Dither active balancing of motion stages for scanning probe microscopes.

Abstract

The present disclosure relates to a z-position motion stage for use in a scanning probe microscope system, a scanning probe microscope system, and a method of operating said motion stage, the motion stage (1) comprising a scanner body (10) and a drive dither (30) for driving a cantilever (51) of a probe (50) associated with the drive dither (30) in an oscillatory motion (31), the stage further comprising at least a first force balancing means (60) acting on the scanner body at a position opposite the drive dither (30) across a neutral center (N) of the motion stage (1), the force balancing means (60) comprising at least a first balancing dither (61) configured to oscillate in unison with the drive dither.

Description

[Technical field]

[0001] The present disclosure relates to a motion stage for use in a scanning probe microscopy system, and in particular to a z-position motion stage having a scanner body and a dither for driving a probe cantilever in an oscillating motion.

[0002] The present disclosure further relates to a scanning probe microscope system including a motion stage, particularly a motion stage having a scanner body and a dither for driving a cantilever of a probe in an oscillatory motion.

[0003] The present disclosure is further directed to a method of operating a scanning probe microscope system or position motion stage, and in particular to a system or motion stage having a scanner body and dither for driving a cantilever of a probe in an oscillatory motion. [Background technology]

[0004] Scanning probe microscopy (SPM) refers to a broad class of microscopy methods based on scanning a surface, either continuously or periodically, i.e. intermittently, with a probe tip that is kept in contact with the surface to be probed. The methods allow the detection and mapping of surface features of a sample, such as trenches, dimples, edges and roughness, as well as subsurface features, with high accuracy and resolution. The high resolution allows the detection of nanometer-sized structures, and as a result has become very popular, for example, as a tool in the manufacture of semiconductor devices. However, SPMs are used in many other applications as well, for example for imaging and analysis of soft tissue or biological samples.

[0005] A scanning probe microscope system typically comprises a scan head or motion stage to provide relative movement (xyz) between a substrate to be probed and a probe tip associated with the motion stage, e.g., the tip of a probe at the working end of a cantilever. Generally, the motion stage comprises a means, e.g., a holder, for reversibly holding one or more probe tips, typically including a probe tip disposed at or near the end of the cantilever. The cantilever is typically driven by an actuator (commonly referred to as a dither) acting on the probe tip, e.g., via the holder, to provide the cantilever with a periodic, oscillating, motion having a known amplitude for interaction with a surface.

[0006] To provide a relative motion, e.g., a scanning motion, between a probe tip, e.g., a driven probe tip, and the surface of a substrate to be probed, the motion stage typically comprises one or more precision translation means or actuators, typically piezo driven actuators. To reduce the separation distance between the probe tip, e.g., a driven probe tip, and the surface of a substrate to be probed, the motion stage typically comprises a coarse translation means and a fine translation means. The coarse stroke actuators are commonly called large stroke actuators or large stroke z-positioning actuators. Due to their relatively high mass, large stroke actuations can cause imbalances or parasitic oscillations in the scan head. To mitigate the imbalance for large stroke actuation, US Pat. No. 6,590,208 discloses a balanced momentum probe holder with a first actuator and a second actuator at opposing ends that both either extend or retract in response to a signal from a detector. WO 2019 / 070120 relates to a z-position motion stage for use in an SPM system, comprising a support element having actuators that are rotationally symmetric in shape about a notional common longitudinal axis to allow precise movement in the z-direction to follow the sample topology and provide high inherent stiffness.In embodiments also comprising a balance actuator, a second identical motion actuator, the support element is also symmetrical about a plane perpendicular to the longitudinal axis. This additional symmetry has been reported to balance the support element in the z-direction, improving its dynamic behavior in use.

[0007] As background, US Pat. No. 6,323,483 describes a high bandwidth repulsive microactuator, and in particular relates to increasing the bandwidth of its Z-positioning actuators.

[0008] A potential disadvantage of providing a driving dither on or along a motion stage is that during operation, the motion stage itself typically also experiences a net resultant force imposed by the driving dither, which may, depending on the circumstances, cause significant displacements that may cause inaccuracies during scanning probe microscope operation. This displacement may be particularly detrimental to the performance of a scanning probe microscope when the driving dither operates at a frequency that coincides with or overlaps with a resonant mode or natural frequency of the scanner. To avoid or mitigate significant displacements or resonances of the scanner, the scanner may be sized and / or shaped to reduce resonances along specific directions within a given frequency range. To this end, known scanners, such as those disclosed by U.S. Pat. No. 5,574,278, are typically designed to have a relatively stiff body or casing. Alternatively or additionally, lateral displacements or resonances at stage level induced by known stage drive dither can be reduced by positioning the probe holder and / or by driving the dither at or near the longitudinal axis of symmetry of the stage.The above design criteria severely limit the design or form factor of the scanner body and corresponding scanning probe microscope system. Summary of the Invention [Problem to be solved by the invention]

[0009] It is an object of the present disclosure to provide a motion stage and / or scanning probe microscopy system that can mitigate one or more of the above-mentioned disadvantages and operate with improved precision.

