Systems and methods of measurement apparatus fabrication

Abstract

An apparatus includes a plurality of bonded substrates. The plurality of bonded substrates form one or more measurement devices. Each measurement device includes at least one gas inlet. The gas inlet is coupled to a plurality of flow restrictions, which are coupled to either a reference chamber or a measurement chamber. The reference chamber is coupled to a reference nozzle and the measurement chamber is coupled to a measurement nozzle. One or more pressure sensors are configured to measure and / or infer differential pressure between the reference chamber and the measurement chamber. Each measurement device can have a total internal volume of less than about 15 mm3.

Description

SYSTEMS AND METHODS OF MEASUREMENT APPARATUS FABRICATIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of US application 63 / 653,436 which was filed on May 30, 2024 and which is incorporated herein in its entirety by reference.FIELD

[0002] The present disclosure relates to measurement devices, for example, devices for measuring heights of a substrate in lithographic apparatuses and systems.BACKGROUND

[0003] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which is alternatively referred to as a mask or a reticle, can be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g., comprising part of, one, or several dies) on a substrate (e.g., a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate.

[0004] Before a pattern is projected from a patterning device onto a layer of radiation sensitive material provided on a substrate the height of the substrate is measured. In order to achieve this, the lithographic apparatus is provided with a height measurement apparatus. The height measurement apparatus measures the height of the substrate across a surface of the substrate. The substrate height measurements are used to form a substrate height map which assists accurate projection of a pattern onto the substrate.

[0005] An air gauge is a unique distance measuring device capable of very high resolution. In the context of lithographic apparatuses, an air gauge has no sensitivity to layers below the surface being measured. An air gauge can sense only the top surface of resist on a substrate, which is an ideal reference surface for focus control in wafer lithography.

[0006] Current methods of fabricating air gauges for lithographic apparatuses require costly drilling and milling techniques. These techniques limit the size and complexity and manufacturability of the device.SUMMARY

[0007] Accordingly, it is desirable to improve fabrication of air gauge based measurement devices.

[0008] In some aspects, an apparatus can include a plurality of bonded substrates. The plurality of bonded substrates can include one or more measurement devices. Each measurement device can contain a gas inlet coupled to a plurality of flow restrictions and / or orifices. Each flow restriction and / or orifice can be coupled to either a reference chamber or a measurement chamber. The reference andmeasurement chambers can be coupled to a reference and measurement nozzle respectively. Each measurement device can further include one or more pressure sensors configured to measure or infer differential pressure between the reference chamber and the measurement chamber. The total internal volume of each measurement device can be less than about 15 mm3.

[0009] In some aspects, a method of fabricating one or more measurement devices can include an etching step and a bonding step. In the etching step, one or more substrates are etched to create features. Then the plurality of substrates can be bonded such that the features in the plurality of substrates create one or more channels. The one or more channels can form one or more measurement devices as described in the above paragraph.

[0010] Further features of the present disclosure, as well as the structure and operation of various embodiments, are described in detail below with reference to the accompanying drawings. It is noted that the present disclosure is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.BRIEF DESCRIPTION OF THE DRAWINGS / FIGURES

[0011] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable a person skilled in the relevant art(s) to make and use embodiments described herein.FIG. 1 A shows a schematic of a reflective lithographic apparatus, according to some aspects.FIG. IB shows a schematic of a transmissive lithographic apparatus, according to some aspects.FIG. 2 shows a more detailed schematic of the reflective lithographic apparatus, according to some aspects.FIG. 3 shows a schematic of a lithographic cell, according to some aspects.FIG. 4 shows a measurement device, according to some aspects.FIG. 5 shows a measurement device array, according to some aspects.FIGS. 6A, 6B, and 6C and 6D show arrangements of measurement device arrays, according to some aspects.FIG. 7 shows a method of fabricating one or more measurement devices, according to some aspects.

[0012] The features of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements. Additionally, generally, the leftmost digit(s) of a reference number identifies the drawing in which the reference number first appears.Unless otherwise indicated, the drawings provided throughout the disclosure should not be interpreted as to-scale drawings.DETAILED DESCRIPTION

[0013] This specification discloses one or more embodiments that incorporate the features of the present disclosure. The disclosed embodiment(s) are provided as examples. The scope of the present disclosure is not limited to the disclosed embodiment(s). Claimed features are defined by the claims appended hereto.

[0014] The embodiment(s) described, and references in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment! s) described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0015] Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “on,” “upper” and the like, can be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0016] The term “about” as used herein indicates the value of a given quantity that can vary based on a particular technology. Based on the particular technology, the term “about” can indicate a value of a given quantity that varies within, for example, 10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value).

[0017] Embodiments of the disclosure can be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the disclosure may also be implemented as instructions stored on a machine -readable medium, which can be read and executed by one or more processors. A machine- readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Further, firmware, software, routines, and / or instructions can be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions in fact result fromcomputing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc.

[0018] Before describing such embodiments in more detail, however, it is instructive to present an example environment in which embodiments of the present disclosure can be implemented.

[0019] Example Lithographic Systems

[0020] FIGS. 1 A and IB show schematic illustrations of a lithographic apparatus 100 and lithographic apparatus 100’, respectively, in which aspects of the present disclosure can be implemented. Lithographic apparatus 100 and lithographic apparatus 100’ each include the following: an illumination system (illuminator) IL configured to condition a radiation beam B (for example, deep ultra violet or extreme ultra violet radiation); a support structure (for example, a mask table) MT configured to support a patterning device (for example, a mask, a reticle, or a dynamic patterning device) MA and connected to a first positioner PM configured to accurately position the patterning device MA; and, a substrate table (for example, a wafer table) WT configured to hold a substrate (for example, a resist coated wafer) W and connected to a second positioner PW configured to accurately position the substrate W. Lithographic apparatus 100 and 100’ also have a projection system PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion (for example, comprising one or more dies) C of the substrate W. In lithographic apparatus 100, the patterning device MA and the projection system PS are reflective. In lithographic apparatus 100’, the patterning device MA and the projection system PS are transmissive.

