Quartz crystal resonator-based atomic force microscope for inspecting semiconductor inline

Abstract

One embodiment of the present invention may provide a quartz crystal resonator-based atomic force microscope for a semiconductor inline, comprising: an integral head unit including a sensor unit formed in proximity to a target measurement object and including a quartz crystal resonator having a probe attached thereto, a scanner unit connected to the sensor unit and including a z-scanner for scanning in the z-axis direction at different speeds and piezoelectric elements for scanning in the x-axis and y-axis directions respectively, and a driving unit including a signal amplifier for enabling driving of the sensor unit and measurement of signals, wherein the sensor unit, the scanner unit, and the driving unit integrally form a single head unit; a linear transporter connected to the integral head unit for moving the integral head unit over the target measurement object; and a control unit that calculates physical properties and surface structural characteristics of the target measurement object on the basis of the vibration of the quartz crystal resonator and the vibration feedback of the quartz crystal resonator that is transmitted back to the quartz crystal resonator via the target measurement object.

Description

Crystal oscillator-based atomic force microscope for semiconductor inline inspection

[0001] The present invention provides an atomic force microscope optimized for semiconductor inline measurement and inspection equipment based on a quartz crystal oscillator.

[0002] The atomic force microscope is a widely used nanotechnology measurement instrument for observing, measuring, and analyzing surface structures at the nanometer level. It is an advanced tool used in nanotechnology and materials science to image sample surfaces with high spatial resolution and measure surface properties.

[0003] Sensors used for force measurement in these atomic force microscopes are predominantly flexible cantilever sensors, although rigid quartz crystal sensors are also utilized. By attaching a sharp probe to each sensor and scanning the surface, the shape and characteristics of the surface can be determined through the force information obtained.

[0004] There is a difference in that cantilever-based atomic force microscopes measure force information by optically measuring the bending of the cantilever caused by the atomic force between the probe and the sample surface using a laser, whereas quartz crystal-based atomic force microscopes obtain information about the atomic force by measuring the current generated in the quartz crystal itself due to the piezoelectric effect caused by the atomic force between the probe and the sample surface.

[0005] Meanwhile, there are several challenges that need to be addressed to achieve efficient process management for inline equipment manufacturing in semiconductor processes and to improve semiconductor manufacturing yield and throughput.

[0006] First, regarding semiconductor inline metrology and inspection equipment, while cantilevers with high k values ​​can be used for non-contact atomic force microscope (AFM) operation, the bending of the cantilever caused by small atomic forces is very minimal, making optical measurement difficult and thus hindering precise measurement. Furthermore, complete non-contact imaging is difficult with cantilevers, which can lead to serious problems with image reproducibility and stability due to probe wear.

[0007] In addition, improving imaging speed is important in the actual semiconductor inline measurement and inspection stages, and as semiconductor devices become miniaturized, advanced, integrated, and have high aspect ratio structures, more stable and precise measurements are required.

[0008] In addition, when using a cantilever, additional optical measuring elements are required to measure the bending of the cantilever, which increases the size of the atomic force microscope sensor and scan head system, and when implementing a scan system with multiple heads, the size becomes even larger, making it unsuitable for semiconductor inline measurement and inspection equipment.

[0009] In addition, since cantileveres are more expensive and inefficient than crystal oscillators, they have lower price competitiveness in manufacturing semiconductor inline equipment, making it difficult to use them easily in various semiconductor processes.

[0010] As such, while quartz crystal-based atomic force microscopes are superior to conventional cantilever-based atomic force microscopes in terms of scanning speed, non-contact scanning, and device miniaturization, they still fail to meet satisfactory requirements for use in semiconductor in-line measurement and inspection equipment.

[0011] One aspect of the present invention is to provide an atomic force microscope optimized for inline semiconductor measurement and inspection equipment based on a quartz crystal oscillator.

[0012] One aspect of the present invention is to provide an atomic force microscope capable of high-precision measurement, non-contact measurement, and real-time high-speed measurement.

[0013] One aspect of the present invention is to provide a single head unit based on a quartz crystal oscillator and to provide an atomic force microscope equipped with a multi-head unit for improving imaging sensing speed.

[0014] According to one embodiment of the present invention, a crystal oscillator-based atomic force microscope for semiconductor inline can be provided, comprising: a sensor unit including a crystal oscillator formed in close proximity to a workpiece and having a probe attached thereto; a scanner unit connected to the sensor unit and including a z-scanner that scans in the z-axis direction at different speeds and a piezoelectric element that scans in the x-axis and y-axis directions, respectively; a driving unit including a signal amplifier to enable driving and signal measurement of the sensor unit; wherein the sensor unit, the scanner unit, and the driving unit are connected to form a single head unit, and a linear transfer unit connected to the single head unit to move the single head unit over the workpiece; and a control unit that calculates the physical properties and surface structural characteristics of the workpiece based on the vibration of the crystal oscillator and the vibration transmitted from the crystal oscillator through the workpiece to the crystal oscillator.

[0015] In addition, according to one embodiment of the present invention, the z-scanner may include a high-speed z-scanner with a relatively fast speed and a low-speed z-scanner with a relatively slow speed. Here, the high-speed z-scanner is preferably used to measure the surface of the object to be measured at high speed by setting the resonance frequency high, and the low-speed z-scanner is preferably used to correct for the inclination or height difference of the object to be measured.

