Improved positioning apparatus and method

Abstract

The present invention relates to a positioning device (1) for inspecting wafers and chips, comprising a rotor (2) and a stator (3), the rotor including a rotor axis (A) defining a height direction, wherein the rotor (2) is engaged with the stator by a bearing (4) configured to allow rotational movement of the rotor (2) about the rotor axis and axial movement along the rotor axis, wherein the device (1) includes rotary (RT) actuators (5A, 5B) configured to induce rotational movement on the rotor, wherein the rotary actuators (5A, 5B) include a stationary actuator component (5A) attached to the stator and a movable actuator component (5B) attached to the rotor and configured to interact with the stationary actuator component to induce rotational movement of the rotor relative to the stator, wherein the device (1) includes linear height actuators (6A, 6B) disposed along the rotor axis, wherein the actuators are configured to... The device is configured to induce linear motion of the rotor in the height direction, wherein the linear height actuator (6A, 6B) includes a stationary linear component (6A) attached to the stator and a moving linear component (6B) attached to the rotor, the moving linear component being configured to interact with the stationary linear component to induce axial motion of the rotor relative to the stator, wherein the device includes an RT position measuring component (9) configured to acquire the angular position of the rotor relative to the stator and a Z position measuring component (10) configured to acquire the height position of the rotor relative to the stator, wherein the device includes a processor configured to: - receive a measured height value of the height position acquired by the Z position measuring component; - compare the measured height value with a predefined target height value; and - control the linear height actuator to compensate for the difference between the measured height value and the target height value, thereby controlling the height position of the rotor.

Description

Technical Field

[0001] This invention relates to the field of positioning devices and methods for surface irregularities, particularly for inspecting wafers and chips, such as semiconductor wafers. Background Technology

[0002] Semiconductor wafers are typically very thin, circular objects designed to house structures such as chips, transistors, and logic gates. In many applications, it is necessary to inspect the surface of such wafers and / or the structures disposed on or within them for defects.

[0003] Wafer inspection has been largely neglected in much of the semiconductor industry, but it is becoming increasingly critical due to the need for earlier defect detection in the manufacturing process. As critical dimensions shrink, detecting these defects becomes more difficult. It is more challenging to actually detect smaller defects on bare wafers, requiring more data processing and greater pressure to process and inspect faster. While solutions exist for all these problems, each comes with a cost. Generally, wafer inspection falls into two categories: patterned and unpatterned. Simply put, unpatterned wafer inspection involves searching for defects on unprocessed or bare silicon wafers. This invention specifically relates to unpatterned wafer inspection, but can also be applied to patterned wafer inspection.

[0004] One way to inspect wafers, including patterned and unpatterned wafers, is to shine light, preferably a laser, onto the wafer surface and observe the resulting reflected light. Deviations in the reflected light from expected properties, such as with respect to angle, amplitude, diffraction, interference, etc., provide information about defects on the wafer surface. For this type of optical inspection to be possible, the wafer needs to be positioned very precisely to ensure that the deviation is caused by surface defects, not by inaccuracies in the wafer positioning system. This is particularly important when the beam and / or photodetector have a small focal area, i.e., the beam is focused to a predetermined distance with very small error and / or the photodetector is similarly focused to such a predetermined distance with very small error. Rather than changing the focal area of ​​the beam and / or photodetector, it may be more preferable to change the position of the surface being inspected.

[0005] The objective of this invention is to provide a precise positioning device that allows for accurate positioning of wafers or chips. A preferred application of this invention is the detection of defects on wafers or chips with high throughput and reasonable cost.

[0006] Patent document US6,700,249B1 discloses a direct-drive vertical lifting and rotating table, which includes an annular z-axis housing with a central opening, a z-axis rotor assembly supported in the central opening of the z-axis housing, a motor located between the z-axis housing and the z-axis rotor, an annular θ-axis housing with a central opening, an θ-axis rotor assembly supported in the central opening of the θ-axis housing, and a motor located between the θ-axis housing and the θ-axis rotor.

