JP2001056281A - Cantilever for scanning type probe microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cantilever capable of detecting directly a displacement change of a search needle head. SOLUTION: A cantilever 142 has a lever part 140 having a shape of a beam with both ends fixed and made of single crystal silicon, and a roughly triangular pyramid-shaped probe needle part 138 is formed on the center of the lever part 140. The lever part 140 is supported by a first support part 114, and the first support part 114 is supported by a second support part 136 through a silicon oxide film 104. The surface 286 of the lever part 140 on the opposite side of the probe needle part 138 is faced directly to the first support part 114 side, and a groove is formed in the normal direction of the surface 286. Displacement of the probe needle part 138 caused by the change of irregularities on the sample surface is shown as displacement of the surface 286 of the lever part 140 as it is. Therefore, accurate irregularity information on the sample surface can be obtained by detecting the displacement of the surface 286 of the lever part 140.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cantilever used for a scanning probe microscope.

[0002]

2. Description of the Related Art A scanning probe microscope (SPM) has an interaction (for example, an interaction between a probe or a probe portion and a probe portion when the probe or probe portion comes close to or less than 1 μm or less).
This is a device that performs two-dimensional mapping of the interaction by scanning the probe part or sample in the XY direction or XYZ direction while detecting the atomic force, contact force, etc., and is a scanning tunneling microscope (STM) , An atomic force microscope (AFM), a magnetic force microscope (MFM), a scanning near-field light microscope (SNOM), and the like. In particular, AFM is
It is the most widespread among SPMs as a device for obtaining unevenness information on a sample surface.

In the AFM, a cantilever having a sharp protruding portion (probe portion) at the free end of a cantilevered lever portion is brought close to and opposed to a sample, and atoms at the tip of the probe and atoms on the surface of the sample are brought close to each other. Interaction force acting between (atomic force, contact force, etc.)
The sample or cantilever is moved to X while measuring the movement of the lever part displaced by
By scanning in the Y direction and relatively changing the positional relationship between the probe portion of the cantilever and the sample, it is possible to three-dimensionally capture information on the unevenness of the sample.

The amount of elastic deformation of the lever part in SPM
An example of a method of detecting (bending amount) is described in, for example, Japanese Patent Application Laid-Open No. 5-34.
0718 and JP-A-9-15250,
These are incorporated herein by reference. The detection of the amount of deflection of the lever portion described in these documents is performed by using a known “optical lever type displacement detection sensor”. In addition, regarding the detection of the amount of deflection of the lever portion, a “defocus detection method using a critical angle prism”, a “displacement detection sensor using an optical interferometer”, and the like are known.

[0005] SPM measurement using this displacement detection sensor is performed as follows. The probe section X
Scanning is performed in the Y direction, and the amount of deflection of the lever portion in this measurement area is detected as needed by the above-described displacement detection sensor. The detected amount of deflection is imaged with atomic-level resolution as sample information such as surface irregularities of the sample and magnetic force, and is displayed on a monitor.

The cantilever used for such an SPM is described in Thomas R. Albrecht and Calvin F. Quate, "Atomic Re
solution Imaging of a Nonconductor by Atomic Force
Microscopy ”(J. Appl. Pys. 62 (1987), p. 2599), since the Si02 cantilever manufactured by applying the semiconductor IC manufacturing process was proposed, it has been highly accurate with micron order accuracy. Since ICs can be manufactured with high reproducibility and the cost is excellent by using a batch process, ICs manufactured using this IC manufacturing process are mainly used.

At present, there are two types of cantilevers commercially available, a cantilever made of silicon nitride and a cantilever made of silicon. Silicon nitride cantilevers are described in Tomas R. Albrecht et al.'S "Microfabrication of
cantilever styli for the atomic force microscope ''
(J. Vac. Sci. Technol. A8, 3386 (1990)), the mainstream of which is described in US Pat. No. 5,399,232, which is hereby incorporated by reference. Incorporated herein. In addition, silicon cantilevers are available from O. Wolter et al.
sensors for scanning force microscopy "(J. Vac.
i. Technol. B9,1353 (1991)) is the mainstream, and the detailed manufacturing method is disclosed in US Pat. No. 5,051,
379, which are incorporated herein by reference.

In addition, M. Tortonese et al. Have proposed an integrated AFM sensor provided with a function of detecting displacement in the cantilever itself. This integrated AFM sensor
For example, "Atomic force microscopy using a piezoresist
ive cantilever; Transducerand Sensor '91' and PCT
It is described in application WO 92/12398, which is incorporated herein by reference.

In recent years, SPM measurement, in which a cantilever is vibrated at or near its natural frequency to detect a change in amplitude or frequency to perform measurement, has been widely performed. being called.

