JP4785537B2 - Probe, scanning probe microscope, and probe manufacturing method - Google Patents

Description

The present invention relates to a probe suitable for observation of a sample surface , in particular , measurement of thermophysical properties in a minute region of the sample surface , a scanning probe microscope, and a probe manufacturing method .

Currently, a scanning probe microscope (SPM: Scanning Probe Microscope) is used as a microscope for observing a nanometer-order minute region on the sample surface. Among these SPMs, an atomic force microscope (AFM) that uses a cantilever provided with a probe at the tip as a scanning probe has attracted particular attention. This atomic force microscope scans a cantilever probe along the sample surface, and detects the atomic force (attraction or repulsive force) generated between the sample surface and the probe as the amount of deflection of the cantilever. Surface shape measurement is performed. There are two types of cantilevers: optical lever type and self-detecting type because of the difference in the measurement method of the amount of deflection. In such a scanning probe microscope, in recent years, a method has been proposed for measuring the temperature distribution in a minute region of the sample surface as well as the uneven shape of the sample surface (see, for example, Patent Document 1 or 2).
JP-A-8-105801 JP 2001-4455 A

  However, in the probe of the above-mentioned patent document 1, a spindle-shaped groove is formed by etching the silicon substrate and the probe is formed along the shape of the groove. Due to restrictions in the manufacturing process, the shape of the probe is a cone with a large diameter at the root and a sharp tip. For this reason, there is a problem that it is difficult to form a probe having a high aspect ratio ((probe height) / (probe root diameter)).

  When using a probe with such a low aspect ratio, for example, when observing a surface shape having a substantially vertical surface, the side surface of the cone-shaped probe comes into contact with the substantially vertical surface, which is accurate. There was a problem that the surface shape and temperature distribution could not be observed.

  Further, in the probe of Patent Document 2, since a nickel fine wire is used as a cantilever and a probe, the diameter of the root portion of the probe becomes large, and it is difficult to obtain a probe with a high aspect ratio.

  The present invention has been made to solve the above-described problems, and is capable of observing the surface shape of a sample having irregularities with a high aspect ratio with high sensitivity and detecting the temperature characteristics of the sample. It is to provide a probe that is possible.

  In order to solve the above problems, the present invention proposes the following means.

  The probe of the present invention has a cantilever having an insulating layer on the surface, a first metal structure provided on the top surface of the cantilever and having a first end at the tip of the cantilever, and a first metal structure on the top surface of the cantilever. A second metal structure having a second end at the tip of the cantilever, and a first probe base formed in a bar shape on the upper surface of the first end. And a second probe base formed in a bar shape on the upper surface of the second end, and connected to the first probe base and the second probe base. Provided on the upper surface of the first end portion of the first metal structure connected to the first electrode provided at the base end portion of the cantilever, and formed in a rod shape. The first probe base and the second electrode provided at the base end of the cantilever and spaced apart from the first electrode A second probe base portion formed in a bar shape on the upper surface of the second end portion of the second metal structure that is connected to the first end portion and spaced apart from the first probe base portion, and a first probe base portion And a temperature measuring element provided on the upper surface of the second probe base, electrically connecting the first probe base and the second probe base, and comprising a sharpened probe tip. It was decided to have a probe part that also served as a part.

  According to the probe of the present invention, since the temperature measuring element is disposed immediately below the tip of the probe, that is, in the vicinity of the tip of the probe, the surface shape of the sample is measured and the temperature characteristic of the sample is accurately measured. Can be measured. In addition, since the shape is columnar from the probe base to the tip of the probe, the probe can have a high aspect ratio, and therefore can accurately follow and measure irregularities with a high aspect ratio.

  In the above probe, it is preferable that the tip end portion of the probe is made of the same material as the first probe base portion.

  According to the probe of the present invention, since the material constituting the probe tip is the same as the material constituting the first metal structure, the temperature measuring element formed by joining different materials is the same as the probe tip and the second tip. It is formed only at the joint of the probe base. For this reason, a measurement error of temperature characteristics due to the formation of a joint between different materials at the tip of the probe and the first probe base or between the tip of the probe and the second probe base. Therefore, stable measurement results can be obtained.

  Alternatively, in the above probe, the tip end portion of the probe may be made of the same material as that of the second probe base portion.

  According to the probe of the present invention, since the material constituting the probe tip is the same as the material constituting the second metal structure, the temperature measuring element formed by joining different materials is the same as the probe tip and the first tip. It is formed only at the joint of the probe base. For this reason, a measurement error of temperature characteristics due to the formation of a joint between different materials at the tip of the probe and the first probe base or between the tip of the probe and the second probe base. Therefore, stable measurement results can be obtained.

The scanning probe microscope of the present invention includes a probe, the displacement data of the probe portion which is displaced in response to the sample surface shape by the probe portion is brought closer to the surface to be measured of the sample to scan the sample surface Displacement detecting means for detecting, moving means for performing scanning in two directions perpendicular to each other and a direction perpendicular to the surface of the sample parallel to the surface of the sample relative to the sample, and for temperature measurement And a thermoelectromotive force detector that detects a thermoelectromotive force of the element.

  According to the scanning probe microscope of the present invention, a probe having a high aspect ratio and serving as both a temperature measuring element and a probe for measuring a sample surface shape is mounted. For this reason, it is possible to measure the shape, temperature distribution, and thermal characteristics of the sample surface microregion having irregularities with a high aspect ratio on the surface with high sensitivity.

  In addition, the scanning probe microscope of the present invention includes an excitation unit that resonates or forcibly vibrates the probe unit at a vibration frequency, and the displacement detection unit is a vibration detection unit that detects a vibration state of the probe unit.

  According to the scanning probe microscope according to the present invention, when measuring the surface shape of a sample by vibrating a cantilever such as a DFM (Dynamic Force Mode), the resonance frequency of the cantilever is increased, and the interaction with the sample is highly sensitive. Can be measured.

  In the probe of the present invention, the displacement detection means is provided in the cantilever.

  Further, the displacement detecting means is a piezoresistive element.

