Measurement method, measurement equipment, device manufacturing method and computer program product

Abstract

The present application provides a hybrid measurement device for measuring the properties of multiple structures manufactured on a substrate by a lithography process, a method for measuring the properties of multiple structures manufactured by a lithography process, a device manufacturing method and a computer program product. The hybrid measurement device includes: a first illumination system for illuminating a first structure with a first radiation; a first detection system for detecting a first spectrum including at least a portion of the first radiation reflected by the first structure; a second illumination system for illuminating a second structure with a second radiation; a second detection system for detecting a second spectrum including at least a portion of the second radiation reflected by the second structure; a processing system for determining a parameter of interest of the lithography process using the detected first spectrum and the detected second spectrum, the second detection system and the first detection system operating in different ways within the same band or operating in different bands.

Description

[0001] This application is a divisional application of the Chinese patent application with the application date of December 7, 2016, application number 201680074852.2 (international application number PCT / EP2016 / 080058), and invention name “Measurement method, measurement equipment and device manufacturing method”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of European patent application 15202273.7 filed on December 23, 2015, the entire contents of which are incorporated herein by reference. Technical Field

[0004] The present invention relates to methods and apparatus for metrology such as may be used in the manufacture of devices by photolithography, and to methods of manufacturing devices using photolithography. Methods of measuring critical dimensions (line widths) are described as a particular application of such metrology. Methods of measuring asymmetry related parameters such as overlay are also described. Background Art

[0005] A lithographic apparatus is a machine that applies a desired pattern to a substrate, typically a target portion of a substrate. For example, a lithographic apparatus may be used to manufacture integrated circuits (ICs). In this case, a patterning device, alternatively referred to as a mask or reticle, may be used to generate a circuit pattern to be formed on a single layer of the integrated circuit. The pattern may be transferred to a target portion (e.g., including a portion of a die, one or more dies) on a substrate (e.g., a silicon wafer).

[0006] During the lithography process, it is frequently necessary to make measurements of the structures created, for example for process control and verification. Various tools for making these measurements are known, including scanning electron microscopes (SEMs), which are often used to measure critical dimensions (CD). Other specialized tools are used to measure parameters related to asymmetry. One of these parameters is overlay (the accuracy of alignment of two layers in a device). Recently, various forms of scatterometers have been developed for use in the field of lithography. These devices direct a radiation beam onto a target and measure one or more properties of the scattered radiation (e.g., intensity as a function of wavelength at a single reflection angle; intensity as a function of reflection angle at one or more wavelengths; or polarization as a function of reflection angle) to obtain a "spectrum" of properties of interest that can be used to determine the target. Determination of the properties of interest can be performed by various techniques: for example, reconstruction of the target structure by iterative methods such as rigorous coupled wave analysis or finite element methods, library searching, and principal component analysis. Optical scatterometers can be used at much higher production rates on a large proportion or even all production units compared to SEM techniques.

[0007] The targets used by conventional scatterometers are relatively large (e.g., 40 microns by 40 microns) gratings, and the measurement beam produces a spot that is smaller than the grating (i.e., the grating is underfilled). In order to reduce the size of the targets, e.g., to 10 microns by 10 microns or less, e.g., so that they can be located in product features rather than in scribe lines, so-called "small target" metrology has been proposed, in which the grating is made smaller than the measurement spot (i.e., the grating is overfilled). These targets can be smaller than the illumination spot and can be surrounded by product structures on the wafer. Typically small targets are used for measurements of overlay and other performance parameters that can be derived from measurements of asymmetry in the grating structure. By placing the targets in the product features ("in-die targets"), it is expected that the accuracy of the measurements will be increased. For example, since in-die targets are affected by process variations in a more similar manner to product features, improved accuracy is expected, and less interpolation may be required to determine the effects of process variations at the actual feature location. These optical measurements of overlay targets have been very successful in improving overlay performance in high volume production. So-called dark field imaging has been used for this purpose. Examples of dark field imaging measurements can be found in international patent applications US20100328655A1 and US2011069292A1, the entire contents of which are incorporated herein by reference. Published patent publications US20110027704A, US20110043791A, US2011102753A1, US20120044470A, US20120123581A, US20130258310A, US20130271740A and US2015138523 have described 10 other advances in the technology. Similar small target technologies for focus performance and dose performance have also been implemented. The contents of all these previous applications are incorporated herein by reference.

[0008] However, as the technology develops, performance specifications become increasingly stringent. In addition, small target techniques have not yet been developed for the measurement of other parameters such as line width or critical dimension (CD). Another limitation of current methods is that they are performed using optical wavelengths that are much larger than the typical size of real product features. The specific parameter of interest is line width (CD). CD measurement is subject to low accuracy, crosstalk between the parameters of interest and between the parameters of interest and other hidden parameters (process robustness). As microstructures shrink and become increasingly complex in geometry (e.g., becoming 3-D structures), known techniques for CD measurement strive to provide accuracy, precision, and speed. Another parameter of interest is overlap.

[0009] As an alternative to optical measurement methods, the use of X-rays to measure overlap in semiconductor devices has also been considered. One technique is called transmission small angle X-ray scattering or T-SAXS. US2007224518A (Yokhin et al., Jordan Valley) discloses a T-SAXS device applied to the measurement of overlap, and the content of the application is incorporated herein by reference. Lemaillet et al. discussed the profile (CD) measurement using T-SAXS in "Intercomparison between optical and X-ray scatterometry measurements of FinFET structures" (Proc. of SPIE, 2013, 8681). T-SAXS uses X-rays with a wavelength less than 1 nanometer, for example in the range of 0.01 nanometers to 1 nanometer, and therefore the target for T-SAXS can be made of product-like features. T-SAXS signals tend to be very weak, especially when the target size is small. Therefore, the measurement tends to be too time-consuming to use in large-scale manufacturing. T-SAXS equipment can be used to measure targets that are small enough to be considered for placement among product features. Unfortunately, small target sizes require small spot sizes and therefore even longer measurement times.

[0010] Published patent applications US20130304424A1 and US2014019097A1 (Bakeman et al. / KLA) describe hybrid metrology techniques where measurements using x-rays and "optical" measurements using wavelengths in the range of 120 nm to 2000 nm are combined to obtain measurements of parameters such as CD. The CD measurement is obtained by coupling the x-ray mathematical model with the optical mathematical model through one or more commonalities.

[0011] It is known that reflectometry techniques using X-rays (GI-XRS) and extreme ultraviolet (EUV) radiation at grazing incidence are used to measure the properties of films and stacks on substrates. Within the general field of reflectometry, goniometric and / or spectroscopic techniques can be applied. In goniometric techniques, the change in the reflected beam with different angles of incidence is measured. On the other hand, spectroscopic reflectometry measures the spectrum of wavelengths reflected at a given angle (using broadband radiation). For example, EUV reflectometry has been used for inspection of mask blanks before the manufacture of masks (patterning devices) used in EUV lithography. Work on these techniques has been described, for example, by S Danylyuk et al. in "Multi-angle spectroscopic EUV reflectometry for analysis of thin films and interfaces" (Phys. Status Solidi C 12, 3, pp. 318 to 322 (2015)). However, these measurements are different from the measurement of CD in periodic structures. In addition, these known techniques are not suitable for measurement of small targets such as gratings inside a die, especially in view of the very shallow grazing angles involved.

[0012] In European patent application 15160786, which has not been published on the present priority date, it is proposed to use EUV radiation (i.e. radiation with a wavelength in the range of about 1 nanometer to about 100 nanometers) to measure properties such as CD and overlay of target structures. Spectral reflectometry is performed using radiation scattered at zero and / or higher diffraction orders. A grazing incidence angle higher than that which can be used at x-ray wavelengths is used to achieve a smaller spot size than in the case of T-SAXS or GI-SAXS methods. The diffraction signal is further enhanced by using a conical mounting stage between the EUV optical system and the substrate. This allows non-zero incidence azimuth angles relative to the periodic direction of the target structure. The contents of the previous application are hereby incorporated by reference into this document.

[0013] In the mentioned patent application, a form of hybrid metrology is proposed, where larger targets with product-like structures are measured using EUV radiation, while smaller intra-die targets are measured using an angle-resolved scatterometer operating in the more conventional optical band. The results of EUV measurements on several substrates are used to calibrate the optical measurements in high-volume manufacturing. Summary of the invention

[0014] The present invention seeks to provide alternative methods and apparatus for metrology of determining properties of microstructures of the type found in semiconductor manufacturing.

[0015] In a first aspect, the present invention provides a hybrid metrology apparatus for measuring properties of a structure fabricated by a lithographic process, the hybrid metrology apparatus comprising:

[0016] (a) a first illumination system for illuminating the structure with first radiation, the first radiation comprising one or more wavelengths in the range of 1 nanometer to 100 nanometers;

[0017] (b) a first detection system for detecting a first spectrum comprising at least a portion of the first radiation reflected by the periodic structure;

[0018] (c) a second illumination system for illuminating the structure with second radiation, the second radiation comprising one or more wavelengths in the range of 1 nm to 100 nm or in the range of 100 nm to 1000 nm;

[0019] (d) a second detection system for detecting a second spectrum comprising at least a portion of the second radiation reflected by the periodic structure;

[0020] (e) a processing system for determining a property of the structure using the detected first spectrum and the detected second spectrum.

[0021] The present inventors have recognized that radiation in the extreme ultraviolet (EUV) band offers particular advantages to the measurement of CD, overlay and other properties of small measurement targets. Conveniently, these small measurement targets may also have the form of a periodic structure. Compared to commonly practiced optical scatter measurements, EUV radiation will not be as strongly affected by underlying features, and therefore modeling of the periodic structure itself may be more accurate. Compared to X-rays, there is the possibility of focusing EUV radiation into a finer spot without undue loss of power. Compared to X-rays, there is the possibility of using much higher angles of incidence. In addition, by setting up a suitable EUV optical system for illumination and detection of the target, EUV radiation can be formed into a spot small enough for in-die measurement, even when the spot is elongated by grazing incidence. In order to obtain sufficient information for CD measurement, spectral properties spanning the EUV wavelength range may be measured.

[0022] Reference to a wavelength range from 1 nanometer to 100 nanometers is not intended to mean that the apparatus or method should use wavelengths spanning the entire wave range, or even be capable of doing so. An individual embodiment may choose to function with wavelengths only over a subset of the range. The appropriate range will depend on the availability of a suitable source, and the size of the structure to be measured.

[0023] According to the first aspect of the invention as set out above, the EUV metrology equipment can be used to supplement a second metrology equipment, which can operate in a different way within the same band, or can operate in a different band. Different modes of combining the detected spectra can be envisaged, some of which will be explained and exemplified in the following embodiments.

[0024] In a specific embodiment, the metrology system includes a substrate support adapted to receive a semiconductor wafer (eg, a 300 mm wafer) from an automated wafer handler.

[0025] In a second aspect of the invention there is provided a method of measuring a property of a structure fabricated by a lithographic process, the method comprising:

[0026] (a) irradiating the structure with first radiation, the first radiation comprising one or more wavelengths in the range of 1 nanometer to 100 nanometers;

[0027] (b) detecting a first spectrum comprising at least a portion of said first radiation reflected by the periodic structure;

[0028] (C) irradiating the structure with second radiation, the second radiation comprising one or more wavelengths in the range of 1 nm to 100 nm or in the range of 100 nm to 1000 nm;

[0029] (d) detecting a second spectrum comprising at least a portion of the second radiation reflected by the periodic structure;

[0030] (e) determining a property of the structure using the detected first spectrum and the detected second spectrum.