[0016] In addition, according to one embodiment of the present invention, it is preferable that a probe attached to the crystal oscillator measures force information according to a change in distance from the object to be measured, and accordingly, maintains a constant distance between the probe and the object to be measured based on the force or the derivative of the force to enable a non-contact mode.

[0017] In addition, according to one embodiment of the present invention, it is preferable that the head unit be capable of using one of the following operating modes: shear mode, tapping mode, and hybrid mode, depending on the attachment position and angle of the probe attached to the crystal oscillator.

[0018] In addition, according to one embodiment of the present invention, it is preferable that the head unit be positioned in a planar direction parallel to the plane on which the workpiece is placed, in an up-down direction perpendicular to the plane on which the workpiece is placed, or in any one direction on which the workpiece is placed, and operate in any one of a shear mode, a tapping mode, and a mixed mode.

[0019] In addition, according to one embodiment of the present invention, the crystal oscillator is preferably configured to operate in a shear mode in which the sensor unit is also configured to vibrate in the same parallel direction when the head unit vibrates in a direction parallel to the plane on which the object to be measured is placed, and in a tapping mode in which the sensor unit is also configured to vibrate in the same vertical direction when the head unit vibrates in a direction perpendicular to the plane on which the object to be measured is placed, and to operate in either one or simultaneously of the shear mode and the tapping mode.

[0020] In addition, according to one embodiment of the present invention, it is preferable that the probe attached to the crystal oscillator is attached to the end surface in the longitudinal direction of the crystal oscillator.

[0021] In addition, according to one embodiment of the present invention, the atomic force microscope for semiconductor inline inspection based on a quartz crystal includes a plurality of single head units to scan a plurality of parts of a workpiece, and it is preferable that the single head units each operate independently through a plurality of z-scanners and piezoelectric elements.

[0022] In addition, according to one embodiment of the present invention, the control unit is characterized by calculating mechanical properties including viscous force and elastic force of a workpiece using the following formula and using a feedback mechanism through distance control or force control, thereby forming a crystal oscillator-based atomic force microscope for semiconductor inline.

[0023]

[0024]

[0025]

[0026]

[0027]

[0028] The input values ​​of vibration amplitude A and phase θ are measured and substituted into the above formula to calculate the output values ​​of elastic modulus kint and viscosity modulus bint, thereby obtaining the viscoelastic force (Fk, Fb) and energy dissipation (Edis) (kint is the elastic modulus, bint is the viscosity modulus, Fk is the elastic force, Fb is the viscous force, Edis is the energy dissipation, and Q is the quality factor).

[0029] According to one embodiment of the present invention, an atomic force microscope optimized for semiconductor inline measurement and inspection equipment based on a crystal oscillator sensor can be provided.

[0030] In addition, according to an embodiment of the present invention, by implementing a multi-head unit using a plurality of single head units, multiple parts of a workpiece can be scanned simultaneously, and since the z-scanner and piezoelectric element operate independently in each single head unit, the imaging speed of the workpiece can be improved.

[0031] In addition, according to an embodiment of the present invention, by utilizing the piezoelectric effect and resonance principle of a crystal oscillator, minute vibration changes occurring when a probe interacts with the surface of a workpiece can be accurately measured, thereby enabling the analysis of surface structures and physical properties at the atomic level, which has the effect of enabling ultra-precision measurements required in semiconductor processes.

[0032] Furthermore, according to an embodiment of the present invention, by simultaneously utilizing a high-speed z-scanner and a low-speed z-scanner, the surface of an object to be measured can be measured quickly and accurately. That is, the high-speed z-scanner enables rapid imaging scanning, while the low-speed z-scanner is used for detailed measurement, thereby providing the effect of enabling precise and rapid inspection in semiconductor inline inspection.

[0033] In addition, according to an embodiment of the present invention, by providing a high-speed z-scanner, a low-speed z-scanner, and a piezoelectric element together, the size of the head unit can be maintained even if the characteristics of the scanner are modified, making it suitable for the design and fabrication of a multi-head unit structure. Furthermore, since there is no need to use a large-sized piezoelectric element to amplify the range of motion of the piezoelectric element, the miniaturization of the device can be enhanced.

[0034] In addition, according to an embodiment of the present invention, the low-speed z-scanner can compensate for the inclination or height difference of the object to be measured, thereby enabling accurate measurement even when the surface of the object to be measured is non-uniform or various height differences exist. This has the effect of enabling accurate measurement even in complex structures of semiconductor surfaces, such as structures with a high aspect ratio.

[0035] In addition, according to an embodiment of the present invention, since the crystal oscillator can measure changes in force according to changes in distance from the object to be measured, that is, when the object to be measured is in close proximity to the object, precise measurement is possible even in a non-contact mode, and thus surface characteristics can be measured without damaging the surface, which can be particularly useful for semiconductor surface analysis.

[0036] In addition, according to an embodiment of the present invention, various operating modes such as shear mode, tapping mode, and hybrid mode are supported, allowing switching to an appropriate mode depending on the characteristics of the object to be measured, thereby enabling effective analysis of various types of semiconductor surfaces.

