurement sensor.

[0036] The present disclosure is a measurement system, a lithographic apparatus configured to pattern a radiation-sensitive resist, such as a polymer, on a substrate using a design that includes an array of measurement sensors, wherein each measurement sensor is configured in a stationary state and includes a displaceable material dispersed over a local area, and the displaceable material is adapted to reach a displaced state towards predetermined discrete positions within the local area during a displacement process when a physical stressor is applied, and a physical stressor device, such as an etching device or system, adapted to apply a physical stressor for at least a predetermined period of time, and further relates to a measurement system including an imaging device for imaging the measurement sensors to detect and / or quantify manufacturing errors generated by the lithographic apparatus.

[0037] Advantageously, by using the measurement system described above, the measurement information obtained from the measurement sensors can be derived by rapid image recognition processing (such as template matching) applied to a subset of pixels within the total imaging area, based on prior knowledge of the positions of the measurement sensors on the surface of the patterned substrate being observed.

[0038] The present invention will be described below with reference to the accompanying drawings. The drawings are examples of embodiments and do not limit the measurement sensor assembly, measurement system, and method of the present disclosure for detecting and / or quantifying manufacturing errors caused by a lithographic apparatus. As an example, a measurement sensor is generally said to be adapted to generate one of a set of known and finite possible different physical phenomena when a physical process is applied. The drawings may show examples of mechanical actuators.

Brief Description of the Drawings

[0039]

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Embodiments for Carrying Out the Invention

[0040] The present disclosure relates to a method for detecting and / or quantifying manufacturing errors caused by a lithography process. The manufacturing errors may be, for example, CD, CDU, LCDU, overlay, registration, roughness, and edge placement errors including probabilistic factors.

[0041] Preferably, in a first step, at least one design for manufacturing a structure on a substrate is provided using a set of lithography processes. The manufactured structure may define an array of measurement sensors, each measurement sensor being adapted to generate one of a set of known and finite possible different physical phenomena when a physical process is applied. The resulting physical phenomenon may be unknown prior to the application of the physical process, depending on the manufacturing error generated by at least one of the set of lithography processes, and may be a displacement state of the manufactured structure or may have one or more physical objects associated with a manufacturing structure that did not exist prior to the application of the physical process. Next, the set of lithography processes can be applied to obtain the manufactured structure. Subsequently, a physical process may be applied to produce one of a set of known and finite possible different physical phenomena for each measurement sensor. Thereafter, the resulting physical phenomena of all the measurement sensors can be read out, and the resulting physical phenomena of all the measurement sensors can be processed to detect and / or quantify the manufacturing error caused by the lithography process. The resulting physical phenomenon may be digitally stored. The resulting physical phenomena of all the measurement sensors can be read out, for example, by imaging.

[0042] The measurement sensors may be configured such that the resulting physical phenomenon is more conveniently large than the error itself. In this way, the error can be indirectly read by imaging, for example, at a spatial resolution much lower than the length scale of the error. The manufacturing error may be due to an edge placement error, and the edge placement error is less than 5 nm, or the edge placement error is less than 1 nm.

[0043] The lithography process can generally be said to include transferring a design pattern onto a substrate, for example, using an exposure tool and subsequent resist development. Just by performing it once, it is possible to determine the manufacturing errors resulting from the entire lithography process without prior knowledge of metrology. When used in combination with other metrology tools or when there is prior knowledge regarding the relative sizes of different causes of errors that produce manufacturing errors, it is possible to accurately quantify to what extent a particular device or process step contributes to the errors. In this way, a particular lithography process and physical process can be carried out in such a way that the contribution to the overall manufacturing errors due to the exposure tool becomes dominant. Similarly, when using a very well-calibrated and stable exposure tool, it is possible to quantify the errors due to the dry etching or wet etching process. In one embodiment, the set of lithography processes includes at least the exposure and development of a radiation-sensitive resist.

[0044] According to one example, at least one lithography pattern for manufacturing a structure on a substrate is provided by a lithography apparatus and defines an array of metrology sensors. In this example, each metrology sensor is configured in a stationary state and includes a displaceable material dispersed over a local area, and the displaceable material is adapted to reach a displaced state towards predetermined discrete positions within the local area in a displacement process upon application of a physical stressor. The physical stressor can be an etching process or any suitable physical process that causes the displaceable material to reach a displaced state, including, for example, changing the temperature or phase, or applying vibration or evaporation. The displaceable material of the manufactured metrology sensors described above is originally manufactured in a stationary state. In a further step, a physical stressor is applied to each metrology sensor for at least a predetermined period. In a further step, the metrology sensors are imaged to collect data and detect and quantify the errors caused by the lithography apparatus.

[0045] A lithographic apparatus may be an electron beam writer, a laser beam writer, nanoimprint, a stepper, a scanner, or any other used in the field of device nanofabrication. The lithographic apparatus is not necessarily an exposure tool, but may be a pattern transfer tool such as a tool applying dry etching or wet etching. The lithographic process is to be interpreted as broadly covering any suitable use of one or more steps using the lithographic apparatus. One advantage of the methods, systems, and sensors disclosed herein is that any lithographic apparatus can be used and thus measurement data from any lithographic apparatus can be generated. The present technology does not depend on a specific lithographic apparatus. The disclosed methods and systems can turn any lithographic apparatus into a measuring device that generates measurement data regarding itself, whereby no other measuring tool is required other than itself to generate the measurement data, that is, the measurement data can be generated using only the lithographic process. By moving data processing to the substrate, imaging such as an optical microscope can be used to evaluate any lithographic apparatus or the operation of the lithographic apparatus. The substrate on which the structure is disposed may be a rigid semiconductor substrate such as silicon or germanium, a metal such as aluminum or gold, an oxide such as SiO 2 or sapphire or quartz, or any substrate used in device nanofabrication and semiconductor manufacturing.

[0046] A fabrication structure within the context of the present disclosure may be a resist, a polymer, a solid, a liquid, a gel, a laminate, or a combination of these materials.