[0021] The illumination system IL can include various types of optical components, such as refractive, reflective, catadioptric, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for directing, shaping, or controlling the radiation beam B.

[0022] The support structure MT holds the patterning device MA in a manner that depends on the orientation of the patterning device MA with respect to a reference frame, the design of at least one of the lithographic apparatus 100 and 100’, and other conditions, such as whether or not the patterning device MA is held in a vacuum environment. The support structure MT can use mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device MA. The support structure MT can be a frame or a table, for example, which can be fixed or movable, as required. By using sensors, the support structure MT can ensure that the patterning device MA is at a desired position, for example, with respect to the projection system PS.

[0023] The term “patterning device” MA should be broadly interpreted as referring to any device that can be used to impart a radiation beam B with a pattern in its cross-section, such as to create a pattern in the target portion C of the substrate W. The pattern imparted to the radiation beam B can correspond to a particular functional layer in a device being created in the target portion C to form an integrated circuit.

[0024] The terms “inspection apparatus,” “metrology system,” or the like may be used herein to refer to, e.g., a device or system used for measuring a property of a structure (e.g., overlay error, criticaldimension parameters) or used in a lithographic apparatus to inspect an alignment of a wafer (e.g., alignment apparatus).

[0025] The patterning device MA can be transmissive (as in lithographic apparatus 100’ of FIG. IB) or reflective (as in lithographic apparatus 100 of FIG. 1A). Examples of patterning devices MA include reticles, masks, programmable mirror arrays, or programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase shift, or attenuated phase shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam B, which is reflected by a matrix of small mirrors.

[0026] The term “projection system” PS can encompass any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors, such as the use of an immersion liquid on the substrate W or the use of a vacuum. A vacuum environment can be used for EUV or electron beam radiation since other gases can absorb too much radiation or electrons. A vacuum environment can therefore be provided to the whole beam path with the aid of a vacuum wall and vacuum pumps.

[0027] Lithographic apparatus 100 and / or lithographic apparatus 100’ can be of a type having two (dual stage) or more substrate tables WT (and / or two or more mask tables). In such “multiple stage” machines, the additional substrate tables WT can be used in parallel, or preparatory steps can be carried out on one or more tables while one or more other substrate tables WT are being used for exposure. In some situations, the additional table may not be a substrate table WT.

[0028] The lithographic apparatus can also be of a type wherein at least a portion of the substrate can be covered by a liquid having a relatively high refractive index, e.g., water, so as to fill a space between the projection system and the substrate. An immersion liquid can also be applied to other spaces in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems. The term “immersion” as used herein does not mean that a structure, such as a substrate, must be submerged in liquid, but rather only means that liquid is located between the projection system and the substrate during exposure.

[0029] Referring to FIGS. 1A and IB, the illuminator IL receives a radiation beam from a radiation source SO. The source SO and the lithographic apparatus 100, 100’ can be separate physical entities, for example, when the source SO is an excimer laser. In such cases, the source SO is not considered to form part of the lithographic apparatus 100 or 100’, and the radiation beam B passes from the source SO to the illuminator IL with the aid of a beam delivery system BD (in FIG. IB) including, for example, suitable directing mirrors and / or a beam expander. In other cases, the source SO can be an integral part of the lithographic apparatus 100, 100’, for example, when the source SO is a mercury lamp. The sourceSO and the illuminator IL, together with the beam delivery system BD, if required, can be referred to as a radiation system.

[0030] The illuminator IL can include an adjuster AD (in FIG. IB) for adjusting the angular intensity distribution of the radiation beam. Generally, at least the outer and / or inner radial extent (commonly referred to as “o-outer” and “o-inner,” respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. In addition, the illuminator IL can comprise various other components (in FIG. IB), such as an integrator IN and a condenser CO. The illuminator IL can be used to condition the radiation beam B to have a desired uniformity and intensity distribution in its cross section.

[0031] Referring to FIG. 1A, the radiation beam B is incident on the patterning device (for example, mask) MA, which is held on the support structure (for example, mask table) MT, and is patterned by the patterning device MA. In lithographic apparatus 100, the radiation beam B is reflected from the patterning device (for example, mask) MA. After being reflected from the patterning device (for example, mask) MA, the radiation beam B passes through the projection system PS, which focuses the radiation beam B onto a target portion C of the substrate W. With the aid of the second positioner PW and position sensor IF2 (for example, an interferometric device, linear encoder, or capacitive sensor), the substrate table WT can be moved accurately (for example, so as to position different target portions C in the path of the radiation beam B). Similarly, the first positioner PM and another position sensor IF1 can be used to accurately position the patterning device (for example, mask) MA with respect to the path of the radiation beam B. Patterning device (for example, mask) MA and substrate W can be aligned using mask alignment marks Ml, M2 and substrate alignment marks Pl, P2.

[0032] Referring to FIG. IB, the radiation beam B is incident on the patterning device (for example, mask MA), which is held on the support structure (for example, mask table MT), and is patterned by the patterning device. Having traversed the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. The projection system has a pupil conjugate PPU to an illumination system pupil IPU. Portions of radiation emanate from the intensity distribution at the illumination system pupil IPU and traverse a mask pattern without being affected by diffraction at the mask pattern and create an image of the intensity distribution at the illumination system pupil IPU.

