JPH05248810A - Integrated afm sensor - Google Patents

Abstract

PURPOSE:To provide an integrated AFM displacement sensor which can measure a sample with high resolution. CONSTITUTION:An integrated AFM sensor 10 is provided with a cantilever part 12. The cantilever part 12 has two beams 12a, 12b extending from a supporting body 16. The ends of the two beams 12a, 12b are united to form a triangular free end. A probe 14 with a sharp edge is set at the free end. The cantilever part 12 is formed of a laminate of a passivation layer 24, a piezoelectric resistance layer 22 and a silicon layer 20. An electrode 18 electrically connected to the piezoelectric resistance layer 22 is provided via a contact hole 26 at the fixed end of the cantilever part 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated AFM sensor used in, for example, an atomic force microscope.

[0002]

2. Description of the Related Art A scanning tunneling microscope (STM; Scan) is used as an apparatus for observing a conductive sample with atomic resolution.
The Ning Tunneling Microscope was invented by Binnig and Rohrer et al. In this STM, the samples that can be observed are limited to those that are conductive. Therefore, the atomic force microscope (AFM) is used as a device that can observe an insulating sample with atomic resolution using STM elemental technology such as servo technology.
pe) was proposed. This AFM is disclosed in, for example, Japanese Patent Laid-Open No. 62-
130302.

The AFM is equipped with a cantilever having a sharply pointed protrusion (probe) at its free end. When the probe is brought close to the sample, the free end of the cantilever is displaced by the interaction force (atomic force) acting between the atom at the tip of the probe and the atom at the sample surface. Three-dimensional information of the sample is obtained by scanning the probe along the sample surface while electrically or optically measuring the displacement of the free end.
For example, if the probe is scanned while controlling the sample-to-sample distance so as to keep the displacement of the free end of the cantilever constant, the probe tip moves along the unevenness of the sample surface. A three-dimensional image showing the surface shape of the sample can be obtained from.

In the AFM, a displacement measuring sensor for measuring the displacement of the cantilever is generally provided separately from the cantilever. However, recently, an integrated AFM sensor in which the cantilever itself has a function of measuring displacement has been proposed by "M. Tortonese" et al.
This integrated AFM sensor is, for example, "M. Toronese, HY
anada, RCBarrett and CFQuate, Transducers and
Sensors'91: Atomic force microscopy using a piezore
sistive cantilever ”.

Since such an integrated AFM sensor has an extremely simple structure and is small in size, it is expected that a so-called stand-alone AFM that moves the cantilever side can be configured. In the conventional AFM, the sample is moved in the XY directions to change the relative positional relationship between the tip of the cantilever and the probe.
Although limited to about m, the stand-alone AFM has an advantage of being able to remove such a sample size limitation.

Next, FIG. 1 shows the integrated AFM sensor.
This will be described with reference to FIG. First, the manufacturing method will be described. As the start wafer 100, as shown in FIG. 17A, a silicon wafer 110 on which a silicon layer 114 is provided via a separation layer 112 of silicon oxide, for example, a bonded silicon wafer is prepared. Boron (B) is implanted into the extreme surface of the silicon layer 114 by ion implantation to form a piezoresistive layer 116, which is patterned into the shape shown in FIG. 17D, and then the surface is covered with a silicon oxide film 118. Then, a hole for bonding is opened on the fixed end side of the cantilever, and aluminum is sputtered to form the electrode 120. Further, a resist layer 122 is formed on the lower side of the silicon wafer 112.
Is formed, and the resist layer 122 is patterned to form an opening, as shown in FIG. Then, after heat treatment for making ohmic cook contact, the resist layer 1
The separation layer 112 is etched by wet anisotropic etching using 22 as a mask, and finally, the separation layer 112 below the cantilever portion 124 is etched with hydrofluoric acid to form the cantilever portion 124, thereby completing the integrated AFM sensor. The side sectional view is shown in FIG. 17C, and the top view is shown in FIG.
It shows in (d). In the integrated AFM sensor manufactured as described above, a DC voltage of several volts or less is applied between the two electrodes 120 during measurement, and the tip of the cantilever portion 124 is brought close to the sample. When an atomic force acts between the tip of the cantilever portion 124 and the atoms on the sample surface, the cantilever portion 124 is displaced. Accordingly, the piezoresistive layer 116 is
Since the resistance value of the electrode changes, the displacement of the cantilever portion 124 is obtained as a current signal flowing between the two electrodes 120.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Integrated AFM described above
In the displacement sensor, the free end of the cantilever portion is not provided with a probe, but the tip is formed in a triangular shape even though it has a flat plate structure, and the portion is brought close to the measurement sample to perform the AFM measurement. However, such measurement cannot be expected to have high resolution in the sample plane direction.