[0007] Patent document US10,481,102B2 discloses a multi-axis positioning system that can be used in conjunction with an inspection system and includes multiple position sensors corresponding to multiple axes and multiple motors also corresponding to multiple axes to provide high precision, high load capacity, and long stroke for controllable movement of an object in up to six degrees of freedom. Some embodiments of this multi-axis positioning system may include an XY platform assembly, a base plate assembly coupled to the XY platform assembly, a top plate assembly coupled to the base plate assembly, and a chuck fixed to the top plate assembly, wherein the multiple position sensors are configured to measure displacement between the XY platform assembly and the top plate assembly.

[0008] This invention aims to improve upon existing systems and methods by providing a positioning device that allows for precise wafer inspection at high rotational speeds up to 100 Hz (6000 rpm). It should be noted that the wafer is preferably capable of rotating continuously for a large number of cycles; that is, the wafer rotation is not necessarily limited to 360° or less. However, the invention can also be used in processes where the rotation axis remains stationary, for example, during manufacturing or metrology processes applied to a substrate; such as wafers, dies, or chips. In these applications, the positioning device can be used to reposition the substrate, for example, between manufacturing or metrology process steps. Summary of the Invention

[0009] This invention relates to the positioning device as claimed in claim 1, the positioning method as claimed in claim 13, and the wafer inspection method as claimed in claim 15. Further embodiments of the invention are described in the other claims and in this specification.

[0010] Ideally, wafer inspection, particularly the inspection of unpatterned wafers, is performed by rotating the wafer around its axis at the highest possible frequency to reduce processing time. As mentioned above, one way to inspect wafers, including patterned and unpatterned wafers, is to illuminate the wafer surface, preferably with a laser, and observe the resulting reflected light. Deviations in the reflected light relative to expected properties, such as with respect to angle, amplitude, diffraction, interference, etc., provide information about defects on the wafer surface. The rotation of the wafer can be combined with the radial movement of the laser beam, i.e., the movement of the laser beam away from and / or toward the wafer axis. The combination of rotational and radial movements allows scanning substantially the entire surface of the wafer.

[0011] However, if the rotation axis of the positioning device is not perfectly parallel to the wafer axis, i.e., if the wafer is tilted, the wafer will oscillate at a frequency substantially the same as the positioning device's frequency. This oscillation needs to be compensated for by rapidly adjusting the wafer's height, where height refers to its position along the rotation axis. Other in-plane positioning deviations of the wafer can also be compensated for, for example: - A wafer with a saddle shape; - Wafers with predetermined thickness differences at different locations; - etc.

[0012] Because the bearings between the rotor and stator allow for rotational and axial movement of the rotor relative to the stator, and because of the decoupling of the rotary actuator and the linear actuator—both of which are configured to cause corresponding movement of the rotor relative to the stator—this invention enables very rapid changes in rotor height. Note that prior art methods for decoupling motion typically involve a first stage and a second stage, with the first stage including a first moving part on a stationary component and the second stage including a second moving part on the first moving part. This clearly contrasts with this invention, in which both the linear and rotary actuators each have a stationary component attached to the stator that interacts with a moving part attached to the rotor to cause corresponding movement of the rotor relative to the stator. Attached Figure Description

[0013] Figure 1 A positioning device according to the present invention is shown.

[0014] Figure 2 A wafer inspection method according to the present invention is shown.

[0015] Figure 3 A partially enlarged view of an embodiment of a positioning device including an air bearing according to the present invention is shown.

[0016] Figure 4 An embodiment of the present invention, in which a rotor stage pipe is provided in the rotor, is shown. Detailed Implementation

[0017] The invention will now be discussed further with reference to the accompanying drawings.

[0018] As described above, the present invention relates to a positioning device (1) for inspecting wafers and chips, comprising a rotor (2) and a stator (3), the rotor including a rotor axis (A) defining a height direction, wherein the rotor (2) engages the stator via a bearing (4) configured to allow rotational movement of the rotor (2) about the rotor axis and axial movement along the rotor axis. Preferably, the bearing is an air bearing, such as an air bearing bushing. In other embodiments, the bearing is or includes a ball bearing, preferably a ball bushing. Note that air bearings are often preferred because they: - This results in lower friction, leading to more stable rotational speeds and less heat generation; - Less prone to errors, and - No lubrication is required, resulting in a cleaner environment, which is highly preferred when the equipment is used in a cleanroom environment.