[0033] The projection system PS projects an image of the mask pattern MP, where the image is formed by diffracted beams produced from the mark pattern MP by radiation from the intensity distribution, onto a photoresist layer coated on the substrate W. For example, the mask pattern MP can include an array of lines and spaces. A diffraction of radiation at the array and different from zeroth order diffraction generates diverted diffracted beams with a change of direction in a direction perpendicular to the lines. Undiffracted beams (i.e., so-called zeroth order diffracted beams) traverse the pattern without any change in propagation direction. The zeroth order diffracted beams traverse an upper lens or upper lens group of the projection system PS, upstream of the pupil conjugate PPU of the projection system PS, to reach the pupil conjugate PPU. The portion of the intensity distribution in the plane ofthe pupil conjugate PPU and associated with the zeroth order diffracted beams is an image of the intensity distribution in the illumination system pupil IPU of the illumination system IL. The aperture device PD, for example, is disposed at or substantially at a plane that includes the pupil conjugate PPU of the projection system PS.

[0034] The projection system PS is arranged to capture, by means of a lens or lens group L, not only the zeroth order diffracted beams, but also first-order or first- and higher-order diffracted beams (not shown). In some embodiments, dipole illumination for imaging line patterns extending in a direction perpendicular to a line can be used to utilize the resolution enhancement effect of dipole illumination. For example, first-order diffracted beams interfere with corresponding zeroth-order diffracted beams at the level of the wafer W to create an image of the line pattern MP at highest possible resolution and process window (i.e., usable depth of focus in combination with tolerable exposure dose deviations). In some embodiments, astigmatism aberration can be reduced by providing radiation poles (not shown) in opposite quadrants of the illumination system pupil IPU. Further, in some embodiments, astigmatism aberration can be reduced by blocking the zeroth order beams in the pupil conjugate PPU of the projection system associated with radiation poles in opposite quadrants. This is described in more detail in US 7,511,799 B2, issued Mar. 31, 2009, which is incorporated by reference herein in its entirety.

[0035] With the aid of the second positioner PW and position sensor IFD (for example, an interferometric device, linear encoder, or capacitive sensor), the substrate table WT can be moved accurately (for example, so as to position different target portions C in the path of the radiation beam B). Similarly, the first positioner PM and another position sensor (not shown in FIG. IB) can be used to accurately position the mask MA with respect to the path of the radiation beam B (for example, after mechanical retrieval from a mask library or during a scan).

[0036] In general, movement of the mask table MT can be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM. Similarly, movement of the substrate table WT can be realized using a long-stroke module and a short-stroke module, which form part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the mask table MT can be connected to a short-stroke actuator only or can be fixed. Mask MA and substrate W can be aligned using mask alignment marks Ml, M2, and substrate alignment marks Pl, P2. Although the substrate alignment marks (as illustrated) occupy dedicated target portions, they can be located in spaces between target portions (known as scribe-lane alignment marks). Similarly, in situations in which more than one die is provided on the mask MA, the mask alignment marks can be located between the dies.

[0037] Mask table MT and patterning device MA can be in a vacuum chamber V, where an in-vacuum robot IVR can be used to move patterning devices such as a mask in and out of vacuum chamber. Alternatively, when mask table MT and patterning device MA are outside of the vacuum chamber, an out-of-vacuum robot can be used for various transportation operations, similar to the in-vacuum robotIVR. Both the in- vacuum and out-of- vacuum robots need to be calibrated for a smooth transfer of any payload (e.g., mask) to a fixed kinematic mount of a transfer station.

[0038] The lithographic apparatus 100 and 100’ can be used in at least one of the following modes:1. In step mode, the support structure (for example, mask table) MT and the substrate table WT are kept essentially stationary, while an entire pattern imparted to the radiation beam B is projected onto a target portion C at one time (i.e., a single static exposure). The substrate table WT is then shifted in the X and / or Y direction so that a different target portion C can be exposed.2. In scan mode, the support structure (for example, mask table) MT and the substrate table WT are scanned synchronously while a pattern imparted to the radiation beam B is projected onto a target portion C (i.e., a single dynamic exposure). The velocity and direction of the substrate table WT relative to the support structure (for example, mask table) MT can be determined by the (de-)magnification and image reversal characteristics of the projection system PS.3. In another mode, the support structure (for example, mask table) MT is kept substantially stationary holding a programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam B is projected onto a target portion C. A pulsed radiation source SO can be employed and the programmable patterning device is updated as required after each movement of the substrate table WT or in between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography that utilizes a programmable patterning device, such as a programmable mirror array.

[0039] Combinations and / or variations on the described modes of use or entirely different modes of use can also be employed.

[0040] In a further embodiment, lithographic apparatus 100 includes an extreme ultraviolet (EUV) source, which is configured to generate a beam of EUV radiation for EUV lithography. In general, the EUV source is configured in a radiation system, and a corresponding illumination system is configured to condition the EUV radiation beam of the EUV source.

[0041] FIG. 2 shows the lithographic apparatus 100 in more detail, including the source collector apparatus SO, the illumination system IL, and the projection system PS. The source collector apparatus SO is constructed and arranged such that a vacuum environment can be maintained in an enclosing structure 220 of the source collector apparatus SO. An EUV radiation emitting plasma 210 can be formed by a discharge produced plasma source. EUV radiation can be produced by a gas or vapor, for example Xe gas, Li vapor, or Sn vapor in which the very hot plasma 210 is created to emit radiation in the EUV range of the electromagnetic spectrum. The very hot plasma 210 is created by, for example, an electrical discharge causing at least a partially ionized plasma. Partial pressures of, for example, 10 Pa of Xe, Li, Sn vapor, or any other suitable gas or vapor can be required for efficient generation of the radiation. In some aspects, a plasma of excited tin (Sn) is provided to produce EUV radiation.

[0042] The radiation emitted by the hot plasma 210 is passed from a source chamber 211 into a collector chamber 212 via an optional gas barrier or contaminant trap 230 (in some cases also referredto as contaminant barrier or foil trap), which is positioned in or behind an opening in source chamber 211. The contaminant trap 230 can include a channel structure. Contamination trap 230 can also include a gas barrier or a combination of a gas barrier and a channel structure. The contaminant trap or contaminant barrier 230 further indicated herein at least includes a channel structure.