Further, in the conventional manufacturing method of the integrated AFM sensor, the supporting portion for holding the cantilever portion is also made of one silicon wafer, and the thickness and length of each portion can be standardized with high accuracy. There is a problem that you can not.

Specifically, the thickness of a silicon wafer is about 52 for a 4-inch diameter wafer which is the most widely available on the market.
It is 5 μm ± 20 μm, and there are variations. In the integrated AFM sensor described above, a silicon wafer is processed from the surface to form a U shape, and then etching is performed from the lower side of the silicon wafer to form a cantilever. But,
During this formation, it was not possible to avoid variations in the length of the cantilever corresponding to variations in thickness. As a result, there arises a problem that a high resolution sensor cannot be provided.

Recently, in a normal AFM which is not an integrated type, a conductive cantilever is used at the time of AFM measurement to monitor the tunnel current flowing between the sample and the probe while performing the AFM measurement. / ST
M simultaneous measurements are being performed. In addition, by detecting the electrostatic capacitance between the probe and the sample, AFM / SCaM (Scaninng CapaM)
citance Microscopy) measurement is also performed. However,
The conventional integrated AFM sensor has a problem that two or more types of signals cannot be captured with high resolution.

The present invention has been made to solve the above-mentioned requirements and harmful effects, and an object thereof is to provide an integrated AFM displacement sensor capable of measuring a sample with high resolution.

[0012]

In order to achieve such an object, the present invention provides an integrated AFM sensor including a cantilever portion provided with a piezoresistive layer whose resistance value changes according to displacement. The tip of the cantilever portion is provided with a probe that protrudes from the tip and is sharpened.

[0013]

The integrated AFM sensor of the present invention has a sharpened probe on the tip surface of the cantilever portion.
It is possible to obtain high resolution in both the vertical and horizontal directions during M measurement. Further, since the probe protrudes from the surface of the cantilever portion, there is little fear of contact with the sample, and the sensor can be arranged in parallel to the sample, so that the resolution is improved.

[0014]

EXAMPLE An integrated type A according to a first example of the present invention will be described below.
The FM displacement sensor will be described. In FIG. 1, (a) is a side sectional view, (b) is a top view, and (c) is a perspective view.

As shown in FIG. 1, the integrated AFM sensor 10 has a cantilever portion 12. The cantilever portion 12 has two beams 12 extending from the support portion 16.
It has a and 12b. These two beams 12a and 1
2b is integrated at the tip to form a triangular free end, and a probe 14 having a sharp tip is provided at this free end. The cantilever portion 12 is formed by the passivation layer 2
4, the piezoresistive layer 22 and the silicon layer 20 are laminated and formed. At the fixed end of the cantilever portion 12, an electrode 18 electrically connected to the piezoresistive layer 22 is provided via a contact hole 26.

In the integrated AFM sensor of the present invention, since the probe 14 is provided at the free end of the cantilever portion 12, high resolution can be obtained not only in the vertical direction but also in the horizontal direction. Further, in the conventional integrated type AFM sensor not provided with the above-mentioned probe, it was necessary to mount the sensor at a considerable angle so that the tip of the cantilever portion did not come into contact with the sample during measurement. In the integrated AFM sensor of, the probe 14 has the cantilever portion 1
Since it protrudes from the surface of No. 2, there is little concern about the contact, and the resolution can be improved because the sensor can be arranged almost parallel to the sample. Next, the integrated AFM sensor 10 described above
An atomic force microscope incorporating the above will be described with reference to FIG.

As shown in FIG. 2, the integrated AFM sensor 10 includes a tube scanner 30 via a fixing jig 32.
Attached to. The probe 14 at the tip of the cantilever portion 12 is arranged close to the surface of the sample 38 placed on the sample table 36, and is scanned in the XYZ directions by the tube scanner 30 that is deformed according to the voltage applied from the scanner controller 34. It

The displacement measuring circuit 40 includes a voltage applying circuit and a current detecting circuit, and the voltage applying circuit includes an integrated type A through a terminal 42, a contact wire 44 and an electrode 18.
It is electrically connected to the epizoresistive layer 22 of the FM sensor 10 and applies a predetermined DC voltage. The current flowing at this time is constantly measured by the current detection circuit inside the displacement measuring circuit 40. When the cantilever portion 12 is displaced due to the unevenness of the surface of the sample 38 during scanning with the probe 14, the resistivity of the piezoresistive layer 22 changes with this displacement, so that the current flowing through the piezoresistive layer 22 changes. Therefore, the displacement of the cantilever portion 12 is measured by detecting the change in the current value measured by the current detection circuit inside the displacement measurement circuit 40.