[0037] In addition, according to an embodiment of the present invention, the control unit can perform real-time analysis based on vibration data of a crystal oscillator, thereby providing immediate feedback to the semiconductor production line and enabling the rapid resolution of defects or problems that may occur in the process.

[0038] In addition, according to an embodiment of the present invention, mechanical properties such as elasticity and viscosity of a measured object can be precisely calculated based on vibration data of a crystal oscillator, thereby enabling accurate evaluation of the physical properties of a semiconductor material.

[0039] In addition, according to an embodiment of the present invention, the energy dissipation and viscoelastic properties of a substance to be measured can be measured by analyzing the vibration of a crystal oscillator, which is useful for evaluating the properties of semiconductor materials and enables the detection of minute changes occurring during the process, thereby promoting the high quality of the semiconductor process.

[0040] FIG. 1 is a perspective view of the main part of an atomic force microscope for semiconductor inline inspection based on a quartz crystal oscillator according to one embodiment of the present invention.

[0041] FIG. 2 is a perspective view of a single head unit of an atomic force microscope for semiconductor inline inspection based on a quartz crystal oscillator according to an embodiment of the present invention.

[0042] FIG. 3 is a perspective view of a sensor unit according to an embodiment of the present invention.

[0043] FIG. 4 is a diagram showing a crystal oscillator operating in a shear mode, a tapping mode, and a mixed mode of the two in an atomic force microscope for semiconductor inline inspection based on a crystal oscillator according to an embodiment of the present invention.

[0044] FIG. 5 is a schematic diagram showing various attachment examples of a probe attached to a crystal oscillator according to an embodiment of the present invention.

[0045] FIG. 6 is a figure showing an example of an implementation of a multi-head unit in a quartz crystal-based semiconductor inline inspection atomic force microscope according to an embodiment of the present invention.

[0046] Figure 7 is a view of Figure 6 from the top.

[0047] FIG. 8 is a figure showing an example of an implementation of a multi-head unit in an atomic force microscope for semiconductor inline inspection based on a quartz crystal oscillator according to an embodiment of the present invention.

[0048] Figure 9 is a view of Figure 8 from the top.

[0049] The embodiments described in this specification and the configurations illustrated in the drawings are merely preferred examples of the disclosed invention, and various modifications that may replace the embodiments and drawings of this specification may exist at the time of filing this application.

[0050] Additionally, the same reference numerals or symbols presented in each drawing of this specification represent parts or components that perform substantially the same function.

[0051] Furthermore, the terms used in this specification are for describing embodiments and are not intended to limit or / or restrict the disclosed invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0052] Additionally, terms including ordinal numbers, such as “first,” “second,” etc., as used herein may be used to describe various components, but said components are not limited by said terms, and said terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The term “and / or” includes a combination of a plurality of related described items or any of a plurality of related described items.

[0053] In addition, terms such as “~part,” “~unit,” “~block,” “~part,” “~module,” “~base,” “~unit,” and “~head” may refer to a unit that processes at least one function or operation. For example, the above terms may refer to at least one piece of hardware such as an FPGA (field-programmable gate array) or ASIC (application specific integrated circuit), at least one piece of software stored in memory, or at least one process processed by a processor.

[0054] In addition, when referring to “quartz oscillator-based,” the quartz oscillator may mean any quartz oscillator that can be used as a sensor for measuring minute forces by possessing various types of frequencies, vibration modes, external specifications, physical characteristics, etc.

[0055]

[0056] Hereinafter, an embodiment according to the present invention will be described in detail with reference to the attached drawings. However, the following drawings attached to this specification are intended to illustrate a preferred embodiment of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the aforementioned description; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0057] FIG. 1 is a perspective view of a main part of a quartz crystal-based atomic force microscope for semiconductor inline inspection according to an embodiment of the present invention, FIG. 2 is a perspective view of a single head unit in a quartz crystal-based atomic force microscope for semiconductor inline inspection according to an embodiment of the present invention, and FIG. 3 is a perspective view of a sensor unit according to an embodiment of the present invention.

[0058] As described above, the present invention comprises a sensor unit (80) formed in proximity to a workpiece (90) according to the present invention and including a crystal oscillator (84) to which a probe (86) is attached, a scanner unit (60) including a z-scanner that scans in the z-axis direction at different speeds and piezoelectric elements (20) and (40) that scan in the x-axis and y-axis directions, respectively, and a driving unit (70) including a signal amplifier (75) to enable driving and signal measurement of the sensor unit (80), wherein the sensor unit (80), the scanner unit, and the driving unit (70) are connected to form a single head unit (100) and include a linear transfer device connected to the single head unit (100) to move the single head unit (100) over the workpiece (90), and from the vibration of the crystal oscillator (84) and from the vibration of the crystal oscillator (84) It includes a control unit (71) that calculates the physical properties and surface structure characteristics of the object to be measured (90) based on the vibration transmitted to the crystal oscillator (84) through the object to be measured (90).

[0059] An atomic force microscope (1) for semiconductor inline inspection according to one embodiment of the present invention may include a single head unit (100). The single head unit (100) may include a sensor unit (80) including a crystal oscillator (84), a scanner unit (60) including a z-scanner for scanning in the z-axis direction and piezoelectric elements (20) and (40) for scanning in the x-axis and y-axis directions, and a driving unit (70) for driving (control) and signal measurement.