[0047] Physical phenomena can be changes in optical properties, shape, size, XY or Z placement, buckling / bending modes, etc. in the structure or in all or part of an added visible object. It may be due to material removal or addition. The actual type of physical phenomenon is known to the operator before applying the physical process and depends on the pattern, substrate, and physical process. Different types of phenomena can be used individually or simultaneously, and the same combination of pattern, substrate, and physical process can cause multiple types of physical phenomena. As described above, each measurement sensor is adapted to generate one of a set of known and finite different physical phenomena that can occur when the physical process is applied. Examples of physical phenomena include events where the structure of the measurement sensor does not generate, or generates one or more visible objects, near a structure that did not exist before applying the physical process, such as scattering points of light such as cracks, holes, or particles. Further examples of physical phenomena include visually discretely quantifiable changes in the structure itself or in another structure derived from the structure, such as contraction / expansion of an area, movement to the left or right, clockwise or counterclockwise twist, buckling, etc. In one embodiment, the physical phenomenon is a change in the shape, size, or placement of part or all of the structure, preferably where the change in the shape, size, or placement of part or all of the structure is greater than 10 nm.

[0048] Physical processes within the context of the present disclosure can include mechanical stress, release of internal stress, spin coating, selective deposition, selective optical exposure, selective etching, heating, freezing, stress by bending the substrate, bimorph displacement, radiation exposure at a specific wavelength, ultrasonic or megasonic vibrations, and combinations of one or more of the aforementioned physical processes (e.g., selective etching followed by selective deposition).

[0049] The step of reading out the physical phenomena occurring in all measurement sensors can be performed in several ways. The reading out can include, for example, image-based reading used in the same way as a barcode reader, discrete sampling including lasers, or scatter measurements used in a local "probe" mode, or SEM.

[0050] In one embodiment of the method of the present disclosure for detecting and / or quantifying manufacturing errors made by a lithography process, the physical phenomena that occur are visually distinguishable from other physical phenomena of a set of known and finite possible different physical phenomena. This can be achieved, for example, by having a measurement sensor that consists of a displaceable material configured in a stationary state and distributed over a local area, and the displaceable material is adapted to reach a displaced state within the local area in a displacement process when the physical process is applied. The displaceable material can be in a stationary state when the manufactured structure on the substrate is retrieved from the lithography apparatus. As described, the physical process may include several techniques. In one embodiment, the physical process is applied to each measurement sensor for a predetermined period.

[0051] The step of processing the physical phenomena that occur may include computationally processing the physical phenomena that have occurred. For example, processing can include applying Boolean logic to the physical phenomena resulting from at least one design based on the expected results of the physical phenomena, and / or constructing a probability distribution of the count of the physical phenomena that have occurred for one or more various design parameters of the design and comparing it with the expected probability distribution based on the nominal design.

[0052] The step of reading out the physical phenomena that occur may include searching for physical phenomena only at predefined positions of the manufactured structure.

[0053] In one embodiment of the method of the present disclosure for detecting and / or quantifying manufacturing errors caused by a lithography process, at least one design is configured such that one particular physical phenomenon is prioritized. This can be done, for example, by providing two or more designs, at least one of which is distinguishable from the other designs by at least one edge displaced by an integer multiple of the minimum controllable process size of the lithography apparatus. Alternatively, at least one design may be configured such that none of the known and finite set of possible different physical phenomena is prioritized.

[0054] FIG. 1A shows a non-limiting conceptual example of a measurement sensor 100 in a stationary state. The drawing shows two possible displacement states 104 and 105 corresponding to possible distinct physical phenomena. The displaceable material 101 is in a stationary state. From this position, a physical process can be applied to move the displaceable material 101 in predefined directions 102 and 103 to reach one of the two possible displacement states 104 and 105. FIGS. 1B and 1C show the measurement sensor 100, with the displaceable material 101 in each of the possible final states 104 and 105.

[0055] As described, the step of reading out the physical phenomena generated by all measurement sensors can be performed, for example, by imaging. By imaging the measurement sensor after applying the physical process that displaces the displaceable material, it becomes possible to identify the position of the displaceable material in the final state. Such imaging preferably includes determination of the position of the connecting elements, by optical microscopy. Other microscopy techniques such as electron, ion, ultraviolet, or X-ray microscopy can also be used to perform the imaging step.

[0056] In one embodiment, a material including a mechanical actuator is etchable isotropically or anisotropically by contacting an etchant in a wet etching or dry etching process. Isotropically etchable material is understood as a material that is etched at a constant rate regardless of characteristics such as size, crystal orientation, crystal polarity, or roughness. For example, aluminum oxide is a material that is isotropically etchable upon contact with liquid HF or an aluminum etchant. Anisotropically etchable material is understood as a material that is etched at a rate depending on crystal characteristics such as crystal orientation, crystal polarity, or roughness. For example, a specific crystal plane of crystalline Si can be etched at a much slower rate under a specific etchant such as the (111) plane in contact with KOH or TMAH.

[0057] FIG. 2A shows an embodiment of a measurement sensor 200 including a mechanical actuator in the form of vertical nanopillars 202 and 203 disposed on a substrate 204. The mechanical actuator is fixed to a rigid substrate 204 and a connecting element 201 as shown in FIG. 2B. The connecting element 201 connecting both mechanical actuators includes a rigid platform made of a material non-reactive to the etchant, thereby enabling selective etching of the mechanical actuator.

