JPH1138020A - Observation method of scanning probe microscope, probe for scanning probe microscope, and scanning probe microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a probe for a scanning probe microscope to measure a part of a sample which has a vertical or almost vertical slope angle. SOLUTION: A probe 100 is provided with a support part 101, a cantilever- like elastic member 102 extended from the support part 101, and a probe part 103 formed on the free end of the support part 101. The probe part 103 is plane and triangular, and the thickness is thinner than the elastic member part 102. The normal direction on the surface of the probe part 103, a ridge line connecting between two points 106 and 107, and the normal direction on the surface of the elastic member 102 are parallel. A detection mechanism part 104 which detects the vibration of elastic member part 102 has been installed in the vicinity of the boundary part between the elastic member part 102 and the support part 101. The signals detected by the detection mechanism part 104 are taken out outside through two electrodes 105a and 105b. The detection mechanism part 104 is constituted with, for example, a sensor utilizing the piezo resistance effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning probe microscopic observation method for measuring the roughness and inclination angle of a side wall of a step such as an electrode line pattern of an IC semiconductor, a scanning probe microscope using the same, and a scanning probe microscope using the same. The probe used.

[0002]

2. Description of the Related Art Scanning probe microscopes (SPMs) use the interaction (for example, atomic force, contact force) between a probe or a probe when the probe is brought close to or less than 1 μm to the surface of the sample or when the probe is brought into contact with the sample. X) while detecting force
It is a device that performs two-dimensional mapping of the interaction by scanning or moving in the Y direction or XYZ direction, such as a scanning tunneling microscope (STM), an atomic force microscope (AFM), a magnetic force microscope (MFM), It is a general term for a scanning near-field optical microscope (SNOM) and the like. In particular, the AFM is a device that obtains information on the unevenness of the sample surface.
It is the most popular among PM. The AFM detects indirectly the unevenness of the sample surface by detecting the displacement of the cantilever caused by the force acting on the probe when the probe (protrusion) formed at the tip of the cantilever approaches the sample surface, using an optical sensor or the like. Have gained.

[0003] The probe used in the AFM is manufactured using a semiconductor process which is a batch fabrication technique because of its performance and cost advantages. For example, "Europhys. Lett. 2 (1987) p.1281 (T. Albrech
t et al) "reports on a so-called flat lever made by patterning a silicon oxide thin film.
Further, Japanese Patent Application Laid-Open No. 1-262403 proposes a so-called bird's beak type probe which is developed from this.
Also, a silicon nitride cantilever having a pyramid-shaped probe described in U.S. Pat. No. 5,399,232 and a silicon cantilever described in U.S. Pat. It is. The probe of such a cantilever uses a point-terminated (one-point terminal) projection at the tip of the probe as a substantial probe. When the entire probe is viewed, the probe apex angle is 15 °. From 90 degrees to 90 degrees.

The design rule of a semiconductor IC is 256 MB.
A prototype device having a storage capacity of 0.25 μm is manufactured with a device having a storage capacity of, and a 0.15 μm rule is being applied to a 1 GB device. Along with this, a device for inspecting the shape of a device is required to accurately measure a line width of a narrow device having a large aspect ratio and further, an entire shape. As a scanning probe microscope can be applied to such shape measurement,
Research is being actively pursued.

[0005] Yves Martin and H. Kumar Wickramasinghe
Is "Apply. Phys. Lett. Vol.64 No.19 (1994) PP.2489
-2500 ”proposes a new scanning probe microscope for imaging vertical walls. A patent related to this is Japanese Patent No. 2501282. In this scanning probe microscope, the vertical wall of the sample can be measured by using a boot-type probe (a cylindrical probe whose body near the tip is narrowed). Such a probe differs from the above-mentioned point-terminated probe in that different points of the flared portion at the tip cause interaction with the side walls on both sides of the concave portion. In other words, the boot-type probe has a substantial probe at at least two or more locations at the distal end thereof, so that the vertical angle of the probe is substantially 0 ° or less.

The boot type probe has a diameter of φ2 μm to φ2.5 μm.
It consists of a part (thick part) on the cantilever side of m and a thin part connected to the tip, and the thin part has a shape like a boot. The size of the boot-shaped part is the length (height)
2.8 μm, tip of tip is φ3 at flare (tip)
The diameter is 60 nm, and φ210 nm in a constricted portion closer to the cantilever.