[0060] In addition, the atomic force microscope (1) for semiconductor inline based on a quartz crystal oscillator according to one embodiment of the present invention includes a plurality of single head units (100) to scan a plurality of parts of a workpiece (90), and the single head units (100) can each operate independently through a plurality of z-scanners and piezoelectric elements (20), (40).

[0061] Accordingly, the quartz crystal-based atomic force microscope for semiconductor inline according to one embodiment of the present invention satisfies the essential requirements of high precision and high speed measurement in semiconductor processes, thereby enabling rapid and accurate quality inspection on the production line, which can improve production efficiency and minimize the occurrence of defective products.

[0062]

[0063] First, a sensor unit (80) according to one embodiment of the present invention is formed in close proximity to a workpiece (90) and includes a crystal oscillator (84) to which a probe (86) is attached. In FIGS. 1 and 2, the sensor unit (80) is shown positioned on one side of the workpiece (90), but is not limited thereto. The sensor unit (80) is moved to be close to the workpiece (90) to obtain force information with the workpiece (90), and is configured to be connected to a scanner unit (z-scanner) (60) and a driving unit (70) that generate vibrations, respectively, to satisfy this configuration.

[0064] A crystal oscillator (84) used as an atomic force microscope sensor generates minute vibrations when it receives an electrical signal, and at a certain frequency, it vibrates at a resonant frequency. At the resonant frequency, the vibration is maximized, generating very stable and precise vibrations. The resonant frequency is determined by physical characteristics such as the thickness, length, or density of the crystal, and the resonant frequency is controlled by finely adjusting the physical characteristics of the crystal oscillator (84), thereby allowing for detailed analysis of the surface of the object to be measured (90).

[0065] A probe (86) is attached to the crystal oscillator (84), and the probe (86) is formed in a pointed shape having a radius of curvature at the nanometer level. When the probe (86) approaches the surface of the object to be measured (90), a change in the vibration of the crystal oscillator (84) occurs due to the interaction between the probe (86) and the surface of the object to be measured (90). For example, variations in force, friction, tilt, etc., on the surface affect the vibration frequency or amplitude.

[0066] That is, the force (interaction) between the object to be measured (90) and the probe (86) attached to the crystal oscillator (84) is generated as a current signal proportional to the force by the piezoelectric effect of the crystal oscillator (84), and the force information transmitted to the crystal oscillator (84) can be measured and controlled through changes in the amplitude and phase of the vibration according to the distance between the probe (86) and the object to be measured (90) of the crystal oscillator (84).

[0067] Additionally, depending on the relative vibration direction between the probe (86) attached to the crystal oscillator (84) and the object to be measured (90), horizontal force measurement in the x and y directions may be required, vertical force measurement in the z direction may be required, or a combined vibration direction force between the two forces may be measured.

[0068] Since this crystal oscillator (84) can detect changes in force due to proximity to the object to be measured (90), that is, changes in distance from the object to be measured (90), precise measurement is possible even in a non-contact mode. When the distance between the probe (86) and the object to be measured (90) changes, the vibration of the crystal oscillator (84) changes, and through this, the inclination or height difference of the surface is analyzed. That is, while the probe (86) interacts with the surface, the change in vibration of the crystal oscillator (84) is measured to analyze the structural characteristics of the surface and to measure physical properties such as elasticity, viscosity, and friction of the object to be measured (90).

[0069] In this way, according to one embodiment of the present invention, information regarding the force or derivative of the force according to the distance between the probe (86) and the object to be measured (90) is obtained based on the current signal of the crystal oscillator (84) generated by the change in the amplitude of the vibration according to the information regarding the minute force between the probe (86) attached to the crystal oscillator (84) and the object to be measured (90). By utilizing this information, a complete contactless mode is made possible through an active feedback mechanism that maintains a constant distance between the probe (86) and the object to be measured (90) through a constant value of force or a constant value of derivative of the force.

[0070] FIG. 3 is a perspective view of a sensor unit (80) according to an embodiment of the present invention, FIG. 3(a) and FIG. 3(b) show the sensor unit (80) viewed in different directions. Unlike a probe (86) of a general cantilever-based atomic force microscope, the crystal oscillator (84) according to an embodiment of the present invention requires two electrical channels (87) and must also have its position fixed physically.

[0071] In addition, for ease of use, the crystal oscillator (84) must always be fixed at the same position at a constant angle. To achieve this, an electrical board (PCB board) that physically fixes the crystal oscillator (84) may be manufactured in an appropriate shape, and the crystal oscillator (84) may be fixed by methods such as soldering. The PCB board with the crystal oscillator (84) fixed in this way is included in the sensor unit (80), and is mounted on the z-scanner.

[0072] A sensor unit (80) including a crystal oscillator (84) according to an embodiment of the present invention may be attached to and fixed to a z-scanner to be described later. Through this configuration, vibrations from the z-scanner are transmitted to the crystal oscillator (84), or a measurement force signal from the crystal oscillator (84) is connected to a signal amplifier (75). The sensor unit (80) is brought close to the object to be measured (90) by the z-scanner, and the crystal oscillator (84) is finely vibrated by a driving unit (70) at its own frequency (frequencies from several kHz to tens of MHz).