[0031] The present invention also provides a device manufacturing method, comprising:

[0032] transferring a pattern from a patterning device onto a substrate using a photolithographic process, the pattern defining at least one periodic structure;

[0033] measuring one or more properties of the periodic structure to determine values ​​of one or more parameters of the lithographic process; and

[0034] applying corrections in subsequent operations of the lithography process based on the measured properties,

[0035] Wherein the step of measuring the property of the periodic structure comprises measuring the property using a hybrid measurement system or method according to the aspect of the invention set out above.

[0036] Further features and / or advantages of the present invention and the structure and operation of various embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments described herein. These embodiments provided herein are for illustrative purposes only. Based on the teachings contained herein, those skilled in the relevant art will understand additional embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings, in which:

[0038] Figure 1 A lithographic apparatus and other apparatus forming a production facility for semiconductor devices and including a hybrid metrology apparatus according to an embodiment of the present invention are depicted;

[0039] Figure 2 Shown relative to Figure 1 the geometry of incident and reflected rays of a grating target in an EUV metrology section in one embodiment of a hybrid metrology apparatus;

[0040] Figure 3 Schematically illustrates the execution Figure 2 Components of EUV measurement equipment for EUV measurement methods;

[0041] Figure 4 (a) shows the elongation of the spot of radiation at grazing incidence by means of a schematic side view, with the spot S schematically shown at (b) and (c) for different angles of incidence being shown as a schematic illustration of a beam cross section B;

[0042] Figure 5 Schematically shows Figure 3 Components of the illumination system in EUV metrology equipment;

[0043] Figure 6 shows the geometry of incident and reflected rays relative to a grating target in a metrology method according to another metrology device, which can be used in a hybrid metrology device according to the invention;

[0044] Figure 7 Schematically illustrates the execution Figure 6 Components of a measuring device for the method;

[0045] Figure 8 Describes a spectral scatterometer that can be used in a measurement method according to an embodiment of the present invention;

[0046] Fig. 9 depicts a second type of scatterometer that can be used in a metrology method according to an embodiment of the present invention;

[0047] Fig.10 Shown including Fig. 9 A hybrid measurement device of a scatterometer of the type shown in;

[0048] Fig.11 Illustration of the radiation source arrangement for a hybrid metrology device, where EUV ( Fig.11 (a)) and longer wave radiation sources ( Fig.11 (b)) share the pump laser;

[0049] Fig.12 Diagram of the overall arrangement of measuring equipment and Figure 1 Data flow in a first example hybrid metrology device in a production facility shown in;

[0050] Fig.13 Diagram of the overall arrangement of measuring equipment and Figure 1 Data flow in a second example hybrid metrology device in a production facility shown in;

[0051] Fig.14 (a) The diagram shows the general arrangement of the measuring equipment and Figure 1 Data flow in a third example hybrid metrology device in a production facility shown in;

[0052] Fig.14 (b) Illustration of grazing incidence radiation and normal incidence radiation Fig.14 (a) Example of the interaction of overlapping target structures; and

[0053] Fig.15 It is shown that the use of Figure 1 Flow chart of a method for controlling the performance of a metrology method and / or a lithography manufacturing process by performing measurements with a hybrid metrology system. DETAILED DESCRIPTION

[0054] Before describing embodiments of the present invention in detail, it is instructive to present an example environment in which embodiments of the present invention may be implemented.

[0055] Figure 1 At 200 is shown a lithographic apparatus LA as part of an industrial facility implementing a high volume lithographic manufacturing process. In this example, the manufacturing process is applicable to the manufacture of semiconductor products (integrated circuits) on substrates such as semiconductor wafers. Those skilled in the art will appreciate that a wide variety of products can be manufactured by processing different types of substrates with variations of this process. The production of semiconductor products is used only as an example of great commercial significance today.

[0056] In a lithographic apparatus (or simply "litho tool" 200), a measurement station MEA is illustrated as 202 and an exposure station EXP is illustrated as 204. A control unit LACU is illustrated as 206. In this example, each substrate visits a measurement station and an exposure station to have a pattern applied. For example, in an optical lithographic apparatus, a projection system is used to transfer a product pattern from a patterning device MA to a substrate using conditioned radiation and a projection system. This is done by forming an image of the pattern in a layer of radiation-sensitive resist material.

[0057] The term "projection system" used in the present invention should be interpreted broadly to cover any type of projection system suitable for the exposure radiation used, or for other factors such as the use of immersion liquid or the use of vacuum, including refractive, reflective, reflective-refractive, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof. The pattern forming device MA can be a mask or mask that imparts a pattern to a radiation beam transmitted or reflected by the pattern forming device. Well-known operating modes include stepping mode and scanning mode. As is well known, the projection system can work in a variety of ways with a support and positioning system for the substrate and the pattern forming device to apply the desired pattern across the substrate to many target portions. A programmable pattern forming device can be used instead of a mask with a fixed pattern. For example, the radiation may include electromagnetic radiation in the deep ultraviolet (DUV) or extreme ultraviolet (EUV) band. The present disclosure is also applicable to other types of lithography processes, such as imprint lithography and direct write lithography (e.g., performed by an electron beam).

[0058] The lithographic apparatus control unit LACU controls all movements and measurements of the various actuators and sensors to receive the substrate W and mask MA and to perform the patterning operations. The LACU also includes signal processing and data processing capabilities to perform the required calculations associated with the operation of the apparatus. In practice, the control unit LACU will be implemented as a system of many sub-units, each of which handles real-time data acquisition, processing and control of a subsystem or component within the apparatus.

[0059] Before the pattern is applied to the substrate at the exposure station EXP, the substrate is processed at the measurement station MEA so that various preparatory steps can be performed. The preparatory steps may include using a level sensor to map the surface height of the substrate, and using an alignment sensor to measure the position of alignment marks on the substrate. The alignment marks are nominally arranged in a regular grid pattern. However, due to inaccuracies in the generation of the marks and also due to deformations of the substrate throughout its processing, the marks deviate from the ideal grid. Therefore, in the case where the device is to print product features at the correct position with very high accuracy, in addition to measuring the position and orientation of the substrate, the alignment sensor must actually measure the positions of many marks in detail across the substrate area. The device can be a so-called dual-stage type with two substrate stages, each of which has a positioning system controlled by a control unit LACU. While exposing one substrate on one substrate stage at the exposure station EXP, another substrate can be loaded onto the other substrate stage at the measurement station MEA, so that various preparatory steps can be performed. Therefore, the measurement of alignment marks is very time-consuming, and providing two substrate stages can achieve a considerable increase in the productivity of the device. If the position sensor IF is not capable of measuring the position of the substrate table when the substrate table is at the measurement station and at the exposure station, a second position sensor may be provided to enable the position of the substrate table to be tracked at both stations. The lithographic apparatus LA may, for example, be of a so-called dual stage type having two substrate tables WTa and WTb and two stations (an exposure station and a measurement station) between which the substrate table is exchangeable.

[0060] Within a production facility, the apparatus 200 forms part of a "litho cell" or "litho cluster", which also includes a coating apparatus 208 for applying photoresist and other coatings to substrates W for patterning by the apparatus 200. At the output side of the apparatus 200, a baking apparatus 210 and a developing apparatus 212 are provided for developing the exposed pattern into a solid resist pattern. Between all these apparatuses, a substrate handling system is responsible for supporting the substrates and transferring them from one apparatus to the next in the apparatus. These apparatuses, often collectively referred to as tracks, are under the control of a track control unit, which itself is controlled by a management control system SCS, which also controls the lithographic apparatus via a lithographic apparatus control unit LACU. Thus, the different apparatuses can be operated to maximize productivity and process efficiency. The management control system SCS receives configuration scheme information R, which provides in great detail the definition of the steps to be performed to produce each patterned substrate.

[0061] Once the pattern has been applied and developed in the lithography unit, the patterned substrate 220 is transferred to other processing equipment such as 222, 224, and 226. A wide range of processing steps are implemented by various equipment in a typical manufacturing facility. For example, the equipment 222 in this embodiment is an etching station, and the equipment 224 performs a post-etching annealing step. Additional physical and / or chemical processing steps are applied to additional equipment 226, etc. Many types of operations may be required to make a real device, such as deposition of materials, modification of surface material properties (oxidation, doping, ion implantation, etc.), chemical mechanical polishing (CMP), etc. In actual applications, equipment 226 may represent a series of different processing steps performed in one or more equipment.

[0062] As is well known, the manufacture of semiconductor devices involves many repetitions of such processing to build device structures layer by layer with appropriate materials and patterns on substrates. Thus, the substrates 230 that arrive at the photolithography cluster may be newly prepared substrates, or they may be substrates that have been completely processed previously in this cluster or in another device. Similarly, depending on the desired processing, substrates 232 may be returned upon leaving device 226 for subsequent patterning operations in the same photolithography cluster, they may be designated for patterning operations in different clusters, or they may be finished products to be sent for cutting and packaging.

[0063] Each layer of product structure requires a set of different process steps, and the equipment 226 used for each layer can be completely different in type. In addition, even if the processing steps to be applied by the equipment 226 are nominally the same, there may be multiple assumed identical machines working in parallel to perform step 226 on different substrates in a large facility. Small differences in the settings or defects between these machines may mean that they affect different substrates in different ways. Even relatively common steps for each layer such as etching (equipment 222) can be implemented by multiple etching equipment that are nominally the same but work in parallel to maximize productivity. In addition, in practice, different layers require different etching processes, such as chemical etching, plasma etching, according to the details of the material to be etched and special requirements such as anisotropic etching as an example.

[0064] Previous and / or subsequent processes may be performed in other lithographic apparatuses as just mentioned, and may even be performed in different types of lithographic apparatuses. For example, some layers in the device manufacturing process that are very demanding in terms of parameters such as resolution and overlay may be performed in more advanced lithographic tools than other layers that are less demanding. Thus, some layers may be exposed in immersion lithographic tools, while other layers are exposed in "dry" tools. Some layers may be exposed in tools operating at DUV wavelengths, while other layers are exposed using EUV wavelength radiation.

[0065] In order to correctly and consistently expose the substrate exposed by the lithography apparatus, it is necessary to inspect the exposed substrate to measure properties, such as overlay error between subsequent layers, line width, critical dimension (CD), etc. Therefore, the manufacturing facility where the lithography unit LC is located also includes a hybrid measurement system 240 that receives some or all of the substrates W that have been processed in the lithography unit. The measurement results are provided directly or indirectly to the management control system SCS. If an error is detected, the exposure of subsequent substrates can be adjusted, especially if the measurement can be performed quickly enough so that other substrates of the same batch are still to be exposed. In addition, the already exposed substrates can be stripped and reworked to improve the yield, or discarded, thereby avoiding further processing of the substrates that are known to be defective. In the case where only some target portions of the substrate are defective, further exposure can be performed only on those target portions that are good.

[0066] For example, the hybrid measurement system 240 may be used to determine that an important performance parameter such as overlay or critical dimension (CD) does not meet specified accuracy requirements in the developed resist. Prior to the etching step, there is an opportunity to strip the developed resist and reprocess the substrate 220 by the lithography cluster. As is also known, the metrology results 242 from the equipment 240 may be used to maintain accurate performance of the patterning operation in the lithography cluster by managing small adjustments over time by the control system SCS and / or the control unit LACU 206, thereby minimizing the risk of manufacturing defective products and requiring rework. Of course, the hybrid measurement system 240 and / or other measurement equipment (not shown) may be applied to measure properties of processed substrates 232, 234 and newly introduced substrates 230.