When the side wall of a trench or a hole in a semiconductor is measured using this probe, the flare at the tip of the probe is overhanging, so that the portion comes closest to the sample surface (side wall). Therefore, by scanning the probe while keeping the distance between such a protruding portion of the probe and the sample surface constant, it is possible to measure the surface roughness and the inclination angle of the side wall.

Japanese Unexamined Patent Publication No. 3-104136 discloses a method for manufacturing such a boot-type probe, and the probe is manufactured by photolithography using a single-crystal silicon wafer as a start wafer. After forming a circular mask of about φ1 μm or less, dry etching is performed with CF 4 gas, and the silicon wafer is dug down substantially vertically to form a silicon-shaped probe portion having a substantially cylindrical shape. When the dry etching conditions are changed, the center of the cylindrical portion of the probe bulges or narrows. By selecting these conditions, a substantially cylindrical probe made of single-crystal silicon with a narrow middle portion of the cylindrical portion is obtained. Thereafter, the probe portion is protected by a resist or the like, and patterning of the lever portion and etching from the back surface of the wafer are performed to obtain a cantilever having a boot-type probe.

On the other hand, the tip of the probe of the cantilever for AFM has a possibility that the tip of the probe is worn or broken due to contact with the sample surface during measurement (scanning), and the probe material performs stable AFM measurement. You need to pay attention to it. For example, Matsuyama et al. Reported at the 55th Annual Conference of the Japan Society of Applied Physics (Preliminary Collection, p.473) on the wear of probe materials. Single crystal silicon and silicon nitride are often used as a probe material, but when compared, silicon nitride films are less likely to wear than single crystal silicon. Report that the silicon nitride film having a stoichiometry of 3 to 4 is more difficult to wear.

[0010]

The root portion of the side wall of a sample having a high aspect ratio is not limited to a scanning probe microscope for imaging a vertical wall by Yves Martin et al. In order to measure as accurately as possible, a probe having a small apex angle and a high aspect ratio is required.

Apply. Phys. Lett. Vol. 64 No. 19 (1994)
The scanning probe microscopy of Yves Martin et al. For imaging vertical walls, described in PP.2498-2500, is an application of non-contact mode AFM, but occasionally uses a probe during measurements in air. May come into contact with the sample surface. In other words, although the non-contact mode AFM measurement method is applied, since the bandwidth of the feedback circuit of the apparatus is finite, the probe is completely in contact with a sample having large irregularities or a sample having a step-shaped step portion. It is difficult to measure without having to do it. In this regard, for example, the author of the paper, Eve Martin et al.
194154 proposes a method of measuring the side wall of a sample having a similar step by applying the contact mode AFM method performed while exciting the probe, and the fact that Virgil B. Elings et al. −27
0434, a microscope that can measure the side wall by applying the contact mode AFM method, which is also performed while exciting the probe, proposes the measurement of the vertical wall by the complete non-contact mode AFM measurement method. Difficulty is inferred.

When the probe comes into contact with the sample, the probe is worn or broken, and the shape of the probe changes during the measurement.
Yves Martin et al.'S scanning probe microscopy for imaging vertical walls is used, for example, to measure the shape of the electrode pattern of a semiconductor IC according to the submicron pattern rule, as described above. Even if worn by only 10 nm, the measurement result changes by 10% or more. Therefore, a change in the shape of the probe due to wear or the like is a very serious problem. In general, measuring instruments need to have high reproducibility, but when considering a scanning probe microscope that images vertical walls by Yves Martin et al. Losing reproducibility is very problematic.

To obtain the reproducibility of data, it is conceivable to frequently calibrate the probe shape. However, performing the operation for calibration many times before measuring the measurement sample is a problem in terms of the throughput required for the measuring instrument. This is because the number of samples that can be measured per unit time for the calibration work decreases. Also, if a calibration method that measures the sample for calibration using the same method as the measurement is used for the calibration, the probe may be worn out during the calibration work and may change its shape, Performing calibration work is also problematic.

Further, the probe used in the scanning probe microscopy for imaging a vertical wall described in the article by Yves Martin et al. Is a method for etching single crystal silicon as described in JP-A-3-104136. It is produced.
As described above, silicon is a material that easily wears, and wear is a major problem in terms of the probe material.

[0015] Apply Phys. Lett. Vol. 64 No. 19 (1994)
As described in PP.2498-2500 or JP-A-3-104136, dry etching is used to produce a boot-shaped probe made of single crystal silicon, but it is generally several μm or more. When dry etching is used to perform submicron patterning in the horizontal direction over the depth direction, there is a problem that the shape of the probe changes due to a slight shift in manufacturing conditions.