[0043] The collector chamber 212 can include a radiation collector CO, which can be a so-called grazing incidence collector. Radiation collector CO has an upstream radiation collector side 251 and a downstream radiation collector side 252. Radiation that traverses collector CO can be reflected off a grating spectral filter 240 to be focused in a virtual source point INTF. The virtual source point INTF is commonly referred to as the intermediate focus, and the source collector apparatus is arranged such that the intermediate focus INTF is located at or near an opening 219 in the enclosing structure 220. The virtual source point INTF is an image of the radiation emitting plasma 210. Grating spectral filter 240 is used in particular for suppressing infra-red (IR) radiation.

[0044] Subsequently the radiation traverses the illumination system IL, which can include a faceted field mirror device 222 and a faceted pupil mirror device 224 arranged to provide a desired angular distribution of the radiation beam 221, at the patterning device MA, as well as a desired uniformity of radiation intensity at the patterning device MA. Upon reflection of the beam of radiation 221 at the patterning device MA, held by the support structure MT, a patterned beam 226 is formed and the patterned beam 226 is imaged by the projection system PS via reflective elements 228, 229 onto a substrate W held by the wafer stage or substrate table WT.

[0045] More elements than shown can generally be present in illumination optics unit IL and projection system PS. The grating spectral filter 240 can optionally be present, depending upon the type of lithographic apparatus. Further, there can be more mirrors present than those shown in the FIG. 2, for example there can be one to six additional reflective elements present in the projection system PS than shown in FIG. 2.

[0046] Collector optic CO, as illustrated in FIG. 2, is depicted as a nested collector with grazing incidence reflectors 253, 254, and 255, just as an example of a collector (or collector mirror). The grazing incidence reflectors 253, 254, and 255 are disposed axially symmetric around an optical axis O and a collector optic CO of this type is preferably used in combination with a discharge produced plasma source, often called a DPP source.

[0047] Exemplary Lithographic Cell

[0048] FIG. 3 shows a lithographic cell 300, also sometimes referred to a lithocell or cluster, according to some aspects. Lithographic apparatus 100 or 100’ can form part of lithographic cell 300. Lithographic cell 300 can also include one or more apparatuses to perform pre- and post-exposure processes on a substrate. In some examples, these include spin coaters SC to deposit resist layers, developers DE to develop exposed resist, chill plates CH, and bake plates BK. A substrate handler, or robot, RO picks up substrates from input / output ports I / Ol, I / O2, moves them between the different process apparatuses and delivers them to the loading bay LB of the lithographic apparatus 100 or 100’ . These devices, whichare often collectively referred to as the track, are under the control of a track control unit TCU, which is itself controlled by a supervisory control system SCS, which also controls the lithographic apparatus via lithography control unit LACU. Thus, the different apparatuses can be operated to maximize throughput and processing efficiency.

[0049] Example Measurement Device

[0050] The flatness of a substrate can impact the accuracy of a projection of an image onto the substrate during a lithographic exposure. For example, when the substrate is not flat, focus errors can be introduced. Measuring the height, and therefore flatness, of a substrate before carrying out a lithographic exposure can allow for focus errors to be determined and corrected. In order to achieve this, a lithographic apparatus can be provided with a height measurement device. The height measurement device can measure the height across a surface of the substrate. The substrate height measurements can then be used to form a substrate height map which assists accurate projection of a pattern onto the substrate.

[0051] In some aspects, a height measurement device incorporates one or more air gauges. An air gauge is a unique distance measuring device capable of very high resolution. In the context of lithographic apparatuses, an air gauge has no sensitivity to layers below the surface being measured. Thus, an air gauge can sense only the top surface of resist on a substrate, which is an ideal reference surface for focus control in wafer lithography.

[0052] Current methods of fabricating air gauge measurement devices for lithographic apparatuses utilize costly drilling and milling techniques. These techniques limit the size, complexity and manufacturability of a measurement device.

[0053] In some aspects, microfluidic air gauge measurement devices can be fabricated using wafer fabrication techniques. For example, components of an air gauge (e.g., inlet, reference channel, measurement channel, etc.) can be etched into a plurality of substrates. Then, the substrates can be bonded to form a measurement device. This can result in a smaller device with improved bandwidth and sensitivity and easier integration into a lithography apparatus. Additionally, wafer fabrication techniques can allow for fabrication of multiple measurement devices in parallel with minimal cost increases.

[0054] FIG. 4 shows an example measurement device 400, according to some aspects. Measurement device 400 can comprise a plurality substrates 402. The plurality of substrates 402 can contain features that collectively form a series of channels when the substrates are bonded together. The series of channels can include an inlet 404, flow restrictions 406, a measurement channel 408, and a reference channel 410.

[0055] A sensor 412 can be positioned to measure differential pressure and / or flow between measurement channel 408 and reference channel 410. In some aspects, sensor 412 can be a membrane disposed between two substrates in the plurality of substrates 402.

[0056] The arrows depicted in FIG. 4 show the direction of pressurized air flow through measurement apparatus 400. Air can enter measurement apparatus 400 through inlet 404. Air can then be directed through flow restrictions 406.

[0057] Flow restrictions 406 can control and / or steady the mass flow of pressurized gas as the gas enters measurement channel 408 and reference channel 410. In some aspects, flow restrictions 406 can equally restrict the mass flow of pressurized air entering measurement channel 408 and reference channel 410.

[0058] In some aspects, flow restrictions 406 are orifices with hydraulic diameters smaller than the hydraulic diameter of inlet 404. Flow restrictions 406 can have hydraulic diameters of between about 0.1 to 1.5 pm, for example, but other diameters are contemplated by the inventors as possible as would become apparent to persons skilled in the art.

[0059] Air entering measurement channel 408 through flow restrictions 406 can exit through measurement outlet 409 and flow towards substrate 414. Air entering reference channel 410 through flow restrictions 406 can exit through reference outlet 411 and flow towards a reference surface 416. Because reference surface 416 is set, the pressure at reference outlet 411 can be approximately constant.