  According to the probe of the present invention, since it is not necessary to provide the cantilever with a reflecting surface for reflecting the laser light, it is not necessary to be restricted by the shape of the cantilever, the degree of freedom in designing the probe is improved, and it is easy to manufacture. In addition, since a large-scale device such as a laser light source is unnecessary, the device cost and the device space can be reduced.

  The probe of the present invention includes a step of forming a cantilever by cutting a silicon substrate, a step of forming an insulating film on the upper surface of the cantilever, and a first metal structure on the upper surface of the insulating film on the tip end side of the cantilever. Forming a first end of the body, forming a second end of the second metal structure on the upper surface of the insulating film on the tip end side of the cantilever, and forming an electric current on the upper surface of the first end. The first probe base is formed by casting, the second probe base is formed by electroforming on the upper surface of the second end, and the upper surfaces of the first probe base and the second probe base In addition, the tip of the probe is formed in such a manner that the first probe base and the second probe base are physically and electrically connected to each other by electroforming, thereby forming a probe portion that also serves as a temperature measuring element. Cutting the tip of the probe by electrolytic polishing, cutting the silicon substrate, Forming a main body portion to the base end of the lever, it was to consist of.

According to the manufacturing method of the pulp lobes involved in the present invention, by forming by electroforming probe portion, accurately and a high probe aspect ratio it has been difficult in the conventional production method readily prepared It becomes possible to do.

  Further, by sharpening using a technique such as electropolishing, it becomes possible to observe the temperature characteristics and irregularities of the micro-area of the sample surface with high resolution.

  According to the present invention, a sharpened probe having a high aspect ratio can be obtained. Further, since the temperature measuring element is formed in the vicinity of the sample, it is possible to accurately measure the shape, temperature distribution, and thermal characteristics of a minute region on the sample surface having unevenness with a high aspect ratio.

  Embodiments of the present invention will be described below.

  1 to 12 show an embodiment according to the present invention. FIG. 1 shows a block diagram of a scanning probe microscope. 2 is a perspective view of the probe, FIG. 3 is a plan view, and FIGS. 4 and 5 are cross-sectional views. 6 to 12 show process diagrams of the probe manufacturing process.

As shown in FIG. 1, a scanning probe microscope 1 includes a sample support unit 9 that supports a sample 100, a sample moving unit 3 that moves the sample 100, and a sample upper surface S of the sample 100 that is relatively moved by the sample moving unit 3. And a probe 20 having a probe portion 21 to be scanned, and a vibrating means 51 that vibrates the probe portion 21 of the probe 20 at a frequency at which the cantilever 22 resonates or forcibly vibrates. The probe 20 includes a cantilever 22 provided with a probe portion 21 protruding from a distal end portion, and a main body portion 23 that fixes the proximal end portion of the cantilever 22 in a cantilever state so that the distal end portion is a free end. .
The sample moving means 3 supports the sample supporting portion 9 and moves in the X and Y directions which are two directions parallel to the sample upper surface S and perpendicular to each other and the Z direction which is a direction perpendicular to the sample upper surface S. And a driving device 4 for driving the sample moving means 3. More specifically, the sample moving means 3 includes a coarse movement mechanism that coarsely moves the sample 100 in the X, Y, and Z directions, an XY scanner that finely moves the sample 100, and a Z scanner. An example of the driving device 4 corresponding to the coarse movement mechanism is a stepping motor. Further, the driving device 4 corresponding to the XY scanner and the Z scanner is a piezoelectric element made of, for example, PZT (lead zirconate titanate) or the like. It is possible to slightly move 100 in the XYZ directions. The vibration means 51 is connected to the probe 20 to vibrate the probe 20 so as to vibrate at a predetermined frequency and amplitude, and the excitation means 51 applies a voltage to the piezoelectric element to vibrate the piezoelectric element. A vibration power source 5 is provided.
Further, as shown in FIG. 1, the scanning probe microscope 1 includes a displacement detection unit 6 that detects a vibration state of the probe portion 21 of the probe 20 vibrated by the vibration unit 51. The displacement detector 6 includes a laser light source that irradiates a laser beam onto a reflective surface (for example, formed by coating a metal material such as gold or aluminum: not shown) formed on the back surface of the probe unit 21, and a laser light source A laser power source that is a power source and a photodiode that detects the laser light reflected by the reflecting surface are provided. The laser beam detected by the photodiode is output as a DIF signal, amplified by a preamplifier, converted to DC by an AC-DC converter, and sent to the computer 7. The computer 7 is provided with a Z voltage feedback circuit, which applies a voltage to the Z scanner of the sample moving means 3 based on the DIF signal input to the computer 7 to move the sample 100 minutely in the Z direction.
As shown in FIG. 1, the scanning probe microscope 1 includes a temperature characteristic detection unit 8 that is connected to the probe 20 and measures the thermoelectromotive force generated in the probe unit 21. Further, the computer 7 is connected to the driving device 4, the vibration power source 5, the displacement detecting means 6, and the temperature characteristic detecting unit 8 as described above.

  With the above configuration, the scanning probe microscope 1 measures the surface shape and temperature characteristics of the sample 100 as shown below. First, the excitation means 51 is vibrated by the excitation power source 5 under the control of the computer 7, and the laser beam is irradiated from the displacement detection means 6 to the reflection surface of the cantilever 22 of the probe 20. The cantilever 22 vibrates up and down by the vibration transmitted from the vibrating means 51, whereby the laser light reflected by the cantilever 22 and detected by the photodiode of the displacement detecting means 6 forms a vibration waveform having a constant amplitude and frequency. . In this state, the driving device 4 is driven under the control of the computer 7 to scan the sample 100 in the X and Y directions, and the surface shape and temperature characteristics of the sample 100 are measured. If there is unevenness at the position where the probe portion 21 of the probe 20 is scanned, the vibration amplitude of the laser light detected by the photodiode of the displacement detection means 6 is attenuated. This vibration amplitude is amplified by a preamplifier as a DIF signal, converted into a direct current by an AC-DC converter, and input to the computer 7. The computer 7 is provided with the aforementioned Z voltage feedback circuit. When the vibration amplitude converted into the DIF signal exceeds the threshold value, the drive device 4 is driven based on the input DIF signal, and the vibration amplitude is reduced. The sample moving means 3 is moved and adjusted in the Z direction so as to be constant within the threshold value. The surface shape of the sample 100 is measured by repeating this by moving the sample 100 in the X and Y directions by the driving device 4.