Further, in order to measure a measurement sample on the order of submicrons, it is necessary to use a finer probe, but it is extremely difficult to produce such a probe with good uniformity. Not only between wafers, but also within a single wafer, variations in shape occur depending on the location. This is easy considering the fact that we are trying to produce a thinner probe using a device equivalent to a dry etching device for producing semiconductor ICs with a pattern rule on the order of submicrons. Can understand.

The variation in the shape (dimensions) of the probe ultimately leads to an increase in cost in the manufacture of the probe, which is a serious problem. In other words, in order to measure a very fine uneven portion of the measurement sample, it is necessary to carefully inspect whether or not the probe is finished at least in a dimension smaller than the design dimension at the time of shipping, which increases the inspection cost. . Needless to say, variations in the shape of the probe lead to a considerable decrease in yield, which further increases the cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel scanning probe microscopic observation method for measuring a portion having a slope angle on a sample that is vertical or close to the sample, a novel scanning probe microscope using the same, and a novel scanning probe microscope using the same. Is to provide a simple probe.

[0019]

According to the scanning probe microscopic observation method of the present invention, at least a triangular cantilever-shaped elastic member having a triangular tip is vibrated to substantially trace a trajectory near a free end of the vibrating elastic member. As a typical probe, a change in the vibration state of the elastic member caused by the interaction between the substantial probe and the sample surface is detected, and based on the detected information, the vibration state of the elastic member is changed to a predetermined vibration state. While controlling the positional relationship between the sample surface and the elastic member so as to satisfy the following condition, the sample surface and the elastic member are relatively scanned to obtain information on the sample surface.

A probe for a scanning probe microscope according to the present invention comprises a support, a cantilever-like elastic member held by the support, and a probe provided at a free end of the elastic member. A detecting mechanism for detecting a vibration state of the elastic member, wherein the shape of the probe portion is a triangular flat plate, and a ridge line connecting the normal direction of the surface of the probe portion and two points at the tip thereof. Parallel.

The scanning probe microscope of the present invention comprises a probe for a scanning probe microscope as described above, vibration means for applying a vibration to the probe for a scanning probe microscope to obtain a substantial probe, Vibration detecting means for detecting a change in the vibration state of the scanning probe microscope probe based on the interaction between the substantial tip of the probe, and the substantial probe and the sample surface relatively Scanning means for scanning in a three-dimensional direction, and control means for controlling the scanning means so as to keep the interaction between the sample surface and the substantial probe constant according to information from the vibration detection means. And information processing means for obtaining the unevenness state of the sample surface based on a control signal from the control means.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. A scanning probe microscope probe according to an embodiment of the present invention will be described with reference to FIG. 1A is a side view of a probe for a scanning probe microscope, FIG. 1B is a perspective view of the probe, and FIG. 1C is an enlarged perspective view of a probe part of the probe.

As shown in FIGS. 1A and 1B, a probe 100 has a probe 103 at a free end of a cantilever (elastic member) 102 made of an elastic body extending from a support 101. Are formed. As can be seen from the enlarged view of FIG. 1C, the probe portion 103 has a flat plate triangular shape.
Three ridges terminate at the two vertices 106 and 107 at the tip. The ridge line connecting the surface normal direction of the triangular probe portion 103 and the two terminal points 106 and 107 at the tip is parallel. At the time of measurement, these two end points 106 and 107 or a ridge line connecting these two points acts as a substantial probe and interacts with the sample surface (for example, atomic force, contact force, etc.). Is generated. The actual probe will be described again later.

The cantilever-shaped elastic member 102 and the triangular probe 103 have the same surface normal direction, but different thicknesses and shapes. Elastic member 1
The thickness of 02 is a thickness suitable for obtaining a desired mechanical vibration characteristic such as a resonance frequency, and the thickness of the probe portion 103 is sufficiently small so as to be able to enter the concave portion of the sample.

Near the boundary between the elastic member 102 and the support 101, a detecting mechanism 104 for detecting the vibration state of the elastic member 102 is provided. A signal indicating the vibration state of the elastic member 102 detected by the detection mechanism 104 is extracted to the outside through two electrodes 105a and 105b shown in FIG. In FIG. 1A, two electrodes 1 are shown.
05a and 105b are typically indicated by one reference numeral 105.