[0060] In some aspects, measurement device 400 can measure the height of a surface by measuring and / or inferring a pressure or flow differential between air exiting measurement channel 408 and air exiting reference channel 410. Sensor 412 can be used to measure the pressure differential.

[0061] In some aspects, sensor 412 can comprise a flexible membrane in fluid communication with both measurement channel 408 and reference channel 410. The flexible membrane can be configured to have no deflection when there is no pressure differential between the measurement and reference channels.

[0062] During height measurements, the distance between the measurement nozzle 409 and the substrate can impact the pressure at the measurement nozzle. For example, a decreasing distance between substrate 414 and the measurement outlet 409 can cause an increase of pressure at the measurement nozzle as the flow of pressurized gas experiences greater restriction when exiting measurement nozzle 409. Alternatively, an increasing distance between substrate 414 and the measurement nozzle 409 can cause a decrease of pressure at the measurement nozzle as the flow of pressurized gas experiences less restriction on exiting the measurement nozzle. Because reference surface 416 is kept constant, reference nozzle 411 does not experience a change in pressure.

[0063] In some aspects, when sensor 412 comprises a pressure sensing membrane, the pressure sensing membrane can deflect in response to pressure changes at measurement nozzle 409. The deflection of the pressure sensing membrane can be measured, and used to infer differential pressure between measurement channel 408 and reference channel 410. The surface area of the pressure sensing membrane can affect the sensitivity of differential pressure measurements. For example, a pressure sensing membrane with a larger surface area can be more sensitive to pressure changes. The surfacearea of the pressure sensing membrane can therefore be selected to provide an appropriate sensitivity for a given height measurement.

[0064] In some aspects, the deflection the pressure sensing membrane can be measured using piezo- resistive elements, such as strain gauges. The piezo-resistive elements can be etched onto the surface of the pressure sensing membrane. As the pressure sensing membrane deflects, the piezo-resistive elements undergo mechanical strain, which can change the electrical resistance of the piezo-resistive elements. The resistances of the piezo-resistive elements can be measured and used to determine differential pressure between the measurement channel 408 and reference channel 410. In some aspects, the resistances of the piezo-electric elements are measured by an analysis module (not shown). Electrical connections can couple the piezo-resistive elements to the analysis module. The electrical connections can be disposed on a substrate in the plurality of substrates 402.

[0065] Any conceivable number or configuration of piezo-resistive elements can be disposed on a pressure sensing membrane. In some aspects, the piezo-resistive elements can be arranged in a Wheatstone bridge circuit. A Wheatstone bridge circuit configuration can compensate for the effects of temperature on an output signal of the piezo-resistive elements, which can reduce background noise in a substrate height measurement.

[0066] In some aspects, the deflection of a pressure sensing membrane can be measured optically (e.g., by laser light incident on the pressure sensing membrane).

[0067] Sensor 412 can comprise other pressure sensors (e.g., non-membrane pressure sensors) and / or differential pressure sensing schemes can be employed in measurement device 400. A further discussion of pressure sensing technologies can be found in U.S. Patent Pub. 2019 / 0017816, published on January 17, 2019, and herein incorporated by reference.

[0068] In some aspects, measurement device 400 can be used to measure the multiple regions of a surface of substrate 414. For example, measurement nozzle 409 of measurement device 400 can be scanned across the surface of substrate 414. Alternatively, substrate 414 can be scanned beneath measurement nozzle 409 of measurement device 400. In some aspects, the z-position of the measurement device 400 can be fixed at a predetermined value during measurements.

[0069] Each measurement device 400 can have a total internal volume of less than about 15 mm3. In some aspects, the total internal volume is less than 5 mm3. In further aspects, the total internal volume is less than 1 mm3. An internal volume as described herein can be the volume of the channels that comprise a measurement device (i.e., inlet 404, flow restrictions 406, measurement channel 408, and reference channel 410).

[0070] In some aspects, measurement sensitivity of a measurement device 400 can be related to the internal volume of the device. For example, smaller measurement devices can have higher bandwidths and faster frequency responses. Here, bandwidth can refer to the speed at which the measurement device can respond to changes in pressure. Measurement devices 400 with internal volumes less than about 5 mm3can have bandwidths up to about 20 kHz.

[0071] In some aspects, measurement device 400 can be integrated into a lithography apparatus. For example, measurement device 400 can be positioned in a carrier in a lithography apparatus and used to measure the height of a surface of a wafer and / or a lithography stage.

[0072] While FIG. 4 shows a measurement device fabricated using five substrates, it can be understood by one of ordinary skill in the art that a measurement device can be fabricated using more or fewer substrates. In some aspects, a measurement device can be fabricated using two substrates. In some aspects, a measurement device can be fabricated from a single substrate (e.g., using 3D printing techniques, as would become apparent to persons skilled in the art).

[0073] In some aspects, more than one measurement device can be fabricated in the plurality of substrates. For example, channels for an array of measurement devices can be etched simultaneously.

[0074] FIG. 5 shows a cross section of a measurement array 500, according to some aspects. Measurement array 500 can contain a plurality of measurement devices 501. In some aspects, measurement devices 501 are configured similar to measurement device 400, as described in FIG. 4. Commonly numbered elements between FIGS. 4 and 5 can have similar structure and function.

[0075] As described in reference to FIG. 4, air entering measurement devices 501 through inlets 404 can flow through flow restrictions 406 into measurement channel 408 and reference channel 410. Air exiting measurement channel 408 flows through measurement nozzle 409 and is incident on a surface to be measured. Air exiting reference channel 410 flows though reference nozzle 411 and is incident on reference surface 416. Pressure sensing membrane 412 can measure the pressure differential between measurement channel 408 and reference channel 410. The pressure differential can be used to measure the height of a surface of a substrate.

[0076] As shown in FIG. 5, more than one measurement device 501 can share a common inlet 404. This can simplify fabrication and / or save space, allowing for measurement devices 501 to be fabricated closer together.