  Further, in parallel with the measurement of the surface shape of the sample 100, the thermoelectromotive force generated in the probe portion 21 is measured. The measurement results of the surface shape and temperature characteristics of the sample 100 are displayed by the computer 7 together with the scanning positions of the sample 100 in the X and Y directions.

Next, a detailed configuration of the probe 20 mounted on the scanning probe microscope 1 will be described.
FIG. 2 is an overall perspective view of the probe 20, but is described so as to be upside down with respect to the direction in which it is mounted on the scanning probe microscope 1.

  As shown in FIG. 2, the probe 20 is provided on the upper surface of the first metal structure 29, the second metal structure 30, and the first end 291 of the first metal structure 29, and has a rod shape. The first probe base portion 292 formed and the second probe base portion 302 formed on the upper surface of the second end portion 301 of the second metal structure 30 and formed in a rod shape are sharpened. The tip 21 of the probe, the cantilever 22 provided with the probe 21 protruding from the tip, and the base end of the cantilever 22 are cantilevered so that the tip is a free end. And a main body portion 23 to be fixed. The cantilever 22 and the main body 23 include a silicon substrate, in particular, a silicon active layer 24 and a silicon support layer 25 made of silicon, and a BOX layer 26 made of SiO 2 interposed between the silicon active layer 24 and the silicon support layer 25. It is formed from a bonded SOI substrate 27 (Silicon on Insulator).

  Further, as shown in FIGS. 3, 4 (cross section AA ′ in FIG. 3) and FIG. 5 (cross section CC ′ in FIG. 3), an insulating film 28 is formed on the surface of the cantilever 22. On the top, a first metal structure 29 and a second metal structure 30 are formed from the front end portion to the base end portion. The insulating film 28 is a silicon oxide film made of SiO2. The first metal structure 29 is a metal film made of chromium, and the second metal structure 30 is a metal film made of nickel. The first metal structure and the second metal structure are not limited to chromium and nickel, but may be any material that can form a thermocouple, such as gold, platinum, platinum rhodium, nichrome, chromel, and alumel. . The probe portion 21 is provided so as to protrude on the front end portion of the surface of the cantilever 22, the first end portion 291 of the first metal structure 29, and the second end portion 301 of the second metal structure 30. The first probe base 292 is formed in a bar shape, the second probe base 302 is also formed in a bar shape, and the probe tip 70 is sharpened. The first probe base 292 is made of chromium and has conductivity. The material for forming the first probe base 292 is not limited to chromium, but may be any material that can be formed by an electroforming method described later, such as gold, copper, rhodium, palladium, tungsten, and the like. The second probe base 302 is made of nickel and has conductivity. The material for forming the second probe base 302 is not limited to nickel, but may be any material that can be formed by an electroforming method to be described later, such as gold, copper, rhodium, palladium, tungsten, and the like. The probe tip 70 is made of nickel and has electrical conductivity. The material forming the probe tip 70 is preferably formed of the same material as the first probe base 292 or the second probe base 302. The material to be formed is not limited to nickel or chromium, and any material that can be formed by an electroforming method to be described later may be used. For example, gold, copper, rhodium, palladium, tungsten, or the like may be used.

  In the probe 20 of this embodiment, the probe tip 70 is directly formed on the first probe base 292 and the second probe base 302 by electroforming, so the temperature of the sample is the first temperature. The temperature characteristic detecting means 8 shown in FIG. 1 is used to transmit a state with little loss to the probe portion 21 also serving as a temperature measuring element formed by the probe base portion 292, the second probe base portion 302, and the probe tip portion 70. The temperature characteristic of the sample 100 can be measured. In addition, since the tip portion 21 is sharpened and the base portion is formed in a rod shape, the probe portion 21 can be a probe portion having a high aspect ratio. For this reason, even if the sample 100 has a surface shape having unevenness with a high aspect ratio, the probe unit 21 accurately follows the unevenness, and measures the depth and width of the unevenness with high accuracy. An observation image can be obtained. Furthermore, it is possible to measure the temperature characteristics of the deeply uneven portion.

Next, a method for manufacturing the probe 20 of this embodiment will be described. As described above, the cantilever 22 and the main body 23 of the probe 20 are formed from the SOI substrate 27 including the silicon active layer 24, the BOX layer 26, and the silicon support layer 25. Here, the thickness of the silicon active layer 24 is set to the thickness of the cantilever 22, and the thicknesses of the BOX layer 26 and the silicon support layer 25 are set to the thickness of the main body portion 23. Hereinafter, it demonstrates in order.
As shown in FIGS. 6A to 6C, the cantilever 22 is formed in the cantilever forming step. First, as shown in FIG. 6A, a photoresist film 31 is formed in a range where the cantilever 22 is formed by photolithography. Then, as shown in FIG. 6B, by using the photoresist film 31 as a mask, the silicon active layer 24 is etched until it reaches the BOX layer 26, whereby the silicon active layer 24 around the portion that becomes the cantilever 22 is cut out. . Then, by removing the photoresist film 32, the cantilever 22 is formed as shown in FIG. The photoresist film may be a positive type or a negative type. As a method for etching the cantilever 22, either dry etching or wet etching may be used, but dry etching is preferable. Examples of dry etching include reactive ion etching (RIE) and DRIE (Deep Reactive Ion Etching). In the case of wet etching, there is anisotropic etching using an alkaline etchant such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH).