[0058] First, the connecting element 201 of FIGS. 2A and 2B is in a pre-constrained state and is connected to mechanical actuators 202 and 203. Such a pre-constrained state can be induced, for example, by manufacturing the connecting element from a material having a higher coefficient of thermal expansion than the substrate at a temperature higher than room temperature. FIG. 2C shows the result after the etching process has removed at least one of the mechanical actuators of the measurement sensor 210, while the connecting element 201 is preferably made of a material that reacts little to the etching solution. When a physical stressor is applied to the measurement sensor 210, the connecting element displaces by a distance 211 from the constrained state towards the remaining mechanical actuator 212 of the measurement sensor and reaches an unconstrained position as shown in FIG. 2C. The driving force for the displacement of the connecting element can be, for example, a tensile stress such as the thermal constraint generated in the connecting element during the manufacturing process. The final state of the mechanical actuator corresponds to a partial or complete etching of the mechanical actuator to the extent that it releases the connecting element to which it is connected. This may include the connecting element physically separating from the mechanical actuator before being completely released due to the high tensile force. The mechanical actuator is preferably etched laterally and isotropically by the etching solution in a wet etching process such as hydrofluoric acid or an aluminum etching solution. Depending on the material composition of the nanopillars, other wet etching solutions such as KOH, TMAH, H2SO4, or pirah etching may be used. The etching process can be stopped at a desired time, for example, by drying the substrate in an etching stop solution such as deionized water or by immersion.

[0059] In another embodiment, the coupling element (alternatively may be called a beam) is a pre-constrained element connected to at least two mechanical actuators within the measurement sensor. The coupling element may be disposed in a pre-constrained state over the actuators. When the time required for the first actuator to act elapses, the coupling element is released from the substrate and is pulled by the tensile stress towards the other actuator, as a result of which it remains attached to the substrate at the moment of displacement. The displacement experienced by the coupling element from the first elapsed actuator leaves a physical record on the substrate while releasing the stress of the measurement sensor, thereby preventing the other actuator from creating its own physical record after the other actuator has elapsed. The displacement of the coupling element from the first elapsed actuator can be detected later, thereby enabling one to know which actuator elapsed first. If the stress is compressive, the direction of displacement can be reversed. If the coupling element has a stress gradient or consists of a bimorph, the displacement direction can be out-of-plane. Thus, the present disclosure describes a lithography method for creating a system that defines "timers" on-chip and makes them mutually exclusive, such that only the first elapsed actuator among two or more connected actuators can generate displacement from its predefined position. Thus, the other connected actuators will remain in their predetermined positions even after eventually disappearing while leaving a physical record.

[0060] The physical phenomenon can be a crack caused by a crack mechanism in which a displaceable material moves from a stationary state to a displaced state. The crack can be caused by a connecting element pulling on a mechanical actuator. By pulling, the attached layer can be torn, leaving a crack gap in the layer. This crack gap can be used for selective etching of the underlying layer to form optically observable holes. This crack gap can also be used for selective growth of a material using the underlying layer as a seed material, thereby creating optically observable particles. Thus, the resulting crack gap can be used to selectively and spatially amplify data regarding the displaced state, thereby simplifying data collection by imaging. Such gaps, holes, and particles are non-limiting examples of physical objects that arise in connection with fabricated structures that did not exist prior to the application of a physical process. The physical objects created in connection with the fabricated structure, and the displaced state of the fabricated structure, are examples of a set of known and finite possible different physical phenomena that are caused upon application of a physical process.

[0061] In the case of a measurement device with one connecting element connecting two mechanical actuators, one-dimensional displacement is achieved. However, multiple actuators can be connected to multiple connecting elements, enabling recording of physical displacements in any direction within the plane of the substrate surface.

[0062] In a further embodiment, the displaceable material of each measurement sensor comprises a liquid or a gel, the liquid or gel is displaced to a displaced state upon application of a physical stress, and the step of simultaneously applying a physical stress to each measurement sensor for at least a predetermined period includes simultaneously changing the temperature or phase of the liquid, gel, substrate, or applying vibration or evaporation.

[0063] FIG. 5 shows a schematic example of a measurement sensor 500, where the displaceable material includes a liquid or a gel. The sensor described above is defined by lithography 500, shown in the top view of FIG. 5A, and is arranged in two end regions 501 and a connecting region 502 connecting the two end regions 501. The "end region" and "connecting region" should be interpreted broadly to include any suitable shape having two ends towards which the liquid or gel can be displaced. This may include, for example, a single line region. FIG. 5B shows a side view of FIG. 5A, and the sensor is defined on a substrate by lithography. FIG. 5C shows the defined sensor 500 with a liquid or gel 502 deposited on top of the sensor, occupying all the available space. FIG. 5D is a side view of the sensor and the liquid or gel shown in FIG. 5C. FIG. 5E shows the shape of the defined sensor with the liquid or gel 502 deposited on top, whereby, upon application of a physical process 504, the liquid or gel can be displaced towards one of the end regions. The physical process can be, for example, a drying process, a temperature change, a phase change, or a vibration. The physical stressor can cause tension or instability in the liquid or gel. FIG. 5F is a side view of FIG. 5E. By applying the physical stressor, the liquid or gel will move towards one of the end regions, which is usually caused by the minimization of the surface energy of the liquid or gel. Thereby, an observable physical record of the displacement is effectively created. FIG. 5G shows the displacement of the liquid or gel 502 towards the left end region 505, while the right end region 506 shows that the liquid or gel is empty due to the displacement. The liquid or gel can be adapted to return to a stationary state when the physical stressor is released or deactivated by a physical process such as increasing the moisture content during air or ultrasonic treatment. Thereby, it can be effectively possible to reset the device to its initial state and reuse the measurement device multiple times. FIG. 5H shows a side view of FIG. 5G.

[0064] Preferably, the displaceable substance is displaceable within the plane of the surface of the substrate. In an embodiment, the displaceable substance is composed of a liquid or a gel, or a solid substance. Further, the displacement of the substance can create a physical record observable in the displaced state. This can effectively convert nanometer-scale defects into the presence or absence of an observable structure, or a change in a structure with a size exceeding 100 nm, which can be easily detected optically.