[0077] Measurement array 500 can contain a plenum 503. Plenum 503 can supply air to measurement devices 501. A gas supply (not shown) can supply air to plenum 503. A mass flow controller (not shown) can control the mass flow rate of air in plenum 503.

[0078] In some aspects, the mass flow rate of air entering measurement devices 501 can impact the sensitivity of differential pressure measurements. For example, the mass flow rate can be configured such that the flow of air in measurement devices 501 is sufficient to measure pressure differences between the measurement and reference chamber without generating turbulent air effects. In some aspects, plenum 503 can be configured such that all measurement devices 501 receive the same pressurized air flow. In other examples, plenum 503 can be configured such that at least two measurement devices 501 receive different pressurized air flows.

[0079] In some aspects, measurement devices 501 in measurement array 500 can simultaneously measure multiple location of a surface of a substrate.

[0080] In some aspects, measurement array 500 is integrated into a lithography apparatus. For example, measurement array 500 can be positioned in a carrier in a lithography apparatus. The carrier can position measurement array 500 to measure one or more regions of a substrate. In some aspects the measurement array can be moved across the substrate.

[0081] FIGS. 6A, 6B, 6C, and 6D show bottom views of a measurement arrays 600A, 600B, 600C, and 600D respectively, according to some aspects. The bottom view of measurement arrays 600A, 600B, 600C and 600D can show relative positions of measurement nozzles 409.

[0082] In FIG. 6A, measurement nozzles 409 are arranged as a series of linear arrays, according to some aspects. The linear arrays can be aligned such that measurement nozzles of successive rows and columns align with each other. In some aspects, array 600A can cover an entire surface of a 300 mm wafer. For example, array 600 can have about 100 rows and about 100 columns. In other examples, array 600 A can comprise a smaller number of rows and / or columns. In some aspects, array 600 A can be a single linear array (e.g., one row of measurement devices).

[0083] In FIG. 6B, measurement nozzles 409 are arranged as a series of staggered linear arrays, according to some aspects. In array 600B, successive rows of linear arrays can be staggered such that measurement nozzles of each row are not perpendicularly aligned with the row above. A series of staggered linear arrays can provide greater coverage (i.e., have more measurement devices spaced closer together) than the series of linear arrays described in FIG. 6A. In some aspects, array 600B can cover an entire surface of a 300 mm wafer. For example, array 600B can have about 100 rows. In other examples, array 600B can comprise a smaller number of rows. In some aspects, array 600B can comprise two staggered rows.

[0084] In FIG. 6C, measurement nozzles 409 are arranged in two perpendicular linear arrays, according to some aspects. Array 600C can be rotated such that the measurement nozzles can measure different portions of a substrate. The measurement array 600C need only be rotated 90 degrees to get full coverage of the substrate. The configuration of array 600C can balance fast substrate measurements with a simplified fabrication design.

[0085] FIG. 6D shows a circular array of measurement nozzles 409, according to some aspects. In array 600D, measurement nozzles 409 are arranged in circular pattern that extend radially from the center of the array. Similar to arrays 600A and 600B, array 600D can cover an entire surface of a 300 mm wafer.

[0086] In some aspects, the configurations of arrays 600A, 600B, and 600D can measure an entire surface of a lithography wafer simultaneously.

[0087] Arrays 600A, 600B, 600C, and 600D can contain any conceivable number of measurement devices. In some aspects, the number of measurement devices contained in an array can be determined by the area the array is intended to measure and / or by spacing concerns in a lithography apparats.

[0088] In some aspects, measurement nozzles 409 in arrays 600A, 600B, 600C, and 600D can have any conceivable spacing. The spacing between measurement devices can be determined by the size ofthe measurement devices. In some aspects, the spacing between measurement devices in uniform. In other aspects, the spacing between measurement devices is non uniform.

[0089] The spacing, size, and number of measurement nozzles 409 shown in arrays 600A, 600B, 600C, and 600D are for illustration purposes and are not necessarily drawn to scale. Furthermore, arrays 600 A, 600B, 600C, and 600D are example configurations and are non-limiting. Other array configurations can be envisaged based on the devices and techniques described herein.

[0090] FIG. 7 shows a method 700, according to some aspects. Method 700 can be used to fabricate one or more measurement devices as described in FIGS. 4 and 5.

[0091] In step 702, features are formed in one or more substrates, according to some aspects. Features can include channels and / or through holes. The one or more substrates can be comprised of silicon, glass, copper foil laminates (e.g., precursors to PCB boards), plastics, polymers, or the like.

[0092] In some aspects, features are formed via etching. Etching can create nanometer and / or micrometer scale features on the one or more substrates. Each substrate in the one or more substrates can have different etched features, which when combined, can create a series of channels that form a measurement device. Substrates can be etched on multiple sides (e.g., top and bottom sides). Portions of a substrate can be coated and / or patterned before etching begins to guide the etching process.

[0093] A variety of etching techniques can be deployed. For example, wet etching, laser etching, deep reactive ion etching, or the like can be used to create desired features in the one or more substrates. In some aspects, the etching technique can be tailored to the material of a substrate. For example, silicon substrates can be etched using wet etching (e.g., KOH for silicon dioxide or H3PO4 for silicon nitride) and / or deep reactive ion etching techniques. On the other hand, glass substrates can be etched via a combination of laser etching (to damage the glass surface) and wet etching with an acid, such as KOH. Other conceivable etching techniques can be used.

[0094] In some aspects, other techniques, such as 3D printing, can be used to form features in the one or more substrates. For example, a 3D printer can print a plurality of substrates with features (e.g., channels and through holes) that, when combined, can create a series of channels that form a measurement device. A 3D printer can also print a single substrate comprising a series of channels that form a measurement device. In this case, a pressure sensor can be added to the substrate after the substrate is printed. A 3D printed substrate can comprise materials such as plastic compounds, resins, metals, or the like.