[0067] Each generation of photolithographic manufacturing technology (often referred to as a technology "node") has tighter specifications for performance parameters such as CD. One of the main challenges in metrology is that it is desirable to have metrology target sizes smaller than those typically used for metrology equipment 240. For example, current targets use targets having dimensions of 5 microns by 5 microns or less. These small dimensions will permit wider use of so-called "in-die" or "on-product" metrology, where the target is located within product features (instead of being confined to scribe line areas between product areas). The only metrology technology currently used for in-die CD metrology is electron microscopy (CD-SEM). This known technology exhibits limitations for future nodes and only provides very limited geometric information of the structure.

[0068] Within the hybrid metrology system 240, a first metrology device 242 (MET1) and a second metrology device 244 (MET2) and optionally further devices (MET3, etc.) are provided for measuring parameters at desired stages during the manufacturing process. A common example of a metrology device in a modern lithography production facility is a scatterometer (e.g., an angle-resolved scatterometer or a spectral scatterometer), and it can be applied to measure the properties of the developed substrate at 220 before etching in device 222. The hybrid metrology system 240 differs from known examples in that multiple metrology types can be performed within the hybrid metrology system to obtain a better overall measurement of one or more parameters of interest for a given target structure.

[0069] Each of the measurement devices 242, 244 may have a specific illumination system for radiation having specific characteristics. More detailed examples of the types of devices that can be combined are given below. In each case, the measurement processing system 246 receives first spectral data 248 from a first detection system within the first measurement device 242, and receives second spectral data 250 from a second detection system within the second measurement device 244. The measurement processing system 246 combines these spectra with hybrid calculations to obtain a measurement 252 of CD or other parameters that is reported to the management control system SCS. In some embodiments, the measurement processing system 246 also controls the operation of one or more of the measurement devices 242, 244 to change the parameters of its operation based on the spectral data received from another measurement device in the measurement device.

[0070] One of the devices within the hybrid metrology system (e.g., the second metrology device 244) may be designed to operate with radiation at visible or UV wavelengths, while another of the devices (e.g., the first metrology device 242) may be designed to operate with EUV radiation. In other embodiments, both the first and second metrology devices may be designed to operate with EUV radiation having the same or different wavelengths. One of the devices may be designed to operate with grazing incidence, while the other device is designed to operate with normal or near normal incidence. One of the devices may be designed to obtain a frequency-resolved spectrum of radiation scattered by a target structure, while the other of the devices may be designed to obtain an angle-resolved spectrum. One of the metrology devices (e.g., the second metrology device 244) may be an angle-resolved scatterometer, a spectral scatterometer, a spectroscopic ellipsometer, and / or a spectroscopic Mueller ellipsometer. Common hardware may be used to implement more than one of these types of metrology devices. These and other variations may be used in a hybrid metrology system to obtain more information about a structure, and therefore give a more accurate measurement of a parameter of interest. Three or more metrology devices may be provided in a hybrid metrology system, and the first and second metrology devices are labeled here only for convenience. These additional metrology devices may be used together to make one measurement, or they may be used in different sub-combinations.

[0071] In an embodiment of the hybrid metrology system 240 according to the present disclosure, it is proposed to use an EUV wavelength for measurement in at least one of the metrology devices. In some embodiments, EUV reflectometry (especially spectral EUV reflectometry) is adopted as part of a CD metrology solution for future technology nodes. In the above-mentioned pending European patent application No. 15160786, it is shown that EUV reflectometry provides the benefits of high sensitivity that is robust with respect to process variations and selective with respect to the parameters of interest.

[0072] Like optical scatterometers used in today's production facilities, EUV metrology equipment can be used to measure structures in resist materials processed in a lithography cell (i.e., "development inspection" or ADI), and / or to measure structures after they have been formed in harder materials (i.e., "etching inspection" or AEI). For example, EUV metrology equipment 242 can be used to inspect a substrate after it has been processed by a development equipment 212, an etching equipment 222, an annealing equipment 224, and / or other equipment 226. In contrast, X-ray technology will generally be limited to AEI and cannot be used to measure structures formed only in resist. This limits the possibility of reworking a substrate if the substrate fails inspection.

[0073] EUV Spectral Reflectometry

[0074] Figure 2 The EUV measurement method is shown in the figure. Figure 3 FIG. 3 shows an EUV measurement device 300. The device can be used to measure Figure 1 242 or the second metrology device 244 for measuring parameters of a processed substrate W in a production facility.

[0075] exist Figure 2 In , the target T is schematically illustrated as comprising a one-dimensional grating structure located at the origin of a spherical reference coordinate system. Axes X, Y and Z are defined relative to the target. (Of course, in principle any arbitrary coordinate system may be defined, and each component may have its own local reference coordinate system that may be defined relative to the reference coordinate system shown). The periodic direction D of the target structure is aligned with the X axis. The figure is not a true perspective view, but only a schematic illustration. The XY plane is the plane of the target and substrate, and is shown tilted towards the observer for clarity, which is represented by the tilted view of circle 302. The Z direction defines the direction N perpendicular to the substrate. In Figure 2 , one of the incident rays is labeled 304 and has a grazing angle of incidence α. In this example, the incident ray 304 (and all incident rays forming the radiation spot S) is substantially in a plane parallel to the XZ plane, i.e., the plane defined by the directions D and N and represented by the circle 306. The reflected ray 308, which is not scattered by the periodic structure of the target T, emerges in the figure toward the right side of the target at an elevation angle α.

[0076] To perform spectroscopic reflectometry, ray 308 and other reflected rays are decomposed into a spectrum 310 including rays having different wavelengths. For example, a grazing incidence diffraction grating 312 may be used to generate the spectrum. The spectrum is detected by a detector 313. Such a detector, which may be, for example, a CCD image detector having an array of pixels, is used to transform the spectrum into an electrical signal and ultimately into digital data for analysis.

[0077] In a practical system, the spectrum of radiation 304 may be subject to temporal variations, which would interfere with the analysis. In order to normalize the detected spectrum for these variations, a reference spectrum is captured by a second detector 314. To generate the reference spectrum, source radiation 316 is diffracted by another diffraction grating 318. The zero-order reflected rays of the grating 318 form the incident rays 304, while the first-order diffracted rays 320 of the grating 318 form the reference spectrum detected by the reference spectrum detector 314. An electrical signal and data representing the reference spectrum are obtained for analysis.

[0078] From the measured spectra obtained for one or more values ​​of the angle of incidence α, a measurement of a property of the target structure T can be calculated. In the hybrid metrology system 240, such a measurement is obtained by using the detected spectrum in combination with one or more spectra detected by other metrology devices on the same target structure. Different ways of doing this combination are further described below.

[0079] Go to Figure 3 , providing EUV measurement equipment 300 for Figure 2 The method measures the properties of a measurement target T formed on a substrate W. Various hardware components are schematically represented. The actual implementation of these components can be performed by relevant technical personnel according to known design principles using a mixture of existing components and specially designed components. Support members (not shown in detail) are provided for holding the substrate in a desired position and orientation relative to other components to be described. Radiation source 330 provides radiation to irradiation system 332. Irradiation system 332 provides an EUV radiation beam represented by ray 304, which forms a focused radiation spot on target T. Irradiation system 332 also provides a reference spectrum 320 to detector 314. It is convenient to think of components 312, 313, etc. as detection system 333.

[0080] The substrate W in this example is mounted on a movable support with a positioning system 334 so that the angle of incidence α of the ray 304 can be adjusted. In this example, while the source 330 and the illumination system 332 remain stationary, for convenience, it is chosen to tilt the substrate W to change the angle of incidence. In order to capture the reflected ray 308, the detection system 333 is provided with a further movable support 336 so that the movable support can be moved through an angle 2α relative to the stationary illumination system, or through an angle α relative to the substrate. In the grazing incidence regime of reflectometry, it is convenient to define the angle of incidence α with reference to the plane of the substrate as shown. Of course, the angle of incidence can also be defined as the angle between the direction of incidence of the incident ray I and the direction N perpendicular to the substrate.

[0081] Additional actuators (not shown) are provided for moving each target T into position where the focused radiation spot S is located. (From another perspective, the spot is moved into position where the target is located.) In practical applications, there may be a series of individual targets or target locations to be measured on a single substrate, and there may also be a series of individual targets or target locations to be measured on a series of substrates. In principle, it is not important whether the substrate and targets are moved and reoriented while the illumination system and detector remain stationary, or whether the substrate remains stationary while the illumination system and detector move, or whether different components having relative movement are achieved by a combination of these techniques. The present disclosure encompasses all these variations.

[0082] If already referenced Figure 2 As depicted, the radiation reflected by the target T and substrate W is separated into a spectrum 310 of rays of different wavelengths before it impinges on a detector 313. The detector 306 comprises, for example, a position-sensitive EUV detector, which is typically an array of detector elements. The array may be a linear array, but in practice a two-dimensional array of elements (pixels) may be provided. The detector 313 may be, for example, a charge coupled device (CCD) image sensor.

[0083] A processor 340, which may be part of the measurement processing system 246 or a subsystem local to the measurement device 300, receives signals from the detectors 313 and 314. Specifically, the signal ST from the detector 313 represents the target spectrum, and the signal SR from the detector 314 represents the reference spectrum. The processor 340 may subtract the reference spectrum from the target spectrum to include a reflectance spectrum of the target normalized relative to changes in the source spectrum. The resulting reflectance spectrum for one or more incident angles is used in the processor 340 to indirectly calculate a measurement of a property of the target (e.g., CD or overlap).

[0084] In practice, the radiation from source 330 may be provided in a series of short pulses, and the signals SR and ST may be captured together for each pulse. The differential signal for each individual pulse is calculated and then summed up into the total reflectance spectrum for this target at this angle of incidence. In this way, instabilities in the source spectrum between pulses are corrected. The pulse rate may be thousands or even tens of thousands per second (hertz). The number of pulses summed up to measure one reflectance spectrum may be, for example, tens or hundreds. Even with so many pulses, the physical measurement takes only a fraction of a second.

[0085] In such EUV-SR metrology applications in semiconductor manufacturing, a small grating target may be used. Detectors 313 and 314 are used to capture multiple diffraction spectra while setting the grazing incidence angle α to various values. Reconstruction calculations may be performed using the detected spectra and mathematical models of the target structure to achieve measurement of CD and / or other parameters of interest. Exemplary reconstruction methods are illustrated in the pending applications. In the hybrid metrology system that is the subject of the present disclosure, the reconstruction method is modified to take into account the measurement of the CD and / or other parameters of interest by two or more metrology devices (and not only Figure 3 Spectrum detected by the measuring device shown in the figure).

[0086] In the case of briefly considering the target itself, the size of the lines and spaces will depend on the target design, but the period of the structure can be, for example, less than 100 nanometers, less than 50 nanometers, less than 20 nanometers, even less than 10 nanometers and as low as 5 nanometers. The lines of the grating structure can have the same size and pitch as the product features in the product area of ​​the substrate. For measurement purposes only, the lines of the grating structure can actually be the lines of the product structure rather than the lines of the target structure formed in the dedicated target area. Such small features can be formed by imprint lithography or by direct write methods, such as in EUV lithography processes. Such small features can also be formed using current DUV lithography by so-called double patterning processes (usually multiple patterning). Technologies in this category include, for example, pitch doubling achieved by lithography-etch-lithography-etch processes (LELE) and self-aligned dual-damascene in the back end of the line layer (BEOL). For the purpose of explanation, it will be assumed in the following examples that CD is the parameter of interest. However, in the case where there are two gratings overlapping each other, another parameter of interest may be the overlap. This parameter can be measured based on the asymmetry in the EUV-SR diffraction orders, as described separately below. The incident angle can be raised if necessary to adequately penetrate underlying structures.