Recently, using SPM, one second per second
Perform high-speed scanning such as performing raster scanning over the screen,
Attempts have been made to observe microscopic movements of biological samples and the like. Further, attempts have been made to use SPM technology for high-density recording, and a cantilever-shaped probe having a high resonance frequency has been demanded in order to increase the input / output speed. Such high-speed scanning SPM is attracting attention as an inspection device for microstructures such as semiconductors because of the shortened measurement time as well as living organisms.

[0011]

In all the above-mentioned cantilevers, the probe is provided at the free end of a lever portion which is a cantilever-shaped leaf spring having one end fixed to a support portion. Is detected as equivalent to the displacement of the probe. For this reason, it cannot be said that the displacement change of the tip of the probe actually tracing the sample surface is accurately detected. In the current SPM measurement, a servo measurement in which the measurement is performed by scanning the surface of the sample in the X and Y directions while keeping the amount of deflection of the lever portion constant is mainly used. From this, it can be considered that in servo measurement, whether the displacement of the tip of the probe is detected or the amount of deflection of the lever is detected, no change occurs in the scale of the image of the concavo-convex image of the sample surface. I have. However, there is always a time lag in the servo that keeps the amount of deflection of the lever portion constant with respect to the unevenness of the sample surface, and this causes a drag of the probe to affect the image.

Further, in SPM measurement or the like for performing high-speed scanning such as raster scanning of one screen or more per second,
In order to scan the cantilever at high speed, displacement detection cannot be performed in time with the current servo, and constant height measurement for directly imaging the amount of deflection of the cantilever is mainly used. In the constant height measurement, the drag of the probe is directly imaged. In addition, since the amount of deflection of the lever is detected instead of the displacement of the probe, accurate height information cannot be obtained, and an image is formed on a different height scale from the actual sample surface. A problem has occurred.

In addition, in recent years, it has been desired to accurately measure the bottom of a fine hole having a high aspect ratio, such as a trench, a contact hole, or a damascene. For this reason, several probes having a high aspect ratio have been developed, and AFM measurement of a fine hole having a high aspect ratio has been attempted. However, since the tip of the probe is too thin, the tip of the probe is curved during the AFM measurement, causing a problem that an accurate AFM image cannot be imaged. In addition, since the tip of the probe is thin, there is a problem that the servo cannot sufficiently follow a large step during the AFM measurement and the tip of the probe is easily damaged.

In consideration of such a problem, Japanese Patent Laid-Open No.
A cantilever having a doubly supported beam shape such as that disclosed in Japanese Patent Laid-Open No. 15602 and Japanese Patent Laid-Open No. 5-231815 is conceivable. However,
In a conventional doubly supported beam, the actual SP
It did not spread in M measurements. For example, Japanese Patent Laid-Open No. 1-1
In the double-supported beam as shown in No. 5602, the support portion of the cantilever is on the measurement sample side, the cantilever is replaced only by the cantilever, and the workability of the cantilever replacement by the measurer is lower than that of the cantilever using the currently mainstream semiconductor process. Was. In addition, since the cantilever itself is large, the resonance frequency is low, which is not suitable for SPM measurement that vibrates the mainstream cantilever at present. in addition,
Since it is difficult to fabricate in a semiconductor process, it is difficult to fabricate cantilevers having the same characteristics. The cantilever disclosed in Japanese Patent Application Laid-Open No. Hei 5-231815 is manufactured by applying a semiconductor process. However, a cantilever and a probe are arranged directly below a support portion, and a portion for measurement such as a cantilever of a cantilever is used. It was impossible to observe the sample surface with an optical microscope or the like, and it was difficult to align the position to be measured with the cantilever. In addition, the surface of the support portion on the probe side is almost the height of the probe, and the probe cannot be placed in contact with or near the sample surface due to the contact between the sample surface and the support portion, and SPM measurement cannot be performed. And other problems occurred frequently. Further, both cantilevers had high spring constants, and were not suitable for SPM for observing the surface without damaging the sample.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a cantilever capable of directly detecting a change in displacement of a probe tip.

In addition, the present invention has solved the problem of the conventional cantilever having a doubly-supported beam shape. The object of the present invention is to provide so-called AC mode measurement in which the cantilever is vibrated to perform SPM measurement. Another object of the present invention is to provide a cantilever that allows the tip of the probe to vibrate perpendicularly to the sample surface.

[0017]

SUMMARY OF THE INVENTION In a cantilever for a scanning probe microscope having a probe portion, a doubly supported lever portion and a support portion, the support portion is provided on substantially one side of a surface including the lever portion and the probe. It is characterized by being done.

In addition, in a cantilever for a scanning probe microscope having a probe part, a lever part of a doubly supported shape, and a support part, a flat surface (reflection surface) for detecting displacement is provided directly behind the probe part. Is more preferable.