[0019] The device (1) includes a rotary (RT) actuator (5A, 5B) configured to induce rotational motion on a rotor. The rotation is preferably continuous and can continue substantially indefinitely, i.e., the rotational motion is preferably not limited to a specific angular range or a finite number of complete rotations.

[0020] The rotary actuators (5A, 5B) include a stationary actuator component (5A) and a movable actuator component (5B). The stationary actuator component is attached to the stator, and the movable actuator component is attached to the rotor and configured to interact with the stationary actuator component to cause rotational motion of the rotor relative to the stator. Preferably, the rotary actuators (5A, 5B) are electromechanical actuators, including the stationary actuator component (5A) and the movable actuator component (5B). Here, preferably, the stationary actuator component and the movable actuator component include a magnet, an electromagnet, an electromagnetic coil, a permanent magnet, a magnetic material, or any combination thereof. More preferably, the stationary actuator component includes an electromagnetic coil, and the movable actuator component includes a permanent magnet or an electromagnet, wherein the electromagnetic coil of the stationary actuator component is configured to induce a magnetic field at the location of the permanent magnet or electromagnet of the movable actuator component, thereby generating torque on the rotor.

[0021] The device (1) includes linear height actuators (6A, 6B) disposed along the rotor axis and configured to induce linear motion of the rotor in the height direction. The linear height actuators (6A, 6B) include a stationary linear component (6A) attached to the stator and a movable linear component (6B) attached to the rotor, the movable linear component being configured to interact with the stationary linear component to induce axial motion of the rotor relative to the stator. In some embodiments, the device includes one linear height actuator; in other embodiments, the device includes multiple linear height actuators, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, or more. Preferably, the stationary linear component and the movable linear component include magnets, electromagnets, electromagnetic coils, permanent magnets, magnetic materials, or any combination thereof. More preferably, the stationary linear component includes an electromagnetic coil substantially surrounding the rotor axis and is preferably at least partially inserted into a cavity of the movable linear component, which includes a permanent magnet or an electromagnet. More preferably, the linear height actuator is a voice coil actuator or includes a voice coil actuator.

[0022] In a preferred embodiment, the rotary actuator and the linear height actuator are separate. In other preferred embodiments, the rotary actuator and the linear actuator are combined into a single 2D actuator configured to actuate a combination of rotary and axial motion. Here, the stationary actuator component and the stationary linear component can preferably also be combined into a stationary 2D actuator component attached to the stator, and / or the moving actuator component and the moving linear actuator component can preferably be combined into a moving 2D actuator component attached to the rotor.

[0023] The device includes an RT position measuring component (9) configured to acquire the angular position of the rotor relative to the stator, and a Z position measuring component (10) configured to acquire the height position of the rotor relative to the stator. Preferably, the RT position measuring component is an RT encoder, and / or the Z position measuring component is a Z encoder. In some embodiments, the RT encoder and the Z encoder are combined into a 2D encoder. In other embodiments, the RT encoder and the Z encoder are substantially separate.

[0024] The RT position measuring component, preferably an RT encoder, and the Z position measuring component, preferably a Z encoder, can serve multiple roles. The encoder is configured to acquire position information of the rotor relative to the stator, including the rotor's rotation angle and height. This position information can be used to control the rotor, for example, by adjusting the rotor's height using a linear height actuator, or by decreasing or increasing the rotor's angular velocity according to a preset trajectory using a rotary actuator. Therefore, phenomena such as tilting, saddle-shaped deformation, and thickness variations can be quickly and accurately compensated for, even at high speeds, such as up to 100Hz. This is achieved by also achieving a motion bandwidth of approximately 100Hz in the height direction, particularly due to the decoupling of rotational and axial motions and the fact that the actuators are supported on the stator, meaning the rotor's mass can remain relatively small, thus allowing for rapid movement. Furthermore, position information may be needed in the case of wafer inspection to identify any irregularities. For example, the position information can be combined with observations indicating irregularities made by the inspection method. This combination can then be used in further inspections to examine the location of irregularities in more detail. Therefore, this can help optimize the wafer manufacturing process.