[0087] In a multiple patterning process, structures are formed in one layer of a product not in one patterning operation but in two or more patterning steps. Thus, for example, a first group of structures may be interleaved with a second group of structures, and the groups of structures may be formed in different steps in order to achieve a higher resolution than one step alone could produce. Although the placement of the groups of structures should be identical and perfect relative to other features on the substrate, of course, each true pattern exhibits a certain positional offset. Any unintentional positional offset between the groups of structures may be considered a form of overlap and may be measured by techniques similar to those used to measure overlap between layers. In addition, the overlap for features in a bottom or upper layer may be different for each group when multiple groups of features are formed in a single layer, and the overlap for each of these groups may be measured independently if desired.

[0088] Figure 4 The diagram illustrates the elongation of the radiation spot, which is challenging to implement in-die metrology using grazing incidence reflectometry. Figure 4In (a), a substrate W and a target T are shown in cross-section. Representative incident rays 304 and reflected rays 308 are illustrated, which have an angle of incidence α relative to the substrate W. Because these rays are representative rays, it should be taken into account that the incident radiation as a whole includes many rays that form a beam schematically indicated at 404. Similarly, the reflected radiation includes many rays 308 that form a beam schematically indicated at 408. In order to utilize the smallest possible target, the radiation spot is formed by focusing the rays of the beam 404 so that the rays converge to precisely define a minimum beam diameter where they meet the surface of the substrate W. In the illustration, the incident beam 404 is at a minimum diameter d B The reflected beam 408 (ignoring scattering effects) includes scattered rays as shown. Because the grazing incidence angle α is relatively small (in other words, closer to zero than to 90°), the diameter ds of the radiation beam 404 when projected onto the target T is smaller than the beam diameter d B Several times larger. Diameter d S With d B The ratio between depends on the sine of the angle α, as Figure 4 (a) shown.

[0089] like Figure 4 (b), in order to achieve a circular spot S that fits within the area of ​​the target T, the beam 404 should have a strongly elliptical cross section as shown at B. When the angle α is, for example, 5°, the minimum diameter d of the beam B The allowable diameter d of the light spot should be S More than 10 times smaller (sin5°=0.087). For lower angles of incidence, the minimum beam diameter will have to be tens, hundreds, or even thousands of times smaller. It will be virtually impossible to obtain a spot that fits within a small target area, such as 5 square microns. Even in the case of α=5°, the minimum beam diameter d B should be about 436 nm to achieve a spot size below 5 μm. Figure 4 As seen in (c), an increase in the grazing incidence angle α greatly relaxes the minimum diameter requirement of the beam 404. The ellipse B' can be much wider than the ellipse B in order to achieve a spot S' that fits within the area of ​​the target T. For example, for the case where α = 20°, the beam diameter will only increase by a factor of three. The minimum diameter d B Spot sizes as large as 1.7 microns can be achieved, without exceeding 5 microns. The inventors have recognized that the use of these higher angles of incidence enables smaller spot sizes to be within the capabilities of EUV optical designs, compared to known techniques, particularly X-ray reflectometry (GI-XRS).

[0090] Figure 5 Pictured Figure 3A possible arrangement of an irradiation system 332 in an EUV measurement device. A radiation source such as a plasma is represented at 330. For EUV lithography, various types of sources have been tested and constructed experimentally or commercially. Any of these sources can be applied in the present device depending on the required wavelength range. Plasma sources include tin (Sn), but also Xe or Ar or Kr or Ne or N, or any combination thereof. Laser driven light sources and harmonic generator sources can be applied. Plasma sources are not the only types of sources that can be applied. Synchrotron sources can obtain more useful power levels and are more controllable in terms of wavelength and power, but these sources are not yet commercially available in compact form. In some embodiments of the present disclosure, a higher harmonic generation (HHG) type source or an inverse Compton scattering (ICS) source can be used. In the following description Fig.10 The HHG source is shown in the figure.

[0091] An EUV radiation beam 500 having desired spectral characteristics is emitted in a range of directions. At the exit of the source 330 (i.e., the entrance to the irradiation system 332), a first aperture 502 is provided to act as an entrance pupil for the irradiation system. An incident beam 504 having a well-defined divergence is incident on a focusing optical element or system. Such a focusing system is implemented in the present illustration by a 2-dimensional curved mirror 506 (e.g., an ellipsoidal mirror). The mirror 506 generates a converging beam 508, which is focused to form a light spot at a target location on the substrate W. Optionally, a second aperture 510 is provided to limit the diameter of the beam 404 at the target. Specifically, the aperture 510 can be made adjustable in height and / or width so that different shapes B′ of the beam can be generated according to different requirements / sizes and different incident angles α.

[0092] The reflected beam 408 enters the detection system 333 (not shown in this view), carrying information about the structure of the target. Optionally, a second focusing mirror 520 is provided to reduce the divergence of the beam as it enters the detection system 333.

[0093] like Figure 2 and Figure 3 As seen in FIG. 3 , a reference spectrum 320 is formed and detected by a reference spectrum detector 314. Figure 5In the illustrated example illumination system, the grating 318 for generating the reference spectrum 320 is integrated into the curved mirror 506. In an alternative embodiment, the reference spectrum grating may be provided as a separate element in series with the mirror 506. In addition, in order to focus the radiation from the beam 504 into the beam 508, the single two-dimensional curved mirror 506 may be replaced by a series of two or more one-dimensional curved (cylindrical) mirrors. The grating (regardless of where it is provided) may be of the "flat field" type, so that a spectrum that can be well resolved is formed across a linear or planar pixel array in the detector 314. Similarly, in the case of a two-dimensional curved focusing mirror 520 provided at the detection side, one or more curved mirrors in one dimension may be provided. The curved mirror may be integrated with the grating 312 that forms the spectrum 310 of the radiation reflected by the target. It should be noted that in order to obtain the desired spectral resolution, it may not be necessary to focus the beam 408 in two dimensions.

[0094] Figure 5 Also shown in outline is a second metrology device, labeled 522. This illustrates where the illustrated layout allows space within the hybrid metrology device 240 for a second illumination system and a second detection system acting on the same target structure.

[0095] In co-pending European patent application 15160786, experimental results and simulations are presented to illustrate the choice of wavelength and the choice of angle of incidence that can be used in such a device. It is seen in particular in the wavelength range of 15 nanometers to 40 nanometers and above 40 nanometers that the reflectivity of the various materials of interest remains substantially even up to angles of 10 degrees, 20 degrees and 30 degrees. See again Figure 4 and Figure 5 , this range of incidence angles allows the implementation of an optical design that achieves the desired small radiation spot, even at grazing incidence using available EUV optical technology.

[0096] Compared to X-rays with higher energy (shorter λ), grazing incidence can be achieved at higher angles α in EUV wavelengths of 1 nm to 100 nm. The phenomenon of "total internal reflection" is familiar in optical devices at visible wavelengths, where materials such as glass have a refractive index greater than 1. At EUV wavelengths, materials typically have a refractive index less than 1, and the phenomenon of "total external reflection" results. The angle up to which a considerable reflection can be obtained can be called the critical angle. The advantage of the relatively shallow penetration depth at EUV wavelengths is that measurements representative of the surface structure of the substrate can be obtained without significant interference from buried features typically present in semiconductor products. As further explained below, it is possible to obtain a grazing incidence at EUV wavelengths. Figure 1 One method of operation of a hybrid metrology system exploits this shallow penetration depth.

[0097] The co-pending application also illustrates that the penetration depth of EUV radiation varies with the angle of incidence. For a given structure, a higher penetration depth can be achieved in the direction perpendicular to the substrate by increasing the angle of incidence α to higher values. The range of angles of incidence that can be used to exploit this effect without losing reflectivity is higher in the EUV range (especially in the range of 15 nm to 100 nm) than it is, for example, in X-ray measurement techniques.

[0098] The co-pending application further explains, by simulation and / or experiment, how spectroscopic reflectometry in the EUV wavelength range can yield information about the form of a grating structure (periodic structure) formed on a silicon substrate. The calculations performed confirm that good measurement information about the presence and structure of a grating target should be obtainable by EUV spectroscopic reflectometry. Additional calculations indicate that the detected spectrum may also reveal information about other parameters, such as information about the sidewall angle of the grating.

[0099] The calculations indicate that as the angle of incidence α increases from 2° to 12°, the intensity of the signal carrying the measurement information increases. Therefore, depending on the material and structure to be measured, an angle of incidence α of 5° or more may be selected, for example, an angle in the range of 10 to 40 degrees. The best choice of angle will depend on the availability of spectral components in the source radiation and on the relationship between the reflectivity of different materials and the angle of incidence. That is, the angle of incidence should be selected as a compromise between the intensity of the signal and the intensity of the reflection achieved by the specific material of the target. Similarly, the intensity of the signal (side wall angle information) varies across a range of wavelengths. The range of incident angles and wavelengths for which measurements will be performed can be selected to define an optimal set of measurement parameters for a specific type of target and a specific property of interest. Such a set of measurement parameters may be referred to as a measurement "profile".

[0100] As is well known, EUV optical equipment cannot work in a normal atmospheric environment. The pending application schematically illustrates the housings of different parts of the EUV measurement equipment. This EUV measurement equipment has features to facilitate the management of vacuum and low-pressure gas environments within the equipment, especially in a high-volume manufacturing environment. In the case where the entire equipment will be contained in a vacuum environment, the cost and time delay required to re-establish the vacuum environment after loading and unloading the wafer or wafer bath will seriously degrade productivity. At the same time, it may be necessary to have as many beam paths as possible in a high vacuum environment. Different parts of the EUV optical system are contained in different chambers. Suitable walls can define these chambers, and windows allow EUV radiation to pass between chambers. In the example described in the pending patent application, the first chamber contains a radiation source and an irradiation system. A first gas environment condition, such as a high vacuum, is maintained in the first chamber. In the second chamber, a substrate with a target structure is supported on a substrate support, wherein a second gas environment condition is maintained around the target. The second gas environment condition can be, for example, a low-pressure gas environment, such as using hydrogen, argon. In this way, when substrates are exchanged through some form of airlock mechanism, the desired gas environment conditions can be established and re-established relatively quickly and without undue cost. Although the transmission losses in the second gas environment conditions may be greater than in the case of high vacuum, these losses can be tolerated for limited travel distances and operating productivity. Components of the detection system such as grating 312 and detector 313 are located in the third chamber, which is maintained in the third gas environment conditions. The third gas environment conditions can be, for example, high vacuum.

[0101] Figure 6 Another modification example of the EUV metrology method is illustrated, and Figure 7 The corresponding measurement equipment is shown in the figure. This method and apparatus incorporates certain modifications described in more detail in the above-mentioned pending application. It should be understood that the components marked as "7xx" in these examples are the same as those in Figures 2 to 5 The components marked as “3xx” in the method and apparatus are the same. Therefore, the modified EUV metrology apparatus includes, for example, an illumination system 730 , an illumination system 732 , and a detection system 733 .

[0102] Again, an X, Y, Z coordinate system is defined relative to the substrate. Again, it is assumed that the target T comprises a one-dimensional grating having a periodic direction D parallel to the X-axis of the substrate. Again, the substrate and the target may be tilted to change the angle of incidence. The detection system 733 further comprises a diffraction grating 712 to split the reflected rays 708 into spectra 710 having different wavelengths. The reflected spectrum 710 is captured by a detector 713, and a signal ST is provided to a processor 740. However, compared to Figure 2The positioning system 734 can be operated so that the incident angle of the incident ray 704 can be varied not only at a grazing angle of incidence α, but also at an angle α, which is marked here as azimuth change.