[0073] The crystal oscillator (84) according to one embodiment of the present invention is configured to operate in a shear mode in which the sensor unit (80) is also configured to vibrate in the same parallel direction when the head unit (100) vibrates in a direction parallel to the plane on which the object to be measured (90) is placed, and in a tapping mode in which the sensor unit (80) is also configured to vibrate in the same vertical direction when the head unit (100) vibrates in a direction perpendicular to the plane on which the object to be measured (90) is placed, and to operate in either one or simultaneously of the shear mode and the tapping mode.

[0074] According to one embodiment of the present invention, as shown in FIG. 4, the crystal oscillator (84) may be attached in a horizontal direction with respect to the plane on which the object to be measured (90) is placed on the sensor unit (80) (80a), attached in a vertical direction with respect to the plane on which the object to be measured (90) is placed on the sensor unit (80) (80b), or attached at an angle with respect to the plane on which the object to be measured (90) is placed on the sensor unit (80) (80c), and may operate in any one of the following modes of operation: shear mode, tapping mode, and hybrid mode.

[0075] As illustrated in FIG. 4, various embodiments are shown in which the crystal oscillator (84), attached to the sensor unit (80) constituting the single head unit (100) of FIG. 1, is fixed in multiple directions. This is a drawing illustrating an example in which a plurality of single head units (100) are provided to improve the imaging speed of the atomic force microscope (1).

[0076] It is possible for the crystal oscillator (84) to be attached in a direction perpendicular to the plane on which the object to be measured (90) is placed (80a), or for the crystal oscillator (84) to be attached in a direction horizontal to the plane on which the object to be measured (90) is placed and for the two legs of the crystal oscillator (84) to be placed horizontally (80b), or for the crystal oscillator (84) to be placed at an angle to the plane on which the object to be measured (90) is placed (80c), so the atomic force microscope (1) can be used in a desired mode among shear mode, tapping mode, and mixing mode.

[0077] In this way, according to one embodiment of the present invention, various operating modes such as shear mode, tapping mode, and hybrid mode are supported, and switching to an appropriate mode according to the characteristics of the object to be measured (90) is possible, thereby enabling effective analysis of various types of semiconductor surfaces.

[0078] According to one embodiment of the present invention, the probe (86) attached to the crystal oscillator (84) may be a commercially available cantilever end probe (86), and other types of probes (various solids such as silicon, carbon nanotubes, diamond tubes, quartz, nano dielectric spheres, etc.) may also be attached.

[0079] According to one embodiment of the present invention, a probe (86) attached to a crystal oscillator (84) may have a different shape depending on the operating mode (shear mode or tapping mode) of a single head unit (100) according to various vibration directions (see FIG. 5). That is, depending on the vibration direction of the crystal oscillator (84), the probe (86) attached to the crystal oscillator (84) may include a shear mode in the x,y plane direction in which it vibrates parallel to the surface of the object to be measured (90), and a tapping mode in the z direction in which it vibrates vertically.

[0080] FIG. 5 illustrates an example of a probe (86) having a nanometer-scale radius of curvature attached to a crystal oscillator (84) according to an embodiment of the present invention, but is not limited thereto, and the vibration modes of a plurality of crystal oscillators (84) can be arbitrarily adjusted according to the convenience of the user.

[0081] The positions of the various probes (86) attached to the crystal oscillator (84) according to an embodiment of the present invention illustrated in FIG. 5 may be attached to the end surface in the longitudinal direction of the crystal oscillator (84). That is, depending on the direction and angle of attachment, the probes (86) may be attached in a direction parallel to the longitudinal direction of the crystal oscillator (84) (Fig. 5(a), 5(b), and 5(c)) or in a direction perpendicular to the longitudinal direction (Fig. 5(d)).

[0082] In this way, the single head unit (100) can be operated in various operation modes depending on the various vibration directions of the probe (86) attached to the crystal oscillator (84). That is, depending on the vibration direction of the crystal oscillator (84), the operation may include a shear mode in the x,y plane in which the probe (86) attached to the crystal oscillator (84) vibrates parallel to the surface of the object to be measured (90), and a tapping mode in the z direction in which it vibrates vertically. However, it is not limited to these operation modes, and the vibration modes of the plurality of crystal oscillators (84) can be arbitrarily adjusted according to the user's convenience. The shear mode can be operated when analysis of horizontal vibration is required for the object to be measured (90), and the tapping mode can be operated when analysis of vertical vibration is required for the object to be measured (90).

[0083] That is, the operating mode (shear mode, tapping mode, mixed mode) of the probe (86) for the object to be measured (90) can be determined in various ways depending not only on the position and angle at which the probe (86) is attached, but also on the vibration mode (Fundamental vibration mode, higher vibration mode, etc.) of the crystal oscillator (84) itself.

[0084] In addition, the characteristics of the crystal oscillator (84) used are selected differently depending on the type of object to be measured (90), thereby enabling optimal imaging and characteristic measurement.