[0010] Another or further object is to provide a motion stage and / or scanning probe microscopy system which allows for more relaxed requirements regarding its shape and / or dimensioning. [Means for solving the problem]

[0011] Aspects of the present disclosure relate to a z-position motion stage, particularly a z-position motion stage for use in a scanning probe microscope system, the z-position motion stage comprising a scanner body; and a drive dither. The drive dither is configured to provide a first vibration for driving a cantilever of a probe associated with the drive dither in an oscillatory motion. The drive dither can be provided along a first terminal end face of the scanner body, proximate a first edge of the scanner body. The stage further comprises at least one force balancing means acting on the scanner body at a position opposite the drive dither across a rest or neutral center of the motion stage. The rest or neutral center of the scanner body refers to a neutral bending plane along a longitudinal axis of the scanner body 10. The force balancing means comprises at least one balance dither configured to oscillate in unison with the drive dither.

[0012] Unless otherwise specified in this specification, the balancing means is generally referred to as a first balancing means and is capable of generating a resultant force acting on the scanner body in a direction opposite to the resultant force of the drive dither on the scanner body at a position opposite to the static or neutral center of the motion stage, advantageously even when the drive dither operates at a frequency that overlaps or coincides with a resonant mode of the z position motion stage.

[0013] Depending on the geometry of the z positioning stage and / or the targeted resonance mode, the rest or neutral centre of the z positioning stage may be considered to be the centre of mass of the z positioning stage. Alternatively or additionally, the rest or neutral centre of the z positioning stage may be defined by a point, axis and / or plane to which the z positioning stage is connected (fixed) to a stationary reference point, typically the metro frame of the scanning probe microscope system.

[0014] The balance dither preferably operates in unison with the drive dither. By operating the balance dither in unison with the drive dither, the effective counter force is maximized and / or undesirable resonances of the z position motion stage are reduced.

[0015] In a preferred embodiment, the z position motion stage is configured with a first force balancing means arranged to at least partially counter nodding or bending resonances of the scanner body which may cause undesirable rotational errors and / or displacements of the scanner body in directions along the lateral scanning directions (xy) relative to the substrate to be probed when the z position motion stage is not being inspected.

[0016] In other or further preferred embodiments, the first force balancing means is arranged to at least partially counteract a stretching or breathing resonance (expansion or compression of the scanner body along the length of the scanner body) along the length of the scanner body, generally along the direction of coarse translation (z), thereby mitigating the resonance, e.g. reducing the initial separation distance between the probes across the surface to be probed and improving accuracy during operation.

[0017] In a preferred embodiment, the first force balancing means is provided along a first terminal end face of the scanner body at a position opposite the drive dither across the rest or neutral center of the motion stage. The first force balancing means can thus be understood to be arranged, in use, to at least partially cancel the resultant force exerted on the scanner body by the drive dither. By canceling or at least reducing the net resultant force on the scanner body, the scanner body mitigates nodding or bending resonances of the scanner body, which in turn mitigates undesirable lateral and / or vertical and / or rotational parasitic displacements of the scanner along the face, which may appear as disturbances during scanning operations.

[0018] Locating the drive dither and the balancing means at opposing positions along the first terminal end face of the scanner body advantageously allows for the drive dither and / or means for holding a probe to be located even at off-center or near the edge of the scanner body while still mitigating unwanted resonances of the scanner body. Locating the drive dither and / or means for holding a probe even at off-center or near the edge of the first terminal end face of the scanner body can be advantageous for a number of reasons, including, but not limited to, providing sufficient space for an optical path.

[0019] In another embodiment or further preferred embodiment, the force balancing means is arranged along a second terminal end face of the scanner body opposite the first terminal end face. It can therefore be considered that the force balancing means should be arranged relative to the drive dither in use such that the resultant force induced by the balancing means at least partially cancels the resultant force induced by the drive dither in a direction along the longitudinal axis of the scanner body between the first terminal end face and the second terminal end face. In this way, the embodiment has been found to at least partially counteract stretching or breathing resonance of the scanner body, for example in a direction along the longitudinal axis of the scanner body between the first terminal end face and the second terminal end face.

[0020] Advantageously, in some preferred embodiments, the z position motion stage can be constructed with a plurality of force balancing means arranged to at least partially cancel resonant modes of the stage along any principal geometric direction (x, y, z) and / or to at least partially cancel resonances having components along multiple cardinal directions.

[0021] In certain preferred embodiments, the motion stage includes a first force balancing means and a second force balancing means, the first force balancing means and the second force balancing means being disposed along the first terminal end face of the scanner body and along the second terminal end face of the scanner body at a location opposite the drive dither across the rest or neutral center (N) of the motion stage. Thus, the embodiments may be understood to be configured to at least partially counteract displacements due to multiple resonant modes of the scanner body, such as bending and extensional resonances, or even complex resonances having components along multiple cardinal directions.

[0022] The first force balancing means and the second force balancing means each include one or more balancing dithers configured to oscillate in unison with the drive dither.