[0103] Again, the X, Y, Z coordinate system is defined relative to the substrate. Again, it is assumed that the target T comprises a one-dimensional grating having a periodic direction D parallel to the X-axis of the substrate. Again, the substrate and the target may be tilted to change the angle of incidence. However, non-zero azimuth angles of incidence are allowed The azimuth angle is defined relative to the periodic direction D of the grating target T. (In the case of a two-dimensional periodic target, D can be any of the main periodic directions.) That is, when the incident direction is projected onto the plane of the substrate, the azimuth angle between the incident ray and the periodic direction D is is non-zero and may be very large. That is, the irradiation direction is outside the plane defined by the periodic direction D and the direction N perpendicular to the substrate. Specifically, the incident ray travels in a plane that is inclined to the periodic direction D. The inclined plane is represented by circle 707, which is orthogonal to the plane of the substrate but inclined relative to the periodic direction and the XZ plane. It should be understood that although the choice of labels for planes and axes is arbitrary, the grazing incidence angle and azimuth angle are defined with reference to the physical properties of the periodic structure of the target.

[0104] As explained in the co-pending application, when a non-zero azimuth angle is used, the diffraction efficiency of the different diffraction orders can be substantially increased. This in turn has an impact on the spectrum of the reflected (zero-order) ray 708.

[0105] In implementing the apparatus 700, different arrangements of positioning systems can be used to achieve non-zero azimuth angles. Reference numeral 734 indicates a positioning subsystem having actuators for rotating about the X-axis and Y-axis of the substrate. The desired combination of command values ​​Rx and Ry is calculated to cause the substrate to tilt in two dimensions to achieve the desired angle. In another embodiment, an actuator may be provided for rotation and tilting, thereby directly driving the angles α and If from Figure 7 Knowing that the rotation Rz directly corresponds to the desired azimuth Also in this case, the command value can be generated more directly from the desired measurement angle.

[0106] In other areas of metrology, the type of mounting required to vary both the grazing incidence (polar) angle and the azimuth angle is referred to as a "conical mount", and that term may also be employed in such EUV reflectometry equipment. In general, the skilled person will appreciate that any form of command and any form of actuation mechanism may be used to implement this example, provided that it is suitable for achieving a known non-zero incidence azimuth angle. It will also be appreciated that the relative orientation of the incidence direction to the target is important (and of course correct XY positioning of the target relative to the radiation spot S is also important).

[0107] In addition, in this modified method and apparatus 700, a third detector 750 is provided to receive another spectrum 752. The spectrum 752 includes radiation diffracted first by the periodic structure of the target T. The angle P at which the first-order diffracted radiation is directed depends on the pitch of the target grating and the wavelength of the diffracted radiation. In the case of spectral EUV reflectometry, where the incident radiation includes a range of wavelengths, the radiation diffracted by the target is spread into a spectrum at a range of angles β, as shown. This first-order spectrum (similar to the reflectance spectrum 710) contains information about the target structure. The signal SF captured by the detector 750 is supplied to the processor 740 for use (together with the signals SR and ST) to calculate an improved measurement of the property of interest of the target.

[0108] Capturing the first order diffraction spectrum can be of particular benefit in resolving a property of the target that is associated with asymmetry. Such a property is overlap.

[0109] Although the angle β ranges from Figure 6 , but for convenience it will be appreciated that a fairly wide range of angles may be encountered, including "backward" diffraction. This is particularly the case for the following reasons: (i) the range of wavelengths of interest may span more than one octave (e.g., the 10 nm to 40 nm or even 5 nm to 50 nm ranges mentioned in the examples above); and (ii) in many potential applications, the pitch of the finest target grating (which may be a product feature) is of magnitude similar to the magnitude of the wavelength of the radiation. Figure 7 Such an angle range is shown in the figure. Referring to the angle β' defined relative to the normal direction N, an angle range of, for example, -90° to +20° can be expected.

[0110] To accommodate wide variations in the diffraction angle β (or β'), an additional actuator 754 may be provided to move the detector 750 to an appropriate position as the grazing incidence angle α is varied by the actuator 734 and as the first order diffraction angle β varies with grating pitch and wavelength. Alternatively or in addition, the detector 750 may be made large range and / or placed near the target close to the substrate. Figure 7 This is schematically shown in . If desired, collimating optics can be provided to reduce the spread of angles so that they can be captured on a conveniently sized and conveniently placed detector 750. In the hybrid metrology system 240 disclosed herein, the detector 750 and any second or additional metrology devices should be designed to avoid conflict with each other.

[0111] Second measurement equipment example

[0112] Figure 8 A known spectroscopic scatterometer 800 is depicted which may be used as one of the measurement devices in a hybrid metrology system 240 of the type described above. It comprises a broadband (white light) radiation projector 802 which projects radiation onto a substrate W. The reflected radiation is passed to a spectrometer 804 which measures the spectrum 806 (intensity as a function of wavelength) of the specularly reflected radiation. From this data, the structure or profile 806 which gave rise to the detected spectrum may be reconstructed by calculation within a processing unit PU. The processing unit PU may be part of the metrology processing unit 246, or it may be in a processor local to the device 800. Such a scatterometer may be configured as a normal incidence scatterometer or an oblique incidence scatterometer.

[0113] Fig. 9 Basic elements of a known angle-resolved scatterometer 900 that can be used as one of the metrology devices in a hybrid metrology system 240 of the type described above are shown. In a metrology device of this type, the radiation emitted by the radiation source 11 is conditioned by an illumination system 912. For example, the illumination system 912 may include a collimating device using a lens system 912a, a color filter 912b, a polarizer 912c and an aperture 913. The conditioned radiation follows an illumination path IP in which it is reflected by a partially reflective surface 915 and focused via a microscope objective 916 into a light spot S on a substrate W. A metrology target T may be formed on the substrate W. The lens 916 has a high numerical aperture (NA), preferably at least 0.9 and more preferably at least 0.95. If desired, an immersion fluid may be used to obtain a numerical aperture greater than 1.

[0114] In other examples of angle-resolved scatterometers, reflective optics may be used instead of the refractive optics shown. Fig. 9Examples of can operate with wavelengths in the near UV, visible and / or near infrared ranges (e.g., from 350 nm to 1000 nm). For shorter UV wavelengths, such as in the DUV or VUV ranges of 100 nm to 300 nm, reflective optics become more practical and a controlled gas environment becomes necessary. The NA of such a system can be lower. On the other hand, the spacing of the optical components in the reflective optical system can make it easier to integrate the first measurement device with the second measurement device into the hybrid measurement system 240.

[0115] As in the lithographic apparatus LA, one or more substrate tables may be provided to hold the substrate W during metrology operations. The substrate table may be similar in form to Figure 1 The substrate tables WTa, WTb are similar or identical. (In the example where the inspection apparatus is integrated with the lithography apparatus, the substrate tables may even be the same substrate tables.) Coarse and fine positioners may be configured to accurately position the substrate relative to the measuring optical system. Various sensors and actuators are provided, for example, to obtain the position of the target of interest and bring the target of interest to a position below the objective lens 916. Many measurements will typically be made of targets at different locations across the substrate W. The substrate support may be moved in the X and Y directions to obtain different targets, and in the Z direction to obtain the desired focus of the optical system on the target. When the optical system actually remains substantially stationary and only the substrate moves, it is convenient to consider and describe the operation as if the objective lens and the optical system are in different locations on the substrate. Assuming that the relative position of the substrate to the optical system is correct, it is not important in principle whether one or both of the substrate and the optical system moves in the real world.

[0116] When the radiation beam is incident on the beam splitter, part of the radiation beam is transmitted through the beam splitter (partially reflective surface 915 ) and follows a reference path RP towards a reference mirror 914 .

[0117] Radiation reflected by the substrate (including radiation diffracted by any measurement target T) is collected by lens 916 and follows a collection path CP where it passes through partially reflecting surface 915 to detector 919. The detector may be located in a back-projected pupil plane P at the focal length F of lens 916. In practice, the pupil plane itself may be inaccessible and may instead be re-imaged onto a detector located in a so-called conjugate pupil plane P' using auxiliary optics (not shown). The detector may be a two-dimensional detector, enabling measurement of a two-dimensional angular scattering spectrum or diffraction spectrum of a substrate target T. In the pupil plane or conjugate pupil plane, the radial position of the radiation defines the angle of incidence / exit of the radiation in the plane of the focused spot S, and the angular position around the optical axis O defines the azimuth of the radiation. The detector 919 may be an array of, for example, CCD or CMOS sensors, and an integration time of, for example, 40 milliseconds per frame may be used.

[0118] Radiation in reference path RP is projected onto a different part of the same detector 919 or alternatively onto a different detector (not shown). A reference beam is often used, for example, to measure the intensity of incident radiation to allow normalization of intensity values ​​measured in a scattered spectrum.

[0119] Various components of the illumination system 912 can be adjusted to implement different measurement "configurations" within the same device. The color filter 912b can be implemented, for example, by a set of interference filters to select different wavelengths of interest within the range of (for example) 405 nanometers to 790 nanometers or even lower (such as, 200 nanometers to 300 nanometers). The interference filter can be tunable rather than comprising a set of different filters. A grating can be used instead of an interference filter. The polarizer 912c can be rotatable or interchangeable so as to implement different polarization states in the radiation light spot S. The aperture device 913 can be adjusted to implement different illumination distributions. The aperture device 913 is located in a plane P" that is conjugate to the pupil plane P of the objective lens 916 and the plane of the detector 919. In this way, the illumination distribution defined by the aperture device defines the angular distribution of the radiation light incident on the substrate transmitted through different parts of the aperture device 913.

[0120] Detector 919 can measure the intensity of scattered light at a single wavelength (or narrow wavelength range), at multiple wavelengths, or at an integrated intensity over a wavelength range. In addition, the detector can measure the intensity of transverse magnetic polarized light and transverse electric polarized light separately, and / or the phase difference between transverse magnetic polarized light and transverse electric polarized light.

[0121] In the case where the metrology target T is arranged on a substrate W, this may be a 1-dimensional grating which is printed such that after development the bars are formed by solid resist lines. The target may be a 2-dimensional grating which is printed such that after development the grating is formed by solid resist columns or vias in the resist. The bars, columns or vias may alternatively be etched into the substrate. Such a pattern is sensitive to chromatic aberrations in the lithographic projection apparatus, in particular the projection system PS. The illumination symmetry and the presence of these aberrations will manifest themselves in variations in the printed grating. Therefore, scatterometry data of the printed grating are used to reconstruct the grating. Parameters of the 1-dimensional grating (such as line width and shape) or parameters of the 2-dimensional grating (such as column or via width or length or shape) may be input to a reconstruction process performed by the processing unit PU based on knowledge of the printing step and / or other scatterometry processes. The technology disclosed herein is not limited to the inspection of grating structures, and any target structure (including a blank substrate or a substrate having only a flat layer on it) is included in the term "target structure".

[0122] In addition to the measurement of parameters by reconstruction, angle-resolved scatterometry is also useful in the measurement of asymmetry of features in products and / or resist patterns. A particular application of asymmetry measurement is for overlay measurements, where the target includes a set of periodic features superimposed on another set of periodic features. For example, the use of Fig. 9 In short, while the positions of the diffraction orders in the diffraction spectrum of a target are determined solely by the periodicity of the target, the asymmetry of the intensity levels in the diffraction spectrum is indicative of the asymmetry in the individual features that make up the target. Fig. 9 In the example of , where the detector 919 may be an image sensor, this asymmetry in the diffraction orders manifests itself directly as an asymmetry in the pupil image recorded by the detector 919. This asymmetry may be measured by digital image processing in the unit PU and calibrated for known overlap values. In a hybrid metrology system, spectra from more than one metrology device 242, 244 may be used to improve the measurement of asymmetry.