The detection mechanism 104 is formed of, for example, a sensor utilizing the piezoresistance effect of silicon. However, the detection mechanism 104 is not limited to this, and other various elements may be applied. For example, a sensor using the piezoresistive effect of polysilicon can be used instead of the above-described sensor, or a sensor using a piezoelectric effect such as zinc oxide or PZT (lead zirconate titanate) can be used. It is also possible to apply. In general, sensors utilizing the piezoresistive effect have the advantage of being easy to fabricate, while sensors utilizing the piezoelectric effect have the advantage of low thermal noise, high sensitivity, and high frequency bandwidth. doing.

The typical dimensions of the probe 100 actually manufactured are as follows. The strip-shaped cantilever-shaped elastic member 102 has a length of 80 μm, a width of 30 μm, a thickness of 4.5 μm, and a flat triangular probe. The portion 103 has an axial length of 10 μm, a base width of 5 μm, and a thickness of 0.2 μm. The elastic member 10
The mechanical resonance frequency of the cantilever-shaped portion combining the probe 2 and the probe 103 is about 600 kHz, and the probe 103 having a triangular flat plate has a higher mechanical resonance frequency.

The elastic member 102 is optimally designed according to the frequency band of the measuring circuit, but has a length of 20 to 300.
μm, the width is about 10 to 80 μm, and the thickness is about 1 to 8 μm. The probe section 103 is designed in consideration of the resonance frequency of the elastic member section 102 and the shape of the measurement sample. A value smaller than the width of the concave portion of the sample is selected for the thickness dimension, and the axial length is selected. Has a width of 3 to 20 μm, a base width of 2 to 15 μm, and a thickness of 0.05 to 0.5 μm.

Next, the positional relationship between the probe and the sample will be described with reference to FIG. FIG. 2A shows an arrangement state of the probe at the time of measurement of the sample surface, and FIG. 2B shows an enlarged view of the vicinity of a probe portion of the probe.

As shown in FIG. 2A, the probe 1
00 indicates that the axial direction of the probe portion 103 (therefore, the axial direction of the elastic member portion 102) corresponds to the sample 2 placed on the sample stage 202.
01 is fixed to the probe holding member 203 so as to be parallel to the average surface normal direction. Probe holding material 20
3, an electrode pattern 204 is formed by printing, and this electrode pattern 204 is electrically connected to the electrode 105 of the probe 100 via a wire 208. Accordingly, a signal from the detection mechanism 104 reflecting the vibration state of the elastic member 102 is guided to the vibration detection circuit (indicated by reference numeral 432 in FIG. 4B) via the electrode pattern 204.

In practice, the probe 100 has two electrodes 105a and 105b as shown in FIG. 1 (b). Therefore, the probe holding member 203 also has two electrode patterns, each of which has a separate electrode pattern. Electrode 10 through wire
2A, one of the electrodes of the probe 100 is represented by reference numeral 105, one of the wires is represented by reference numeral 208, and one of the electrode patterns of the probe holding member 203 is represented by reference numeral 204 in FIG. Is shown in

On the opposite side of the probe holding member 203, an electrode pattern 206 is formed by printing, and a piezoelectric body 205 is adhered. The electrode 207 on the opposite side of the piezoelectric body 205 is connected via a wire 209 to another electrode (not shown) formed on the probe holding member 203. The piezoelectric body 205 is connected to a piezoelectric body driving circuit (designated by reference numeral 433 in FIG. 4B) via these electrode patterns, receives an AC voltage generated by the piezoelectric body driving circuit, and The elastic member 102 and the probe 103 are excited at a frequency near the resonance frequency.

As shown in FIG. 2B, the thickness of the elastic member 102 is substantially equal to the width between the two projections of the sample 201, and the elastic member 102 enters the concave portion of the sample 201. Although the thickness of the probe part 103 cannot be
The probe portion 103 can enter between the two protrusions of the sample 201. In addition, since the probe portion 103 has a flat plate shape and is substantially raised from the inclination angle of the two projections of the sample 201 when viewed from the direction of the drawing, the sample 2
01 can reach the root of the two protrusions.

Two end points 106 at the tip of the probe 103
A ridge line connecting one or both of 107 and 107 comes closest to the sample 201, and a portion closest to the sample 201 acts as a site that causes interaction. In FIG. 2B, the sample 2
The terminal point 107 is located closest to the side wall of the right protrusion of FIG. 01, and this acts as a site that causes an interaction. However, the terminal point 106 is closest to the side wall of the right protrusion of the sample 201. , Which act as sites for causing interaction. In addition, two terminal points 106 and 10 are provided on the bottom surface between the two protrusions of the sample 201.
The ridge connecting 7 is located closest, which acts as a site for causing interaction.