An output signal of the displacement measuring circuit 40 indicating the displacement of the cantilever portion 12 is taken into a computer 48, and the computer 48 uses the signal to keep the distance between the cantilever portion 12 and the sample 38 constant, for example, a scanner controller. Digital feedback control of 34 is performed. A stage controller 46 is provided so as to roughly move the sample table 36. The computer 48 controls the scanner controller 34 and the stage controller 46, performs image processing based on these control signals and the signal of the displacement measuring circuit 40, forms an observation image of the sample 38, and displays it on the monitor 50. .. Next, a method of manufacturing the integrated AFM sensor shown in FIG. 1 will be described with reference to FIGS.

First, a SOI (Si
A silicon bonded wafer, which is one of the wafers, is prepared. The upper silicon layer 56 of this wafer is n-type doped with phosphorus (P) and has a thickness of 20 μm. The plane directions of the silicon layers 52 and 56 above and below the silicon oxide separation layer 54 are both (100).
It is the direction. After cleaning this wafer, SiO ₂ layers 58 and 60 are formed on the upper and lower sides of the wafer by deposition in a diffusion furnace (FIG. 3A).

Next, the upper SiO ₂ layer 60 is patterned to form a rectangular opening, and the silicon layer 56 is anisotropically etched with EDP (ethylene diamine pyrocatechol water) using this as a mask. A concave portion 62 having a thickness of the thinnest portion of about 3 μm and an inclined surface of the (111) plane is formed (FIG. 3B).

Then, the SiO ₂ layers 5 on and under the wafer are formed.
After removing 8 and 60 once, 100nm above and below the wafer
Thick SiO ₂ layers 64 and 66 are formed again, and boron (B) is ^added to the surface side of the upper silicon layer 56 by ion ^implantation at 10 ^{15 ions / cm 2.} The piezoresistive layer 68 is formed by implanting the piezoresistive layer 68 at a certain concentration (FIG. 3C).

Next, a thick film resist 70 is coated to a thickness of 10 μm on the SiO ₂ layer 66 and patterned so as to form a probe using the slope of the recess 62. At this time, the patterning shape of the resist is such that it extends in the (110) direction of silicon as shown in FIG. Further, the opening 72 is formed in the SiO ₂ layer 64 on the lower side of the wafer (FIG. 3D).

The separation layer 5 is formed by using the resist 70 as a mask.
Up to 4, anisotropic plasma dry etching is performed using SF ₆ + C ₂ BrF ₅ to completely remove the silicon layer 56. Then, after removing the resist 70, a SiO ₂ layer 74 is deposited on the surface for passivation (FIG. 4A).

Next, in order to take out the electrodes from the piezoresistive layer 68, the contact holes 7 are formed in the SiO ₂ layers 74 and 66.
6 is opened (FIG. 4B), and aluminum is deposited by sputtering to form an electrode 78 (FIG. 4).
(C)).

Then, the silicon layer 52 is anisotropically etched by EDP until reaching the separation layer 54, using the SiO ₂ layer 64, which is covered with polyimide 80 on the upper side of the wafer and has the opening 72 as a mask, (see FIG. 4 ( d)).

Finally, as shown in FIG. 5, the silicon oxide separation layer 54 is removed by etching with buffered hydrofluoric acid and the polyimide 80 is removed to obtain the integrated AFM sensor of FIG.

Next, another embodiment of the integrated AFM sensor of the present invention is shown in FIG. This integrated AFM sensor
Integrated AFM manufactured by the same process as the above-mentioned embodiment
For the probe of the sensor, FIB (Forcused Ion Beam)
) The shape of the tip of the probe 14 is further sharpened by processing with a device. As a result, it becomes possible to perform AFM measurement with higher resolution.