[0085]

[0086] And, according to one embodiment of the present invention, the scanner unit (60) is connected to the sensor unit (80) and includes a z-scanner that scans in the z-axis direction at different speeds and piezoelectric elements (20) and (40) that scan in the x-axis and y-axis directions, respectively.

[0087] That is, the sensor unit (80) is connected to the scanner unit (60) so that scanning is performed in the z-axis direction, the x-axis direction, and the y-axis direction, respectively, and the crystal oscillator (84) is mounted on the z-scanner and configured so that the probe (86) can come close to the object to be measured (90) in any one of the above operating modes, or it may be configured so that the two modes can operate simultaneously by using a different vibration mode having a different frequency of the crystal oscillator (84) itself.

[0088] A z-scanner according to one embodiment of the present invention may include a high-speed z-scanner (50) with a relatively fast speed and a low-speed z-scanner (30) with a relatively slow speed.

[0089] In addition, the high-speed z-scanner (50) according to one embodiment of the present invention measures the surface of the object to be measured (90) at high speed by setting the resonance frequency high, and the low-speed z-scanner (30) can be used to correct the inclination or height difference of the object to be measured (90).

[0090] FIG. 2 is a drawing showing the scanner unit (60) including two high-speed and low-speed z-scanners, where the high-speed z-scanner (50) can be manufactured by increasing the translational stiffness (K) to increase the resonance frequency. On the other hand, the relatively low-speed z-scanner (30) is designed and manufactured with an emphasis on increasing the travel range, although the resonance frequency is lower (lower K value) compared to the high-speed z-scanner (50).

[0091] A high-speed z-scanner (50) according to one embodiment of the present invention is a scanner that scans the surface of a workpiece (90), and the scan area can be manufactured to be approximately several micrometers to several hundred nanometers. The purpose of the scanner is to enable it to track the microstructure of the workpiece (90) surface at high speed due to a high resonant frequency. In this case, by using a piezoelectric element (40) with a large range of motion and increasing the K value, the resonant frequency can be increased while maintaining the range of motion of the scanner.

[0092] As such, the present invention is suitable for designing and manufacturing a multi-head unit structure, as the size of the head unit (100) can be maintained even when the characteristics of the scanner are modified.

[0093] In addition, the low-speed z-scanner (30) according to one embodiment of the present invention may be used to correct height differences of the sensor unit (80) caused by the inclination of the substrate of the object to be measured (90), to correct height differences caused by thermal movement (drift), or to correct height differences caused when the height of the surface measurement area of ​​the object to be measured (90) is different. That is, it is used for the purpose of correcting height differences that occur while measuring with the high-speed z-scanner (50). By doing so, accurate measurement can be performed even when the surface of the object to be measured (90) is non-uniform or various height differences exist, and this enables accurate measurement even in complex structures of semiconductor surfaces, such as structures with a high aspect ratio.

[0094] Here, the low-speed z-scanner (30) can be manufactured with a structure that amplifies the range of motion of the piezoelectric element (20). That is, by using such an amplification structure, unlike the case where a large-sized piezoelectric element must generally be used to increase the range of motion of the piezoelectric element, the horizontal size of the high-speed z-scanner (50) can be made equal to or smaller, thereby enabling the miniaturization of the device.

[0095] Thus, according to one embodiment of the present invention, by providing a high-speed z-scanner (50), a low-speed z-scanner (30), and piezoelectric elements (20), (40) together, the size of the head unit can be maintained even if the characteristics of the scanner are modified, making it suitable for designing and manufacturing a multi-head unit structure, and there is no need to use large-sized piezoelectric elements to amplify the range of motion of the piezoelectric elements (20), (40), thereby allowing for the miniaturization of the device.

[0096] In addition, by utilizing force or differential force information based on the distance between the probe (86) attached to the crystal oscillator (84) and the object to be measured (90), a complete contactless mode is possible through the active feedback mechanism of the high-speed z-scanner (50) which maintains a constant distance between the probe (86) and the object to be measured (90) through a constant value of force or differential force of a constant value, and the crystal oscillator (84) moves in the x and y horizontal directions through the piezoelectric elements (20) and (40) attached to each z-scanner, thereby enabling the acquisition of topographical and structural surface information of the object to be measured (90).

[0097] Accordingly, according to one embodiment of the present invention, by utilizing a high-speed z-scanner (50) and a low-speed z-scanner (30) simultaneously, the surface of the object to be measured (90) can be measured quickly and accurately. That is, the high-speed z-scanner (50) enables fast imaging scanning, and the low-speed z-scanner (30) is used for detailed measurement, thereby enabling precise and fast inspection in semiconductor inline inspection.

[0098]

[0099] In addition, according to one embodiment of the present invention, a driving unit (70) including a signal amplifier (75) is included to enable driving and signal measurement of the sensor unit (80).

[0100] A driving unit (70) according to an embodiment of the present invention can measure the mechanical properties of the object to be measured (90) based on the input of vibration generated by the sensor unit (80) and the output of vibration measured by a vibration measuring unit connected to the crystal oscillator (84) after being converted while passing through the object to be measured (90). That is, the driving unit (70) can calculate information on the mechanical properties and force of the object to be measured (90) based on the amplitude and phase of the input and output vibrations. The mechanical properties may include viscous force and elastic force.