[0025] In one embodiment, the Z-position measuring component is a Z encoder, which preferably includes a set of circumferential scale marks (21) disposed along the height direction on the rotor circumferential surface, and a Z sensor (22) configured to read the height position of the circumferential scale marks, the Z sensor being attached to the stator. The set of circumferential scale marks may include grooves and / or printed lines on the circumferential surface. Typically, the set of circumferential scale marks includes grooves surrounding the rotor circumferential surface, these grooves preferably being equidistant along the height direction. Thus, they form a diffraction grating. In this embodiment, preferably, the Z sensor includes a light beam, preferably a substantially monochromatic light beam, such as an LED beam or a laser beam, configured to be directed to the circumferential scale marks, and the Z sensor includes a photodetector configured to receive reflected light from the rotor circumferential surface and the circumferential scale marks disposed thereon. From the reflected light, the Z sensor, or a processing device functionally cooperating with the Z sensor, can be configured to acquire a value of the rotor height position. Note that the Z sensor being attached to the stator indicates that the Z sensor has a fixed position relative to the stator at least during equipment operation. The attachment here can be direct or indirect; that is, the Z-sensor can be mounted on the stator, or it can be mounted on another object, such as an experimental platform on which the stator is also mounted. In the embodiments, the Z-encoder is an incremental encoder or an absolute encoder. In an incremental encoder, markers, such as lines, are equidistant, and position is typically inferred by counting the number of markers. In an absolute encoder, position information is encoded in markers, such as grooves forming an coded grating.

[0026] In an embodiment, the Z-position measuring component includes a confocal sensor, a laser interferometer, a capacitance probe, an inductive sensor, an inductive encoder, a laser sensor, a gap measuring sensor configured to measure the gap between a substrate and a fixed reference, or any combination thereof, including a combination comprising the aforementioned set of circumferential scale marks and a Z-sensor. The Z-position measuring component can thus provide height position feedback.

[0027] In one embodiment, the RT position measuring component is an RT encoder or includes an RT encoder, preferably comprising a set of axial scale marks (23) disposed circumferentially on a rotor circumferential surface, and an RT sensor (24) configured to read the angular position of the axial scale marks (23), the RT sensor being attached to the stator. The set of axial scale marks may include grooves and / or printed lines on the circumferential surface. Typically, the set of axial scale marks includes grooves surrounding the rotor circumferential surface, these grooves preferably being equidistant in the angular direction. Thus, they form a diffraction grating. In this embodiment, preferably, the RT sensor includes a light beam, preferably a substantially monochromatic light beam, such as an LED beam or a laser beam, configured to be directed to the axial scale marks, and the RT sensor includes a photodetector configured to receive reflected light from the rotor circumferential surface and the axial scale marks disposed thereon. From the reflected light, the RT sensor, or a processing device functionally cooperating with the RT sensor, can be configured to acquire a value of the rotor angular position. Note that the RT sensor being attached to the stator indicates that the RT sensor has a fixed position relative to the stator at least during equipment operation. The attachment here can be direct or indirect; that is, the RT sensor can be mounted on the stator, or the RT sensor can be mounted on another object, such as an experimental platform on which the stator is also mounted. In embodiments, the RT encoder is an incremental encoder or an absolute encoder. In an incremental encoder, markers, such as lines, are equidistant, and position is typically inferred by counting the number of markers. In an absolute encoder, position information is encoded in markers, such as grooves forming an coded grating.

[0028] In an embodiment, the RT position measurement component includes a confocal sensor, a laser interferometer, a capacitance probe, an inductive sensor, an inductive encoder, a laser sensor, a gap measurement sensor configured to measure the gap between a substrate and a fixed reference, or any combination thereof, including a combination comprising the aforementioned set of axial scale marks and the RT sensor. The RT position measurement component can thus provide angular position feedback.

[0029] The device includes a processor configured as follows: - Receive the measured height value of the height position obtained by the Z position measuring component, preferably the Z position measuring component includes a Z encoder or a Z encoder; - Compare the measured height value with a predefined target height value, and - Control the linear height actuator to compensate for the difference between the measured height value and the target height value, thereby controlling the height position of the rotor.

[0030] Therefore, the height of the rotor can be actively controlled. Preferably, the processor includes a PID height controller configured to control the rotor height.

[0031] The target height value can be a dynamic input from, for example, a gap sensor that measures the gap between the optics and the substrate, such as a wafer, die, or chip.