Further, another embodiment of the integrated AFM sensor of the present invention is shown in FIG. In the present embodiment, a p-type silicon layer produced by implanting arsenic (As) is used for the piezoresistive layer, and since p-type silicon exhibits a high piezo coefficient in the (100) direction, Select the extending direction to this direction. The integrated AFM sensor of this embodiment has the following two points,
It is manufactured by the same process as the above-mentioned embodiment. Part 1
In the step of FIG. 3C, arsenic is implanted instead of boron to form a piezoresistive layer. The second is Figure 3
In the step (d), the resist 70 is patterned so as to extend in the diagonal direction of the concave portion 62 and the tip end thereof contacts the corner of the concave portion 62 as shown in FIG. In the integrated AFM sensor manufactured in this way, the probe has the shape shown in the figure because it is manufactured by utilizing the corners of the recess. The integrated AFM sensor of this example manufactured in this way was capable of AFM measurement with high resolution in both the vertical and vertical directions. An integrated AFM sensor according to the second embodiment of the present invention will be described below with reference to FIGS. 10 and 11.

As shown in FIG. 10, the integrated type A of this embodiment is used.
The FM sensor includes a supporting portion 21 configured to be attachable to an atomic force microscope (not shown), and a cantilever portion 23 made of, for example, silicon nitride and extending from the supporting portion 21.
And a silicon probe 25 provided on the tip portion 23a of the cantilever portion 23, and a substantially U-shaped arrangement from the support portion 21 via the tip portion 23a of the cantilever portion 23. A resistance layer 27 whose resistance value changes in accordance with the above, and an electrode portion 29 for applying a predetermined voltage to the resistance layer 27 are provided. The resistance layer 2
7 is made of silicon doped with boron (B).

The probe 25 has a triangular pyramid shape, that is, a tetrahedron shape, and the sharpness thereof is regulated to be extremely higher than that of the conventional one, so that high resolution measurement can be achieved. ing.

Next, a method of manufacturing the integrated AFM sensor of this embodiment having such a structure will be described with reference to FIG. The left-right direction in the figure is the azimuth (11
0).

First, a silicon wafer 31 is prepared as a start wafer, and boron (B; 10 ²⁰ ions / cm ³⁾ is applied from the surface of the silicon wafer 31. The resistance layer 27 having a thickness of 1 μm is formed by doping the above concentration (FIG. 11).
(See (a)).

Next, the resistance layer 27 is subjected to dry etching (see (b)) and patterned into a shape as shown in (c). As a result, the contour of the resistance layer 27 shown in FIG. 10A is formed.

A silicon nitride layer 33 having a thickness of 1 μm is deposited by LP-CVD on the surface of the silicon wafer 31 side on which the resistance layer 27 is thus formed (see (d)), and then dry etching is performed. , The same (e) and (f)
As shown in FIG. 10, the silicon nitride layer 33 and the silicon wafer 31 are partially removed to remove the cantilever portion 23 (see FIG.
(See (a)). The depth Y of the portion thus removed (see (e) in the above) is 5 μm. Probe 2
Since the length of 5 (see FIG. 10) is determined by the depth Y, when a long probe is required, it is necessary to further advance etching. For convenience of explanation, the state (f) shows the state in which the silicon nitride layer 33 is removed.

As shown in (f), the tip A of the etched and remaining cantilever shape has a triangular shape, and the length B of the remaining portion is 250 μm.
It has become. Note that the remaining portion (reference B
2) Cantilever part 2 composed of
3 (see FIG. 10A) usually has a spring constant of 0.01.
The length B is 100 so that it becomes about 10 N / m.
The thickness is designed to be about μm to 500 μm, but it may be designed to be longer depending on the thickness of the silicon nitride layer 33 (see (e) in the figure).

Next, the silicon wafer 31 thus processed is heated to 950 ° C. in a thermal diffusion furnace to expose the silicon surface 35 exposed in the process shown in FIG.
Are oxidized to form a silicon oxide film 37 (the same (g)
reference).

After that, a Pyrex glass (Corning # 7740) 41 having a groove 39 formed on one surface in advance is anodically bonded onto the silicon nitride layer 33 by a dicing saw (see (h)). After this bonding, the Pyrex glass 41 is processed again into a shape as shown in (i) by a dicing saw.