  Next, as shown in FIG. 7A, an insulating film 28 is formed on the surface of the cantilever 22 in the insulating film forming step. The insulating film 28 is formed by a thermal oxidation method. At this time, the oxide film 33 is also formed on the back surface side of the cantilever 22, that is, on the surface of the silicon support layer 25 on the portion that becomes the main body portion 23. That is, as shown in FIG. 7A, the oxide film 33 is formed simultaneously with the formation of the insulating film 28 on the entire surface of the silicon support layer 25. Next, as shown in FIG. 7B, the back surface portion of the main body portion 23 and the entire side where the cantilever 22 is formed are patterned with a photoresist film 32. Then, as shown in FIG. 7C, the oxide film 33 other than the portion where the photoresist film 32 is patterned is removed by hydrofluoric acid, and finally, as shown in FIG. Remove.

  Next, as shown in FIGS. 8A to 8C, a first metal structure 29 and a second metal structure wiring 30 are formed on the insulating film 28 in the metal structure forming step. . First, as shown in FIG. 8A, a portion other than the portion that becomes the first metal structure 29 is patterned with a photoresist film 34. Next, as shown in FIG. 8B, a chromium film is formed on the entire surface by sputtering. Then, as shown in FIG. 8C, the first metal structure 29 is formed by removing the photoresist film 34.

In addition, the method of forming the chromium film used as the first metal structure 29 is not limited to the sputtering method, and may be an evaporation method. In addition, a chromium film is formed on the entire surface by sputtering or vapor deposition in advance, and a photoresist film is patterned on a portion that becomes the first metal structure 29. Subsequently, the first metal structure 29 may be formed by removing a portion of the chromium film where the photoresist film is not formed by etching.
Similarly, the metal structure 30 is also formed. A portion other than the portion that becomes the second metal structure 30 is patterned with a photoresist film. Next, a nickel film is formed on the entire surface by sputtering. Then, the second metal structure 30 is formed by removing the photoresist film.

  Note that the method for forming the nickel film to be the first metal structure 30 is not limited to the sputtering method, and may be a vapor deposition method. In addition, a nickel film is formed on the entire surface in advance by a sputtering method or a vapor deposition method, and a photoresist film is patterned on a portion to be the second metal structure 30. Subsequently, the second metal structure 30 may be formed by removing the nickel film where the photoresist film is not formed by etching.

Next, a probe portion is formed. In the probe portion forming step, the first probe base portion 292 is formed on the upper surface of the first end portion 291 of the first metal structure 29, and the second end portion 301 of the second metal structure 30 is formed. A second probe base 302 is formed on the upper surface of the first probe base, and a probe tip 70 is formed on the upper surfaces of the first probe base 292 and the second probe base 302.
The probe portion forming step is composed of two steps, a probe base portion forming step and a tip portion forming step.
FIGS. 9A to 9D show a probe base forming process. First, as shown in FIG. 9A, a photoresist film 35 having a thickness substantially equal to the height of the first probe base 292 is formed on the entire cantilever 22 side. As the photoresist film 35, there are a positive resist and a negative resist, but a negative resist in which a pattern of a portion irradiated with ultraviolet rays, an electron beam, a laser, or the like is preferable. For example, SU-8 (Kayaku Microchem Corporation) Company SU-8 series). Then, masking is performed at the position of the first probe base 292 so as to be equal to the cross-sectional shape of the base. Here, since the cross-sectional shape of the base portion is a quadrangular shape, masking is performed in a quadrangular shape. Then, as shown in FIG. 9B, the photoresist film 35 is exposed, and a developing solution is dropped to melt the unexposed range. Next, as shown in FIG. 9C, the first metal structure 29 is infiltrated into the electrolytic solution as one electrode, and chromium is electroformed into the hollow portion by electroforming, and the photoresist film 35 is formed. By removing, the second probe base 292 can be formed as shown in FIG.

  Although not shown, a photoresist film having a thickness substantially equal to the height of the second probe base 302 is formed on the entire cantilever 22 side in the same manner. As the photoresist film, there are a positive resist and a negative resist, but a negative resist in which a pattern of a portion irradiated with ultraviolet rays, an electron beam, a laser, or the like is preferable. For example, SU-8 (Kayaku Microchem Corporation) Manufactured SU-8 series). Then, masking is performed at the position of the second probe base 302 so as to be equal to the cross-sectional shape of the probe base. Here, since the cross-sectional shape of the probe base is quadrangular, it is masked into a quadrangular shape. Then, the photoresist film is exposed and a developer is dropped to dissolve the unexposed area. Next, the second metal structure 30 is infiltrated into the electrolyte as one electrode, nickel is electroformed into the cavity by electroforming, and the photoresist film is removed, thereby removing the second probe base 302. Can be formed.

FIGS. 10A to 10C show the tip portion forming step.
As shown in FIG. 10A, the photoresist film 36 is formed so that the tips of the first probe base 292 and the second probe base 302 (not shown) protrude. Next, the entire photoresist film 36 is exposed. Subsequently, a photoresist film 37 having a thickness of at least the height of the probe tip 70 is formed on the entire surface of the photoresist film 36. As the photoresist film 37, there are a positive resist and a negative resist, but a negative resist in which a pattern of a portion irradiated with ultraviolet rays, an electron beam, a laser or the like is suitable is suitable. For example, SU-8 (Kayaku Microchem Corporation Company SU-8 series). Next, as shown in FIG. 10B, a mask is masked at the position of the probe tip 70 in the range of the cross-sectional shape of the probe tip 70. Then, the photoresist film 37 is exposed to remove the mask. By doing so, an unexposed range including a polishing margin is formed in a range where the probe tip portion 70 is formed. A developer is dropped into the unexposed range to dissolve the unexposed range. Next, as shown in FIG. 10 (c), the tip of the probe is obtained by infiltrating the electrolytic solution with the second metal structure 30 as one electrode and electroforming nickel into the hollow portion by electroforming. 70 can be formed.
Next, the tip 70 of the probe exposed from the photoresist film 37 is sharpened by polishing the polishing margin by electrolytic polishing, and if the photoresist film 36 and the photoresist film 37 are removed, the tip is sharpened. Thus, the probe portion 21 whose base portion is rod-shaped is formed.