[0101] A signal amplifier (75) according to one embodiment of the present invention can be used to amplify the current signal of a weak crystal oscillator (84) at an early stage. Generally, since the signal coming from the crystal oscillator (84) is very small and highly susceptible to ambient noise, the signal amplifier (75) may be fixed to the low-speed z-scanner (30) so as to amplify the signal at a close distance to the crystal oscillator (84).

[0102] Here, the signal from the crystal oscillator (84) may be electrically connected directly through the contacts of the PCB board connected to the crystal oscillator (84). Additionally, a metal protective cover may be installed on the signal amplifier (75) to protect the circuit and reduce generated noise.

[0103] In addition, according to one embodiment of the present invention, the driving unit (70) may be configured to change the arrangement of the multi-head units so that the multi-head units can approach the object to be measured (90) simultaneously and in parallel.

[0104]

[0105] According to one embodiment of the present invention, a sensor unit (80), a scanner unit, and a driving unit (70) may be connected to form a single head unit (100).

[0106] The single head unit (100) may use any one of the operating modes of Shear Mode, Tapping Mode, and Hybrid Mode depending on the attachment position and angle of the probe (86) attached to the crystal oscillator (84), or the head unit (100) may be positioned in a plane direction parallel to the plane on which the object to be measured (90) is placed, or in an up-down direction perpendicular to the plane on which the object to be measured (90) is placed, or in any one direction on which the object to be measured (90) is placed, and operate in any one of the operating modes of Shear Mode, Tapping Mode, and Hybrid Mode.

[0107] In addition, the atomic force microscope (1) for semiconductor inline based on a quartz crystal oscillator according to one embodiment of the present invention includes a plurality of single head units (100) to scan a plurality of parts of a workpiece (90), and the single head units (100) can each operate independently through a plurality of z-scanners and piezoelectric elements (20), (40). That is, by implementing a multi-head unit arranged in a specific array on the workpiece (90) including a plurality of single head units (100), the imaging scan speed can be improved.

[0108] FIGS. 6 and FIGS. 7 illustrate an example in which the imaging speed of an atomic force microscope (200) can be improved by providing a multi-head unit using multiple single head units (100) of FIG. 1. FIG. 6 shows an example in which eight single head units (100) are placed on each side of the object to be measured (90), and FIG. 7 shows the positions of the 16 single head units (100) of FIG. 6 as seen on the upper surface of the object to be measured (90).

[0109] FIGS. 8 and 9 illustrate an example in which the imaging speed of an atomic force microscope (200) can be improved by providing a multi-head unit using multiple single head units (100) of FIG. 1. FIG. 8 shows an example in which four single head units (100) are placed in each area of ​​a workpiece (90), and FIG. 9 shows the positions of 16 single head units (100) of FIG. 8 shown on the upper surface of the workpiece (90).

[0110] An atomic force microscope (200) equipped with a multi-head unit according to an embodiment of the present invention scans a plurality of parts of a workpiece (90) by including a plurality of single head units (100), and the single head units (100) each operate independently through a plurality of z-scanners and piezoelectric elements (20), (40), thereby enabling an improved imaging speed of the workpiece (90).

[0111]

[0112] In addition, according to one embodiment of the present invention, a linear transfer device is included that is connected to the single head unit (100) and moves the single head unit (100) over the workpiece (90).

[0113] The linear conveyor includes a horizontal x-direction linear conveyor (10a) that conveys the single head unit (100) in the horizontal x-direction, and a horizontal y-direction linear conveyor (10b) that conveys the single head unit (100) in the horizontal y-direction. The linear conveyor is connected to the head unit (100) and serves to convey the head unit (100) from outside the object to be measured (90) to near the object to be measured (90), thereby enabling the conveyance of the head unit (100) in the x and y plane directions.

[0114]

[0115] In addition, according to one embodiment of the present invention, the control unit (71) calculates the physical properties and surface structure characteristics of the object to be measured (90) based on the vibration of the crystal oscillator (84) and the vibration transmitted from the vibration of the crystal oscillator (84) to the crystal oscillator (84) through the object to be measured (90).

[0116] Here, the control unit (71) may include a vibration measuring unit (72) that measures the vibration of the crystal oscillator (84) and the vibration transmitted from the vibration of the crystal oscillator (84) to the crystal oscillator (84) through the object to be measured (90).

[0117] A control unit (71) according to one embodiment of the present invention can perform hardware-related control to control a crystal oscillator (84) so ​​as to measure a semiconductor three-dimensional structure at high speed through the vibration measuring unit (72), and software algorithm-related control optimized for the characteristics of the crystal oscillator (84).

[0118] A control unit (71) according to one embodiment of the present invention calculates the mechanical properties of a workpiece (90), including viscous force and elastic force, using the following formula and can also use it as a feedback mechanism through distance control or force control.

[0119]

[0120]

[0121]

[0122]

[0123]

[0124] The input values ​​of vibration amplitude A and phase θ are measured and substituted into the above formula to calculate the output values ​​of elastic modulus kint and viscosity modulus bint, thereby obtaining the viscoelastic force (Fk, Fb) and energy dissipation (Edis) (kint is the elastic modulus, bint is the viscosity modulus, Fk is the elastic force, Fb is the viscous force, Edis is the energy dissipation, and Q is the quality factor).