[0123] As is also known, an inspection device implementing angle-resolved scatter measurements can be provided with arrangements for performing so-called dark field imaging. For the sake of simplicity, these arrangements are not illustrated here. Examples of dark field imaging applied to overlapping measurements on small targets are known from the patent publications mentioned in the introduction and incorporated herein by reference. The dark field imaging branch can be combined with an optical system for acquiring the target position before angle-resolved scatter measurements and for focusing the light spot S during the capture of the spectrum. By using different apertures 913, different illumination modes are possible.

[0124] Hybrid Measurement System Example

[0125] Fig.10 Shown schematically as Figure 1 The hybrid measurement system 1000 is an example of a hybrid measurement system 240 of the present invention. The hybrid measurement system can be a stand-alone device, or can be incorporated into the lithography apparatus LA or the lithography cell LC. Of course, the apparatus can be used in combination with other apparatuses (such as SEM apparatuses) as part of a larger measurement system.

[0126] In this example, the hybrid metrology system 1000 includes a first metrology device 1002 using EUV radiation at grazing incidence, which may be similar to the above devices 300 or 700. A second metrology device 1004 is provided in the form of a scatterometer, which may be connected to Fig. 9 1002. The first metrology device 1002 comprises a first radiation source 1010, a first irradiation system 1012, a substrate support 1016, a first detection system 1018 and a processor 1020. In this example, the source 1010 comprises a generator of EUV or x-ray radiation, for example, based on high-order harmonic generation (HHG) technology. These sources can be purchased from, for example, KMLabs (http: / / www.kmlabs.com / ) of Boulder Colorado, USA. The main components of the radiation source are a pump laser 1030 and a HHG gas chamber 1032. A gas supply 1034 supplies a suitable gas to the gas chamber, where the suitable gas is optionally ionized by a power supply 1036. The pump laser can be, for example, a fiber-based laser with an optical amplifier, thereby generating pulses of infrared radiation with a duration of less than 1 ns (1 nanosecond) per pulse, wherein the pulse repetition rate can reach several megahertz as required. The wavelength can be, for example, on the order of about 1 μm (1 micrometer). The laser pulses are delivered as a first radiation beam 1040 to the HHG gas cell 1032 where a portion of the radiation is converted to a higher frequency, the first radiation being converted to a beam 1042 including coherent radiation having one or more desired EUV wavelengths.

[0127] The radiation may contain multiple wavelengths. If the radiation is also monochromatic, the measurement calculation (reconstruction) can be simplified, but it is easier to generate radiation with multiple wavelengths in the case of HHG. These situations are design choices and can even be selectable options within the same device. Different wavelengths will provide different levels of contrast, for example, when imaging structures of different materials. For example, in order to inspect metal structures or silicon structures, different wavelengths can be selected as wavelengths for imaging the features of (carbon-based) resists or for detecting contaminants of these different materials. One or more filter devices 1044 can be set. For example, a filter device such as an aluminum (Al) film can be used to cut off the basic IR radiation to prevent further transmission into the inspection device. A grating can be set to select one or more specific harmonic wavelengths from the wavelengths generated in the gas chamber. Some or all of the beam path can be contained in a vacuum environment, remembering that EUV radiation is absorbed when traveling in air. Various components of the radiation source 1010 and the irradiation optical device 1012 can be adjustable to implement different measurement "configurations" within the same device. For example, different wavelengths and / or polarizations may be made selectable.

[0128] For mass production applications, the choice of a suitable source will be guided by cost and hardware size, not just by theoretical capabilities, and the HHG source is selected here as an example. Other types of sources that are applicable in principle are also available or under development. Examples are synchrotron sources, FEL (free electron laser) sources, and so-called x-ray lasers. Sources based on inverse Compton scattering can also be used. Depending on the material of the structure being inspected, different wavelengths can provide the required degree of penetration into the underlying layer. In order to distinguish the smallest device features and defects among the smallest device features, short wavelengths are likely to be preferred. For example, wavelengths in the range of 1 nanometer to 20 nanometers or 1 nanometer to 10 nanometers can be selected. Wavelengths shorter than 5 nanometers have very low critical angles when reflected from materials that are generally concerned in semiconductor manufacturing. Therefore, selecting a wavelength greater than 5 nanometers will provide a stronger signal at higher angles of incidence. On the other hand, if the inspection task is to detect the presence of a certain material, such as to detect contaminants, wavelengths up to 50 nanometers can be useful.

[0129] From the first radiation source 1010, the filtered beam 1042 enters an inspection chamber 1050, in which a substrate W including a structure of interest is held for inspection by a substrate support 1016. The structure of interest is labeled T. The gas environment within the inspection chamber 1050 is maintained as a near vacuum by a vacuum pump 1052, so that EUV radiation can pass through the gas environment without undue attenuation. The illumination optical device 1012 has the function of focusing the radiation into a focused beam 1056, and may include, for example, a two-dimensional curved mirror, or a series of one-dimensional curved mirrors, as described above. The focusing is performed to achieve a circular or elliptical spot with a diameter of less than 10 microns when projected onto the structure of interest. The substrate support 1016 includes, for example, an XY translation stage and a rotation stage, by which any portion of the substrate W can be brought to the focus of the beam in a desired orientation. Thus, a radiation spot S is formed on the structure of interest.

[0130] The reflected radiation 1060 is captured by the detector 1018 and the first spectrum is provided to the processor 1020 for use in calculating properties of the target structure T. The first illumination system 1012 and the first detection system 1018 thus form a first metrology apparatus. Such a first metrology apparatus may include Figures 2 to 7 An EUV spectroscopic reflectometer of the kind shown in . A tilt of the substrate in one or more dimensions may also be provided.

[0131] A second metrology device 1004 within the hybrid metrology system is schematically indicated at 1004. Such a device comprises a second radiation source (not separately illustrated), a second illumination system (not separately illustrated), and an independent detector (not separately illustrated). These components may be, for example, Figure 8 Irradiation system and detection system of the spectral scatterometer, Fig. 9 The optical design may be adapted to use reflective optics as desired. The second metrology device 1004 may alternatively or additionally include an EUV metrology device. For example, it may perform spectroscopic reflectance measurements using EUV radiation in the same manner as the first metrology device of the example, but at a different angle of incidence that is closer to the normal direction N.

[0132] To assist in aligning and focusing the light spot S with the desired product structure, the second metrology device 1004 may also be provided with auxiliary optics using auxiliary radiation under the control of the metrology processor 1020. The metrology processor 1020 may also communicate with a position controller 1072, which operates the translation stage and the rotation stage. The processor 1020 receives very accurate feedback about the position and orientation of the substrate via sensors. The sensors 1074 may include, for example, interferometers, which may give an accuracy of about the order of picometers.

[0133] In operation of the hybrid measurement system 1000, first spectral data 1082 captured by the first detection system 1018 is delivered to the measurement processing unit 1020. Second spectral data 1084 captured by the second detection system within the second measurement device 1004 is delivered to the measurement processing unit 1020 and used together with the first spectral data to calculate one or more measurement results of the parameter of interest. As will be explained, the manner in which the data is combined may be different from the manner in which the data is combined in a known hybrid measurement system. For example, based on the spectral data obtained from one of the measurement devices, the measurement configuration of the other measurement devices may be adjusted before the spectra are captured by the other devices. Alternatively or in addition, the spectral data obtained from one of the measurement devices may be used to characterize the structure and / or material of a portion of the entire target structure T before using the spectral data obtained from the other measurement devices to calculate the properties of the structure. All of these operations may be automatically processed by the measurement processor 1020.

[0134] Fig.11 An example of a hybrid metrology system 1100 is illustrated in which portions of a first radiation source are shared with a second radiation source. It will be appreciated that arranging multiple radiation sources within a single hybrid metrology system can be challenging in terms of cost and physical space. In particular, for those modern sources that provide high brightness and / or control of wavelength, a pump laser is provided. The pump laser may be designed to produce pulses in the femtosecond time range. Examples of radiation sources using pump lasers are Fig.10 A higher harmonic generation (HHG) source is shown in Figure 1. Another example is a supercontinuum source, which is used to provide broadband radiation in known scatterometers.

[0135] exist Fig.11 In the embodiment of the invention, the operation modes (a) and (b) of the hybrid metrology system are observed. In the main body of the system, a first illumination system IL1 and a first detection system DET1 form a first metrology device, which may be an EUV spectroscopic reflectometer. Between these components, a second illumination system IL2 and a second detection system DET2 are arranged to form a second metrology device. Fig.11In (a), the first measurement device is operated using a HHG source. The movable mirror 1102 is positioned to guide the pump radiation from the pump laser LAS into the HHG chamber. The first radiation is generated in the HHG chamber as described above and then enters the first illumination system IL1. In Figure 11 (b), the second measurement device is operated using, for example, a supercontinuum generator SCG. The element used for this purpose is, for example, a photonic crystal fiber. The movable mirror 1102 is moved to a second position so that the radiation from the pump laser LAS enters the supercontinuum generator. This produces a second radiation to be supplied to the second illumination system IL2.

[0136] Application Examples

[0137] Fig.12 A general example of a hybrid metrology system is shown, in which a first metrology device, a second metrology device and optionally a third metrology device are provided. Each metrology device comprises a source SRC1 / 2 / 3, an illumination system IL1 / 2 / 3 and a detection system DET1 / 2 / 3. A hybrid metrology device comprising both an EUV metrology device 244 for performing and an optical metrology device 240 for performing longer wavelengths than conventional scatterometry can be produced. The two devices can work simultaneously on the same part or different parts of the same substrate W. The two devices can actually operate at different times while sharing common components, such as substrate handling and positioning systems. The metrology device can be integrated with the lithography device LA itself, or integrated in the lithography unit LC. In the measurement processing unit MPU, a dedicated module 1210-1 / 2 / 3 is provided to process the spectral data received from each of the detection systems DET1 / 2 / 3 to a certain extent. The pre-processed results are delivered from these dedicated modules to a hybrid processing module 1212 which combines the information from the separate spectra to obtain a measurement of the desired parameters of the target structure T.

[0138] Fig.13 Another example of a hybrid metrology system 1300 is shown. In this example, a dedicated processing module 1310-1 receives first spectral data captured by a first detection system DET1 using a first radiation 1320-1. This first spectral data may be, for example, spectral reflectometer data from a grazing incidence EUV radiation beam. This first spectral data may include using Figures 2 to 7 The second measurement device is then operated using radiation 1320-2, and second spectral data is captured by the second detection system DET2. However, before operating the second measurement device, settings for the second radiation source SRC2 and / or the second illumination system IL2 are sent in response to the parameters calculated by the processing module 1310-1.

[0139] After operating the second measurement device, the second spectral data is processed by the hybrid processing module 1312 to obtain a measurement result of the desired parameter of the target structure T. In some embodiments, the first spectral data can be directly or indirectly combined with the second spectral data in the hybrid processing module 1312. For example, the first spectral data can be used to change the parameters used to process the second spectral data. In other embodiments, it is possible that the first spectral data is obtained only for controlling the configuration scheme used to obtain the second spectral data, and the first spectral data is not directly used to obtain the final measurement result.

[0140] See especially Figures 12 to 15 For example, the methods and devices described herein can also be applied to the measurement of asymmetry-related features such as overlay. Overlay between layers in semiconductor products may be difficult to measure using EUV spectroscopic reflectometry at some incident angles and / or wavelengths due to the shallow penetration depth of the radiation. Nevertheless, by providing the illustrated device with a wide range of wavelengths (e.g. 1 nm to 100 nm) and the possibility of using elevated incident angles in the second measurement device, practical measurements of overlay can be expected.

[0141] Fig.14 Another example of a hybrid metrology system 1400 is shown. In one embodiment of this example, the parameter of interest is related to the asymmetry of the target structure, for example to obtain a measure of overlap. As shown at FIG. 14( b), the target structure T may include grating features T1 and T2 in the lower layer, and the upper layer. Either or both of these structures may be buried under another layer, not shown. When measuring overlap, the reported measurements of known methods may be very sensitive to asymmetry that is not caused by overlap. Using Fig.14 The application of a systematic hybrid measurement technique can help to isolate those effects that are truly due to the parameter of interest from asymmetries having other causes.