  Next, as shown in FIGS. 11A to 11C, the main body portion 23 is formed in the main body portion forming step. First, as shown in FIG. 11A, in order to protect the cantilever 22 on which the probe portion 21, the first metal structure 29, and the second metal structure 30 (not shown) are disposed, A photoresist film 38 is formed on the entire surface on the 22 side. Next, as shown in FIG. 12B, the silicon support layer 25 other than the main body 23 is etched using the oxide film 33 formed in the insulating film forming step as a mask. In this case, either dry etching or wet etching may be used, but wet etching is preferable. Then, as shown in FIG. 11C, the oxide film 33 and the BOX layer 26 other than the main body 23 are removed by hydrofluoric acid, and the photoresist film 38 is removed, thereby removing the probe 20 shown in FIG. Is produced.

  In the present embodiment, the cross-sectional shape of the probe base and the probe tip is a quadrangle, but is not limited to this, and may be any shape such as a circle or a semicircle.

13 to 23 show an embodiment according to the present invention. FIG. 13 shows a block diagram of a scanning probe microscope. FIG. 14 is a plan view of the probe, and FIGS. 15 to 22 are process diagrams of the probe manufacturing process. FIG. 23 shows an example in which a slit is formed at the base of the cantilever of this embodiment. In this embodiment, the same members as those used in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.
As shown in FIG. 13, the scanning probe microscope 2 according to the present embodiment includes a sample support unit 9 that supports the sample 100, a sample moving unit 3 that moves the sample 100, and a sample of the sample 100 by the sample moving unit 3. A probe 201 having a probe portion 21 that is relatively scanned on the upper surface S and an excitation means 51 that vibrates the probe portion 21 of the probe 201 at a frequency at which the cantilever 22 resonates or forcibly oscillates are provided. The probe 201 includes a cantilever 22 provided with a probe portion 21 projecting from a distal end portion, and a main body portion 23 that fixes a proximal end portion of the cantilever 22 in a cantilever state so that the distal end portion is a free end. .
The sample moving means 3 supports the sample supporting portion 9 and moves in the X and Y directions which are two directions parallel to the sample upper surface S and perpendicular to each other and the Z direction which is a direction perpendicular to the sample upper surface S. And a driving device 4 for driving the sample moving means 3. More specifically, the sample moving means 3 includes a coarse movement mechanism that coarsely moves the sample 100 in the X, Y, and Z directions, an XY scanner that finely moves the sample 100, and a Z scanner. An example of the driving device 4 corresponding to the coarse movement mechanism is a stepping motor. The driving device 4 corresponding to the XY scanner and the Z scanner is, for example, a piezoelectric element made of PZT (lead zirconate titanate) or the like. When a voltage is applied, a sample is applied according to the voltage application amount, polarity, etc. It is possible to slightly move 100 in the XYZ directions. The vibration means 51 is connected to the probe 201 to vibrate the probe 201 so as to vibrate at a predetermined frequency and amplitude, and the excitation means 51 applies a voltage to the piezoelectric element to vibrate the piezoelectric element. A vibration power source 5 is provided.

  Further, the displacement detecting means 60 for measuring the displacement of the probe portion 21 measures the displacement of the probe portion based on the resistance change detected by the piezoresistive element provided at the proximal end portion of the cantilever 22 and detecting the bending of the cantilever. It was supposed to be.

  FIG. 14 is an overall plan view of the probe 201, which is shown upside down with respect to the direction in which it is mounted on the scanning probe microscope 2. FIG.

  As shown in FIG. 14, the probe 201 includes a first metal structure 29 and a second metal structure 30, a probe portion 21 having a sharpened tip and a base formed in a rod shape, a probe A cantilever 22 provided with a needle portion 21 protruding from the distal end portion, and a main body portion 23 for fixing the base end portion of the cantilever 22 in a cantilever state so that the distal end portion becomes a free end. A piezoresistive element 40 for detecting the bending of the cantilever 22 is formed at the base end portion of the cantilever 22, and a piezoresistive element electrode wiring 41 for detecting a change in resistance of the piezoresistive element 40 is formed on the main body portion 23 of the cantilever 22. And 42 are formed. The cantilever 22 and the main body 23 include a silicon substrate, in particular, a silicon active layer 24 and a silicon support layer 25 made of silicon, and a BOX layer 26 made of SiO 2 interposed between the silicon active layer 24 and the silicon support layer 25. It is formed from a bonded SOI substrate 27 (Silicon on Insulator).

  Next, a method for manufacturing the probe 201 of this embodiment will be described. 16 and 18 are cross-sectional views taken along the line BB ′ of FIG. 14, and FIGS. 15, 17, and 19 to 23 are cross-sectional views taken along the line AA ′ of FIG.

As described above, the cantilever 22 and the main body 23 of the probe 201 are formed from the SOI substrate 27 including the silicon active layer 24, the BOX layer 26, and the silicon support layer 25. Here, the thickness of the silicon active layer 24 is set to the thickness of the cantilever 22, and the thicknesses of the BOX layer 26 and the silicon support layer 25 are set to the thickness of the main body portion 23. Hereinafter, it demonstrates in order.
As shown in FIGS. 15A to 15C, the cantilever 22 is formed in the cantilever forming step. First, as shown in FIG. 15A, a photoresist film 31 is formed in a range where the cantilever 22 is formed by a photolithography technique. Then, as shown in FIG. 15B, by using the photoresist film 31 as a mask, the silicon active layer 24 is etched until it reaches the BOX layer 26, whereby the silicon active layer 24 around the portion that becomes the cantilever 22 is cut out. . Then, by removing the photoresist film 31, the cantilever 22 is formed as shown in FIG. The photoresist film may be a positive type or a negative type. As a method for etching the cantilever 22, either dry etching or wet etching may be used, but dry etching is preferable. Examples of dry etching include reactive ion etching (RIE) and DRIE (Deep Reactive Ion Etching). In the case of wet etching, there is anisotropic etching using an alkaline etchant such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH).