[0032] In one embodiment, the processor is configured as follows: - Receive the measured angle value of the angular position obtained by the RT position measuring component, preferably wherein the RT position measuring component is an RT encoder or includes an RT encoder; - Compare the measured angle value with a predefined target angle value, and - Control the rotary actuator to compensate for the difference between the measured angle value and the target angle value, thereby controlling the angular position and / or speed of the rotor.

[0033] Therefore, the angular position and / or angular velocity of the rotor can be actively controlled. Preferably, the processor includes a PID angle controller configured to control the angular position and / or angular velocity of the rotor.

[0034] As described above, the bearing is preferably an air bearing. More preferably, the bearing is an air bearing comprising a circumferential slit between the inner surface (15) of the stator and the outer surface (11) of the rotor. Alternatively, the bearing is an air bearing comprising a circumferential slit between the outer surface of the stator and the inner surface of the rotor. Note that the former alternative refers to an embodiment in which the rotor is located inside the stator, and the latter alternative refers to an embodiment in which the rotor is located outside the stator. It should be noted that the former alternative is discussed in the embodiments disclosed in this patent application, but any embodiment discussed in the manner of the former alternative also corresponds to the latter embodiment, wherein "inner" and "outer" when referring to the stator or rotor surface are interchanged.

[0035] In a preferred embodiment, the air bearing includes one or more primary porous sections, one or more primary throttling orifices and / or one or more primary feed orifices (25), which are disposed in the stator and configured to allow pressurized air to be supplied to the circumferential slit.

[0036] In a preferred embodiment, the air bearing includes a set of primary radial conduits (12, 13) disposed in the stator, each primary radial conduit extending from the outer surface (14) of the stator to the inner surface (15) of the stator, preferably configured to allow fluid, preferably air, to escape from the circumferential slit to the external atmosphere. These primary radial conduits allow the circumferential slit of the air bearing and the pressurized fluid therein to be decoupled from the presence of other optional features of the invention, such as circumferential rings and / or pedestal conduits.

[0037] In a preferred embodiment, the air bearing includes one or more circumferential grooves (16) disposed in the outer casing surface (15) of the rotor or the inner casing of the stator, the grooves being configured to receive pressurized fluid from the circumferential slits and / or circumferential rings and to allow pressurized air to be discharged into the atmosphere, for example via a primary radial conduit, thereby stabilizing the rotor during rotation, for example by preventing undesirable radial and tilting movements of the rotor during pressure changes of the pressurized fluid supplied to, for example, the air bearing or the circumferential ring.

[0038] In a preferred embodiment, the device includes a circumferential edge (17) disposed in the outer surface (15) of the rotor and a corresponding circumferential edge (18) disposed in the inner surface (15) of the stator, wherein the circumferential ring (27) is defined by the following: - Rotor outer casing surface (15). - A circumferential edge (17) is provided on the outer surface (15) of the rotor. - The inner surface of the stator (15), and - A circumferential edge (18) is provided in the inner surface (15) of the stator.

[0039] Here, the device preferably includes one or more secondary porous sections, one or more secondary throttling orifices and / or one or more secondary feed orifices (35), which are disposed in the stator and configured to allow pressurized air to be supplied to the circumferential ring (27).

[0040] The device preferably also includes a set of secondary radial conduits (19, 20) disposed in the stator, each secondary radial conduit extending from the outer surface (14) of the stator to the inner surface (15) of the stator, located on the opposite side of the circumferential ring (27) compared to the primary radial conduits, and preferably configured to allow fluid, preferably air, to escape from the circumferential slits and / or the circumferential ring to the outside. Preferably, the device is configured to provide pressurized fluid to the circumferential ring at pressures selected to compensate for the mass of the rotor and / or the substrate fixed to the rotor.

[0041] The circumferential ring can act as a mass compensator and / or provide axial force to the rotor. Fluid pressure supplied to one or more secondary porous sections, one or more primary throttling orifices, and / or one or more primary feed orifices (35) allows for the arrangement of the rotor height or the axial force applied thereto. This is a low-speed and precise fitting mechanism, primarily used to compensate for different substrates being tested, which may have different masses, or to press the substrate against another surface. Furthermore, the fluid pressure can also be used to arrange the average height of the rotor relative to the stator during rotor rotation. This is particularly useful for ensuring that a Z-position measuring component, preferably including a Z encoder or gap measuring sensor, can accurately and correctly measure the rotor's height position. For example, if a gap measuring sensor is used, i.e., a sensor that measures the axial gap between the substrate and an external reference, such a sensor can have a high resolution, higher than, for example, a Z encoder, but may only have such resolution within a small gap measurement range. The fluid pressure supplied to the circumferential ring can be controlled to ensure that the substrate is displaced in the axial direction, for example, raised or lowered within the gap measurement range.

