CN210834963U

CN210834963U - Atomic force microscope

Info

Publication number: CN210834963U
Application number: CN201921389176.5U
Authority: CN
Inventors: 不公告发明人
Original assignee: Changxin Memory Technologies Inc
Current assignee: Changxin Memory Technologies Inc
Priority date: 2019-08-26
Filing date: 2019-08-26
Publication date: 2020-06-23
Anticipated expiration: 2029-08-26

Abstract

An atomic force microscope comprises a wafer clamping device, a wafer clamping device and a wafer clamping device, wherein the wafer clamping device is used for fixing a wafer and enabling the wafer to be erected; the first micro-cantilever and the second micro-cantilever are provided with probes and used for scanning the front side and the back side of the wafer respectively through the probes when the wafer is erected; and the first position detection device and the second position detection device are respectively used for detecting the offset of the first micro-cantilever and the second micro-cantilever to obtain the morphology images of the front surface and the back surface of the wafer. The wafer clamping device fixes the wafer and enables the wafer to be erected, when the wafer is erected, the gravity borne by the wafer vertically downwards along the surface of the wafer, so that the influence of the gravity on the wafer is minimized, the wafer is prevented from being bent or deformed, when the front side and the back side of the erected wafer are scanned through the first micro-cantilever and the second micro-cantilever, the influence of the bending or deformation on a measurement result is prevented, and the accuracy of the wafer shape measurement is improved.

Description

Atomic force microscope

Technical Field

The utility model relates to a semiconductor preparation field especially relates to an atomic force microscope.

Background

Atomic Force Microscope (AFM), an analytical instrument that can be used to study the surface structure of solid materials including insulators.

The atomic force microscope senses and amplifies the acting force between the sharp probe on the cantilever and the atoms of the sample to be detected by using the micro-cantilever, so that the detection aim is fulfilled, and the atomic force microscope has atomic resolution, and is widely applied to the advanced scientific and technological fields of nano materials, biomedicine and the like with the nano-scale ultrahigh detection precision. The atomic force microscope can observe both conductor and nonconductor, so making up the deficiency of scanning tunnel microscope. The atomic force microscope is a utility model of geld binning, a research center in zurich, IBM, in nine, eight and five years, and its purpose is to make non-conductors to adopt an observation method similar to a Scanning Probe Microscope (SPM). The biggest difference between Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM) is that instead of using electron tunneling effect, the surface properties of a sample are presented by detecting contact between atoms, atomic bonding, van der waals force or cassimel effect, etc.

The basic principle of the atomic force microscope is as follows: one end of a micro-cantilever which is sensitive to weak force is fixed, the other end of the micro-cantilever is provided with a micro-needle point, the micro-needle point is lightly contacted with the surface of a sample, and because the weak repulsive force exists between atoms at the tip end of the micro-needle point and atoms on the surface of the sample, the micro-cantilever with the micro-needle point moves up and down in the direction vertical to the surface of the sample corresponding to an equipotential surface of the acting force between the micro-needle point and the atoms on the surface of the sample by controlling the constancy of the force during scanning. The position change of the micro-cantilever corresponding to each scanning point can be measured by an optical detection method or a tunnel current detection method, so that the information of the surface topography of the sample can be obtained.

In the manufacturing process of an integrated circuit, because the edge of a wafer is deposited for many times and the edge is not easily etched, some film layers are accumulated, the edge of the wafer is seriously polluted, the film layers are peeled off or particles (particles) at the edge of the wafer can move into the wafer to pollute the whole wafer when the wafer is cleaned by a wet method, so that the yield is reduced, and the appearance of the surface of the wafer, particularly the appearance of the edge of the wafer, needs to be detected in the manufacturing process of the wafer.

However, the accuracy of the conventional atomic force microscope for measuring the surface topography of the wafer still needs to be improved.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that improve the measuring precision of wafer surface morphology.

The utility model provides an atomic force microscope, include:

the wafer clamping device is used for fixing the wafer and enabling the wafer to be erected;

the first micro-cantilever and the second micro-cantilever are provided with probes and used for scanning the front side and the back side of the wafer respectively through the probes when the wafer is erected;

and the first position detection device and the second position detection device are respectively used for detecting the offset of the first micro-cantilever and the second micro-cantilever to obtain the morphology images of the front surface and the back surface of the wafer.

Optionally, the wafer clamping device includes a first carrying table and a clamping groove located on the first carrying table, and the wafer is fixed in the clamping groove.