  Next, as shown in FIG. 16, the piezoresistive element 40 is formed at the base end portion of the cantilever 22 in the piezoresistive element forming step. First, as shown in FIG. 16A, the entire side where the cantilever 22 is formed is patterned with a photoresist film 50. Next, as shown in FIG. 16B, the photoresist film 50 in a range where the piezoresistive element 40 is formed is removed by a photolithography technique. Then, as shown in FIG. 16C, by using the photoresist film 50 as a mask, boron is ion-implanted into the silicon active layer 24 to remove the photoresist film 50, so that the cantilever is shown in FIG. A piezoresistive element 40 is formed at the base end portion of 22. The photoresist film may be a positive type or a negative type.

  Next, as shown in FIG. 17A, an insulating film 28 is formed on the surface of the cantilever 22 in the insulating film forming step. The insulating film 28 is formed by a thermal oxidation method. At this time, the oxide film 33 is also formed on the back surface side of the cantilever 22, that is, on the surface of the silicon support layer 25 on the portion that becomes the main body portion 23. That is, as shown in FIG. 17A, the oxide film 33 is formed simultaneously with the formation of the insulating film 28 on the entire surface of the silicon support layer 25. Next, as shown in FIG. The back surface of the main body 23 and the entire side where the cantilever 22 is formed are patterned with a photoresist film 51. Then, as shown in FIG. 17C, the oxide film 33 other than the portion where the photoresist film 51 is patterned is removed by hydrofluoric acid, and finally, as shown in FIG. Remove.

  Next, as shown in FIGS. 18A to 18D, electrode wiring is formed on the piezoresistive element 40. First, as shown in FIG. 18A, the photoresist film 52 is used to pattern a portion other than the connection portion between the piezoresistive element 40 and the piezoresistive element electrode wires 41 and 42. Next, the portion of the insulating film 28 not protected by the resist is removed with hydrofluoric acid, and the resist 52 is further removed. Next, as shown in FIG. 18B, an aluminum film as an electrode wiring material is formed by sputtering on the entire surface of the cantilever 22 on which the piezoresistive element is formed, and as shown in FIG. 18C, the piezoresistive element is formed. A photoresist film 53 is formed on the portions to be the electrode wirings 41 and 42. As shown in FIG. 18D, the part of the aluminum film where the photoresist 53 is not formed is removed, and the photoresist film 53 is removed, thereby forming the piezoresistive element electrode wires 41 and 42.

The method of forming the piezoresistive element electrode wires 41 and 42 is not limited to the sputtering method, and may be a vapor deposition method. Further, a photoresist film 53 is formed in advance on the entire surface, and a portion of the photoresist film 53 where the piezoresistive element electrode wires 41 and 42 are to be formed is removed. Subsequently, an aluminum film may be formed by a sputtering method or a vapor deposition method, and then the photoresist film 53 may be removed to form the piezoresistive element electrode wirings 41 and 42.
Next, as shown in FIGS. 19A to 19C, a first metal structure 29 and a second metal structure wiring 30 are formed on the insulating film 28 in the metal structure forming step. . First, as shown in FIG. 19A, a portion other than the portion that becomes the first metal structure 29 is patterned with a photoresist film 54. Next, as shown in FIG. 19B, a chromium film is formed on the entire surface by sputtering. Then, as shown in FIG. 19C, the first metal structure 29 is formed by removing the photoresist film 54.

In addition, the method of forming the chromium film used as the first metal structure 29 is not limited to the sputtering method, and may be an evaporation method. In addition, a chromium film is formed on the entire surface by sputtering or vapor deposition in advance, and a photoresist film is patterned on a portion that becomes the first metal structure 29. Subsequently, the first metal structure 29 may be formed by removing a portion of the chromium film where the photoresist film is not formed by etching.
Although not shown, the metal structure 30 is also formed in the same manner. A portion other than the portion that becomes the second metal structure 30 is patterned with a photoresist film. Next, a nickel film is formed on the entire surface by sputtering. Then, the second metal structure 30 is formed by removing the photoresist film.

  Note that the method for forming the nickel film to be the first metal structure 30 is not limited to the sputtering method, and may be a vapor deposition method. In addition, a nickel film is formed on the entire surface in advance by a sputtering method or a vapor deposition method, and a photoresist film is patterned on a portion to be the second metal structure 30. Subsequently, the second metal structure 30 may be formed by removing the nickel film where the photoresist film is not formed by etching.

Next, a probe portion is formed. In the probe portion forming step, the first probe base portion 292 is formed on the upper surface of the first end portion 291 of the first metal structure 29, and the second end portion 301 of the second metal structure 30 is formed. A second probe base 302 is formed on the upper surface of the first probe base, and a probe tip 70 is formed on the upper surfaces of the first probe base 292 and the second probe base 302.
The probe portion forming step is composed of two steps, a probe base portion forming step and a tip portion forming step.
FIGS. 20A to 20D show a probe base forming process. First, as shown in FIG. 20A, a photoresist film 56 having a thickness substantially equal to the height of the first probe base 292 is formed on the entire cantilever 22 side. As the photoresist film 56, there are a positive resist and a negative resist, but a negative resist in which a pattern of a portion irradiated with ultraviolet rays, an electron beam, a laser, or the like is preferable. For example, SU-8 (Kayaku Microchem Corporation) Company SU-8 series). Then, masking is performed at the position of the first probe base 292 so as to be equal to the cross-sectional shape of the base. Here, since the cross-sectional shape of the base portion is a quadrangular shape, masking is performed in a quadrangular shape. Then, as shown in FIG. 20B, the photoresist film 56 is exposed and a developing solution is dropped to dissolve the unexposed range. Next, as shown in FIG. 20 (c), the first metal structure 29 is infiltrated into the electrolytic solution as one electrode, and chromium is electroformed into the hollow portion by electroforming, and the photoresist film 56 is formed. By removing, the second probe base 292 in FIG. 20D can be formed.