Next, the scanning probe microscopic observation method of the present invention will be described with reference to FIG. FIG. 3A shows the state of the probe vibrating in the fundamental mode.
(B) shows the state of the probe vibrating in a higher-order mode, FIG. 3 (c) shows the state of the vibrating cantilever at the moment, and FIG. 3 (d) vibrates. It shows how the cantilever is seen at a time interval of one cycle or more. In these figures, the elastic member portion and the probe portion are shown as one cantilever in order to clearly show the state of vibration.

In FIG. 3A, when the piezoelectric body 303 is excited, its vibration energy is transmitted to the cantilever 302 via the support 301. When this matches the resonance mode of the cantilever 302, the cantilever 302
Vibration occurs in the fundamental mode as shown in FIG. 3A, or in a higher mode as shown in FIG. 3B.
The free end of the cantilever 302 has a maximum amplitude, and in an actual scene, this amplitude is set to about 0.005 to 0.3 μm.

As shown in FIG. 3C, the shape of the vibrating cantilever 302 at the moment is a very thin triangular plate, but it is longer than one cycle of the vibration. The trajectory of the cantilever beam 302 as viewed in time has a shape in which the free end has an increased thickness, as shown in FIG.

In the scanning probe microscopic observation method of the present invention,
The trajectory of the vibrating cantilever 302 is regarded as a substantial probe, and observation of the sample surface is performed based on the interaction between the substantial probe and the sample surface.

As shown in FIG. 3D, the substantial probe has two vertices 303 and 304 and an arc-shaped ridge connecting these two points. Such a shape can be obtained only by vibrating the cantilever beam 302, and it is extremely difficult to produce this shape as one solid using a semiconductor process.

Next, a scanning probe microscope according to the present invention will be described with reference to FIG. FIG. 4A shows a schematic configuration of a scanning probe microscope, and FIG. 4B shows a configuration of a controller.

As shown in FIG. 4A, the probe 1
00 is arranged to face the sample 401. On the apparatus base 407, a coarse movement stage including a rotary stage 402, an X coarse movement stage 403, and a Y coarse movement stage 405 is provided, on which a sample 401 is held.
The X coarse movement stage 403 and the Y coarse movement stage 405 are driven by the X coarse movement stage drive mechanism 404 and the Y coarse movement stage drive mechanism 406 based on a control signal from the computer 419, whereby the probe 100 and the sample 40 are moved.
1 can adjust the relative position in the horizontal direction. The rotary stage 402 is also driven by a drive mechanism (not shown) based on a control signal from the computer 419, and thereby the normal direction of the surface of the probe 103 of the probe 100 and the measurement pattern on the sample 401 to be measured. Can be adjusted relative to the extension direction.

The probe 100 is attached to the scanner 411 via the holding member 417, and the scanner 411 is adhered and held by the scanner holding member 410. The scanner holding member 410 is attached via a Z coarse movement stage 409 to a column 408 erected on an apparatus base 407. By moving the Z coarse movement stage 409 up and down, the scanner holding member 410, the scanner 411, and the probe 10
0 moves up and down together, so that the distance between the probe 100 and the sample 401 can be adjusted.

The scanner 411 is a tube-type scanner made of a piezoelectric material, and transmits control drive signals from a controller 418 and a computer 419 to the scanner electrode 412.
To cause slight movement in the XY and Z directions.
Thus, the probe 100 supported by the scanner 411
Can be scanned with respect to the sample 401.

X displacement sensor 414 and Y displacement sensor 4
16 is held by an X displacement sensor holding section 413 and a Y displacement sensor holding section 415 fixed to the scanner holding member 410, respectively. For this reason, the X displacement sensor 414 and the Y
The displacement sensor 416 moves up and down together with the scanner 411,
Its relative position does not change and remains constant. Scanner 4
The movement of 11 is monitored by the X displacement sensor 414, the Y displacement sensor 416, and the like, and the output from them is taken into the controller 418 or the computer 419.