[0023] In a preferred embodiment, the second force balancing means comprises at least two second balanced dithers distributed at positions along the second terminal end face opposite the drive dither and the first force balancing means. By providing at least two second balanced dithers, it is further possible to advantageously mitigate potential extension resonances, for example due to the drive dither and the forces of the first force balancing means. Alternatively or additionally, by providing at least two second balanced dithers, it is possible to mitigate potential nodding or bending resonances along the bottom of the scanner body, for example in a direction along the second terminal end face of the scanner body.

[0024] In a particularly preferred embodiment, the scanner body comprises a first end member defining the first terminal end surface and a second end member defining the second terminal end surface. The first end member and the second end member are disposed across opposite ends of a central member, whereby each of the first end member and the second end member is attached to the central member by one or more spring members, e.g. spring blades. The central member advantageously comprises a long stroke actuator acting on the first end member and the second end member to provide translational movement in a direction transverse to, and preferably perpendicular to, the first terminal end surface. To provide a stable reference point for the z-position motion stage at least during operation of the long stroke actuator, the scanner body is reversibly connectable to a metro frame of the scanning probe microscope system, preferably via the central member, e.g. by a mount provided along the central member. The one or more spring members advantageously provide the scanner body with compliance for translational movement. It will be appreciated that the provision of a first balancing means and / or second balancing means in accordance with the present disclosure is particularly effective in mitigating undesirable resonance modes of the z position motion stage, which may be particularly prone to resonate, e.g. bending modes, in the frequency range associated with actuating the cantilever of a typical commercially available probe tip, as compared to a stage having a relatively stiff scanner body.

[0025] Another or further aspect of the present disclosure relates to a scanning probe microscope system, in particular a scanning probe microscope system comprising a z position motion stage according to the present disclosure, preferably further comprising a mount for reversibly associating the z position motion stage with a metro frame of the scanning probe microscope system.

[0026] Still further or other aspects of the present disclosure relate to a method of operating a scanning probe microscopy system according to the present disclosure or a method of operating a positional motion stage according to the present invention, the method comprising at least associating a probe with the z positional motion stage; and driving a drive dither, typically at a target drive frequency associated with a target resonant mode of the cantilever of the probe; and operating the first force balancing means in unison with the drive dither while at least the drive dither is driven at a frequency associated with a resonant mode of the scanner body. As disclosed herein, driving the drive dither and the first force balancing means in unison advantageously mitigates parasitic motion resulting from undesired translations from a resonant mode of the scanner body, for example mitigating parasitic motion during probing of a substrate region of interest.

[0027] These and other features, aspects, and advantages of the devices, systems, and methods of the present disclosure will become better understood from the following description, appended claims, and accompanying drawings. [Brief description of the drawings]

[0028] [Figure 1A] FIG. 1A illustrates exemplary resonance stages of a scanner during operation. [Figure 1B] FIG. 1B illustrates a top view of one embodiment of the scanner. [Figure 1C] FIG. 1C shows the displacement of the cantilever and scanner body as a function of driving frequency. [Figure 2A] FIG. 2A provides a partial side view of an embodiment of a scanner having a force balancing means. [Figure 2B] FIG. 2B provides a partial side view of an embodiment of a scanner having a force balancing means. [Figure 2C] FIG. 2C provides a partial side view of an embodiment of a scanner having a force balancing means. [Figure 3A] FIG. 3A provides a schematic top view of another or further embodiment of a scanner having a force balancing means. [Figure 3B] FIG. 3B provides a schematic top view of another or further embodiment of a scanner having a force balancing means. [Figure 3C] FIG. 3C provides a schematic top view of another or further embodiment of a scanner having a force balancing means. [Figure 3D] FIG. 3D provides a schematic side view of an embodiment of a scanning probe microscopy system including yet another or additional embodiment of a z position motion stage. [Figure 4A] FIG. 4A provides a schematic side view of an embodiment of a scanning probe microscopy system including yet another or additional embodiment of a z-position motion stage. [Figure 4B] FIG. 4B provides a schematic side view of yet a further or alternative embodiment of the z position motion stage. [Figure 4C] FIG. 4C provides a schematic side view of yet a further or alternative embodiment of the z position motion stage. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The terms used to describe particular embodiments are not intended to limit the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. The word "and / or" includes any and all combinations of one or more of the associated listed items. It will be understood that the words "comprises" and "comprising" specify the presence of the stated features but do not exclude the presence or addition of one or more other features. When a particular step of a method is referred to as following another step, it will be further understood that the other step may follow directly, or one or more intermediate steps may be performed before performing the particular step, unless otherwise specified. Similarly, when a connection between structures or components is described, it will be understood that the connection may be established directly or through an intermediate structure or component, unless otherwise specified.

[0030] As used herein, the term "dither" can be understood as an actuator, typically including a piezoelectric actuator or a stack of piezoelectric actuators, configured to provide a vibratory motion to the probe tip in a frequency range, including but not limited to 5 kHz to 500 kHz or 10 kHz to 1 MHz, to excite a resonant mode of the cantilever of the probe tip. In contrast, a large stroke actuator is configured to provide a relatively large and slower displacement to position the probe, e.g., the probe held and excited by the dither, relative to the substrate depending on a control parameter, e.g., the resonant amplitude.