[0042] In embodiments, the device includes multiple air bearings. For example, the device includes a second air bearing comprising a second circumferential slit (34) between the stator and rotor, optionally provided with one or more porous sections, one or more throttling orifices, and / or one or more feed orifices (28), which are disposed in the stator and configured to allow pressurized air to be supplied to the second circumferential slit (34). In cases with more air bearings, each air bearing preferably includes a circumferential slit between the stator and rotor, optionally provided with one or more porous sections, one or more throttling orifices, and / or one or more feed orifices, which are disposed in the stator and configured to allow pressurized air to be supplied to the circumferential slit. Preferably, in the case of having multiple air bearings, such as 2, 3, 4, 5, 6, 7, 8, 9, 10 or more air bearings, radial conduits are provided between axially adjacent air bearings and / or between axially adjacent circumferential rings for discharging pressurized air from said adjacent circumferential slits and / or circumferential rings. Note that this allows for modular construction of the device, particularly where a larger device is desired, at least in the axial direction.

[0043] In a preferred embodiment, the rotor includes a platform (6), preferably a chuck. A chuck is a plate that securely mounts a wafer during wafer handling applications. In many cases, the chuck has circular vacuum grooves or a pattern of micropores that allows the chuck to hold the wafer in place. Lifting pins mounted in the chuck assembly allow the plate to automatically raise and lower the wafer throughout the wafer manufacturing and testing process.

[0044] In one embodiment, the linear height actuator includes a mezzanine channel extending substantially along the height direction from the stator to the rotor, and a rotary joint configured to seal the mezzanine channel so as to allow fluid to flow between the rotor and the stator without leakage. This is particularly preferred if the rotor includes a chuck. Here, a vacuum can be supplied to the chuck via the mezzanine channel.

[0045] Preferably, the stage conduit includes a stator inlet (7) in the stator and a rotor inlet (8) in the rotor. The stage conduit allows at least a partial vacuum to be provided to the stage. In a preferred embodiment, the device includes a rotary joint (9) at the stator inlet (7) and / or the rotor inlet (8), which is configured to seal the stage conduit to allow fluid to flow between the rotor and the stator without leakage. For this purpose, the rotary joint can be attached to the stator with a stationary rotary joint component and to the rotor with a movable rotary joint component. This is particularly useful if the stage includes a wafer chuck that holds the wafer to the top of the chuck by relying on internal negative pressure. In a very preferred embodiment, the linear height actuator is substantially hollow.

[0046] Alternatively or additionally, the rotor includes one or more rotor platform pipes, each comprising an axial portion (41) extending from an axial end of the rotor (table-mounted or potentially mounted at an axial end) into a portion of the rotor (2), and the rotor platform pipes comprising a radial portion (42) fluidly connecting the axial portion (41) to a circumferential groove (43) disposed in an outer casing surface of the rotor (2) and / or an inner casing surface of the stator (3), wherein the stator (3) includes one or more stator platform pipes (44) fluidly connected to the circumferential groove. The stator platform pipes (44) may be connected to, for example, a pump for supplying pressurized fluid or vacuum to components of the rotor. Thus, vacuum may be supplied, for example, to a chuck via the stator platform pipes, the circumferential groove, and the rotor platform pipes.

[0047] The present invention also relates to a positioning method for positioning a substantially flat substrate, preferably a wafer, die, or chip, comprising the following steps: - Provide a rotor and a stator, wherein the rotor is engaged with the stator by a bearing configured to allow rotational movement of the rotor (2) about a rotor axis and axial movement along the rotor axis; - Fix the substrate onto the rotor; - To rotate the rotor together with the base plate about the rotor axis, wherein the rotor rotates relative to the stator; - Obtain the angular position of the rotor relative to the stator, and obtain the height position of the rotor relative to the stator; - Compare the measured altitude value at the altitude position with the predefined target altitude value, and - Control the linear height actuator to compensate for the difference between the measured height value and the target height value, thereby controlling the height position of the rotor relative to the stator.