[0095] In step 704, one or more measurement devices are configured by aligning the one or more substrates, according to some aspects. The one or more substrates can be aligned such that features in the one or more substrates form a series of channels that comprise one or more measurement devices.

[0096] In some aspects, one or more pressure sensing membranes can be positioned between two substrates in the one or more substrates.

[0097] In some aspects, the one or more measurement devices comprise an air gauge as described in FIG. 4. The one or more measurement devices can be configured to have internal volumes less than about 15 mm3, less than about 5 mm3and / or less than about 1 mm3.

[0098] The size of the one or more measurement devices can affect the frequency response. For example, it takes less time to reach equilibrium in a smaller device. In some aspects, the frequency response for a measurement device with an internal volume of about 15 mm3can be at least 2 kHz. As devices get smaller, the frequency response can improve, and in some instances, reach over 20 kHz.

[0099] In some aspects, the one or more measurement devices can be configured to measure the height of a substrate, for example, by measuring differential pressure between a measurement nozzle and a reference nozzle. The one or more measurement devices can create a height map of a substrate by measuring the height at different areas of the substrate. The one or more measurement devices can measure multiple areas of a substrate simultaneously. The one or more measurement devices can be scanned across the surface of the substrate, or the substrate can be scanned beneath the one or more measurement devices.

[0100] In step 706, the plurality of substrates are bonded, according to some aspects. The plurality of substrates can be bonded such that the features in the plurality of substrates align to create channels, which can form one or more measurement devices.

[0101] The plurality of substrates can be bonded via fusion bonding, anodic bonding, adhesive bonding, eutectic bonding, gluing or the like. In some aspects, more than one bonding technique can employed. For example, a substrate comprising sensitive electronics, such as electrical connections for strain gauges, can be bonded via a lower temperature bonding technique (e.g., eutectic bonding), while other substrates without such limitations can be bonded via a higher temperature bonding technique (e.g., fusion bonding).

[0102] The one or more measurement devices can be configured to form an array of measurement devices. The array of measurement devices can be linear array, a staggered array, a circular array, or the like. The array of measurement devices can take any of the forms described in reference to FIGS. 6A, 6B. 6C, and 6D. The configuration of the array can be determined by the etching and bonding steps. For example, the spacing, positioning, and number of etched regions in the plurality of substrates can determine the number and configuration of measurement devices in the array of measurement devices.

[0103] The method steps of FIG. 7 can be performed in any conceivable order and it is not required that all steps be performed. Moreover, the method steps of FIG. 7 described above merely reflect an example of steps and are not limiting. That is, further method steps and functions are envisaged based aspects described in reference to FIGS. 1-6.

[0104] The embodiments may further be described using the following clauses:1. An apparatus comprising: a plurality of bonded substrates comprising one or more measurement devices, each measurement device comprising:at least one gas inlet, the gas inlet coupled to a plurality of flow restrictions and / or orifices, wherein each flow restriction and / or orifice is coupled to either a reference chamber or a measurement chamber, one or more sensors configured to measure and / or infer differential pressure or flow between the reference chamber and the measurement chamber the reference chamber coupled to a reference nozzle, and the measurement chamber coupled to a measurement nozzle; and wherein each measurement device has a total internal volume of less than about 15 mm3.2. The apparatus of clause 1, wherein the plurality of bonded substrates are silicon wafers, glass wafers, and / or bonded polymer layers.3. The apparatus of clause 1, wherein the one or more measurement devices have a frequency response of at least 2 kHz.4. The apparatus of clause 1, wherein the one or more pressure sensors comprise at least one membrane disposed between the reference chamber and the measurement chamber and containing one or more strain gauges.5. The apparatus of clause 1, wherein the one or more measurement devices form an array of measurement devices.6. The apparatus of clause 5, wherein the array of measurement devices form a linear array, staggered linear array, or circular array.7. The apparatus of clause 5, wherein the array of measurement devices is up to about 300 by 300 mm.8. The apparatus of clause 1, wherein each measurement devices has a total internal volume of less than about 5 mm3.9. The apparatus of clause 1, wherein the apparatus is configured to be moved linearly and / or rotated to measure different portions of components on a wafer table in a lithography system.10. A lithography system comprising the apparatus of clause 1.11. A method comprising: etching a plurality of substrates to create features; bonding the plurality of substrates such that the etched regions in the plurality of substrates create one or more channels, the one or more channels forming one or more measurement devices, wherein each measurement device in the one or more measurement devices comprises: at least one gas inlet, the gas inlet coupled to a plurality of flow restrictions and / or orifices, wherein each flow restriction and / or orifice is coupled to either a reference chamber or a measurement chamber, one or more sensors configured to measure the pressure or flow differential between the reference chamber and the measurement chamber , the reference chamber coupled to a reference nozzle, andthe measurement chamber coupled to a measurement nozzle; and wherein each measurement device in the one or more measurement devices has a total internal volume of less than 15 mm3.12. The method of clause 11, further configuring the one or more pressure sensors to comprise a membrane with one or more strain gauges.13. The method of clause 11, wherein the bonding comprises fusion bonding, gluing, anodic bonding, adhesive bonding, and / or eutectic bonding.14. The method of clause 11, wherein the etching comprises wet etching, plasma etching, deep reactive ion etching, and / or laser etching techniques.15. The method of clause 11, further configuring the one or more measurement devices to measure a height map of a substrate in a lithography system.16. The method of clause 11, further configuring the one or more measurement devices to have a frequency response of at least 2 kHz.17. The method of clause 11, further configuring the one or more measurement devices to form an array of measurement devices.18. The method of clause 17, further configuring the array of measurement devices as a liner array, staggered linear array, and / or circular array.19. The method of clause 17, further configuring each measurement device in the one or more measurement devices to have a total internal volume of less than 5 mm3.20. The method of clause 17, further configuring the array of measurement devices to up to about 300 by 300 mm.