[0031] As used herein, the term "operating in harmony" can be understood to include operating at essentially related frequencies. As will be apparent from this specification, the phase difference can depend on many aspects, including but not limited to the rigidity or compliance of the scanner, the placement of the balancing means and the drive dither relative to the stationary or neutral center of the scanner body, and / or the target resonance mode of the scanner to be mitigated. For example, assuming a rigid scanner behavior, it will be understood that the first force balancing means is preferably driven essentially in phase with the drive dither to mitigate potential bending or nodding oscillations of the z position motion stage by at least partially compensating for the resultant force exerted on the scanner body by the drive dither. Similarly, it will be appreciated that force balancing means arranged across the rigid scanner body opposite the drive dither, for example along a second terminal end face of the scanner body opposite the first face, are preferably operated to mitigate a potential stretching or breathing oscillation of the z-position motion stage by at least partially compensating for the resultant longitudinal force exerted on the scanner body by the drive dither. It will be appreciated that the phase shift can be adjusted appropriately if the scanner includes elements with non-linear behavior, for example dampers (pistons). For example, the drive state of the balancing means in a given situation for a particular scanner design can be checked experimentally, for example by measuring parasitic motion, and adjusted accordingly.

[0032] Coordinated operation may advantageously be provided by using a controller, such as a single controller or frequency generator, to drive the drive dither and one or more force balancing means. Optionally, the drive dither and one or more force balancing means may be controlled by individual control means arranged to operate in coordinated fashion.

[0033] The term "stationary or neutral center of the scanner body" is intended to refer to a point, an axis, or even a balance plane or a displacement center for a given resonant mode. For example, in the case of a breathing or extensional resonant mode of a free-standing body, the neutral center or stationary center generally passes through its center of mass. The stationary or neutral center of the scanner body can therefore refer to a neutral bending plane along the longitudinal axis of the scanner body 10. In the case of a body that is connected to a stationary reference frame, e.g. the metro frame of the scanning probe microscope system, the stationary or neutral center is generally defined by the connection.

[0034] It will further be appreciated that, depending on the circumstances, undesirable displacement or resonance of the scanner body due to the force applied by the dither may be more or less pronounced. For example, potential displacement may become more pronounced as the moment of the resultant force applied by the drive dither on the scanner body relative to the static or neutral center increases, and potential reverse displacement may increase with increasing drive force and / or more off-center or asymmetric placement of the drive dither relative to the scanner body. Alternatively or additionally, displacement may become less pronounced as the match or overlap between the drive frequency of the drive dither and the natural frequency of a particular resonant mode of the scanner decreases.

[0035] The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. In the drawings, absolute and relative sizes of systems, components, layers and regions may be exaggerated for clarity. The embodiments may be described with reference to schematic and / or cross-sectional illustrations of idealized embodiments and intermediate structures of the invention in some cases. In this specification and the drawings, like numbers refer to like elements throughout. Relative terms and derivatives thereof should be construed to refer to the orientation as described at the time or as shown in the drawings under discussion. These relative terms are for convenience of the specification and do not require that the system be constructed or operated in a particular orientation, unless specifically stated otherwise.

[0036] 1A and 1B show various aspects of the resonant modes of a z position motion stage 1 for use in a scanning probe microscope system 100. FIG. 1A provides an exemplary schematic side view of the z position motion stage 1 at various stages A-1, A-2, and A-3 during operation. At stage A-1, the scanner is stationary. The scanner includes a driven dither 30 attached to a first terminal end face 21 of the scanner body 10. As shown, the driven dither 30 is eccentrically mounted near a first end 22 of the terminal end face. A probe 50 tip including a cantilever 51 having a probe tip is associated with the driven dither 30, for example, via a mount (not shown for clarity). The motion stage also generally includes a large stroke z motion actuator. The large stroke z motion actuator is configured to provide relative motion between the dither and its associated probe along the z direction. For clarity, aspects of the scanner balancing are omitted from FIGS. 1A and 1B. These aspects, and others relating to the large stroke z-motion actuator, are described in more detail with respect to FIGS.

[0037] Activating the drive dither can result in an oscillatory motion 31, as represented by the deformation, which can resonate the cantilever at a corresponding resonant frequency, as shown at A-2.

[0038] In addition to driving the cantilever, the drive dither 30 exerts a net resultant, oscillatory force on the scanner body 10 .

[0039] As shown in FIG. 3A-3, this force can then excite a bending or nodding resonance in the scanner body 10, as indicated by the double-headed arrow, across a neutral plane N along the longitudinal axis of the scanner body 10. To briefly explain the principles of parasitic motion, note that the scanner embodiment is fixed to a stationary reference along the bottom end of the scanner body 10 opposite the first terminal end 21. It will be understood that the principles of mitigating parasitic motion are not limited to such a configuration, but can be generally applied to scanners having fixed references at different locations, for example, at a central location or at the sides.

[0040] The force exerted by the dither is different from the force generated by a z-displacement actuator, e.g., a Large Stokes z-motion actuator, already because z-motion actuators do not generally operate to provide an oscillatory motion along the z-direction, and already because they are generally even unsuitable for exciting resonant modes of a cantilever probe due to their relatively high mass (inertia) associated with the purpose of providing a relatively large displacement according to a control parameter along the z-direction, e.g., during a landing operation, or for being able to follow the z-topology of a substrate surface during a scanning operation.