[0065] In the case of a mechanical actuator, each mechanical actuator, or each of the two end regions of the gel or liquid, can represent a timer. Each timer can define an expected trigger time for the mechanical actuator or end region to reach the displaced state when a physical stressor is applied. The concept of a "timer" can be illustrated as in the example of FIG. 6. In FIG. 6, one actuator is being etched. The etching process is started at a predetermined time. The actuator is etched laterally. Since the etching rate and width of the actuator are known, an expected time for etching the entire actuator can be provided. FIGS. 7A-7B show a further explanation of the use of the timer to obtain a physical record on a substrate that can be used to detect and / or quantify manufacturing errors caused by a lithographic apparatus. In FIG. 7A, two actuators 202 and 203 are shown. Since the width of 203 is wider, its "timer" is designed such that the default timer value is larger. Thus, the expected result of the etching process is that actuator 202 reaches its final state before actuator 203, as shown in FIG. 7B. The connecting element 201 creates an observable physical record when it reaches its unconstrained state.

[0066] By applying a physical stress, the measurement sensor remains in a state where the displaceable material is displaced in the direction of a mechanical actuator having a longer trigger time, effectively imprinting the final state of the measurement sensor after actuation. The direction of displacement may be reversed according to the physical phenomenon of the experiment, such as in the case of a displaceable material subjected to compressive stress. The displacement direction may be in-plane, out-of-plane, or a combination of both of the substrate. A single measurement sensor includes at least two actuators, and additional actuators may be added in different directions on the surface of the substrate, enabling the manufacture of a measurement sensor in which the displaceable material can be displaced two-dimensionally on the surface.

[0067] FIG. 3 shows a diagram of a measurement sensor 300 in which two actuators 302 and 303 are designed with different widths and thus have a predetermined difference in trigger time at startup. By defining actuators with different trigger times, the manufacturing error of the measurement sensor can be quantified. Since the trigger time of the right actuator 303 is longer for the displaceable material 301, when the actuator is actuated, it preferentially moves to the right displacement state 305 and does not move to the left displacement state 304. When the displacement state is on the left side, it is known that the lithography error of the measurement sensor was performed by a lithography system that overcomes the trigger time bias, and this can be used to quantify the spatially performed error. By defining actuators whose difference gradually decreases until they become the same, it becomes possible to identify unknown physical biases such as edge placement errors induced by the lithography apparatus during the manufacturing process. In one embodiment, each mechanical actuator or end region is designed such that its size is proportional to a predetermined time required to reach the final state corresponding to the expected trigger time of the actuator.

[0068] FIG. 4A shows an example of an array 400 of binary measurement sensors 401 distributed on a substrate. Such an array includes measurement sensors arranged in an M×N matrix configuration, where JPEG2025516135000002.jpg1647 and JPEG2025516135000003.jpg is 1334. The pattern defines an array of at least 10 measurement sensors and enables collecting information on an inaccurate lithography apparatus by measuring the final states of some of the measurement sensors until statistically significant results are obtained. Within the same array, different biases can be designed for each sensor, enabling quantifying and testing the limitations of lithography accuracy. Ideally, the accuracy limitation of the lithography apparatus is achieved when the bias difference between actuators is less than 1 nm and a random displacement is applied to the sensors at startup. The array can refer to a set of discrete measurement sensors that are not necessarily dispersed in one continuous area and are not necessarily arranged in any particular periodic or aperiodic pattern, regardless of the presence or absence of other intervening structures.

[0069] FIG. 4B shows a bitmap or matrix barcode representation of an array 400 of measurement sensors 401. Similar to a barcode reader that reads a matrix barcode, any optical system capable of identifying the final states of the measurement sensors can read the entire encoded data of that optical system if appropriate instructions for interpreting the bit string are known or provided.

[0070] The measurement sensors disclosed in this specification can be patterned with many measurement sensors and executed at least 5 times or at least 10 times in parallel on the substrate by simultaneously starting up all the sensors. This number of times can be more than 100 times, more than 1 million times, or even more than 1 billion times on a single substrate. By detecting the results of some experiments, statistics can be obtained and used to measure the error of lithography patterning. This is because the preset time of the actuator is designed by lithography according to the size of the actuator, and it is known which actuator needs to elapse first. If the statistics are different from the expected results, or if the preset time of the actuator is slightly different from the design, it indicates that the tool has made an error in lithography. For example, as shown in the first column of the device in Figure 4, it is possible to design a sensor including actuators having the same preset time such that the probability of each actuator elapsing first is expected to be 50%. In this example, it is shown that 50% of the actuators are in the raised state and 50% are in the final lowered state. If an imbalance is detected in the statistics, for example, if one of the actuators elapses first with an 80% probability, it can be understood that the lithography apparatus has introduced a bias and the result is that one of the actuators has consistently larger islands than the other.

[0071] The disclosed measurement sensor can also be configured to not only sense errors such as edge placement errors introduced by a lithographic apparatus, but also obtain a quantitative measurement thereof. This is done by patterning a sensor with a known bias at a pre-set time, or by equivalently using a bias of a known size, the timer-based embodiment of FIG. 6. For example, patterning a sensor with a 4 nm bias during the final state and observing that one side elapses first with 100% probability means that the accumulation of tool errors is less than 4 nm. It is possible to compile data from many sensors with different known nanometric or sub-nanometric biases to create a statistical output curve, and use this statistical output curve to evaluate the noise floor of the measurement technique under a given process condition involved in the construction of an individual measurement sensor. The apparatus including the measurement sensor.

[0072] The disclosed measurement sensor can generate independent statistics regarding different EPEs induced by a lithographic apparatus. For example, as shown in FIG. 8, it is possible to generate statistics that quantify the overlay error in X, independent of the overlay error in Y. Also, as shown in FIG. 8, it is possible to quantify the overlay independently of the quantification of CDU. In some cases, it is not possible to quantify one component of the EPE independently of another component of the EPE, in which case, using statistics from different measurement sensors aimed at quantifying a particular set of EPE components, the contribution of the EPE components can be removed in order to obtain an accurate measurement of the remaining EPE components.