[0125] According to one embodiment of the present invention, the control unit (71) can perform real-time analysis based on the vibration data of the crystal oscillator (84), thereby providing immediate feedback to the semiconductor production line and enabling rapid response to defects or problems that may occur in the process. In addition, according to one embodiment of the present invention, mechanical properties such as elasticity and viscosity of the object to be measured (90) can be precisely calculated based on the vibration data of the crystal oscillator (84), thereby enabling accurate evaluation of the physical properties of the semiconductor material.

[0126]

[0127] As such, according to one embodiment of the present invention, since fine surface characteristics and physical properties can be analyzed at high speed in real time during the semiconductor production process, quality control of the process is facilitated. By satisfying the essential requirements of high-precision and high-speed measurement for semiconductor processes, rapid and accurate quality inspection is possible on the production line, thereby improving production efficiency and minimizing the occurrence of defective products.

[0128]

[0129] Specific embodiments have been illustrated and described above. However, the invention is not limited to the embodiments described above, and those skilled in the art may make various modifications without departing from the essence of the technical concept of the invention as described in the following claims.

Claims

1. A sensor unit formed in close proximity to the object to be measured and comprising a crystal oscillator with a probe attached; A scanner unit connected to the sensor unit and comprising two z-scanners that scan in the z-axis direction at different speeds, a piezoelectric element that scans in the x-axis direction, and a piezoelectric element that scans in the y-axis direction; A driving unit including a signal amplifier to enable driving and signal measurement of the above sensor unit; is included, The sensor unit, scanner unit, and driving unit are connected to form a single head unit, and include a linear transfer unit connected to the single head unit to move the single head unit over the object to be measured. A quartz crystal-based semiconductor inline atomic force microscope comprising: a control unit that calculates the physical properties and surface structural characteristics of a workpiece based on the vibration of the quartz crystal oscillator and the vibration transmitted from the vibration of the quartz crystal oscillator through the workpiece to the quartz crystal oscillator.

2. In claim 1, the two z-scanners are, A crystal oscillator-based atomic force microscope for semiconductor inline, characterized by including a high-speed z-scanner with a relatively high speed and a low-speed z-scanner with a relatively slow speed.

3. In Paragraph 2, The above high-speed z-scanner measures the surface of an object to be measured at high speed by setting the resonance frequency high, and The above low-speed z-scanner is a quartz crystal-based semiconductor inline atomic force microscope characterized by being used to correct for tilt or height differences of the object being measured.

4. In claim 1, the probe attached to the crystal oscillator is, A quartz crystal-based semiconductor inline atomic force microscope characterized by measuring force information based on changes in distance from the object to be measured, and thereby enabling a non-contact mode by maintaining a constant distance between the probe and the object to be measured based on the force or the derivative of the force.

5. In claim 1, the head unit is, A quartz crystal-based semiconductor inline atomic force microscope characterized by enabling the use of any one of a shear mode, a tapping mode, and a hybrid mode depending on the attachment position and angle of a probe attached to the quartz crystal.

6. In Clause 1, the head unit is, Shear mode when vibrating parallel to the plane on which the object to be measured is placed, Tapping mode and when vibrating in a direction perpendicular to the plane on which the workpiece is placed A crystal oscillator-based atomic force microscope for semiconductor inline, characterized by operating in one of the mixed modes when vibrating in a direction inclined with respect to the plane on which the object to be measured is placed.

7. In Paragraph 1, the crystal oscillator is, When the head unit vibrates in a direction parallel to the plane on which the object to be measured is placed, the sensor unit also operates in a shear mode such that it vibrates in the same parallel direction, or When the head unit vibrates in a direction perpendicular to the plane on which the object to be measured is placed, the sensor unit also operates in a tapping mode such that it vibrates in the same perpendicular direction, or A crystal oscillator-based atomic force microscope for semiconductor inline, characterized by operating in a mixed mode in which the shear mode and tapping mode operate simultaneously.

8. In claim 1, the probe attached to the crystal oscillator is, A quartz crystal-based semiconductor inline atomic force microscope characterized by being attached to the longitudinal end surface of the above-mentioned quartz crystal.

9. In claim 1, the crystal oscillator-based semiconductor inline atomic force microscope is, Scanning multiple parts of a workpiece including multiple single head units, and A crystal oscillator-based semiconductor inline atomic force microscope characterized in that the above single head units each operate independently through a plurality of z-scanners and piezoelectric elements.

10. In claim 1, the control unit is, A quartz crystal-based semiconductor inline atomic force microscope characterized by calculating the mechanical properties of a workpiece, including viscosity and elasticity, using the following formula and also using a feedback mechanism through distance control or force control. The amplitude A and phase θ of the vibration of the crystal oscillator, which are input values, are measured and substituted into the above formula to calculate the output values, the elastic modulus kint and the viscosity modulus bint, and through this, the viscoelastic force (Fk, Fb) and energy dissipation (Edis) can be obtained (kint is the elastic modulus, bint is the viscosity modulus, Fk is the elastic force, Fb is the viscous force, Edis is the energy dissipation, and Q is the quality factor).

Images