[0041] FIG. 1B illustrates a top view of a z-position motion stage 1 for use in a scanning probe microscope system. Similar to the motion stage illustrated in FIG. 1A, the scanner includes a drive dither 30 located along the first terminal end face 21 of the scanner body near the first end 22 of the scanner body. A cantilevered probe 50 is associated with the drive dither 30 via a mount 40, such as a clamp or vacuum mount. For purposes of the present invention, the motion stage includes a means 60 for countering resonance of the scanner body. Said means, referred to as a first force balancing means 60, is located along the first terminal end face 21 near the second end 23 opposite the first end 22. The balancing means 60 includes a first balance dither 61. The first balance dither is configured to oscillate in harmony with the drive dither. As shown, the first force balancing means acts on the scanner body at a location opposite the driven dither 30 across the neutral center N of the motion stage, which in this case is the neutral bending plane along the longitudinal axis of the scanner body 10 (see also A-3 in FIG. 1A). In some embodiments, the force balancing means 60 comprises a single first balanced dither 61 or a stack of multiple balanced dithers. In some embodiments, the force balancing means 60 can comprise a combination of one or more balanced dithers and a holder or mount, as shown, for example, in FIG. 2B.

[0042] It will be appreciated that the concepts of mitigating scanner resonances disclosed herein are not limited to scanners having the geometric shapes shown or rectangular cross sections, but can be applied equally to scanners having any shape and / or cross section, for example, elongated tubular scanners having rounded cross sections.

[0043] FIG. 1C shows the displacement of the scanner at a position along the first terminal end face 21 of the scanner body 10 as a function of the frequency at which the drive dither 30 is driven. The upper plot (labeled 40) shows the frequency response of the cantilever associated with the drive dither as a function of drive frequency. The peaks in frequency (labeled f1) correspond to the resonant modes of the cantilever. The lower plot (labeled TP3) shows the frequency response G measured by optical interferometry along the first terminal end face 21 of the scanner at a position (labeled TP3) in FIG. 1B. During recording, the first force balancing means 60 was inactive. As can be observed from the presence of multiple peaks, the z-position motion stage can be excited at multiple frequencies or natural frequencies. The peaks (labeled f1) were found to correspond to nodding or bending modes of the stage. It was found that bending resonances are effectively suppressed in response to activating the first force balancing means 60. Measurements at positions TP1 and TP2 showed comparable results. The resonances at f2 and f3 could also be suppressed similarly. The resonances at f4 and f5 are considered to be at least less important within the context of noise reduction during the scanning operation, since the impact at these frequencies was found to be at least an order of magnitude (10 times) smaller (note the logarithmic scale along the vertical axis).

[0044] Various other or further aspects will now be described with reference to Figure 2. Figure 2A provides a partial cross-sectional side view of the embodiment shown in Figure 1B, and Figures 2B and 2C show embodiments including further or additional features.

[0045] In one embodiment, as shown, for example, in FIG. 2A, the z-position motion stage 1 comprises at least a scanner body 10 and a drive dither 30 disposed along a first terminal end face of the scanner body near a first end of the scanner body. The drive dither 30 is configured to provide a first vibration 31 for driving a cantilever of a probe (see FIG. 2C) associated with the drive dither in an oscillatory motion. The stage further comprises at least a first force balancing means 60 acting on the scanner body at a position opposite the drive dither 30 across a rest or neutral center N of the motion stage 1. The force balancing means 60 comprises at least a first balancing dither 61 configured to oscillate in unison with the drive dither. Due, at least in part, to the off-center position of the drive dither 30, the scanner body 10 is subjected to a resultant force F30 during operation of the drive dither 30 that provides a moment on the scanner. It can be understood that the above force includes a lateral component F30-1 in a direction along the first terminal end surface 21 and a vertical component in a direction along the longitudinal direction of the scanner body 10. As disclosed herein, it has been found that the net resultant force and corresponding moment exerted on the scanner body 10 by the drive dither 30 and the balancing means can be effectively reduced, and thus the z position motion stage 1 can be stabilized even when the drive frequency of the drive dither 30 matches a resonant mode of the scanner.

[0046] The magnitude of the resultant force applied by the balancing means, and conversely the magnitude of the net resultant force applied on the scanner body 10 during operation, can be advantageously controlled by controlling the drive amplitude of one or more first balancing dithers. It has been found that controlling the amplitude provides an effective way of adjusting the force applied on the scanner body by the balancing means. Thus, the first force balancing means can be used to counteract the resultant force of the drive dithers over a wide range, even when the drive amplitude of the cantilever is changed, for example, during a surface probing operation or during subsequent operations.

[0047] In some embodiments, the z position motion stage includes a controller for driving the balance dither, preferably a single controller for driving the driving dither and any balancing dither. Alternatively, the dither may be controlled by a separate controller or controller of the scanning probe microscopy system 100.

[0048] In a preferred embodiment, as shown for example in Figure 2B, the first force balancing means 60 is positioned from the static or neutral center N at a distance d2 that corresponds to the distance to the static or neutral center of the drive dither 30. Preferably, the drive dither and first force balancing means 60 are positioned approximately equidistant from the static or neutral center N.