Further, the silicon wafer 31 is dipped in an aqueous potassium hydroxide solution, and this portion is etched.
The etching is stopped in a portion where the resistance layer 27 is not present while leaving the silicon nitride layer 33, and in the portion where the resistance layer 27 is present, the resistance layer 2 functioning as an etching stop layer.
Out of 7, the concentration is 10 ²⁰ ions / cm ³ Stop at some point. The silicon wafer 31 at the portion where the silicon oxide film 37 is formed is processed into a tetrahedral shape with the silicon oxide film 37 covering one surface (see (i)). The portion 43 thus processed into the tetrahedron shape becomes the probe 25 (see FIG. 10) through the subsequent process. One of the slopes 43a indicated by the reference numeral 43 has a surface orientation of (11
1).

After that, the silicon oxide film 37 is etched with hydrofluoric acid, leaving the portion indicated by the reference numeral 43. As a result, the probe 25 is formed at the tip of the silicon nitride layer 33 (see (j)). Finally, the aluminum electrode portions 29 are processed on the base end portions of the resistance layers 27, respectively. Note that a silicon oxide film or the like may be formed on the surface as a protective layer.

As a result, the integrated AFM sensor as shown in FIG. 10 is formed (see (k) in FIG. 10). In addition,
Pyrex glass 41 remaining after the above process
Will function as the support portion 21 (see FIG. 10).

As described above, in the integrated AFM sensor of this embodiment, the bonding technique (anodic bonding method) shown in the process of FIG. Can be manufactured more easily than the conventional manufacturing method using silicon.

That is, since the semiconductor IC process is a process for processing the surface of a silicon wafer, it is a very suitable method for producing the cantilever portion 23.
However, it cannot be said that this is an appropriate method for manufacturing the support portion 21. Therefore, in the present embodiment, the anodic bonding method is applied, and the Pyrex glass 41 to be processed into the supporting portion 21 through the silicon nitride layer 33 and the subsequent process.
The manufacturing process is simplified by providing a process for bonding and.

Further, in the past, in order to form the cantilever portion, etching was carried out with a potassium hydroxide aqueous solution or the like so as to penetrate the wafer from the lower side, but in the process of FIG. 11 (i). , The concentration of doped boron is 10 ²⁰ ions / cm ³ Resistance layer 2
By using 7 as the etching stop layer, the manufacturing process is simplified.

Further, since the probe 25 can be manufactured at the same time in the manufacturing process of the support portion 21 and the cantilever portion 23, the manufacturing process is simplified. Moreover, in this process, the tip 25a of the cantilever portion 23, which is formed into a tetrahedral shape by self-alignment, is configured to have three ridges intersecting at its apex, and thus is generally used. It can be made extremely sharp as compared with the existing probe. The resolution in the AFM measurement corresponds to the sharpness of the probe, and in this respect, the integrated AFM sensor of this embodiment to which the probe 25 is applied can perform the AFM measurement with high resolution. ..

Further, since the alignment accuracy between the support portion 21 and the cantilever portion 23 can be set to an extremely small optimum value of several μm, there is no variation in thickness and length, and the cantilever according to a desired design is obtained. An integrated AFM sensor having the section 23 can be provided.

Although the electrode portion 29 is formed in the last process in the above-mentioned embodiment, before the anodic bonding,
After forming a contact hole in the silicon nitride layer 33 and depositing a metal to form an electrode connected to the resistance layer 27, a Pyrex glass 41 on which a metal is previously deposited or patterned is used to simultaneously perform anodic bonding and the resistance layer. It is also possible to apply a process of electrically connecting with 27.

An integrated AFM sensor according to the third embodiment of the present invention will be described below with reference to FIG.
In the description of this embodiment, the same components as those in the second embodiment will be designated by the same reference numerals and the description thereof will be omitted.

The integrated AFM sensor of this embodiment is
In addition to M measurement, STM or SCaM, or LFM measurement (Lateral Force Microscopy) can be performed at the same time.

As shown in FIG. 12, the structural difference from the first embodiment is that a P-type wafer is used as a start wafer, and that a plurality of systems of first to third resistance layers 45,
47 and 49 are applied. Further, since the P-type wafer is applied, the probe 25 itself has conductivity. This is because, in addition to the point where a P-type wafer is used as the start wafer, the concentration distribution formed when boron is doped has a sufficient concentration even at the probe 25 portion.

In this embodiment, the tetrahedral probe 25 is
It is deposited on the first resistance layer 45 extending along the central portion of the cantilever portion 23 to the tip portion 23a and electrically connected. By operating the first resistance layer 45 and the probe 25, STM measurement or the like is performed. Further, the second and third resistance layers 47 and 49 formed on both sides of the first resistance layer 45 via the tip portion 23 a of the cantilever portion 23, respectively, are arranged with respect to the longitudinal axis of the cantilever portion 23. It is configured symmetrically and is used for LFM measurement and the like.