In the controller 418, as shown in FIG. 4 (b), various functional units, specifically, the probe 1 based on a control signal from a computer 419.
Piezoelectric body driving circuit 4 for vibrating 00 at a predetermined frequency
33, a vibration detection circuit 432 that amplifies a signal from the detection mechanism unit 104 of the probe 100 and detects a change in the vibration state of the elastic member unit 102, and outputs a signal from the vibration detection circuit 432 to a certain set value supplied from the computer 419. The scanner 411 is driven in the X and Y directions based on signals from the servo circuit 435 that drives and controls the scanner 411 in the Z direction, the Z drive circuit 431 that drives the scanner 411 in the Z direction, and the XY scanning waveform generation circuit 436 so that the scanner 411 is maintained. An XY drive circuit 430 for driving, a coarse movement stage drive circuit 434 for driving the coarse movement stages 403 and 405, and the like are included. Further, due to the configuration of the coarse movement stage, for example, the coarse movement stage drive circuit 434 may have a function of driving the rotary stage 402 (shown in FIG. 4B). Further, the computer 419 controls the servo circuit 4 of the controller 418.
Calculates the unevenness of the sample surface based on the 35 control signals,
In addition to displaying on the monitor 420 which is a display means, it also functions as a command input device such as a keyboard.

As shown in FIGS. 2A and 4A, the probe 100 is arranged so that the axial direction of the probe 103 is parallel to the average surface normal direction of the sample 401. . The piezoelectric member 205 for exciting the probe 100 includes the elastic member 102 and the probe 103 of the probe 100.
An AC voltage having a frequency near the resonance frequency is applied. As a result, the elastic member 102 of the probe 100 and the probe 1
03 vibrates in a direction parallel to the average plane of the sample 401.

While the probe 100 is excited, the sample 40
1 and between the tip of the probe portion 103 (strictly, the vertices of the substantial probe indicated by reference numerals 303 and 304 in FIG. 3D or the ridge line connecting them) and the surface of the sample 401. When the interaction occurs, the side wall of the protrusion on the sample 401 is probed in the surface normal direction of the probe portion 103 (the direction parallel to the average surface of the sample), and the bottom surface between the protrusions on the sample 401 is probed. A force is applied in the axial direction of the needle portion 103 (in the direction of the normal to the average surface of the sample), and the vibration state of the elastic member portion 102 changes.

The change in the vibration state is detected by the detection mechanism 104 of the probe 100 and the vibration detection circuit 432. The servo circuit 435 drives and controls the position of the scanner 411 in the Z direction via the drive circuit 431 so as to keep this detection signal at a constant set value from the computer 419. The computer 419 transmits the control signal at this time to:
The sample 4 at the XY direction position of the probe 103 at that time
01 is acquired as position information in the Z direction, and the XY direction position and the Z direction position information are subjected to arithmetic processing to calculate the surface shape of the sample 401. The calculated surface shape is displayed on the monitor 420 as a three-dimensional image, for example.

By the way, in the conventional scanning probe microscope using a probe having a probe which protrudes almost perpendicularly from the free end of the cantilever, it is necessary to prevent the support portion of the probe from colliding with the sample. The probe is mounted on the device such that the cantilever extends obliquely downward. as a result,
The probe is supported in a posture in which the axis of the probe is inclined with respect to the average surface normal direction of the sample. Therefore, the obtained information depends on the inclination direction of the probe. For example,
The image obtained when measuring a sample that has symmetry with respect to the tilt direction of the probe (the direction parallel to the plane including the average axis of the sample and the probe axis) retains the symmetry in that direction. Instead, it becomes distorted with no symmetry.

However, in the scanning probe microscope of the present invention, as described above, the probe 100 is arranged such that the axis of the probe 103 is parallel to the average surface normal direction of the sample 401. Therefore, the information obtained does not depend on the tilt direction of the sample surface. Therefore, a measurement result of a sample having symmetry in the main scanning direction of the probe unit 103 (a direction parallel to the plane in FIG. 2B) is accurate without losing the symmetry.

Here, the difference between the scanning probe microscope of the present invention and the conventional shear force mode AFM will be described. Shear force mode AFM is disclosed in US Pat.
254854, etc., and can be said to be similar to the scanning probe microscope of the present invention only in that the probe is vibrated.

However, in the conventional shear force mode AFM, a probe whose tip is terminated at one point is used, and the radius of curvature of the tip is about 10 nm. Also,
Since the trajectory drawn by the tip of the vibrating probe lowers the lateral resolution, it is desirable that the width of the trajectory of the vibration of the probe tip be as small as possible as long as the vibration state of the probe can be detected.

As described above, the shear force mode AFM
Except that the probe is vibrated, the scanning of the present invention, in which the trajectory of the vibration of the probe part when the probe is vibrated is used as a substantial probe, and the shape characteristic is positively used, It is very different from a scanning probe microscope.