[0142] Available in Fig.14One way in which the accuracy of the overlay measurement can be improved can be seen in the enlarged schematic detail of (b). The first radiation 1420-1 used in the first measurement device has grazing incidence and very little penetration into the stack formed on the substrate W. The first spectral data is captured by the first detection system DET1 and has minimal influence from the lower layer. The properties of the upper layer containing the grating feature T2 can then be measured and reported by the dedicated module 1410-1. The second radiation 1420-2, which has a higher angle of incidence and may have different wavelength characteristics and other properties, penetrates more completely into the stack. Therefore, the second spectral data contains asymmetry information related to the parameter of interest, specifically, overlap. In the case of combining the processing of these spectra in the hybrid processing module 1412, the knowledge obtained from the first spectrum can be used to adjust the overlap measurement performed in the second spectrum to remove the influence of the lower layer.

[0143] The overlap between layers is just one example of an asymmetry-related parameter of a target structure. In a multiple patterning process, structures are formed in one layer of a product not in one patterning operation but in two or more patterning steps. Thus, for example, a first group of structures may be interleaved with a second group of structures and the groups may be formed in different steps in order to achieve a higher resolution than one step alone could produce. While the placement of the groups should be identical and perfect relative to other features on the substrate, of course, each real pattern exhibits a certain positional offset. Any unintentional positional offset between the groups may be considered as a form of overlap and can be measured by the asymmetry of the target grating or product features formed by the multiple patterning process. For simple grating structures, other types of asymmetry may also be measured, such as sidewall asymmetry and trench bottom asymmetry. Furthermore, the use of a hybrid measurement system is described herein to reduce the crosstalk between these different asymmetry-related parameters to isolate the measurement of the parameters of interest.

[0144] Although the asymmetry can be measured from the (zero-order) reflectance spectra 310, 710 (in Figure 3 and Figure 7 ), but the asymmetry information will be Figure 7In the example of , the first-order diffraction spectrum 752 detected is stronger. Therefore, the method of EUV measurement may include using a signal SF representing the first-order diffraction spectrum from a periodic structure to measure the asymmetry in the structure. The structure may be measured in only one direction, or may be measured in an orientation rotated (Rz) 180°. As is known from the diffraction-based overlap in the case of visible wavelengths, the asymmetry can be calculated by comparing the intensity of the +1-order diffracted radiation and the -1-order diffracted radiation. By rotating the target by 180°, signals SF(+1) and SF(-1) can be obtained and the signals SF(+1) and SF(-1) can be compared. The asymmetry, such as any other attribute of the target, can be calculated by reconstruction methods. Alternatively, a simpler calculation combined with a previous calibration can be more directly based on comparing the +1-order spectrum with the -1-order spectrum. However, compared to simply comparing the +1-order intensity with the -1-order intensity in the case of a single wavelength, the information available using full reconstruction in combination with spectral methods can assist in more accurate measurements. In EUV reflectometry, one advantage is that the target can be made of product features or product-like features, which is not possible with current optical technology using longer wavelengths. The sensitivity to overlay is expected to be greater than current tools. Fig.14 Further improvements in accuracy can be obtained by combining different types of measurements in a hybrid measurement system.

[0145] With modern laser pump sources such as the HHG and ICS types mentioned above, high power can be provided in one or more desired wavelengths compared to conventional sources. Sufficient penetration into the stack can thus be obtained, even with a single wavelength as in the EUV patent. Of course, the wavelength of the second radiation can be longer than that of the EUV radiation. Penetration and contrast can be increased by going to a longer wavelength, with a possible loss of spatial resolution as a tradeoff. Using the principles disclosed herein and the sources and optical systems described, a person skilled in the art has a full range of options to choose from in designing an effective hybrid metrology system.

[0146] Any of the devices 300, 700 may be used as a Figure 1 FIG. 2 schematically illustrates an (EUV) first metrology device 244 in a lithography production facility system.

[0147] Fig.15 The hybrid metrology approach in the management of lithography manufacturing systems (e.g. Fig.10 to Fig.14 The steps are listed here and then explained in more detail:

[0148] S21: processing the wafer to produce a structure on the substrate;

[0149] S22: measuring CD and / or other parameters across the substrate;

[0150] S23: Update the measurement configuration scheme;

[0151] S24: Update the lithography and / or process configuration scheme.

[0152] At step S21, a structure is produced across a substrate using a lithography manufacturing system. At S22, an EUV metrology device 244 is used along with another metrology device 240 and an information source to measure properties of the structure across the substrate. At step S23, the metrology configuration and calibration of the EUV metrology device 244 and / or another metrology device 240 are optionally updated in view of the obtained measurements. For example, in the case where the EUV metrology device 244 has a lower productivity than the optical metrology device 240, a few accurate measurements using EUV radiation can be used to improve the calculation of the measurements made using the optical metrology device for a specific substrate design and process.

[0153] At step S24, the measurement result of CD or other parameter is compared with the expected value, and the measurement of CD or other parameter is used to update the settings of lithography equipment and / or other equipment within the lithography manufacturing system. By providing EUV metrology equipment as part of a hybrid metrology system, productivity and / or accuracy can be improved and the performance of the entire lithography production facility can be improved. Even at the smallest technology nodes, product features and / or product-like features can be directly measured, and in-die targets can be provided and measured without consuming excessive area.

[0154] In the above steps, it is assumed that sufficient targets across a substrate and across multiple substrates are measured so that a statistically reliable model of the process can be derived. The distribution of CD and other parameters need not be fully expressed as variations across the substrate. For example, the distribution of CD and other parameters can be expressed as an intra-field distribution common to all fields (each instance of patterning using the pattern forming device M at a different location on the substrate W), and low-order inter-field variations that are repeatedly superimposed with the intra-field variations. The settings of the lithography process adjusted in step S24 may include intra-field settings as well as inter-field settings. The settings may be applicable to all operations of the device, or specific to a particular product layer.

[0155] in conclusion

[0156] Although specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced in other ways than those described. In connection with novel objects as implemented on substrates and pattern forming devices, an embodiment may include a computer program comprising one or more sequences of machine-readable instructions describing a method of measuring objects on a substrate and / or processing the measurement results to obtain information about a lithography process. The computer program may be, for example, a computer program comprising one or more sequences of machine-readable instructions describing a method of measuring objects on a substrate and / or processing the measurement results to obtain information about a lithography process. Figure 1 Such a computer program is executed in the unit MPU246 in the production facility of . A data storage medium (eg, a semiconductor memory, a magnetic disk, or an optical disk) in which such a computer program is stored may also be provided.

[0157] Although the patterning device has been described as being in the form of a physical reticle, the term "patterning device" in this application also includes a data product of a pattern transmitted in digital form, for example for use in conjunction with a programmable patterning device.

[0158] Although the above may specifically refer to embodiments of the invention used in the context of optical lithography, it will be appreciated that the invention may be used in other applications (e.g., imprint lithography) and is not limited to optical lithography where the context permits. In imprint lithography, the topography in the patterning device defines the pattern produced on the substrate. The topography of the patterning device may be pressed into a layer of resist provided to a substrate on which the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. After the resist is cured, the patterning device is removed from the resist, leaving a pattern therein.

[0159] Further embodiments according to the invention are given in the following numbered aspects:

[0160] 1. A hybrid metrology device for measuring properties of a structure manufactured by a photolithography process, the hybrid metrology device comprising:

[0161] (a) a first illumination system for illuminating the structure with first radiation, the first radiation comprising one or more wavelengths in the range of 1 nanometer to 100 nanometers;

[0162] (b) a first detection system for detecting a first spectrum comprising at least part of said first radiation reflected by the periodic structure;

[0163] (c) a second illumination system for illuminating the structure with second radiation, the second radiation comprising one or more wavelengths in the range of 1 nm to 100 nm or in the range of 100 nm to 1000 nm;

[0164] (d) a second detection system for detecting a second spectrum comprising at least a portion of the second radiation reflected by the periodic structure;

[0165] (e) a processing system for determining a property of the structure using the detected first spectrum and the detected second spectrum.

[0166] 2. A system according to aspect 1, wherein the processing system is arranged to use the detected first spectrum to control one or more parameters of the second detection system and / or the second illumination system for capturing the second spectrum.

[0167] 3. A system according to aspect 1, wherein the processing system is arranged to use the detected second spectrum to control one or more parameters of the first detection system and / or the first illumination system used for capturing the first spectrum.

[0168] 4. A system according to any preceding aspect, wherein for the first radiation, a grazing incidence angle α relative to a direction parallel to the substrate is less than 45 degrees; and for the second radiation, a polar incidence angle θ relative to a direction perpendicular to the substrate is less than 45 degrees.

[0169] 5. The system of aspect 4, wherein the grazing incidence angle is greater than 2 degrees.

[0170] 6. A system according to aspect 4, wherein the grazing incidence angle for the first radiation is between 5° and 45°, optionally between 10° and 30°.

[0171] 7. A system according to clause 4, 5 or 6, wherein the grazing incidence angle for the first radiation is adjustable as a parameter of a measurement arrangement.

[0172] 8. A system according to any preceding aspect, wherein the first radiation has an extent of less than 10 microns, optionally less than 5 microns when projected onto the structure.

[0173] 9. The system according to any of the preceding aspects, wherein the incident azimuth angle of the first radiation can be adjusted as a parameter of the measurement configuration scheme.

[0174] 10. A system according to any preceding aspect, wherein the first radiation comprises a range of wavelengths, sequentially or simultaneously, and wherein the first detection system is a spectral detection system, the first spectrum representing the distribution of wavelengths in the reflected first radiation.

[0175] 11. A system according to aspect 10, wherein the first detection system is further arranged to capture a higher order spectrum representing the distribution of wavelengths in one or more higher diffraction orders diffracted by the structure.

[0176] 12. The system according to any of the preceding aspects, wherein the second detection system is a spectral detection system, the second spectrum representing the distribution of wavelengths of the reflected first radiation.

[0177] 13. A system according to any preceding aspect, wherein the second detection system is an angle-resolved detection system and the first spectrum represents the distribution of diffracted radiation in the reflected first radiation.

[0178] 14. The system according to any of the preceding aspects, wherein the second radiation comprises one or more wavelengths in the range of 100 nanometers to 1000 nanometers.

[0179] 15. The system of aspect 14, wherein the second radiation comprises one or more wavelengths in the range of 350 nanometers to 900 nanometers.

[0180] 16. The system of any one of aspects 1 to 13, wherein the second radiation comprises one or more wavelengths in the range of 1 nanometer to 100 nanometers.

[0181] 17. A system according to any of the preceding aspects, wherein the processor is arranged to use the first spectrum and the second spectrum to determine properties of a structure having one or more upper layers and one or more lower layers, and wherein the processor is arranged to use the first spectrum to distinguish properties of the upper layer from properties of the entire structure.

[0182] 18. A system according to any preceding aspect, wherein the property of the structure is related to a degree of asymmetry.

[0183] 19. The system of clause 18, wherein the property of the structure is overlap between substructures in the upper layer and the lower layer.

[0184] 20. The system according to any of the preceding aspects, further comprising a first radiation source for generating the first radiation and a second radiation source for generating the first radiation.

[0185] 21. The system of clause 20, wherein the first radiation source and the second radiation source share a common pump laser.

[0186] 22. A system according to aspect 20 or 21, wherein the first radiation source is a high order harmonic generator source.

[0187] 23. A system according to aspect 20, 21 or 22, wherein the second radiation source is a high order harmonic generator source.