The integrated AFM sensor having such a structure is the same as that of the second embodiment except for the method of patterning the first to third resistance layers 45, 47 and 49, and the other manufacturing method. Since it is similar to the above, the description thereof will be omitted.

The integrated AFM sensor of the present embodiment is the first
By applying the third resistance layers 45, 47, and 49, STM measurement or SCaM measurement, or LFM measurement simultaneously with these, can be selectively performed as appropriate.

The present invention is not limited to the configuration of the above-described embodiment. For example, a resistance layer for measuring the strain signal of the cantilever portion is arranged on the front surface of the cantilever portion 23, and another signal is arranged on the rear surface. It is also possible to dispose another resistance layer for measuring the above-mentioned condition so as to prevent signal interference between the resistance layers.

An integrated AFM sensor according to the fourth embodiment of the present invention will be described below with reference to FIGS. 13 and 14. In the description of this embodiment, the same components as those in the above-described embodiment will be designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 13, the integrated type A of this embodiment
The FM sensor includes first to third resistance layers 55, 57, 59 (FIG. 14) formed on the surface of the cantilever portion 23.
(See (c)), and a fourth resistance layer 71 formed on the back surface of the resistance layer group 61. The probe 25 is
The second resistance layer 57 of the tip portion 23a of the cantilever portion 23.
Formed on. In addition, the first to fourth resistance layers 5
Each of the electrodes 57, 57, and 59 has an electrode portion 29 formed at the base end portion thereof, and is configured to be electrically connectable to an external circuit (not shown). Next, a method of manufacturing the integrated AFM sensor of this embodiment having such a configuration will be described with reference to FIG.

First, two P-type silicon wafers 51 and 51a are prepared as starting wafers, and boron is doped at a high concentration from the surfaces of these silicon wafers 51 and 51a to form a boron-doped layer 53 having a thickness of 1 μm. (See FIG. 14A). Note that only one silicon wafer 51 is shown in the same (a) to (f).

Next, the boron-doped layer 53 of the one silicon wafer 51 is dry-etched (see (b)) and patterned into a shape as shown in (c). As a result, a resistance layer group 61 including first to third resistance layers 55, 57 and 59 for measuring the displacement of the cantilever portion 23 is formed on the silicon wafer 51.

A silicon nitride layer 63 having a thickness of 1 μm is deposited by LP-CVD on the surface of the silicon wafer 51 side on which the resistance layer group 61 is formed as described above (see (d)), and then by photolithography. A part of the base end side of the silicon nitride layer 63 is removed, and a hole 65 for an electrode part is formed in a shape as shown in (f) (see (e)).

Next, in order to form the contour of the triangular cantilever portion 23 (see FIG. 13) at the tip portion 23a (see FIG. 13) on the silicon wafer 51, the contour as shown in FIG. As described above, the silicon nitride layer 63 and the silicon wafer 51 below the silicon nitride layer 63 are etched and removed to a predetermined depth (see (e) and (f)). Specifically, as shown in (e) and (f), the depth Y (see (e)) of the groove portion 67 formed by scraping is 5 μm from the lower surface of the resistance layer group 61.

After that, an oxidation treatment is performed in a thermal diffusion furnace to form a silicon oxide film 69 on the silicon surface exposed inside the groove 67 (see (e) and (f)). For convenience of explanation, the state (f) shows a state in which the silicon nitride layer 63 is removed.

Next, another silicon wafer 51a on which the boron-doped layer 53 is formed by the process of (a) is prepared, and the boron-doped layer 53 is patterned into the contour as shown in (g). The resistance layer 71 is formed. next,
As shown in (h) of FIG.
1a are joined to each other with their processed surfaces facing each other.

Thereafter, the unprocessed surface of the silicon wafer 51a is oxidized to form a silicon oxide film 73 (see (i)), and after patterning, the silicon wafer 51a is supported by the supporting portion 21 (see FIG. 4). Wet etching is performed on the two silicon wafers 51 and 51a using ethylenediamine-pyrocatechol water so that the remaining silicon oxide film 69 is left in the shape of FIG. By removing in step (i), it is processed into a shape as shown in (i).