  Although not shown, a photoresist film having a thickness substantially equal to the height of the second probe base 302 is formed on the entire cantilever 22 side in the same manner. As the photoresist film, there are a positive resist and a negative resist, but a negative resist in which a pattern of a portion irradiated with ultraviolet rays, an electron beam, a laser, or the like is preferable. For example, SU-8 (Kayaku Microchem Corporation) Manufactured SU-8 series). Then, masking is performed at the position of the second probe base 302 so as to be equal to the cross-sectional shape of the probe base. Here, since the cross-sectional shape of the probe base is quadrangular, it is masked into a quadrangular shape. Then, the photoresist film is exposed and a developer is dropped to dissolve the unexposed area. Next, the second metal structure 30 is infiltrated into the electrolyte as one electrode, nickel is electroformed into the cavity by electroforming, and the photoresist film is removed, thereby removing the second probe base 302. Can be formed.

FIGS. 21A to 21C show the tip portion forming step.
As shown in FIG. 21A, a photoresist film 57 is formed so that the tips of the first probe base 292 and the second probe base 302 protrude. Next, the entire photoresist film 57 is exposed. Subsequently, a photoresist film 58 having a thickness of at least the height of the probe tip 70 is formed on the entire surface of the photoresist film 57. As the photoresist film 58, there are a positive resist and a negative resist, and a negative resist in which a pattern of a portion irradiated with ultraviolet rays, an electron beam, or a laser is preferably used. For example, SU-8 (Kayaku Microchem Corporation Company SU-8 series). Next, as shown in FIG. 21 (b), a mask is masked at the position of the probe tip 70 within the range of the cross-sectional shape of the probe tip 70. Then, the photoresist film 58 is exposed and the mask is removed. By doing so, an unexposed range including a polishing margin is formed in a range where the probe tip portion 70 is formed. A developer is dropped into the unexposed range to dissolve the unexposed range. Next, as shown in FIG. 21 (c), the tip of the probe is obtained by infiltrating the second metal structure 30 as one electrode into the electrolyte and electroforming nickel into the hollow portion by electroforming. 70 can be formed.
Next, the tip portion of the probe portion 21 exposed from the photoresist film 58 is sharpened by polishing the polishing margin by electrolytic polishing, and the photoresist film 57 and the photoresist film 58 are removed. The probe portion 21 is sharpened and the base portion has a rod shape.

Next, as shown in FIGS. 22A to 22C, the main body portion 23 is formed in the main body portion forming step. First, as shown in FIG. 22A, in order to protect the cantilever 22 on which the probe portion 21, the first metal structure 29, and the second metal structure wiring 30 are disposed, the entire surface on the cantilever 22 side is protected. Then, a photoresist film 59 is formed. Next, as shown in FIG. 22B, the silicon support layer 25 other than the main body 23 is etched using the oxide film 33 formed in the insulating film forming step as a mask. In this case, either dry etching or wet etching may be used, but wet etching is preferable. Then, as shown in FIG. 22C, the probe 201 is manufactured by removing the oxide film 33 and the BOX layer 26 other than the main body 23 by hydrofluoric acid and removing the photoresist film 59. In any of the embodiments described above, the cantilever 22 is formed in the above-described cantilever forming step, and the probe portion 21 is formed in the above-described probe portion forming step, thereby forming the cantilever 22 and the probe portion 21. Can be completely separated. For this reason, the cantilever 22 can be formed from the SOI substrate 27, and the probe portion 21 can be formed from nickel by electroforming. Furthermore, since the temperature measurement element forming step can be performed in a state where the probe portion 21 is not formed prior to the probe portion forming step, the first metal structure 29 and the second metal structure wiring are formed. 30 can be easily formed. In each of the above-described steps, patterning is performed by exposing the photoresist film. However, the present invention is not limited to this, and a direct drawing method using an electron beam or the like may be used.

  In the present embodiment, an example in which the first probe base and the second probe base are one each is shown, but the present invention is not limited to this. For example, the first probe base and the second probe are used. A so-called thermopile can be formed by forming a plurality of base parts and connecting them alternately in series. FIG. 23 is a perspective view of an example in which a thermopile is formed. FIG. 24 is a cross-sectional view of an example in which a thermopile is formed. Each is described so as to be upside down with respect to the direction mounted on the scanning probe microscope. A first metal structure 29 and a first connection part 293 are formed on the cantilever 22, and a first end 291 and a first connection part 293 of the first metal structure 29 are further provided on the first connection part 293. The probe base portion 292 and the second probe base portion 302 are formed in an alternating manner. The first probe base portion 292 and the second probe base portion 302 are electrically connected in series by the first connection portion 293 and the second connection portion 303. The probe tip 70 is formed on the second connection portion 303 with the insulating layer 60 interposed therebetween.

  According to this method, since the first probe base and the second probe base are connected in series, the thermoelectromotive force due to the temperature change is increased, and it is possible to perform highly sensitive temperature measurement. Become.

  In the present embodiment, the cross-sectional shapes of the probe base and the probe tip are rectangular, but the present invention is not limited to this and may be any shape such as a circle or a semicircle.

  Furthermore, as shown in FIG. 25, the base end portion of the cantilever 22 may have a slit 24S. As a result, the base end portion of the cantilever 22 has a structure that is easy to bend, thereby enabling measurement with higher accuracy.

As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
Although the cantilever and the main body of the probe are formed from an SOI substrate, the present invention is not limited to this, and a resin, semiconductor, glass, or metal coated with an insulating film may be used. Further, in the probe manufacturing process, the probe section forming process is divided into two processes of sharpening the tip and forming the base, but the present invention is not limited to this. It is also possible to change the cross-sectional shape of the base by further dividing the base into a plurality of steps.
In addition, although a DFM mode scanning probe microscope that measures the surface shape of the sample by applying vibration to the probe is used, the present invention is not limited to this, and the probe may be used in an AFM mode that directly measures the displacement of the probe portion. It is possible to measure unevenness with a high aspect ratio with high sensitivity.
In addition, the probe is provided with one probe portion, but the present invention is not limited to this, and a plurality of probe portions may be provided so as to project as an array. Further, the probe is not limited to that provided in the scanning probe microscope.