Optionally, the wafer clamping device further includes a rotating unit located on the first stage, and the rotating unit is configured to drive the clamping slot to rotate, so that the wafer fixed in the clamping slot is erected.

Optionally, the first carrying table includes a first coarse movement table and a first fine movement table, the first fine movement table is located on the first coarse movement table, and the rotating unit is located on the first fine movement table.

Optionally, the first coarse motion stage and the first fine motion stage control the wafer clamping device to move up and down and back, and a moving range of the first coarse motion stage is larger than a moving range of the first fine motion stage.

Optionally, the first micro-cantilever and the second micro-cantilever are respectively fixed on the second stage and the third stage.

Optionally, the second carrying platform comprises a third coarse movement platform and a fourth fine movement platform, the fourth fine movement platform is located on the third coarse movement platform, the first micro-cantilever is fixed on the fourth fine movement platform, the third carrying platform comprises a fifth coarse movement platform and a sixth fine movement platform, the sixth fine movement platform is located on the fifth coarse movement platform, and the second micro-cantilever is fixed on the sixth fine movement platform.

Optionally, the third coarse movement stage and the fourth fine movement stage control the first micro-cantilever to move left and right, and the fifth coarse movement stage and the sixth fine movement stage control the second micro-cantilever to move left and right.

Optionally, the first position detecting device and the second position detecting device each include a light source and a receiver, the light source is configured to illuminate the back surfaces of the ends of the first micro-cantilever and the second micro-cantilever, the ends having the probe, and the receiver is configured to receive the reflected light.

Optionally, the first position detecting device and the second position detecting device each further include an optical unit, and the optical unit is configured to transmit and irradiate light emitted by the light source onto the back surfaces of the ends of the first micro-cantilever and the second micro-cantilever, where the ends have the probes, and transmit light reflected by the back surfaces of the first micro-cantilever and the second micro-cantilever to the receiver.

Optionally, the light source is a laser, and the receiver is an array photodiode.

Optionally, the atomic force microscope further includes a first feedback unit and a second feedback unit, where the first feedback unit is configured to use a signal obtained by a receiver in the first position detection device as a feedback signal, and use the feedback signal as an internal adjustment signal, and drive a fourth fine motion stage in the second stage to move, so that the wafer and the probe on the first micro-cantilever maintain a constant acting force; the second feedback unit is used for taking a signal obtained by the receiver in the second position detection device as a feedback signal and an internal adjustment signal, and driving the sixth fine motion stage in the third carrying stage to move so as to keep a constant acting force between the wafer and the probe on the second micro-cantilever.

Optionally, the apparatus further comprises an optical microscope unit, and the optical microscope unit is used for observing the surface of the wafer.

Compared with the prior art, the utility model discloses technical scheme has following advantage:

the atomic force microscope of the utility model comprises a wafer clamping device which is used for fixing the wafer and erecting the wafer;

the first micro-cantilever and the second micro-cantilever are provided with probes and used for scanning the front side and the back side of the wafer respectively through the probes when the wafer is erected; and the first position detection device and the second position detection device are respectively used for detecting the offset of the first micro-cantilever and the second micro-cantilever to obtain the morphology images of the front surface and the back surface of the wafer. The wafer clamping device fixes the wafer and enables the wafer to be erected, when the wafer is erected, the gravity borne by the wafer vertically downwards along the surface of the wafer, so that the influence of the gravity on the wafer is minimized, the wafer is prevented from being bent or deformed, particularly, the bending or deformation of the edge of the wafer caused by the gravity is prevented, when the front and the back of the erected wafer are scanned through the first micro-cantilever and the second micro-cantilever, the influence of the bending or deformation on a measurement result is prevented, the accuracy of the wafer shape measurement is improved, and particularly, the accuracy of two sides of the wafer edge shape can be improved.

And when the front and the back of the vertical wafer can be scanned simultaneously through the first micro-cantilever and the second micro-cantilever, the offset of the first micro-cantilever and the offset of the second micro-cantilever can be detected simultaneously and respectively through the first position detection device and the second position detection device, so that the morphology images of the front and the back of the wafer are obtained, and the measurement efficiency is improved.