[0073] The process of imaging a metrology sensor to detect and / or quantify manufacturing errors made by a lithographic apparatus may include microscopic imaging of structures on a substrate. Such imaging characterization techniques are preferably microscopic techniques such as optical and alternatively electron or ion microscopes, electrical characterization or ellipsometry or scatterometry. Using an optical microscope, for example, compared to an electron microscope, the normal wide field of view of the frames acquired with this technique enables measuring many metrology sensors in a single frame. The advantage of the disclosed metrology sensors and methods of using them is that nanometric differences induced during the lithography process can be macroscopically detected with an optical microscope that initially does not have the spatial resolution to detect the original nanometric differences by using the aforementioned sensors. Advantageously, the present technique can be performed by CD-SEM, but is compatible with generating measurement data at the single line level that cannot be performed by interferometry, scattering methods, and optical image measurements using statistical measurements that sample a wide area of at least several micrometers in the side length including at least some individual structures. Furthermore, the measurement data generated by the metrology sensor is independent of the resolution limitations of the optical microscope used to read the data as well as the causes of noise and uncertainty.

[0074] In one embodiment, a metrology sensor assembly comprises a substrate and an array of metrology sensors, each metrology sensor comprising a plurality of mechanical actuators connected in a constrained state by at least one connecting element. In one embodiment, each mechanical actuator is adapted to trigger a mechanical actuation to reach a final state within a predetermined time at the start of an etching process, and each connecting element reaches an unconstrained state when one of the mechanical actuators reaches its final state. The substrate preferably includes a semiconductor substrate having a determined out-of-plane crystal orientation and having a defined out-of-plane crystal orientation, and each metrology sensor comprises two mechanical actuators or two liquid actuators.

[0075] The measurement sensors disclosed herein can be used in a "noise sensing mode", in which many sensors are patterned with actuators that are the same or have a discrete known bias range for quantification, the minimum value of which is the smallest controllable increment that a lithographic apparatus can reliably produce. This can be the minimum feature size in an electron beam lithographic apparatus or the minimum controllable stage feature size. The minimum feature size can also be interpreted broadly as the typical minimum grid resolution used in CAD for designing patterns, but can also be induced by a controllable known variation in the CD or CDU of a pattern or part of a pattern as a result of a particular lithographic process. This sensing mode may be used to characterize the noise floor of a lithographic apparatus with respect to EPE, and the noise floor may be used to compare the performance of different lithographic apparatuses or processes involved in the construction of the disclosed measurement sensors. For example, if changing a particular process parameter in a lithographic apparatus improves the statistics (i.e., reduces the error at the final state of the sensor), this means that the edge placement fidelity is high and the same parameters can be used in other manufacturing processes to obtain more ideal results. Consequently, by using noise sensors, any process parameter of any lithographic apparatus or process step can be optimized to minimize the error at the final state of the sensor in order to minimize roughness such as CD, LCDU, probabilistic factors, and LER and LWR. The noise sensing mode may be further used to characterize the noise floor of measurement sensors patterned by a lithographic apparatus, the statistics of which may be used as a reference for sensors in a "shift sensing mode" (described below) to obtain higher accuracy and accuracy in EPE quantification.

[0076] The measurement sensors disclosed herein may alternatively or additionally be used in a "shift sensing mode" in which the pattern of the measurement sensors is intentionally divided into two or more distinct but complementary patterns that do not function individually as measurement sensors. As shown in FIGS. 8A and 8B, when combined in two or more separate exposures in the same lithography process or separate lithography processes, a complete pattern that functions as a measurement sensor can be formed. For example, the first pattern may define a portion of the actuator and a connecting element connecting the actuators, while the second exposure 802 only defines the remaining portion of the actuator. When the complete pattern is acquired in two exposures, for example, the translational error of the alignment between the first exposure defining pattern 801 and the second exposure defining pattern 802 due to overlay error results in a statistically detectable imbalance. This is because depending on the shift direction, the upper islands are consistently smaller or larger than the lower islands. Complementary patterns may be present in the same mask at different positions or in two or more separate masks at any position within the mask. Complementary patterns may be stitched together by movement of the wafer stage, or the reticle stage, or both. When complementary patterns are present in the same mask, the resulting measurement sensor can sense and quantify, among other things, registration errors and CDU. When present in different masks, the measurement sensor can be used, among other things, to detect overlays. A wide variety of options are possible for dividing the pattern into two or more complementary parts, each of which may detect different EPEs, depending on or independently of other EPEs. For example, the EPE contributions in X and Y may be detected independently. Further, the complementary patterns may be exposed in many ways. For example, the complementary patterns may be exposed as the complete pattern was originally designed, or may be exposed with a controlled offset to force a bias that can be used to quantify errors.For example, a complete pattern designed in CAD may be expected to generate statistically balanced results, for example, due to the mirror symmetry of the pattern, but in practice, instead, it may cause systematic imbalances that exhibit overlay, registration, and stage errors. Exposing complementary patterns using intentionally controlled movement in X or Y between exposures can generate a more balanced statistic that shows a final pattern closer to that of CAD, and this can be used to identify and quantify the errors that caused the imbalance. Further, complementary patterns can form many different measurement sensors by repeating the complementary exposures. There may also be several complementary patterns to form several complete measurement sensors in parallel. Also, there may be several ways to stitch different complementary patterns in different exposures to obtain a complete pattern that functions as a measurement sensor. This shift sensing mode may be used to sense EPE by dividing the pattern into one or more portions that affect the measurement data, both when the components are not positioned relative to each other (e.g., due to overlay error) and when the parts are of different sizes (e.g., due to CD error). The shift sensing mode can be used in a variety of applications, including in particular the detection of EPE such as overlay, rotation error, registration error, drift over time of the stage or beam, stage stitching error, CDU, and LCDU. The shift sensing mode may be even more important for characterizing one of a lithographic apparatus, or a sub-part thereof, such as a stage, a beam deflection system, an overlay alignment system, or a mask. The strategy of dividing the pattern into multiple portions and noise sensing may also be used to optimize proximity effect correction strategies for both single- and multi-pattern approaches using both optical beam lithography and electron beam lithography.