[0049] In other or further preferred embodiments, for example as shown in Figures 2B and 2C, the first force balancing means is oriented mirror symmetrically with respect to the driven dither or probe mount across the rest or neutral center of the z position motion stage. Preferably, a first balancing dither 61 is provided under an angle α2 that matches the mounting angle α1 of the driven dither 30, for example by corresponding mounts 35 and 65 as shown.

[0050] It has been found that orienting the first force balancing means, and in particular the first balancing dither 61, in a mirror symmetric manner with respect to the drive dither across the rest or neutral centre of the z position motion stage at least partially cancels resultant forces applied to the scanner body in both lateral and longitudinal directions.

[0051] In some embodiments, as shown for example in FIG. 2C, the force balancing means 60 comprises a mount 62 for holding a balancing load. The mount 62 allows the user to adjust the mass displaced by the balancing dither. Adjusting the mass can be particularly useful as an additional or alternative means for adjusting the induced force exerted on the scanner body by the first force balancing means. For example, the mount can be configured to hold a mass corresponding to the mass of the probe tip 50 to be used. Thus, it allows the z position motion stage 1 system to be conveniently balanced even after a given probe tip has been replaced with a tip having a different mass.

[0052] 3A-3C provide schematic top views of another or further embodiment of a scanner having a force balancing means 60. In some preferred embodiments, the scanner may include a single force balancing means 60 located at a position along the first terminal end face 21 of the scanner body, as shown in FIG. 3A. As described herein, the single force balancing means and the drive dither 30 may be located approximately equidistant or mirror symmetrically with respect to the rest or neutral center N. Advantageously, the force F60 exerted on the scanner body 10 by the first force balancing means 60 can be controlled in several ways, including adjusting the drive amplitude and / or the mass displaced by the first force balancing means, to match the force F30 by the drive dither 30.

[0053] In another or further embodiment, the first force balancing means 60 comprises a plurality of separated balancing dithers distributed in an arrangement that together at least partially cancel the net resultant force F30 induced by the drive dither. In one embodiment, for example as shown in FIG. 3B, the first force balancing means 60 comprises a first balancing dither and a second balancing dither that respectively generate resultant forces F60a and F60b, which are summed to form a resultant force F60 that at least partially cancels the resultant force F30 by the drive dither. It will be understood that the first force balancing means 60 can in principle comprise any number of balancing dithers, for example 3, 5 or "n" dithers, to generate a resultant associated balancing force F60n. Advantageously, providing multiple balancing dithers can improve the balancing of the z position motion stage along multiple directions and allow mitigation of complex resonances, for example potential twisting resonances about the longitudinal axis of the scanner body. Additionally, embodiments with multiple separated balancing dithers can provide a similar effect to mitigation bending oscillation using smaller dithers compared to embodiments using a single balancing dither, thereby providing space benefit along the terminal end face of the z position motion stage, for example near edge 23.

[0054] In some embodiments, as shown, for example, in FIG. 3D, the scanner body 10 includes a central member 13 and first and second end members 11, 12 disposed across the central member 13. As shown, a first terminal end face 21 is defined by the first end member 11, as described, for example, in connection with FIG. 2A. A second end member opposite the first end member defines a second terminal end face 25 of the scanner body 10. The first and second end members 11, 12 are attached to the central member 13 by one or more spring members 15, e.g., blade springs. The central member 13 is preferably reversibly connectable to a metro frame 90 of the scanning probe microscopy system 100. Further aspects regarding the scanning probe microscopy system 100 are provided below. Central member 13 generally includes at least one large stroke actuator 14 that acts on the first end member 11 and the second end member 12 to provide translation in a direction transverse, preferably perpendicular, to first terminal end face 21. Combining drive dither and z-positioning actuators into a single stage, the z-position motion stage can be advantageous for several reasons, including compatibility of one or more motion stages with one or more scanning probe microscope systems.

[0055] The flexible connection via the spring member 15 advantageously provides the scanner body 10 with adequate compliance to accommodate displacement by the large stroke actuator 14. At the same time, it can be appreciated that the structure with the flexible connection may affect resonant modes and frequencies within the scanner body 10, such as bending or nodding resonances of the first end member 11. To mitigate such potential resonances, the scanner body 10 is provided with counterbalancing means 60 as described herein.

[0056] In another or further preferred embodiment, for example as shown in Figures 4A and 4B, the motion stage includes at least a second force balancing means 70 disposed along a second terminal end face 25 of the scanner body 10 opposite the first terminal end face 21. The provision of at least one second force balancing means 70 has been found to mitigate resonances, e.g., tension or breathing modes, of the scanner body 10 along the axial direction between the opposing end faces of the scanner body 10. Similar to the first force balancing means 60, the second force balancing means 70 includes one or more second balancing dithers 71 configured to oscillate in unison with the drive dither and the first force balancing means 60, if present.