[0048] The positioning method is preferably performed using the positioning device according to the present invention.

[0049] In one embodiment, the method includes the step of providing a target height value, preferably via an external sensor and / or an external processor.

[0050] The present invention also relates to a wafer inspection method, comprising performing a positioning method according to the invention, wherein the substrate is a wafer, the wafer inspection method further comprising the following steps: - A laser that is focused and guided onto the wafer during wafer rotation; - Measure the reflected laser light from the wafer surface, and - The measured reflected laser light is compared with a predefined expected reflection pattern, and deviations from the pattern indicate irregularities on the wafer surface.

[0051] Chip inspection methods in Figure 2 As shown in the image.

Claims

1. A positioning device (1) for inspecting wafers and chips, comprising a rotor (2) and a stator (3), the rotor including a rotor axis (A) defining a height direction, wherein the rotor (2) is engaged with the stator via a bearing (4) configured to allow rotational movement of the rotor (2) about the rotor axis and axial movement along the rotor axis. The device (1) includes rotary (RT) actuators (5A, 5B) configured to induce rotational motion on the rotor. The rotary actuators (5A, 5B) include a stationary actuator component (5A) and a movable actuator component (5B). The stationary actuator component is attached to the stator, and the movable actuator component is attached to the rotor and configured to interact with the stationary actuator component to cause rotational motion of the rotor relative to the stator. The device (1) includes linear height actuators (6A, 6B) disposed along the rotor axis, configured to induce linear movement of the rotor in the height direction. The linear height actuators (6A, 6B) include a stationary linear component (6A) attached to the stator and a movable linear component (6B) attached to the rotor, the movable linear component being configured to interact with the stationary linear component to cause axial movement of the rotor relative to the stator. The device includes an RT position measuring component (9) configured to acquire the angular position of the rotor relative to the stator, and a Z position measuring component (10) configured to acquire the height position of the rotor relative to the stator. The device includes a processor configured to operate as follows: - Receive the measured height value of the height position obtained by the Z position measuring component; - Compare the measured height value with a predefined target height value, and - Control the linear height actuator to compensate for the difference between the measured height value and the target height value, thereby controlling the height position of the rotor.

2. The positioning device according to claim 1, characterized in that, The bearing is an air bearing, which includes a circumferential slit between the inner surface (15) of the stator and the outer cover surface (11) of the rotor.

3. The positioning device according to claim 2, characterized in that, The air bearing includes one or more primary porous sections, one or more primary throttling orifices and / or one or more primary feed orifices (25) disposed in the stator, and the air bearing is configured to allow pressurized air to be supplied to the circumferential slit, and / or wherein the air bearing includes a set of primary radial conduits (12, 13) disposed in the stator, each primary radial conduit extending from the outer surface (14) of the stator to the inner surface (15) of the stator, preferably configured to allow fluid, preferably air, to escape from the circumferential slit to the external atmosphere.

4. The positioning device according to any one of claims 2 or 3, characterized in that, The air bearing includes one or more circumferential grooves (16) disposed in the outer casing surface (15) of the rotor or the inner casing of the stator, the grooves being configured to receive pressurized fluid from the circumferential slits and / or circumferential rings and to allow pressurized air, preferably, to be discharged into the atmosphere via the primary radial channel.

5. The positioning device according to any one of claims 2 to 4, characterized in that, The device includes a circumferential edge (17) disposed in the outer casing surface (15) of the rotor, and a corresponding circumferential edge (18) disposed in the inner surface (15) of the stator, wherein the circumferential ring is defined by the following: - The outer casing surface (15) of the rotor. - The circumferential edge (17) is provided in the outer cover surface (15) of the rotor. - The inner surface of the stator (15), and - The circumferential edge (18) is provided in the inner surface (15) of the stator. The device includes one or more secondary porous sections, one or more secondary throttling orifices and / or one or more secondary feed orifices (35) disposed in the stator, and is configured to allow pressurized fluid, preferably air, to be supplied to the circumferential ring (27).