As can be seen from the above description, in the scanning probe microscope of the present embodiment, a portion having a vertical or near slope angle on the sample can be measured only by feedback control of the probe position only in the Z direction. Measurement can be performed in a short time.

In the present embodiment, the direction of the feedback control of the probe position is performed only in the Z direction. However, the vibration state of the probe is detected in more detail by using a lock-in amplifier in addition to the amplitude, and the phase is used. Based on this, it is also possible to move the probe position in a direction inclined from the Z direction. According to this, it is possible to measure not only the vertical wall but also the side wall of the sample having a portion that slightly overhangs.

The feedback control in this embodiment is performed so that the interaction between the sample and the probe is always kept constant during the sample measurement (scanning).
It is also effective to control the approach and separation of the sample and the probe at each measurement point.

That is, normally, measurement points (for example, 256 points or 512 points at equal intervals) are set on one scan line in sample measurement.
At the time of measurement, the probe is stopped at each of these measurement points, the probe and the sample are approached (approached), and after taking in the desired sample information, they are separated and moved to the next measurement point.
It is effective to perform the vertical movement of the probe using the scanner 411 described in the present embodiment.

Such control is repeatedly executed in the measurement (scanning) area of the sample, and can be used as sample surface information.
According to this measurement, when moving to each measurement point, the probe and the sample are moved while being separated from each other, so that it is possible to reduce a problem that the sample and the probe are unnecessarily contacted and damaged.

Hereinafter, a method for manufacturing the probe 100 will be described with reference to FIG. First, a single crystal silicon bonded wafer having a plane orientation (100) is prepared as a start wafer (FIG. 5A). The two single-crystal silicon layers 501 and 503 are attached to and bonded to an intermediate silicon oxide layer 502. The thickness of the active layer 501 is 1
Although a substrate having a thickness of 0 μm is used, it is thinned by etching to a thickness of 5.5 μm before proceeding to the next process.

After a portion 504 of the active layer 501 on this surface is etched by photolithography using dry etching, a silicon oxide film 505 is formed, and a square opening is formed again by photolithography. Further, after boron is diffused from the opening into the active layer 501 in a diffusion furnace, an annealing process is performed thereon to form the piezoresistive layer 50.
6 (FIG. 5B).

Next, after removing the silicon oxide layer 505 on the surface and depositing the silicon oxide layer 507 again, patterning is performed by photolithography, and openings are formed at two places on the piezoresistive layer 506. Resistance layer 5
6 is formed to take out an electrode (FIG. 5).
(C)).

Subsequently, as shown in FIG. 5D, a silicon nitride film 508 is deposited on the surface to a thickness of 0.2 μm by LP-CVD (low pressure chemical vapor deposition), and as shown in FIG. As shown, a portion 509 is patterned and removed. Thereby, the shape 510 of the probe part of the probe is approximately formed. Further, as shown in FIG. 5F, an opening 511 is formed by removing the silicon nitride film on the electrode lead-out portion of the piezoresistive layer 506 to expose a part of the piezoresistive layer 506.

As shown in FIG. 5G, after the electrodes are formed, the two openings on the piezoresistive layer 506, the electrode pattern 512, and the wiring pattern connecting them are made of chromium and gold using a lift-off process. Is vacuum-deposited and patterned.

Next, after a polyimide film is coated on the surface to form a protective layer 513 against a wet etching solution, wet anisotropic etching is performed with an aqueous potassium hydroxide solution using the silicon nitride layer 514 on the back surface of the wafer as a mask. The part 515 on the back side of the silicon wafer is melted. Next, the exposed silicon oxide layer 516 is removed with hydrofluoric acid (FIG. 5 (i)) to obtain a probe.

As shown in FIG. 5J, the probe is bonded to the probe holding member 519, and the electrode pattern 512 of the probe is connected to the electrode 517 of the probe holding member 519 by a wire 518. The probe holding member 519 is, for example, a ceramic plate, and the electrode 517 is formed by printing and patterning a gold paste. Although not shown, the periphery of the wire 518 is preferably sealed with a protective resin.

As described above, since the probe portion of the probe is formed by film deposition, the variation in the film thickness is kept within 10%, and the probe portion having the same shape can be easily formed. it can. In addition, this reduces the inspection cost and improves the yield, and provides a relatively inexpensive probe.

Further, since the probe portion is formed by film deposition,
A thin and high aspect ratio probe can be manufactured stably.
As a result, if the concave portion is wider than the thickness of the probe portion, it is possible to measure the side wall having a slope angle near 90 degrees.