1 is a block diagram of a scanning probe microscope according to a first embodiment of the present invention. It is a perspective view of the probe of a 1st embodiment of this invention. It is a top view of the probe of a 1st embodiment of this invention. It is sectional drawing of the probe of 1st Embodiment of this invention. It is sectional drawing of the probe of 1st Embodiment of this invention. It is process drawing which shows the cantilever formation process of the probe of 1st Embodiment of this invention. It is process drawing which shows the insulating film formation process of the probe of 1st Embodiment of this invention. It is process drawing which shows the formation process of the metal structure of the probe of 1st Embodiment of this invention. It is process drawing which shows the probe part formation process (base part) of the probe of 1st Embodiment of this invention. It is process drawing which shows the probe part formation process (tip part) of the probe of 1st Embodiment of this invention. It is process drawing which shows the main-body part formation process of the probe of 1st Embodiment of this invention. It is process drawing which shows the main-body part formation process of the probe of 1st Embodiment of this invention. It is a block diagram of the scanning probe microscope of the 2nd Embodiment of this invention. It is a top view of the probe of a 2nd embodiment of this invention. It is process drawing which shows the cantilever formation process of the probe of 2nd Embodiment of this invention. It is process drawing which shows the piezoresistive element formation process of the probe of 2nd Embodiment of this invention. It is process drawing which shows the insulating film formation process of the probe of 2nd Embodiment of this invention. It is process drawing which shows the electrode wiring formation process for piezoresistive elements of the probe of 2nd Embodiment of this invention. It is process drawing which shows the formation process of the metal structure of the probe of 2nd Embodiment of this invention. It is process drawing which shows the probe part formation process (base part) of the probe of 2nd Embodiment of this invention. It is process drawing which shows the probe part formation process (tip part) of the probe of 2nd Embodiment of this invention. It is process drawing which shows the main-body part formation process of the probe of 2nd Embodiment of this invention. It is a perspective view of the probe which shows the example which made the temperature measuring element of this invention the thermopile (thermoelectric stack). It is sectional drawing of the probe which shows the example which used the temperature measuring element of this invention as the thermopile (thermoelectric stack). It is a top view of the probe of a 2nd embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Scanning probe microscope 3 Sample moving means 4 Drive apparatus 51 Excitation means 5 Excitation power supply 6, 60 Displacement detection element 7 Computer 8 Temperature characteristic detection means 9 Sample support part 20, 201 Probe 21 Probe part 22 Cantilever 23 Main body 24 Silicon active layer 24S Slit 25 Silicon support layer 26 BOX layer 27 SOI substrate (silicon substrate)
28 Insulating Film 29 First Metal Structure 291 First End 292 First Probe Base 293 First Connection 30 Second Metal Structure 301 Second End 302 Second Probe Base 303 Second connection portion 33 Oxide films 31, 32, 34, 35, 36, 37, 38, 50, 51
52, 53, 54, 55, 56, 57, 58, 59 Photoresist film 40 Piezoresistive element 41, 42 Electrode wiring for piezoresistive element 60 Insulating layer 70 Probe tip 100 Sample

Claims (9)

A cantilever having an insulating layer on the surface;
A first metal structure provided on an upper surface of the cantilever and having a first end at a tip of the cantilever;
A second metal structure provided on the upper surface of the cantilever and spaced apart from the first metal structure, and having a second end at the tip of the cantilever;
A first probe base formed in a bar shape on the upper surface of the first end portion; and provided on the upper surface of the second end portion so as to be separated from the first probe base portion; Formed on the upper surface of the formed second probe base, the first probe base, and the second probe base, and electrically connecting the first probe base and the second probe base. Connected to the tip of the pointed tip,
Help lobes having a. A cantilever having an insulating layer on the surface;
A first probe base formed in a bar shape on the upper surface of the first end of the first metal structure connected to the first electrode provided at the base end of the cantilever;
Provided on the upper surface of the second end of the second metal structure connected to the second electrode spaced apart from the first electrode at the base end of the cantilever and formed in a rod shape A second probe base,
A temperature provided on the upper surfaces of the first probe base and the second probe base and comprising a probe tip that electrically connects the first probe base and the second probe base. A probe portion also serving as a measuring element;
Help lobes having a. The probe tip, the first probe according to claim 1 or 2 made of the same material as the probe base. The tip of the probe is made of the same material as that of the second probe base .
Probe. And probe according to claim 2,
A displacement detection means for detecting displacement data of the probe portion that is displaced according to a sample surface shape by causing the probe portion to approach the surface to be measured of the sample and scanning the sample surface;
Moving means for performing scanning in two directions that are parallel to the surface of the sample relative to the sample and perpendicular to each other and moving in a direction perpendicular to the surface of the sample;
A thermoelectromotive force detector for detecting a thermoelectromotive force of the temperature measuring element;
A scanning probe microscope. Comprising vibration means for resonating or forcibly vibrating the probe portion at a vibration frequency;
The scanning probe microscope according to claim 5, wherein the displacement detection unit is a vibration detection unit that detects a vibration state of the probe unit .   The scanning probe microscope according to claim 5, wherein the displacement detection means is provided in the cantilever.   The scanning probe microscope according to claim 5, wherein the displacement detection means is a piezoresistive element. Cutting the silicon substrate and forming a cantilever;
Forming an insulating film on the upper surface of the cantilever;
A first end of the first metal structure is formed on the top surface of the insulating film on the tip end side of the cantilever, and a second metal structure is formed on the top surface of the insulating film on the tip end side of the cantilever. Forming the second end portion of the first end portion, forming a first probe base portion on the upper surface of the first end portion by electroforming, and forming the second end portion on the upper surface of the second end portion by electroforming. Forming a probe base, forming a probe tip on the upper surfaces of the first probe base and the second probe base by electroforming, and forming a temperature measuring element;
Sharpening the tip of the probe by electropolishing to form a probe, and cutting the silicon substrate to form a body on the base end side of the cantilever;
Method of manufacturing pulp lobes having a.

Images