The atomic force microscope further comprises a first feedback unit and a second feedback unit, wherein the first feedback unit is used for taking a signal obtained by a receiver in the first position detection device as a feedback signal as an internal adjustment signal and driving a fourth fine motion stage in the second carrying stage to move so as to enable the wafer and the probe on the first micro-cantilever to keep a constant acting force; the second feedback unit is used for taking a signal obtained by the receiver in the second position detection device as a feedback signal and an internal adjustment signal and driving the sixth fine motion stage in the third carrying stage to move so as to keep constant acting force between the wafer and the probe on the second micro-cantilever, so that the front and back features of the wafer can not be influenced when being measured simultaneously, and the accuracy and the efficiency of measuring the front and back features are further improved.

Drawings

Fig. 1 is a schematic structural diagram of an atomic force microscope according to an embodiment of the present invention.

Detailed Description

As background, the accuracy of the conventional afm for measuring the surface topography of the wafer still needs to be improved.

Research shows that when an existing atomic force microscope detects a wafer, the wafer is horizontally placed on a carrying platform, a probe on a micro-cantilever is close to the surface of the wafer from the upper side of the wafer, and when the wafer is horizontally placed, the wafer may bend or deform due to the influence of gravity, so that the shape of the wafer is influenced, particularly the shape of the edge of the wafer is greatly influenced, and the measurement accuracy, particularly the measurement accuracy of the shape of the edge of the wafer, is influenced. In addition, the existing atomic force microscope can only measure one surface of the wafer at a time, and when the back surface and the front surface of the wafer need to be measured, the measurement needs to be carried out twice, so that the measurement efficiency is low.

Therefore, the utility model provides an atomic force microscope which comprises a wafer clamping device used for fixing a wafer and erecting the wafer; the first micro-cantilever and the second micro-cantilever are provided with probes and used for scanning the front side and the back side of the wafer respectively through the probes when the wafer is erected; and the first position detection device and the second position detection device are respectively used for detecting the offset of the first micro-cantilever and the second micro-cantilever to obtain the morphology images of the front surface and the back surface of the wafer. The wafer clamping device fixes the wafer and enables the wafer to be erected, when the wafer is erected, the gravity borne by the wafer vertically downwards along the surface of the wafer, so that the influence of the gravity on the wafer is minimized, the wafer is prevented from being bent or deformed, when the front and the back of the erected wafer are scanned through the first micro-cantilever and the second micro-cantilever, the influence of the bending or deformation on a measurement result is prevented, and the accuracy of the wafer shape measurement is improved. And when the front and the back of the vertical wafer can be scanned simultaneously through the first micro-cantilever and the second micro-cantilever, the offset of the first micro-cantilever and the offset of the second micro-cantilever can be detected simultaneously and respectively through the first position detection device and the second position detection device, so that the morphology images of the front and the back of the wafer are obtained, and the measurement efficiency is improved.

In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to the accompanying drawings. In describing the embodiments of the present invention in detail, the drawings are not necessarily to scale, and the drawings are merely exemplary and should not be construed as limiting the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

An embodiment of the present invention provides an atomic force microscope, please refer to fig. 1, including:

a wafer clamping device for fixing the wafer 20 and making the wafer 20 stand;

a first micro-cantilever 204 and a second micro-cantilever 205 with a probe 206, wherein the first micro-cantilever 204 and the second micro-cantilever 205 are used for scanning the front side and the back side of the wafer 20 through the probe 206 respectively when the wafer 20 is erected;

and the first position detection device 217 and the second position detection device 218 are respectively used for detecting the offset of the first micro-cantilever 204 and the second micro-cantilever 205 to obtain the profile images of the front surface and the back surface of the wafer 20.

The wafer 20 is a wafer used in a semiconductor manufacturing process, and specifically, the wafer may be a wafer after photolithography, etching, deposition, grinding, ion implantation, or thermal treatment. The wafer comprises a front surface and a back surface opposite to the front surface, wherein various film layers can be formed on the front surface of the wafer, the film layers comprise a dielectric layer, a mask layer, a photoresist layer, a deposition material layer and the like, and a metal interconnection structure can be formed in the film layers. In this embodiment, when the wafer 20 fixed on the wafer clamping device is erected, the surface facing the first micro-cantilever 204 is a front surface.

In one embodiment, the material of the wafer 20 may be silicon (Si), germanium (Ge), or silicon germanium (GeSi), silicon carbide (SiC); or silicon-on-insulator (SOI), germanium-on-insulator (GOI); or may be other materials such as group iii-v compounds such as gallium arsenide.

In this embodiment, the wafer clamping device includes a first stage 203 and a slot 221 located on the first stage 203, and the wafer 20 is fixed in the slot 221.