Further, since the silicon nitride film is used as the material of the probe portion, a probe with less wear of the probe portion is provided, which improves the reproducibility of the measurement data. In addition, since the probe part and the elastic member part are parallel and form an integral cantilever, even if the thickness and shape of each are different and designed to the optimal shape for each purpose, manufacturing There are few problems that occur. Thus, the probe can be manufactured stably.

Further, since the mechanism for detecting the vibration state of the elastic member is integrated, there is no need to provide another sensor for the purpose outside, and the scanning probe microscope can be made compact and simple. As a result, it is possible to provide a stable device that is resistant to disturbance vibration having high rigidity.

When the probe is viewed parallel to the line connecting the two end points 106 and 107 of the probe, the shape of the probe is triangular, and its apex angle is as large as 5 to 30 degrees. There is no problem as long as the measurement target portion is limited to, for example, a place where the electrode pattern of the semiconductor IC is parallel, and it is possible to measure the roughness and the inclination angle of the side wall (vertical wall) of the step.

By using the trajectory of the tip of the probe when the probe is vibrated as a substantial probe, a probe whose shape is stable in the fabrication process can be used, and the probe can be vertically or nearly perpendicular to the sample. Measurement of a portion having a slope angle becomes possible.

Further, the probe is arranged so that the axis of the probe portion is parallel to the average surface normal direction of the sample, and the trajectory of the probe tip when the probe is vibrated is substantially the same as the probe. By using as, a portion having a vertical or close-to-slope angle on the sample can be measured with good symmetry.

Further, only by controlling the probe position in the Z direction by a control method equivalent to the conventional shear force mode, it is possible to measure a portion having a vertical or near-slab angle on the sample in a short time. Become. Also,
By controlling the probe position in a direction inclined from the Z direction, it becomes possible to measure a portion having a more inclined vertical wall.

[0074]

According to the present invention, by using the trajectory of the tip of the probe portion when the probe is vibrated as a substantial probe, the portion of the sample having a vertical or near-slab angle can be measured. A scanning probe microscopic observation method and a scanning probe microscope that enable the above are realized. Further, a low-cost probe to be used for this, which has less variation in shape at the time of manufacturing, is provided.

In the scanning probe microscopic observation method and the scanning probe microscope of the present invention, since the axis of the probe portion of the probe is parallel to the average normal direction of the sample, the unevenness of the sample surface is symmetric. Can measure well.

[Brief description of the drawings]

FIG. 1 shows a probe for a scanning probe microscope according to an embodiment of the present invention.

FIG. 2 shows a state at the time of measurement of the probe for a scanning probe microscope of FIG.

FIG. 3 is a diagram for explaining a scanning probe microscopic observation method according to the embodiment of the present invention.

FIG. 4 shows a scanning probe microscope according to an embodiment of the present invention.

FIG. 5 is a diagram for explaining a method of manufacturing the probe for a scanning probe microscope in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 100 Probe 101 Support part 102 Elastic member part 103 Probe part 104 Detection mechanism part

Claims (3)

[Claims] 1. A method according to claim 1, further comprising: vibrating a cantilevered elastic member having at least a triangular tip, and using a trajectory near a free end of the vibrating elastic member as a substantial probe. The change in the vibration state of the elastic member caused by the interaction between the two members is detected, and the positional relationship between the sample surface and the elastic member is adjusted so that the vibration state of the elastic member becomes a predetermined vibration state based on the detected information. A scanning probe microscopic observation method in which the sample surface and the elastic member are relatively scanned while controlling the information to obtain information on the sample surface. 2. A support, a cantilever-like elastic member held by the support, a probe provided at a free end of the elastic member, and detecting a vibration state of the elastic member. A probe for a scanning probe microscope, wherein the probe has a triangular flat plate shape, and a ridge line connecting two points at the tip of the probe is parallel to a surface normal direction of the probe. . 3. A probe for a scanning probe microscope according to claim 2, vibration means for applying a vibration to the probe for a scanning probe microscope to obtain a substantial probe, Vibration detection means for detecting a change in the vibration state of the probe for a scanning probe microscope based on the interaction between the tip of the probe and the three-dimensional direction relative to the substantial probe and the sample surface A control unit that controls the driving unit so as to keep the interaction between the sample surface and the substantial probe constant according to information from the vibration detection unit; and the control. A scanning probe microscope having information processing means for obtaining the unevenness of the sample surface based on a control signal from the means.