[0077] Figures 8A and 8B show examples of cutting patterns of measurement sensors having rectangular and square actuators in a positive resist (a radiation-sensitive polymer used in lithographic patterning). The positive resist can sense and quantify misalignments including overlay and registration, as well as size differences including CDU when separately exposed to manufacture a complete measurement sensor.

[0078] Figure 8A shows a measurement sensor design 803 consisting of cutting patterns 801 and 802 that can sense and quantify Y misalignment independently of X misalignment. When this structure is rotated by 90°, it becomes possible to detect and quantify X misalignment regardless of Y misalignment. An additional specificity of this design is that the misalignment contributes to changing both actuators in opposite directions. In other words, this design amplifies the misalignment by a factor of two, thereby doubling the sensitivity of the measurement sensor. Stage displacements deliberately controlled to induce an imbalance or compensate for an imbalance between actuators may be used to quantify the error. Yet another specificity of this design is that it is not affected by CDU due to two-fold mirror symmetry, which enables this design to sense and quantify alignment errors regardless of CD or CDU errors.

[0079] Figure 8B shows examples of cutting patterns 811 and 812 of a measurement sensor 810 having angular actuators in a positive tone resist. This can sense and quantify small misalignment errors CDU such as overlay and registration when separately exposed to a complete measurement sensor.

[0080] The measurement sensors disclosed in this specification can alternatively or additionally be used in a "breakage sensing mode" and can sense and quantify manufacturing errors such as EPE using a displaceable material that does not reach a displacement state. For example, if a physical discontinuity occurs in a connecting element due to a manufacturing error, the experiment may not be able to create a displacement of the material that can be interpreted as the displacement state of the measurement sensor, and thus may be interpreted as a breakage of the measurement sensor. When the measurement sensor fails, useful data is generated to indicate that the pattern was not generated as expected. For example, very narrow lines used in the manufacture of ICs can probabilistically break, and it is well known that this can have an adverse effect on the yield of semiconductor devices, especially in EUV scanners. The breakage sensing mode may be used, for example, to probabilistically sense a broken line when the connecting element is a beam, since the breakage of the connecting element does not result in a displacement state where breakage is expected. The measurement sensors may be intentionally designed to produce experiments that fail or have a possibility of failing, since any deviation from the expected failed or non-failed behavior generates useful measurement data regarding the lithographic apparatus or process. For example, in an experiment, it may be known that when a particular dimension of a structure is less than 30 nm, a displacement of the material that can be interpreted as the displacement state of the measurement sensor cannot be generated. If a measurement sensor designed to be larger than that size consistently fails to generate measurement data, it may be interpreted that the actual CD is less than 30 nm and smaller than the expected CD. The defect sensing mode can be used in the noise sensing mode or the shift sensing mode, or conversely, the noise and shift sensing modes can be used in the defect sensing mode. By integrating different detection modes, further detection and quantification of EPE becomes possible by detecting measurement sensors that do not generate measurement data.

[0081] FIG. 9 shows an example of a flowchart of a method 900 of the present disclosure for detecting and / or quantifying manufacturing errors. This method includes providing at least one design for manufacturing a structure on a substrate using a set of lithography processes, where at least one pattern defines an array of measurement sensors, and each measurement sensor is adapted to generate one of a set of known and finite possible different physical phenomena when a physical process 901 is applied. Applying a set of lithography processes 902 to obtain the manufactured structure, and by applying the physical process, causing each measurement sensor to generate one of a set of known and finite possible different physical phenomena 903, and reading out the resulting physical phenomena of all measurement sensors and processing the resulting physical phenomena 904.

[0082] Details 1. A method for detecting and / or quantifying manufacturing errors performed by a lithography apparatus, comprising: providing at least one pattern for fabricating a structure on a substrate, wherein the at least one pattern defines an array of measurement sensors, each measurement sensor being configured in a stationary state and including a displaceable material distributed over a local area, the displaceable material being adapted to reach a displaced state towards a predetermined discrete position within the local area in a displacement process when a physical stressor is applied; obtaining the fabricated structure on the substrate from the lithography apparatus, the displaceable material of the measurement sensor being in the stationary state; applying the physical stressor to each measurement sensor for at least a predetermined period; reading out the measurement sensors to detect and / or quantify manufacturing errors caused by the lithography apparatus.

[0083] 2. The method according to item 1, wherein the substrate is a semiconductor substrate.

[0084] 3. The physical stressor is the method according to any one of the preceding items, which is applied to each measurement sensor simultaneously.

[0085] 4. The measurement sensor is the method according to any one of the preceding items, which is read out by imaging.

[0086] 5. Each measurement sensor includes a plurality of mechanical actuators connected by at least one connecting element in a constrained state representing the stationary state. Each mechanical actuator is adapted to trigger mechanical actuation and reach a final state within a predetermined period at the start of the etching process. Each connecting element reaches an unconstrained state representing the displacement state when one of the mechanical actuators reaches its final state. The step of applying the physical stressor to each measurement sensor, at least for a predetermined period, by simultaneously applying the physical actuator to each measurement sensor includes simultaneously etching an array of measurement sensors for at least a predetermined period, according to the method of any one of the preceding items.

[0087] 6. The step of imaging the measurement sensor includes imaging the connecting element, according to the method of item 5.

[0088] 7. The mechanical actuator is made of a material that can be etched isotropically or anisotropically in contact with an etching solution, according to the method of any one of the preceding items.

[0089] 8. The mechanical actuator is a vertical nanopillar disposed on the substrate, according to the method of any one of the preceding items.

[0090] 9. The final state of the mechanical actuator corresponds to partial or complete etching of the mechanical actuator to the extent of releasing the connecting element to which the mechanical actuator is connected, according to the method of any one of the preceding items.

[0091] 10. The mechanical actuator is etched laterally, according to the method of any one of the preceding items.

[0092] 11. The method according to any one of the preceding items, wherein the etching process is a wet etching process.