As shown in (i), the silicon wafer 5
1a remains in the shape of the support portion 21 and the support portion 21 (see FIG.
3) to the right side in the figure, the cantilever portion 23 is formed on both sides of the silicon nitride layer 63.
And a fourth resistance layer 71. The probe 25 has a second resistance layer 57 which is a configuration of the resistance layer group 61.
(Refer to the same (c)) It is formed in the state electrically connected on the tip. Finally, the first to third resistance layers 55, 5
The electrode portions 29 are formed on the fourth resistance layer 71 via the upper surfaces of the base portions 7 and 59 on the base end side and the holes 65 (see (j)).

The integrated type A of this embodiment produced in this way
The cantilever portion 23 applied to the FM sensor is the first
Since the resistance layer group 61 including the third resistance layers 55, 57, and 59 and the fourth resistance layer 71 are arranged on both surfaces of the silicon nitride layer 63, the cantilever portion 23 has one surface. The patterning of the resistance layer can be simplified, and the width of the cantilever portion 23 can be reduced. This results in improved sensitivity of the integrated AFM sensor. Specifically, the spring constant of the strip-shaped cantilever is proportional to the width of the cantilever. Therefore, it can be seen that the spring constant of the integrated AFM sensor of the present embodiment whose width is narrowed by simplifying the resistance layer is also reduced accordingly, and the sensitivity to a weak force is improved.

Further, by providing the resistance layers (61, 71) on both surfaces of the silicon nitride layer 63, the leakage current between the resistance layers (61, 71) can be extremely reduced, resulting in high sensitivity. Is achieved.

Further, in the cantilever portion 23 applied to this embodiment, first and third resistance layers 55 and 59 functioning as guard electrodes on both sides of the second resistance layer 57 to which the probe 25 is connected. Are formed (see the same (c)). As a result, for example, in STM measurement, even when a circuit including the probe 25 and a measurement sample (not shown) is configured to detect a signal other than the force received by the cantilever portion 23, the influence of disturbance noise by the guard electrode is obtained. Is reduced, and highly accurate measurement can be performed.

An integrated AFM sensor according to the fifth embodiment of the present invention will be described below with reference to FIGS. 15 and 16. Since the configuration of the integrated AFM sensor 75 applied to this embodiment is the same as that of each of the above-described embodiments, the description of the configuration, action, and effect will be omitted.

As shown in FIG. 15, the integrated type A of this embodiment is used.
The FM sensor 75 is incorporated in the AFM measurement system 70, and has a base end fixed to a tip end of a holder 79 connected to a tube scanner 77 having a hollow cylindrical shape, and the AFM.
In addition to signals, a plurality of signals are electrically connected to the corresponding first and second signal detection circuits 81 and 83 so that a plurality of signals can be detected. The holder 79 is connected to the tube scanner 77 so that its longitudinal axis is parallel to the axis of the tube scanner 77, and the integrated AFM sensor 75 fixed to the tip of the holder 79 has its axis. The direction (axial direction of the cantilever portion 23) is configured to be parallel to the longitudinal axis of the holder 79. Therefore, the axis of the integrated AFM sensor 75 of this embodiment is the tube scanner 77.
Are defined to be parallel to each other. Although the device configuration for performing the AFM measurement using the integrated AFM sensor of the present invention has already been shown in FIG. 2, this point is different from the device shown in FIG.

The signals detected or processed by the first and second signal detection circuits 81 and 83 via the integrated AFM sensor 75 are processed by the servo controller 85.
Is output to. The servo controller 85 is an integrated AF
The probe 25 of the M sensor 75 (see FIGS. 10 to 14)
A feedback signal obtained by performing a predetermined calculation on the received signal is output to the scanner driver 89 so as to maintain a constant physical quantity between the measurement sample surface 87 and the measurement sample surface 87, and integrated based on the received signal. Type AFM sensor 7
5 has a function of outputting to the computer 91 so as to tabulate the relative position change between the measurement sample surface 5 and the measurement sample surface 87.

Based on the received feedback signal, the scanner driver 89 finely moves the tube scanner 77 by a predetermined amount via the adjusting section 93 provided at a constant interval on the outer peripheral surface of the tube scanner 77, and the integrated AFM sensor. The probe 25 of 75 can be controlled with respect to the surface 87 of the measurement sample in the S direction in the figure.