The wafer clamping device further includes a rotating unit (not shown) on the first stage 203, and the rotating unit is configured to drive the slot 221 to rotate, so that the wafer fixed in the slot 221 is erected. When the wafer 20 is erected, the gravity borne by the wafer 20 is vertically downward along the surface of the wafer 20, so that the influence of the gravity on the wafer is minimized, and thus the wafer 20 is prevented from being bent or deformed due to the gravity, particularly the bending or deformation of the edge of the wafer due to the gravity, and when the front and the back of the erected wafer 20 are scanned by the first micro-cantilever 204 and the second micro-cantilever 205, the influence of the bending or deformation of the wafer 20 on the measurement result is prevented, so that the accuracy of the wafer topography measurement is improved, particularly the measurement accuracy of the edge topography of the wafer is improved.

In an embodiment, the card slot 221 may include a ring-shaped supporting structure and a clamping structure on the ring-shaped supporting structure, before performing the detection, the card slot 221 is placed on the first stage 203, the ring-shaped supporting structure supports the wafer 20 when the wafer 20 is transferred onto the card slot 221, then the clamping structure presses the wafer from the peripheral edge of the wafer, fixes the wafer on the supporting structure, and finally the card slot is rotated by the driving of the rotating unit so that the wafer fixed in the card slot 221 is erected. In an embodiment, the clamping structure includes a card and a driving unit connected to the card, the card presses the edge of the wafer under the driving of the driving unit, and the driving unit includes a cylinder or a motor.

The first stage 203 can drive the vertical wafer 20 on the slot 221 to move up and down and back and forth. In this embodiment, the vertical direction of the wafer 20 is a Z-axis direction, the directions of both sides of the back and front of the wafer 20 are Y-axis directions, the direction of the side of the wafer 20 is an X-axis direction, the Z-axis, the X-axis, and the Y-axis are perpendicular to each other to form a coordinate system, the vertical movement of the wafer 20 on the slot 221 driven by the first stage 203 is a movement along a positive direction or a negative direction of the Z-axis, and the front movement of the wafer 20 on the slot 221 driven by the first stage 203 is a movement along a positive direction or a negative direction of the X-.

In an embodiment, the first stage 203 includes a first coarse stage 202 and a first fine stage 201, the first fine stage 201 is located on the first coarse stage 202, and the rotating unit is located on the first fine stage 201.

The first coarse motion stage 202 and the first fine motion stage 201 control the wafer clamping device 221 to move up and down and back, so that the wafer 20 standing on the wafer clamping device 221 can move up and down and back, and the moving range of the first coarse motion stage 202 is larger than that of the first fine motion stage 201. The first coarse motion stage 202 is suitable for large-scale movement, and the first fine motion stage 201 is suitable for small-scale movement, so that the position of the wafer 20 on the first stage 203 can be adjusted quickly and accurately.

The first coarse movement table 202 and the first fine movement table 201 are respectively provided with a driving unit to drive the first coarse movement table 202 and the first fine movement table 201 to move up and down and back and forth, the driving unit may include an up-down driving unit and a front-back driving unit, the up-down driving unit is used for driving the first coarse movement table 202 and the first fine movement table 201 to move up and down, and the front-back driving unit is used for driving the first coarse movement table 202 and the first fine movement table 201 to move back and forth. In an embodiment, the drive unit comprises a motor, which may be a stepper motor.

The first micro-cantilever 204 and the second micro-cantilever 205 are very sensitive to weak forces, and the first micro-cantilever 204 and the second micro-cantilever 205 are used to detect the amount of force variation between atoms. The first micro-cantilever 204 and the second micro-cantilever 205 are fixed at one end and have a micro-probe 206 at the other end, the probe 206 is close to the surface of the wafer 20, and the first micro-cantilever 204 and the second micro-cantilever 205 with the probe 206 will move up and down in the direction perpendicular to the surface of the sample corresponding to the equipotential surface of the tip of the probe and the force acting between the front surface and the back surface of the wafer 20 by controlling the constancy of the force during scanning due to the extremely weak repulsive force between the atoms at the tip of the probe 206 and the front surface or the back surface atoms of the wafer 20. In this embodiment, the probe 206 on the first micro-cantilever 204 is close to the front surface of the wafer 20, and the probe 206 on the second micro-cantilever 205 is close to the back surface of the wafer 20. When the front and back of the erected wafer 20 can be scanned simultaneously by the first micro-cantilever 204 and the second micro-cantilever 205, the offsets of the first micro-cantilever 204 and the second micro-cantilever 205 can be detected simultaneously by the first position detecting device 217 and the second position detecting device 218, respectively, so that the topographic images of the front and back of the wafer 20 are obtained, and the measuring efficiency is improved.