6. The positioning device according to any one of the preceding claims, characterized in that, The processor is configured as follows: - Receive the measured angle value of the angular position obtained by the RT position measuring component, preferably wherein the RT position measuring component is an RT encoder or includes an RT encoder; - Compare the measured angle value with a predefined target angle value, and - Control the rotary actuator to compensate for the difference between the measured angle value and the target angle value, thereby controlling the angular position and / or rotational speed of the rotor.

7. The positioning device according to any one of the preceding claims, characterized in that, The rotary actuators (5A, 5B) are electromechanical actuators, including the stationary actuator component (5A) and the moving actuator component (5B). Preferably, the stationary actuator component and the moving actuator component include a magnet, an electromagnet, an electromagnetic coil, a permanent magnet, a magnetic material, or any combination thereof.

8. The positioning device according to any one of the preceding claims, characterized in that, The rotor includes a platform (6), preferably including a chuck.

9. The positioning device according to any one of the preceding claims, characterized in that, The stationary linear component and the moving linear component include a magnet, an electromagnet, an electromagnetic coil, a permanent magnet, a magnetic material, or any combination thereof, and more preferably, the linear height actuator is a voice coil actuator or includes a voice coil actuator.

10. The positioning device according to any one of the preceding claims, characterized in that, The linear height actuator includes a sump pipe extending substantially along the height direction from the stator to the rotor, and a rotary joint configured to seal the sump pipe to allow fluid to flow between the rotor and the stator without leakage, or wherein the rotor includes one or more rotor sump pipes, the one or more rotor sump pipes including an axial portion (41) extending from an axial end of the rotor to a portion of the rotor (2) at a circumferential slit level of the air bearing, and the one or more rotor sump pipes including a radial portion (42) fluidly connecting the axial portion (41) to a circumferential groove (43) disposed in the outer casing surface of the rotor (2) and / or the inner casing surface of the stator (3), wherein the stator (3) includes one or more stator sump pipes (44) fluidly connected to the circumferential groove.

11. The positioning device according to any one of the preceding claims, characterized in that, The Z position measuring component is a Z encoder, which preferably includes a set of circumferential scale marks (21) disposed on the circumferential surface of the rotor along the height direction, and a Z sensor (22) configured to read the height position of the circumferential scale marks, the Z sensor being attached to the stator.

12. The positioning device according to any one of the preceding claims, characterized in that, The Z-position measuring component includes a confocal sensor, a laser interferometer, a capacitance probe, an inductive sensor, an inductive encoder, a laser sensor, a gap measuring sensor configured to measure the gap between the substrate and the fixed reference part, or any combination thereof.

13. The positioning device according to claim 12, characterized in that, The Z-position measuring component includes a laser interferometer.

14. The positioning device according to any one of the preceding claims, characterized in that, The RT position measuring component is an RT encoder, which preferably includes a set of axial scale marks (23) arranged in the circumferential direction on the circumferential surface of the rotor, and an RT sensor (24) configured to read the angular position of the axial scale marks (23), the RT sensor being attached to the stator.

15. A positioning method for positioning a substantially flat substrate, preferably a wafer or chip, comprising the following steps: - Provide a rotor and a stator, wherein the rotor is engaged with the stator by bearings configured to allow rotational movement of the rotor (2) about a rotor axis and axial movement along the rotor axis; - Fix the substrate onto the rotor; - To rotate the rotor together with the substrate about the rotor axis, wherein the rotor rotates relative to the stator; - Obtain the angular position of the rotor relative to the stator, and obtain the height position of the rotor relative to the stator; - Compare the measured height value at the stated height location with a predefined target height value, and - Control the linear height actuator to compensate for the difference between the measured height value and the target height value, thereby controlling the height position of the rotor relative to the stator.

16. The positioning method according to claim 15, characterized in that, The positioning device according to any one of claims 1 to 14 shall be used to perform this action.

17. A wafer inspection method, comprising performing the method of any one of claims 15 or 16, wherein the substrate is a wafer, the wafer inspection method further comprising the following steps: - A focused laser is directed onto the wafer during wafer rotation; - Measure the reflected laser light from the surface of the wafer, and - The measured reflected laser light is compared with a predefined expected reflection pattern, and deviations from the pattern indicate irregularities on the wafer surface.

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