The AFM measuring system 70 thus configured
Is used by being fixed to a tube scanner fixing base 95 as shown in FIG. 16, for example. The tube scanner fixing base 95 is directly placed on the measurement sample surface 87 via the three-point supporting balls 97, and as a result, a stand-alone type AFM is configured.

Further, the tube scanner fixing base 95 has
A knob screw 99 connected to the three-point support ball 97 is attached. By operating the knob screw 99, the distance between the probe 25 and the measurement sample surface 87 can be adjusted by the tube scanner 77. It is configured to be controllable up to.

Further, in the cylindrical hole 77a (see FIG. 15) formed through the tube scanner 77 in the axial direction,
Side-viewing rigid endoscope unit 1 with CCD camera 101 attached
03 is inserted, and the part (F) of the measurement sample surface 87 to be measured by the integrated AFM sensor 75 can be optically observed through the display 105. The tube scanner 77 is assembled independently of the side-viewing rigid endoscope section 103, and is constructed so as not to be directly subjected to vibrations from the side-viewing rigid endoscope section 103 in AFM measurement.

The integrated AFM sensor 75 of this embodiment combined with the AFM measuring system 70 in this way constitutes a laterally elongated AFM whose axis is parallel to the axial direction of the tube scanner 77. is doing. Therefore, in particular, it becomes possible to measure the inside of a pipe such as a glass pipe with high accuracy.

[0076]

In the integrated AFM sensor of the present invention, the sharpened probe is provided so as to project from the tip surface of the cantilever portion, so that high spatial resolution in the vertical and horizontal directions can be obtained during AFM measurement. You can Further, by only slightly tilting the integrated AFM sensor with respect to the measurement sample, parts other than the probe do not come into contact with the sample surface, so that image distortion due to contact can be prevented and a good image can be obtained. be able to.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of an integrated AFM sensor according to a first embodiment of the present invention, in which (a) is a side sectional view, (b) is a top view, and (c) is a perspective view. Fig.

FIG. 2 is a diagram showing a configuration of an atomic force microscope incorporating the integrated AFM sensor of FIG.

FIG. 3 is a diagram showing a manufacturing process of the integrated AFM sensor of FIG.

FIG. 4 is a diagram showing a manufacturing process of the integrated AFM sensor of FIG.

5 is a diagram showing a final step of manufacturing the integrated AFM sensor of FIG. 1. FIG.

FIG. 6 is a diagram showing the patterning shape of the resist in the step of FIG.

FIG. 7 is a diagram showing another embodiment of the integrated AFM sensor according to the present invention.

FIG. 8 is a diagram showing yet another embodiment of the integrated AFM sensor according to the present invention.

9A and 9B are diagrams showing resist patterning shapes in a manufacturing process of the integrated AFM sensor of FIG.

10A and 10B are diagrams schematically showing a configuration of an integrated AFM sensor according to a second embodiment of the present invention, FIG. 10A is a perspective view thereof, and FIG. 10B is a partial sectional view thereof.

FIG. 11 is a diagram sequentially showing a manufacturing process of the integrated AFM sensor shown in FIG.

12A and 12B are diagrams schematically showing a configuration of an integrated AFM sensor according to a third embodiment of the present invention, FIG. 12A is a perspective view thereof, and FIG. 12B is a partial sectional view thereof.

FIG. 13 is a diagram schematically showing a configuration of an integrated AFM sensor according to a fourth embodiment of the present invention.

14A to 14C are diagrams sequentially showing a manufacturing process of the integrated AFM sensor shown in FIG.

FIG. 15 is a diagram schematically showing a configuration of an AFM measurement system incorporating an integrated AFM sensor according to a fifth embodiment of the present invention.

16 is a diagram showing a state in which a stand-alone AFM is configured by incorporating the AFM measurement system shown in FIG.

FIG. 17 is a diagram sequentially showing a manufacturing process of a conventional integrated AFM sensor.

[Explanation of symbols]

10 ... Integrated AFM sensor, 12 ... Cantilever part,
12a, 12b ... Beam, 14 ... Probe, 16 ... Support part,
18 ... Electrode, 20 ... Silicon layer, 22 ... Piezoresistive layer,
24 ... Passivation layer, 26 ... Contact hole.

Claims (1)

[Claims] 1. An integrated AFM having a cantilever portion provided with a piezoresistive layer whose resistance value changes according to displacement.
In the sensor, an integrated AFM sensor characterized in that a tip of the cantilever portion is provided with a sharpened probe protruding from the tip.