[0057] In one embodiment, as shown in Figure 4A, the z-position motion stage comprises a drive dither 30 and a first force balancing means 60 provided along a first terminal end face 21 of the scanner body 10, e.g., along the terminal end face 21 of the first end member 11 as shown in Figure 3D, and a single second force balancing means 70 disposed along a second terminal end face 25 of the scanner body 10, e.g., along the second end member 12. The second force balancing means 70 can, in use, advantageously generate a resultant force F70 induced by the second force balancing means 70 that at least partially counters a net resultant force F30 induced by the probe and / or the first force balancing means F60 in the longitudinal direction between the first terminal end face 21 and the second terminal end face 25.

[0058] 4B, the second balancing means comprises at least two second balancing dithers 71 and 72 distributed at locations along the second terminal end face 25. Each location is preferably located on an opposite side of the drive dither 30 and the force balancing means 60, e.g., near opposing edges 26 and 27 of the second terminal end face 25. Providing at least two second balancing dithers 71 and 72 can advantageously mitigate resonant modes in the second end member 12 and / or mitigate resonant modes throughout the scanner body 10 in both the lateral and longitudinal directions.

[0059] It will be appreciated that a z-position motion stage in accordance with the present disclosure may be advantageously used in a scanning probe microscope system, such as the scanning probe microscope system shown in FIG. 3D.

[0060] In one embodiment, the scanning probe microscopy system 100 comprises a z-position motion stage 1, preferably a z-position motion stage 1 as disclosed herein, more preferably a z-position motion stage as described in relation to Figure 3D. Typically, the z-position motion stage comprises a mount 80 for reversibly associating the z-position motion stage with the scanning probe microscopy system 100, for example with a metro frame 90 of the scanning probe microscopy system 100. Alternatively, the z-position motion stage 1 may be an integral part of the scanning probe microscopy system 100.

[0061] Preferably, the scanning probe microscope system comprises coarse translation means 81 which, in use, acts on the z-position motion stage 1, preferably via a mount, to position the motion stage 1 opposite a region of interest along the surface of a substrate to be probed. Alternatively or additionally, the scanning probe microscope system 100 may comprise coarse translation means which acts only on a holder or sample stage for holding a sample to be probed and / or one or more substrates to be probed.

[0062] In some embodiments, the scanning probe microscope system 100 includes a detector, e.g., an optical position detector (e.g., an interferometer system) or a strain gauge system, for detecting one or more of bending, tension and / or other resonances of the scanner body, e.g., by detecting lateral and / or longitudinal displacement of a surface of the scanner body, e.g., a first terminal end face of the scanner body.

[0063] Still further or other aspects of the present disclosure relate to a method of using or operating the z position motion or scanning probe microscopy system 100 disclosed herein. The method includes operating 203 a first force balancing means and / or a further force balancing means in harmony with the drive dither at least while the drive dither is being driven, in particular while the drive dither is being driven at a frequency associated with a resonant mode of the scanner body. Driving the counter of the balancing means acts on the resultant force exerted by the drive dither on the scanner body, thus mitigating the potential response of the scanner. In some embodiments, the balancing means is switched off while the drive dither is being operated at a frequency that does not overlap with the natural frequency of the scanner body. However, it will be understood that this is not a prerequisite. The one or more balancing means can be operated in harmony with the drive dither even when the drive dither is operated at a frequency that does not overlap with the natural frequency of the scanner body.

[0064] In one embodiment, as shown in Figure 4C, the method further comprises associating 201 a probe to the z-position motion stage. In another or further embodiment, the method comprises driving 202 a dither, typically at a target drive frequency associated with a target resonant mode of the cantilever of the probe; and operating 203 the first force balancing means in unison with the drive dither, at least while the drive dither is driven at a frequency associated with a resonant mode of the scanner body. As disclosed herein, driving the drive dither and the first and further force balancing means in unison advantageously reduces noise and parasitic forces, for example during probing a substrate region of interest, due to undesired translations from a resonant mode of the scanner body.

[0065] In some embodiments, the method includes sweeping the drive dither over a sweeping range to detect a target resonant frequency range of the cantilever and a corresponding target operating oscillation frequency of the drive dither. Alternatively, the target resonant frequency may be determined using other known means, e.g., thermal. In other or further embodiments, the method includes sweeping the drive dither to detect a resonant mode of the scanner body within the sweeping range, e.g., using optical interferometry. Advantageously, operation of the force balancing means can be conditioned on the occurrence of a resonant mode in a levant driving range. In a preferred embodiment, the method includes comparing the detected resonant frequencies of the cantilever and the scanner body, and driving one or more of the first and second force balancing means when the target resonant range overlaps with a detected mode of the scanner body. Alternatively, operation of the force balancing means can be conditioned on the overlap of a target driving frequency with a predetermined resonant mode of the scanner body. In a preferred embodiment, the method further comprises determining whether the target drive frequency is within a range associated with one or more bending resonance modes of the scanner body and with a longitudinal resonance mode of the scanner body. Advantageously, operating the first force balancing means and / or the further force balancing means may be operated only if the drive frequency is within the range. This limits operation of the balancing means to conditions where the effect of the net resultant force induced by the drive dither is most significant.

[0066] It will be understood that, although features are described herein as part of the same or separate embodiments for clarity and concise description, the scope of the invention may include embodiments having all or some combination of the described features. Of course, it will be understood that any one of the above embodiments or processes may be combined with one or more other embodiments or processes to provide still further improvements in finding and matching design and advantages.