[0105] Although specific reference can be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, LCDs, thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “wafer” or “die” herein can be considered as specific examples of the more general terms “substrate” or “target portion”, respectively. The substrate referred to herein can be processed, before or after exposure, in for example a track unit (a tool that typically applies a layer of resist to a substrate and develops the exposed resist) and / or a metrology unit. Where applicable, the disclosure herein can be applied to such and other substrate processing tools. Further, the substrate can be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.

[0106] Although specific reference may have been made above to the use of embodiments of the present disclosure in the context of optical lithography, it will be appreciated that the present disclosure can be used in other applications, for example imprint lithography, and where the context allows, is not limited to optical lithography. In imprint lithography a topography in a patterning device defines thepattern created on a substrate. The topography of the patterning device can be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof. The patterning device is moved out of the resist leaving a pattern in it after the resist is cured.

[0107] It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present disclosure is to be interpreted by those skilled in relevant art(s) in light of the teachings herein.

[0108] The terms “radiation,” “beam of radiation” or the like as used herein may encompass all types of electromagnetic radiation, for example, ultraviolet (UV) radiation (for example, having a wavelength I of 365, 248, 193, 157 or 126 nm), extreme ultraviolet (EUV or soft X-ray) radiation (for example, having a wavelength in the range of 5-20 nm such as, for example, 13.5 nm), or hard X-ray working at less than 5 nm, as well as matter beams, such as ion beams or electron beams. The terms “light,” “illumination,” or the like may refer to non-matter radiation (e.g., photons, UV, X-ray, or the like). Generally, radiation having wavelengths between about 400 to about 700 nm is considered visible radiation; radiation having wavelengths between about 780-3000 nm (or larger) is considered IR radiation. UV refers to radiation with wavelengths of approximately 100-400 nm. Within lithography, the term “UV” also applies to the wavelengths that can be produced by a mercury discharge lamp: G- line 436 nm; H-line 405 nm; and / or, I-line 365 nm. Vacuum UV, or VUV (i.e., UV absorbed by gas), refers to radiation having a wavelength of approximately 100-200 nm. Deep UV (DUV) generally refers to radiation having wavelengths ranging from 126 nm to 428 nm, and in some embodiments, an excimer laser can generate DUV radiation used within a lithographic apparatus. It should be appreciated that radiation having a wavelength in the range of, for example, 5-20 nm relates to radiation with a certain wavelength band, of which at least part is in the range of 5-20 nm.

[0109] It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the present disclosure as contemplated by the inventor(s), and thus, are not intended to limit the present disclosure and the appended claims in any way.

[0110] The present disclosure has been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

[0111] While specific embodiments of the disclosure have been described above, it will be appreciated that embodiments of the present disclosure may be practiced otherwise than as described. The descriptions are intended to be illustrative, not limiting. Thus it will be apparent to one skilled in the artthat modifications may be made to the disclosure as described without departing from the scope of the claims set out below.

[0112] The foregoing description of the specific embodiments will so fully reveal the general nature of the present disclosure that others can, by applying knowledge within the skill of the art, readily modify and / or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein.

[0113] The breadth and scope of the protected subject matter 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

CLAIMS1. An apparatus comprising: a plurality of bonded substrates comprising one or more measurement devices, each measurement device comprising: at least one gas inlet, the gas inlet coupled to a plurality of flow restrictions and / or orifices, wherein each flow restriction and / or orifice is coupled to either a reference chamber or a measurement chamber, one or more sensors configured to measure and / or infer differential pressure or flow between the reference chamber and the measurement chamber the reference chamber coupled to a reference nozzle, and the measurement chamber coupled to a measurement nozzle; and wherein each measurement device has a total internal volume of less than about 15 mm3.

2. The apparatus of claim 1, wherein the plurality of bonded substrates are silicon wafers, glass wafers, and / or bonded polymer layers.

3. The apparatus of claim 1, wherein the one or more measurement devices have a frequency response of at least 2 kHz.

4. The apparatus of claim 1, wherein the one or more pressure sensors comprise at least one membrane disposed between the reference chamber and the measurement chamber and containing one or more strain gauges.

5. The apparatus of claim 1, wherein the one or more measurement devices form an array of measurement devices.

6. The apparatus of claim 5, wherein the array of measurement devices form a linear array, staggered linear array, or circular array.

7. The apparatus of claim 5, wherein the array of measurement devices is up to about 300 by 300 mm.

8. The apparatus of claim 1 , wherein each measurement devices has a total internal volume of less than about 5 mm3.

9. The apparatus of claim 1, wherein the apparatus is configured to be moved linearly and / or rotated to measure different portions of components on a wafer table in a lithography system.

10. A lithography system comprising the apparatus of claim 1.

11. A method comprising: etching a plurality of substrates to create features; bonding the plurality of substrates such that the etched regions in the plurality of substrates create one or more channels, the one or more channels forming one or more measurement devices, wherein each measurement device in the one or more measurement devices comprises: at least one gas inlet, the gas inlet coupled to a plurality of flow restrictions and / or orifices, wherein each flow restriction and / or orifice is coupled to either a reference chamber or a measurement chamber, one or more sensors configured to measure the pressure or flow differential between the reference chamber and the measurement chamber , the reference chamber coupled to a reference nozzle, and the measurement chamber coupled to a measurement nozzle; and wherein each measurement device in the one or more measurement devices has a total internal volume of less than 15 mm3.

12. The method of claim 11, further configuring the one or more pressure sensors to comprise a membrane with one or more strain gauges.

13. The method of claim 11, wherein the bonding comprises fusion bonding, gluing, anodic bonding, adhesive bonding, and / or eutectic bonding.

14. The method of claim 11, wherein the etching comprises wet etching, plasma etching, deep reactive ion etching, and / or laser etching techniques.

15. The method of claim 11, further configuring the one or more measurement devices to measure a height map of a substrate in a lithography system.

Images