[0093] 12. The method according to any one of the preceding items, wherein the etching process removes at least one of the mechanical actuators of the measurement sensor.

[0094] 13. The method according to item 12, wherein the connecting element is displaced from the constrained state towards the position in the remaining mechanical actuators of the measurement sensor.

[0095] 14. The method according to any one of the preceding items, wherein the connecting element is made of a chemically stable material in contact with an etching solution for the mechanical actuator material.

[0096] 15. The method according to any one of the preceding items, wherein the connecting element is a pre-constrained element connected to at least two mechanical actuators in the measurement sensor.

[0097] 16. The method according to any one of the preceding items, wherein the connecting element is disposed on the actuator.

[0098] 17. The method according to any one of the preceding clauses, wherein the connecting element is a beam.

[0099] 18. The method according to any one of the preceding items, wherein the connecting element is a mechanically constrained element and is released to the unconstrained state when one of the mechanical actuators reaches its final state.

[0100] 19. The method according to any one of the preceding items, wherein the connecting element that has reached the unconstrained state creates an observable physical record.

[0101] 20. The method according to any one of the preceding items, wherein the displaceable material is lithographically patterned.

[0102] 21. The displaceable substance of each measurement sensor includes a liquid or a gel, and the liquid or the gel is displaced into the displacement state when the physical stress is applied. The step of simultaneously applying the physical stress to each measurement sensor includes, for at least a predetermined period, simultaneously changing the temperature or phase of the liquid, the gel, or the substrate, or applying vibration or evaporation. The method according to any one of the preceding items 1 to 2.

[0103] 22. The method according to item 21, wherein the liquid or the gel is disposed in two end regions and a connection region connecting the two end regions.

[0104] 23. The method according to item 22, wherein when the physical stress is applied, the liquid or the gel is displaced toward one of the end regions.

[0105] 24. The method according to any one of items 21 to 23, wherein the liquid or the gel is adapted to return to the stationary state when the physical stress is released or deactivated.

[0106] 25. The method according to any one of the preceding items, further including a step of interpreting that the displaceable substance does not reach the displacement state as a further manufacturing error.

[0107] 26. The method according to any one of the preceding items, wherein the displaceable substance is displaceable within the plane of the substrate.

[0108] 27. The method according to any one of the preceding items, wherein the displaceable substance creates an observable physical record in the displacement state, and the method further includes a step of physically amplifying the observable physical record.

[0109] 28. The method according to any one of the preceding items, wherein each mechanical actuator or each two end regions of the gel or the liquid represents a timer.

[0110] 29. The method according to item 28, wherein the timer defines an expected trigger time for the mechanical actuator or the end region to reach the displacement state when a physical stress is applied.

[0111] 30. The method according to any one of items 28 to 29, wherein each measurement sensor comprises at least two timers.

[0112] 31. The method according to any one of item 30, wherein the at least two timers are designed with the same expected trigger time.

[0113] 32. The method according to any one of item 30, wherein the at least two timers are designed using trigger times having a predetermined difference.

[0114] 33. The method according to any one of item 30, wherein the difference is used to quantify manufacturing errors.

[0115] 34. The method according to any one of items 32 to 33, wherein the predetermined difference corresponds to an unknown physical bias such as an edge placement error.

[0116] 35. The method according to any one of items 28 to 35, wherein the pattern includes a timer range.

[0117] 36. The method according to any one of items 28 to 35, wherein each mechanical actuator or end region is designed such that its size is proportional to the predetermined time taken to reach the final state and corresponds to the expected trigger time of the timer.

[0118] 37. The method according to any one of the preceding items, wherein the array of measurement sensors is dispersed on the substrate.

[0119] 38. The method according to item 37, wherein the measurement sensors are arranged in an M×N configuration, where M≧2 and N≧2.

[0120] 39. The method according to any one of the preceding items, wherein the pattern defines an array of at least 10 measurement sensors.

[0121] 40. The method according to any one of the preceding items, wherein the step of imaging the measurement sensors to detect and / or quantify manufacturing errors made by the lithographic apparatus includes a microscopy technique such as optical microscopy for imaging the structure on the substrate.

[0122] 41. A measurement sensor assembly, a substrate, an array of measurement sensors, each measurement sensor comprising a plurality of mechanical actuators connected by at least one connecting element in a tensioned state, each mechanical actuator being adapted to trigger a mechanical action to reach a final state at a predetermined time at the start of an etching process, and when one of the mechanical actuators reaches the final state, each connecting element reaches an unconstrained state, the measurement sensor assembly comprising the array of measurement sensors.

[0123] 42. The measurement sensor assembly according to item 41, wherein the substrate comprises a semiconductor substrate with a determined out-of-plane crystal orientation.

[0124] 43. The measurement sensor according to any one of items 41 to 42, wherein the substrate is a semiconductor substrate having a defined out-of-plane crystal orientation, and each measurement sensor comprises two mechanical actuators or two liquid actuators.

[0125] 44. A measurement system, a lithographic apparatus configured to pattern a radiation-sensitive resist, such as a polymer, on a substrate using a design including an array of measurement sensors, each measurement sensor being configured in a stationary state and including a displaceable material dispersed over a local area, the displaceable material being adapted to reach a displaced state towards predetermined discrete positions within the local area during a displacement process upon application of a physical stressor. A physical stress device, such as an etching device or system adapted to apply a physical stress for at least a predetermined period, and The system includes an imaging device for imaging the measurement sensor to detect and / or quantify manufacturing errors caused by the lithography apparatus.

[0126] 45. The measurement system according to item 44, wherein the imaging device includes a microscope, preferably an optical microscope.