[0067] In interpreting the appended claims, it should be understood that the word "comprising" does not exclude the presence of other elements or acts than those recited in a given claim; the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements, and any reference signs in the claims do not limit their scope; several "means" may be represented by one or more of the same or different items or implemented structures or functions. Any of the disclosed devices or parts thereof may be combined together or separated into further parts, unless otherwise specified. When one claim refers to another claim, this may indicate synergistic advantages achieved by a combination of their individual features. However, the mere fact that certain means are recited in mutually different claims does not indicate that a combination of these means cannot also be advantageously used. Thus, the present embodiments may include all operative combinations of the multiple claims, where in principle any preceding claim may be referred to, unless each claim is clearly excluded by the context.

Claims

1. 1. A z-position motion stage for use in a scanning probe microscope system, comprising: a scanner body; and a drive dither disposed along a first terminal end face of the scanner body proximate the first end of the scanner body, the drive dither configured to provide a first vibration for driving a cantilever of a probe associated with the drive dither in an oscillatory motion; It is equipped with wherein the stage further comprises at least a first force balancing means acting on the scanner body at a location opposite the drive dither across a rest or neutral center of the motion stage, the rest or neutral center of the motion stage being a neutral bending plane (N) along the longitudinal axis of the scanner body, and wherein the force balancing means comprises at least a first balancing dither configured to oscillate in unison with the drive dither. The z-position motion stage.

2. 2. The motion stage of claim 1, wherein said first force balancing means is positioned relative to said drive dither such that, in use, a net resultant force induced in a direction along said first terminal end face at least partially cancels a net resultant force induced by said drive dither.

3. 2. The motion stage of claim 1, wherein said first force balancing means is disposed along said first terminal end face of said scanner body near a second end of said scanner body.

4. 2. The motion stage of claim 1, wherein said first force balancing means comprises a plurality of separated balancing dithers distributed in an arrangement that collectively at least partially cancels said net resultant force induced by said drive dithers.

5. 2. The motion stage of claim 1, wherein said first force balancing means is oriented mirror-symmetrically with respect to said drive dither across said rest or neutral center.

6. 10. The motion stage of claim 1, further comprising second force balancing means disposed along a second terminal end face of the scanner body opposite the first terminal end face, wherein the second force balancing means comprises one or more second balancing dithers configured to oscillate in unison with the drive dithers.

7. 7. The motion stage of claim 6, wherein said second force balancing means comprises at least two second balancing dithers distributed at positions along said second terminal end face opposite said drive dither and said force balancing means.

8. 2. The motion stage of claim 1, wherein the scanner body comprises a first end member defining the first terminal end face and a second end member defining the second terminal end face, wherein the first end member and the second end member are disposed across opposite ends of a central member that is reversibly connectable to a metro frame of the scanning probe microscope system, and wherein the central member comprises a large stroke actuator acting on the first end member and the second end member to provide translation in a direction transverse to the first terminal end face, whereby each of the first end member and the second end member is attached to the central member by one or more spring members.

9. A motion stage as described in claim 1, wherein the scanner body comprises a first end member defining the first terminal end face and a second end member defining the second terminal end face, wherein the first end member and the second end member are arranged across opposite ends of a central member that is reversibly connectable to a metro frame of the scanning probe microscope system, and wherein the central member comprises large-stroke actuators acting on the first end member and the second end member to provide translation in a direction perpendicular to the first terminal end face, whereby each of the first end member and the second end member is attached to the central member by one or more spring members.

10. 2. The motion stage of claim 1, wherein the first force balancing means and / or the second force balancing means comprises a mount for holding a balancing load.

11. 10. A scanning probe microscope system comprising a z-position motion stage according to any one of claims 1 to 9 and a mount for reversibly associating the z-position motion stage with a metro frame of the scanning probe microscope system.

12. 11. A scanning probe microscope system according to claim 10, comprising coarse translation means which, in use, acts on the z-position motion stage to position the motion stage opposite a region of interest along the surface of a substrate to be probed.

13. A scanning probe microscope system as described in claim 10, comprising coarse translation means which, in use, acts on the z-position motion stage via the mount to position the motion stage opposite a region of interest along the surface of a substrate to be probed.

14. 11. The scanning probe microscope system of claim 10, further comprising a detector for detecting one or more of a bending resonance of the scanner body and a longitudinal resonance of the scanner body.

15. A method of operating a scanning probe microscope system according to claim 11 or a z-position motion stage according to any one of claims 1 to 10, comprising the steps of: associating a probe with said z-position motion stage; Driving the drive dither at a target drive frequency associated with a target resonant mode of the probe cantilever; and operating the first force balancing means at least when the drive dither is driven at a frequency associated with a resonant mode of the scanner body; The method comprising:

16. operating the second force balancing means at least when the drive dither is driven at a frequency associated with a resonant mode of the scanner body.

16. The method of claim 15, further comprising:

17. 16. The method of claim 15, further comprising determining whether the target drive frequency is within a range associated with one or more of a bending resonance mode of the scanner body and a longitudinal resonance mode of the scanner body.

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