In one embodiment, the first micro-cantilever 204 and the second micro-cantilever 205 can be made of a silicon wafer or silicon nitride wafer that is generally 100-500 μm long and about 500 nm-5 μm thick. The first microcantilever 204 and the second microcantilever 205 have a sharp probe 206 at the tip to detect the interaction force between the wafer 20 and the tip. The first microcantilever 204 and the second microcantilever 205 have certain specifications, such as: length, width, spring constant, and tip shape, and these specifications are selected to select different types of probes depending on the characteristics of the wafer and the mode of operation.

The first micro-cantilever 204 and the second micro-cantilever 205 are fixed on the second stage 209 and the third stage 212, respectively. Specifically, the end of the first micro-cantilever 204 without the probe 206 is fixed on the second stage 209, the tip of the probe 206 on the first micro-cantilever 204 faces the front side of the standing wafer 20, the end of the second micro-cantilever 205 without the probe 206 is fixed on the third stage 212, and the tip of the probe 206 on the second micro-cantilever 205 faces the back side of the standing wafer 20.

The second carrier 209 includes a third coarse moving stage 208 and a fourth fine moving stage 207, the fourth fine moving stage 207 is located on the third coarse moving stage 209, the first micro-cantilever 204 is fixed on the fourth fine moving stage 207, the third coarse moving stage 208 and the fourth fine moving stage 207 control the first micro-cantilever 204 to move left and right, the third carrier 212 includes a fifth coarse moving stage 211 and a sixth fine moving stage 210, the sixth fine moving stage 210 is located on the fifth coarse moving stage 211, the second micro-cantilever 205 is fixed on the sixth fine moving stage 210, and the fifth coarse moving stage 211 and the sixth fine moving stage 210 control the second micro-cantilever 206 to move left and right. In this embodiment, the left-right movement is a movement in the positive direction or the negative direction of the Y axis.

The moving range of the third coarse motion stage 208 is larger than the moving range of the fourth fine motion stage 207. The third coarse motion stage 208 is adapted to move in a large range, and the fourth fine motion stage 207 is adapted to move in a small range, so that the position of the first micro-cantilever 204 on the second stage 209 can be adjusted quickly and accurately.

The moving range of the fifth coarse movement stage 211 is greater than that of the sixth fine movement stage 210. The fifth coarse motion stage 211 is suitable for large-scale movement, and the sixth fine motion stage 210 is suitable for small-scale movement, so that the position of the second micro-cantilever 205 on the third stage 212 can be adjusted quickly and accurately.

The third coarse movement table 208 and the fourth fine movement table 207 are respectively provided with a driving unit so as to drive the third coarse movement table 208 and the fourth fine movement table 207 to move left and right, the driving unit comprises a left driving unit and a right driving unit, and the left driving unit and the right driving unit are used for driving the third coarse movement table 208 and the fourth fine movement table 207 to move left and right. In an embodiment, the drive unit comprises a motor, which may be a stepper motor.

The fifth coarse movement table 211 and the sixth fine movement table 210 are respectively provided with a driving unit to drive the fifth coarse movement table 211 and the sixth fine movement table 210 to move left and right, the driving unit comprises a left driving unit and a right driving unit, and the left driving unit and the right driving unit are used for driving the fifth coarse movement table 211 and the sixth fine movement table 210 to move left and right. In an embodiment, the drive unit comprises a motor, which may be a stepper motor.

In this embodiment, the first position detecting device 217 is used for detecting the offset of the first micro-cantilever 204 to obtain a topographic image of the front surface of the wafer 20. The second position detecting device 218 is configured to detect an offset of the second micro-cantilever 205, and obtain a topographic image of the back surface of the wafer 20.

The first position detecting device 217 and the second position detecting device 218 each include a light source 213 for illuminating the back surface of the end of the first micro-cantilever 204 and the second micro-cantilever 205 having the probe 206, and a receiver 214 for receiving the reflected light.