Claims

1. A method for detecting and / or quantifying manufacturing errors performed by a lithography process, wherein the method is A step of providing at least one design for fabricating a structure on a substrate using a set of lithography processes, wherein the fabricated structure defines an array of measuring sensors, each measuring sensor is adapted to produce one of a known and finite set of different physical phenomena that may occur when a physical process is applied, and the resulting physical phenomenon is Before the application of the aforementioned physical process, it was unknown, Depending on the manufacturing error that occurs by at least one of the set of lithography processes, Having a displacement state of the manufactured structure, or having one or more physical objects related to the manufactured structure that did not exist before the application of the physical process, Larger than the aforementioned error, The process, A step of obtaining the manufactured structure by applying a set of lithography processes, The process of applying the aforementioned physical process to generate one of the known and finite set of different possible physical phenomena for each measurement sensor, The process of reading out the physical phenomena generated by all measurement sensors, A step of processing the physical phenomena generated by all measurement sensors to detect and / or quantify the manufacturing error caused by the lithography process, Includes, A method wherein, after performing the above steps, each measuring sensor includes data relating to the error created by the lithography process.

2. The method according to claim 1, wherein the physical phenomenon that occurs is visually distinguishable from other physical phenomena in the set of different possible physical phenomena.

3. The method according to claim 1, wherein the manufacturing error is due to an edge placement error, and the edge placement error is less than 5 nm, or the edge placement error is less than 1 nm.

4. The method according to claim 1, wherein the step of processing the physical phenomenon that occurred includes computationally processing the physical phenomenon that occurred.

5. The method according to claim 4, further comprising the step of applying Boolean logic to the resulting physical phenomenon based on the expected physical results from the at least one design.

6. The method according to claim 4, further comprising the step of constructing a probability distribution of the count of physical phenomena that occurred for one or more different design parameters of the aforementioned design.

7. The method according to claim 1, wherein the set of lithography processes includes at least exposure and development of a radiation-sensitive resist.

8. The method according to claim 1, wherein the step of reading out the physical phenomenon that occurred includes searching for the physical phenomenon only at a predetermined location of the manufactured structure.

9. The method according to claim 1, wherein the physical phenomenon that occurred is digitally stored.

10. The method according to claim 1, wherein the physical phenomena occurring at all measurement sensors are read out using imaging.

11. The method according to claim 1, wherein each measuring sensor is configured in a stationary state and includes a displaceable material distributed over a local region, the displaceable material being adapted to reach a displacement process within the local region in the application of the physical process.

12. The method according to claim 11, wherein the displaceable material is in the stationary state when the fabricated structure on the substrate is obtained from the lithography process.

13. The method according to claim 1, wherein the physical process is applied to each measuring sensor for a predetermined period of time.

14. The method according to claim 1, wherein at least one design is configured such that one particular physical phenomenon takes precedence.

15. The method according to claim 14, wherein two or more designs are provided, and at least one of the designs is distinguishable from the other designs by at least one edge that is displaced by an integer of the minimum controllable process size of the lithography apparatus.

16. The method according to claim 1, wherein the at least one design is configured such that none of the known and finite set of different physical phenomena take precedence.

17. The method according to claim 1, wherein the physical phenomenon is a change in the shape, size, or arrangement of part or the whole of the structure, preferably the change in the shape, size, or arrangement of part or the whole of the structure is greater than 10 nm.

18. The method according to claim 1, wherein each measuring sensor comprises a plurality of mechanical actuators connected by at least one coupling element in a tensioned state representing the stationary state, each mechanical actuator is adapted to trigger mechanical action to reach a final state within a predetermined time at the start of the etching process, each coupling element reaches an unconstrained state representing the displacement state when one of the mechanical actuators reaches its final state, and the step of simultaneously applying the physical actuators to each measuring sensor for at least a predetermined period of time comprises simultaneously etching the array of measuring sensors for at least a predetermined period of time.

19. The method according to claim 18, wherein the final state of the mechanical actuator corresponds to partial or complete etching of the mechanical actuator to the extent that it releases the connecting element to which the mechanical actuator is connected.

20. The method according to claim 11, wherein the displaceable material of each measuring sensor comprises a liquid or gel, the liquid or gel is displaced to the displaced state when the physical stressor is applied, and the step of simultaneously applying the physical stressor to each measuring sensor comprises simultaneously changing the temperature or phase of the liquid or gel or the substrate, or adding vibration or evaporation, for at least a predetermined period of time.

21. The method according to claim 20, wherein the liquid or gel is disposed in two end regions and a connecting region connecting the two end regions, and the liquid or gel is displaced toward one of the end regions by the application of the physical process.

22. The method according to claim 18, wherein each mechanical actuator or each of the two end regions of the gel or liquid represents a timer.

23. The method according to claim 22, wherein the timer defines an expected trigger time for the mechanical actuator or the end region to trigger the displaceable material to reach the displaced state when the physical process is applied.

24. The method according to claim 22, wherein each mechanical actuator or end region is designed such that its size is proportional to a predetermined time it takes to reach the final state and corresponds to the expected trigger time of the timer.

25. It is a measurement system, A lithography apparatus configured to pattern a radiation-sensitive resist, such as a polymer, onto a substrate in order to manufacture a structure using a design that includes an array of measuring sensors, wherein each measuring sensor is adapted to produce one of a known and finite set of different possible physical phenomena when a physical process is applied, the resulting physical phenomenon is Before the application of the aforementioned physical process, it was unknown, Depending on the manufacturing error generated by the lithography apparatus, The manufactured structure is in a displaced state, or has one or more physical objects related to the manufactured structure that did not exist before the application of the physical process. Larger than the aforementioned error, After performing the above steps, each measurement sensor includes data relating to the error created by the lithography process. Lithography equipment, A system adapted to apply the physical process to each measuring sensor, A measurement system equipped with the following features.

26. The measurement system according to claim 25, wherein each measurement sensor is configured in a stationary state and includes a displaceable material distributed over a local region, the displaceable material being adapted to reach a displaced state toward a predetermined discrete position within the local region in the displacement process when the physical process is applied.

27. The measurement system according to claim 25, further comprising an imaging device for imaging the measurement sensor in order to detect and / or quantify the manufacturing error performed by the lithography apparatus.

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