[0188] 24. The system of any one of aspects 20 to 23, wherein the second radiation source is a supercontinuum source.

[0189] 25. The system of any one of aspects 20 to 23, wherein the first radiation source and / or the second radiation source is an inverse Compton scattering source.

[0190] 26. A method of measuring a property of a structure fabricated by a photolithographic process, the method comprising:

[0191] (a) irradiating the structure with first radiation, the first radiation comprising one or more wavelengths in the range of 1 nanometer to 100 nanometers;

[0192] (b) detecting a first spectrum comprising at least a portion of said first radiation reflected by the periodic structure;

[0193] (c) irradiating the structure with a second radiation, the second radiation comprising one or more wavelengths in the range of 1 nm to 100 nm or in the range of 100 nm to 1000 nm;

[0194] (d) detecting a second spectrum comprising at least a portion of the second radiation reflected by the periodic structure;

[0195] (e) determining a property of the structure using the detected first spectrum and the detected second spectrum.

[0196] 27. A method according to clause 26, wherein step (e) is performed so as to use the detected first spectrum to control one or more parameters of the second detection step (d) and / or the second illumination step (c) for capturing the second spectrum.

[0197] 28. A method according to clause 26, wherein step (e) is performed to use the detected second spectrum to control one or more parameters of the first detection step (b) and / or the first illumination step (a) for capturing the first spectrum.

[0198] 29. A method according to any one of clauses 26 to 28, wherein for the first radiation, a grazing incidence angle α relative to a direction parallel to the substrate is less than 45 degrees; and for the second radiation, a polar incidence angle θ relative to a direction perpendicular to the substrate is less than 45 degrees.

[0199] 30. The method of clause 29, wherein the grazing incidence angle is greater than 2 degrees.

[0200] 31. A method according to clause 29, wherein the grazing incidence angle for the first radiation is between 5° and 45°, optionally between 10° and 30°.

[0201] 32. A method according to clause 29, 30 or 31, wherein the grazing incidence angle for the first radiation is adjusted as a parameter of a measurement arrangement.

[0202] 33. A method according to any one of clauses 26 to 32, wherein the first radiation has an extent of less than 10 microns, optionally less than 5 microns when projected onto the structure.

[0203] 34. A method according to any one of clauses 26 to 33, wherein the incident azimuth angle of the first radiation is adjusted as a parameter of a measurement arrangement.

[0204] 35. A method according to any one of aspects 26 to 34, wherein the first radiation comprises a range of wavelengths sequentially or simultaneously, and wherein the first detection step (b) uses a spectral detection system, and the first spectrum represents the distribution of wavelengths in the reflected first radiation.

[0205] 36. The method of aspect 10, wherein the first detecting step (b) further comprises capturing a higher order spectrum representing a distribution of wavelengths in one or more higher diffraction orders diffracted by the structure.

[0206] 37. A method according to any one of aspects 26 to 36, wherein the second detection step (d) uses a spectral detection system, the second spectrum representing the distribution of wavelengths in the reflected first radiation.

[0207] 38. A method according to any one of aspects 26 to 37, wherein the second detection step (d) uses an angle-resolved detection system and the first spectrum represents the distribution of diffracted radiation in the reflected first radiation.

[0208] 39. The method of any one of aspects 26 to 38, wherein the second radiation comprises one or more wavelengths in the range of 100 nanometers to 1000 nanometers.

[0209] 40. The method of clause 39, wherein the second radiation comprises one or more wavelengths in the range of 350 nanometers to 900 nanometers.

[0210] 41. The method of any one of aspects 26 to 38, wherein the second radiation comprises one or more wavelengths in the range of 1 nanometer to 100 nanometers.

[0211] 42. A method according to any one of Aspects 26 to 41, wherein the first spectrum and the second spectrum are used to determine properties of a structure having one or more upper layers and one or more lower layers, and wherein step (e) includes using the first spectrum to distinguish properties of the upper layer from properties of the structure as a whole.

[0212] 43. A method according to any one of aspects 26 to 42, wherein the property of the structure is related to a degree of asymmetry.

[0213] 44. A method according to clause 43, wherein the property of the structure is overlap between substructures in the upper layer and the lower layer.

[0214] 45. A device manufacturing method comprising:

[0215] transferring a pattern from a patterning device onto a substrate using a photolithographic process, the pattern defining at least one periodic structure;

[0216] measuring one or more properties of the periodic structure to determine values ​​of one or more parameters of the lithographic process; and

[0217] applying corrections in subsequent operations of the lithography process based on the measured properties,

[0218] The step of measuring a property of the periodic structure comprises measuring the property using a hybrid metrology apparatus according to any one of aspects 1 to 25.

[0219] 46. ​​The device manufacturing method according to clause 45, wherein the functional device pattern defines product features with critical dimensions less than 50 nanometers, optionally less than 20 nanometers.

[0220] 47. A device manufacturing method comprising:

[0221] transferring a pattern from a patterning device onto a substrate using a photolithographic process, the pattern defining at least one periodic structure;

[0222] measuring one or more properties of the periodic structure to determine values ​​of one or more parameters of the lithographic process; and

[0223] applying corrections in subsequent operations of the lithography process based on the measured properties,

[0224] Wherein the step of measuring a property of the periodic structure comprises measuring the property using a method according to any one of aspects 26 to 44.

[0225] The terms "radiation" and "beam" as used with respect to a lithographic apparatus encompass all types of electromagnetic radiation, including ultraviolet (UV) radiation (e.g., having a wavelength equal to or approximately 365 nm, 355 nm, 248 nm, 193 nm, 157 nm or 126 nm) and extreme ultraviolet (EUV) radiation (e.g., having a wavelength in the range of 1 nm to 100 nm), as well as particle beams such as ion beams or electron beams.

[0226] The term "lens," where the context allows, may refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic, and electrostatic optical components.

[0227] The above description of specific embodiments will fully reveal the general nature of the embodiments of the present invention, so that others can easily modify and / or adapt these specific embodiments for various applications by applying knowledge in the art without departing from the overall concept of the present invention and without excessive experimentation. Therefore, based on the teachings and guidance given herein, such adaptations and modifications are intended to fall within the meaning and scope of the equivalents of the disclosed embodiments. It should be understood that the wording or terminology herein is for the purpose of illustrative description rather than restrictive, and therefore the terms or wording in this specification should be interpreted by those skilled in the art based on the teachings and guidance.

[0228] The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. A hybrid metrology apparatus for measuring properties of a plurality of structures fabricated on a substrate by a photolithography process, the hybrid metrology apparatus comprising: (a) a first illumination system for illuminating a first structure with a first radiation, the first radiation comprising one or more wavelengths in the range of 1 nanometer to 100 nanometers; (b) a first detection system for detecting a first spectrum comprising at least part of the first radiation reflected by the first structure; (c) a second illumination system for illuminating a second structure with a second radiation, wherein the first structure and the second structure are located on different portions of the substrate, the second radiation comprising one or more wavelengths in the range of 1 nm to 100 nm or in the range of 100 nm to 1000 nm; (d) a second detection system for detecting a second spectrum comprising at least a portion of the second radiation reflected by the second structure; (e) a processing system for determining one or more properties of a structure on the substrate using the detected first spectrum and the detected second spectrum, The second detection system and the first detection system operate in different ways within the same band or in different bands.

2. The hybrid measuring device according to claim 1, wherein: The property is related to the degree of asymmetry.

3. The hybrid measuring device according to claim 1, wherein: The first structure and the second structure are located in a same layer on a substrate.

4. The hybrid measuring device according to claim 1, wherein: The first structure and the second structure are respectively located in different layers on the substrate.

5. Hybrid metrology apparatus according to claim 1, wherein the processing system is arranged to use the detected first spectrum to control one or more parameters of the second detection system and / or the second illumination system for capturing of the second spectrum.

6. Hybrid metrology apparatus according to claim 1, wherein the processing system is arranged to use the detected second spectrum to control one or more parameters of the first detection system and / or the first illumination system used for capturing of the first spectrum.

7. A hybrid metrology apparatus according to any preceding claim, wherein for the first radiation, a grazing incidence angle α relative to a direction parallel to the substrate is less than 45 degrees; and for the second radiation, a polar incidence angle θ relative to a direction perpendicular to the substrate is less than 45 degrees.

8. The hybrid measurement device according to any one of claims 1 to 6, wherein the first radiation comprises a range of wavelengths sequentially or simultaneously, and wherein the first detection system is a spectral detection system, the first spectrum representing the distribution of wavelengths in the reflected first radiation.

9. The hybrid metrology apparatus according to any one of claims 1 to 6, wherein the second detection system is a spectral detection system, the second spectrum representing the distribution of wavelengths in the reflected second radiation.

10. Hybrid metrology apparatus according to any one of claims 1 to 6, wherein the second detection system is an angle-resolved detection system and the first spectrum represents the distribution of diffracted radiation in the reflected first radiation.

11. The hybrid metrology apparatus according to any one of claims 1 to 6, further comprising a first radiation source for generating the first radiation and a second radiation source for generating the second radiation.

12. The hybrid metrology apparatus of claim 11, wherein the first radiation source and the second radiation source share a pump laser.

13. A method of measuring properties of a plurality of structures produced by a photolithographic process, the method comprising the steps of: (a) irradiating a first structure with first radiation, the first radiation comprising one or more wavelengths in the range of 1 nanometer to 100 nanometers; (b) detecting a first spectrum comprising at least a portion of said first radiation reflected by a first structure; (c) irradiating a second structure with a second radiation, wherein the first structure and the second structure are located on different portions of the substrate, the second radiation comprising one or more wavelengths in the range of 1 nm to 100 nm or in the range of 100 nm to 1000 nm; (d) detecting a second spectrum comprising at least a portion of the second radiation reflected by the second structure; (e) determining one or more properties of a structure on the substrate using the detected first spectrum and the detected second spectrum, in, The irradiating the second structure with the second radiation and the irradiating the first structure with the first radiation operate differently within the same wavelength band or operate in different wavelength bands.

14. The method of claim 13, wherein step (e) is performed to use the detected first spectrum to control one or more parameters of step (d) and / or step (c) for capturing of the second spectrum.

15. The method of claim 13, wherein step (e) is performed to use the detected second spectrum to control one or more parameters of step (b) and / or step (a) for capturing of the first spectrum.

16. A method according to any one of claims 13 to 15, wherein the plurality of structures are on a substrate, and for the first radiation, a grazing incidence angle α relative to a direction parallel to the substrate is less than 45 degrees; and for the second radiation, a polar incidence angle θ relative to a direction perpendicular to the substrate is less than 45 degrees.

17. A method according to any one of claims 13 to 15, wherein the first radiation has an extent of less than 10 microns when projected onto the first structure.

18. The method according to any one of claims 13 to 15, wherein: The first radiation sequentially or simultaneously comprises a range of wavelengths, and wherein step (b) uses a spectrum detection system, the first spectrum represents the distribution of wavelengths in the reflected first radiation.

19. The method of claim 13, wherein step (b) further comprises capturing a high-order spectrum representing a distribution of wavelengths in one or more higher diffraction orders diffracted by the first structure.

20. A device manufacturing method, comprising: transferring a pattern from a patterning device onto a substrate using a photolithographic process, the pattern defining at least a plurality of structures; measuring one or more properties of the structure to determine values ​​of one or more parameters of the lithographic process; and applying corrections in subsequent operations of the lithography process based on the measured properties, Wherein the step of measuring a property of the structure comprises measuring the property using a hybrid metrology apparatus according to any one of claims 1 to 12.

21. A computer program product comprising machine readable instructions for causing a processor to perform the method according to any one of claims 13 to 19.

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