In one embodiment, the light source 213 is a laser that can emit laser light toward the back of the ends of the first and

second micro-cantilevers

204 and 205 with the probes 206, and the laser light is reflected by the back of the ends of the first and

second micro-cantilevers

204 and 205 with the probes 206 and received by the corresponding receivers 214. The receiver 214 is an array photodiode. When the probe 206 scans the back and front surfaces of the wafer, due to the interaction force between the atoms on the front and back surfaces of the wafer and the atoms on the tips of the probes 206 of the first micro-cantilever 204 and the second micro-cantilever 204, the first micro-cantilever 204 and the second micro-cantilever 205 will curve and fluctuate with the topography of the surface of the wafer 20, and the reflected light beams will be shifted accordingly, so that the change of the position of the light spots detected by the arrayed photodiode array can obtain the topography information on the front and back surfaces of the wafer. In this embodiment, the receiver 214 of the first position detecting device 217 is located on the fourth fine motion stage 207, and the receiver 214 of the second position detecting device 218 is located on the sixth fine motion stage 210.

The first position detecting device 217 and the second position detecting device 218 each further include an optical unit for transmitting and emitting light emitted from the light source 213 to the back of the end of the first micro-cantilever 204 and the second micro-cantilever 205 having the probe 206, and transmitting light reflected from the back of the first micro-cantilever 204 and the second micro-cantilever 205 to the receiver 214.

In one embodiment, the optical unit includes a first mirror 216 and a second mirror 215, the first mirror 216 is used for emitting the light emitted from the light source 213 to the back of the end of the first micro-cantilever 204 and the second micro-cantilever 205 having the probe 206, and the second mirror 215 is used for reflecting the light reflected from the back of the first micro-cantilever 204 and the second micro-cantilever 205 to the receiver 214.

The afm further includes a first feedback unit and a second feedback unit (not shown in the figure), where the first feedback unit is configured to use the signal obtained by the receiver 214 in the first position detection device 217 as a feedback signal, as an internal adjustment signal, and drive the fourth fine motion stage 207 in the second stage 209 to move, so that the wafer 20 and the probe 206 on the first micro-cantilever 204 maintain a constant acting force; the second feedback unit is configured to use a signal obtained by the receiver 214 in the second position detection device 218 as a feedback signal, as an internal adjustment signal, and drive the sixth fine motion stage 210 in the third stage 212 to move, so that the wafer 20 and the probe 206 on the second micro-cantilever 205 maintain a constant acting force, and thus, when the front and back features of the wafer are measured simultaneously, the front and back features are not affected by each other, and the accuracy and the efficiency of measuring the front and back features are further improved.

In an embodiment, the atomic force microscope further includes two optical microscope units 220, where the optical microscope units 220 are used to observe the surface of the wafer 20, and in this embodiment, the number of the optical microscope units 220 is two, the two optical microscope units 220 can respectively observe the front surface and the back surface of the wafer 20, specifically, the two optical microscope units 220 are respectively located on one focusing stage 219, the two corresponding focusing stages 219 are respectively located on the third coarse movement stage 208 and the fifth coarse movement stage 211, and the focusing stage 219 is used to adjust the focusing power of the optical microscope unit 220.

In one embodiment, when the atomic force microscope is used for measuring the topography, the wafer 20 is placed on a wafer clamping device, and the wafer clamping device fixes the wafer 20 and makes the wafer 20 stand; the first stage 203 drives the vertical wafer 20 to move to a position to be measured, the second stage 209 and the third stage 212 drive the first micro-cantilever 204 and the second micro-cantilever 205 to move, so that the probe 206 on the first micro-cantilever 204 and the second micro-cantilever 205 moves to a proper position (the distance is generally 5-10 nm) away from the wafer 20, the first stage 203 drives the vertical wafer 20 to move up and down so that the probe 206 on the first micro-cantilever 204 and the second micro-cantilever 205 scans the front surface and the back surface of the wafer 20, meanwhile, the second stage 209 (the fourth fine motion stage 207 in the second stage 209) drives the probe 206 on the first micro-cantilever 204 to move, so that a constant acting force is kept between the probe 206 on the first micro-cantilever 204 and the front surface of the wafer 20, and meanwhile, the third stage 212 (the sixth fine motion stage 210 in the third stage 210) drives the probe 206 on the second micro-cantilever 206 to move, so that a constant force is maintained between the probe 206 on the second micro-cantilever 205 and the front surface of the wafer 20; after scanning the wafer 20 by one row, the first stage 200 drives the wafer 20 to move back and forth, and performs the next row scanning on the wafer 20.

The embodiment of the utility model provides an atomic force microscope, because the wafer presss from both sides the fixed wafer 20 of device, and make wafer 20 erect, when wafer 20 erects, the gravity that wafer 20 received is downward along wafer 20's surface vertical, make the influence that gravity caused the wafer fall to minimumly, thereby prevent the wafer 20 bending or the deformation that gravity caused, especially prevent the bending or the deformation at wafer edge that gravity caused, when scanning the front and the back of the wafer 20 of erectting through first little cantilever 204 and the little cantilever 205 of second, prevent the influence of the bending or the deformation of wafer 20 to the measuring result, thereby improve the precision to wafer topography measurement, especially improve the measurement accuracy of wafer edge topography. Moreover, when the front and back surfaces of the standing wafer 20 are scanned simultaneously by the first micro-cantilever 204 and the second micro-cantilever 205, the offset amounts of the first micro-cantilever 204 and the second micro-cantilever 205 can be detected simultaneously by the first position detecting device 217 and the second position detecting device 218, so that the topographic images of the front and back surfaces of the wafer 20 are obtained, and the measuring efficiency is improved.

Although the present invention has been disclosed in the preferred embodiments, it is not intended to limit the present invention, and any person skilled in the art can use the above-mentioned method and technical contents to make possible changes and modifications to the technical solution of the present invention without departing from the spirit and scope of the present invention, therefore, any simple modification, equivalent changes and modifications made to the above embodiments by the technical substance of the present invention all belong to the protection scope of the technical solution of the present invention.

Claims

1. An atomic force microscope, comprising:

2. The afm of claim 1, wherem the wafer clamping device comprises a first stage and a pocket on the first stage, the wafer being held in the pocket.

3. The afm according to claim 2, wherem the wafer clamping device further comprises a rotating unit on the first stage, and the rotating unit is configured to rotate the pocket so that the wafer held in the pocket is erected.

4. The afm of claim 3, wherem the first stage comprises a first coarse stage and a first fine stage, the first fine stage being positioned on the first coarse stage, and the rotating unit being positioned on the first fine stage.

5. The afm of claim 4, wherein the first coarse motion stage and the first fine motion stage control the wafer chuck to move up and down and back, and a moving range of the first coarse motion stage is larger than a moving range of the first fine motion stage.

6. The afm of claim 1, wherem the first and second microcantilevers are fixed to the second and third stages, respectively.

7. The afm of claim 6, wherem the second stage comprises a third coarse motion stage and a fourth fine motion stage, wherem the fourth fine motion stage is positioned on the third coarse motion stage, wherem the first microcantilever is fixed on the fourth fine motion stage, wherem the third stage comprises a fifth coarse motion stage and a sixth fine motion stage, wherem the sixth fine motion stage is positioned on the fifth coarse motion stage, and wherem the second microcantilever is fixed on the sixth fine motion stage.

8. The afm of claim 7, wherem the third coarse motion stage and the fourth fine motion stage control the first microcantilever to move left and right, and wherein the fifth coarse motion stage and the sixth fine motion stage control the second microcantilever to move left and right.

9. The afm of claim 6, wherem each of the first position detection device and the second position detection device comprises a light source for illuminating a back surface of the end of the first microcantilever and the second microcantilever having the probe, and a receiver for receiving the reflected light.

10. The afm of claim 9, wherem each of the first position detection device and the second position detection device further comprises an optical unit for transmitting and irradiating light emitted from the light source to the back of the end of the first microcantilever and the second microcantilever having the probe, and transmitting light reflected from the back of the first microcantilever and the second microcantilever to the receiver.

11. The afm of claim 9, wherem the light source is a laser and the receiver is an array photodiode.

12. The afm of claim 9, further comprising a first feedback unit and a second feedback unit, wherein the first feedback unit is configured to use a signal obtained by the receiver of the first position detection apparatus as a feedback signal as an internal adjustment signal, and drive a fourth fine motion stage of the second stage to move so as to maintain a constant force between the wafer and the probe on the first micro-cantilever; the second feedback unit is used for taking a signal obtained by the receiver in the second position detection device as a feedback signal and an internal adjustment signal, and driving the sixth fine motion stage in the third carrying stage to move so as to keep a constant acting force between the wafer and the probe on the second micro-cantilever.

13. The afm according to claim 1, further comprising an optical microscope unit for observing the surface of the wafer.