On the other hand, in the above-mentioned cantilever for a scanning probe microscope, it is more preferable that the amount of displacement of the probe portion is detected by strain resistance.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 9 schematically show a method of manufacturing a cantilever for a scanning probe microscope (SPM) of the present invention.

First, as shown in FIG. 1, a so-called bonded SOI (Silicon On Insulator) substrate 108 is prepared. This bonded SOI substrate 108 has a plane orientation (10
0) First silicon substrate 10 made of single crystal silicon
After forming the intermediate silicon oxide film 104 on the surface of No. 2, a second silicon substrate 106 made of single crystal silicon having a plane orientation of (100) to be an active layer is bonded. For example, the thickness of the first silicon substrate 102 is 500 μm,
The thickness of the intermediate silicon oxide film 104 is 1 μm, and the thickness of the second silicon substrate 106 is 5 μm.

Next, as shown in FIG. 2, an etching mask 110 for forming a second support portion, which will be described later, is formed on the back surface of the first silicon substrate 102 by patterning a silicon oxide film or a silicon nitride film. Formed. On the other hand, a silicon nitride film 112 is formed on the surface of the second silicon substrate 106.

As shown in FIG. 3, a silicon nitride film 112 is formed by photolithography and dry etching.
And the second silicon substrate (active layer) 106 with the SOI substrate 1
08, the intermediate silicon oxide film 104 is selectively removed until it is exposed to form a first support portion 114, a lever base portion 120 that is a base of the lever portion, and a probe that is a base of the probe portion. The part 122 is formed.

The first support part 114 is divided into two parts, and the probe forming part 122 is provided on an extension of the groove dividing the first support part 114. Lever base part 1
Numerals 20 extend from the divided first support portions 114 toward the probe forming portions 122, respectively.
2 forms the prototype of the doubly supported beam. Surface 11 of lever base portion 120 opposite to probe forming portion 122
8 faces the groove dividing the first support portion 114.

The width (lateral dimension) of the lever base portion 120 is determined by the pattern formation of photolithography, and is, for example, 2 μm.
It is. The shape of the lever base portion 120 is formed in consideration of the displacement direction of the probe after completion, and is, for example, 45 degrees with respect to the end surface of the first support portion 114 on the lever base 120 side. ° extends.

Lever base section 120 and probe forming section 122
FIG. 10 shows an enlarged view of the vicinity of the connecting portion. As shown in FIG. 10, the etching surface 124 of the probe forming portion 122
It is inclined from the 10> direction, for example, 45 °. Further, the etching surface 126 of the probe forming portion 122
The inclination from the 110> direction determines the height of the probe portion (in other words, the aspect ratio). For example, when a probe portion having a height of 10 μm is formed, approximately 70 ° is selected.

Next, as shown in FIG.
A wall 128 of a silicon oxide film is formed by a thermal diffusion furnace on the side end surface of the second silicon substrate 106 on which the 14, the lever base 120, and the probe forming part 122 are formed.

As shown in FIG. 5, the silicon nitride film 112 on the surface of the probe
Expose 6. FIG. 11 is an enlarged view of the vicinity of the probe forming portion 122 of the remaining silicon nitride film 112. As shown in FIG. 11, the ends 280 and 282 of the silicon nitride film 112 on the probe forming portion 122 side are formed parallel or perpendicular to the <110> direction.

As shown in FIG. 6, the second silicon substrate 106 of the probe forming portion 122 is subjected to wet anisotropic etching until the intermediate silicon oxide film 104 is exposed, so that the second silicon substrate 106 has a shape close to the probe portion of the cantilever. Triangular pyramid shaped probe base 1
Form 30. In this wet anisotropic etching, an aqueous solution of potassium hydroxide (KOH) having a predetermined concentration, tetramethylammonium hydroxide (TMAH), ethylenediamine pyrocatechol and water (called EDP or EPW) or the like is used.

In the wet anisotropic etching of single crystal silicon such as the second silicon substrate, the silicon substrate
Since the (111) plane is more difficult to be etched than the (100) plane, the end portion 28 of the silicon nitride film 112 remaining in the lever base portion 120 is wet-etched.
Single crystal silicon is etched from 0,282 so as to expose the (111) plane.

FIG. 12 is an enlarged view of the vicinity of the probe base 130.
Shown in As shown in FIG. 12, three sides of the (111) plane exposed from the end 282 of the silicon nitride film 112, the (100) plane of the intermediate silicon oxide film 104, and the wall 128 of the silicon oxide film on the etching surface 126 side are formed. The triangular pyramid-shaped single crystal silicon becomes the probe base 130. The probe base 130 becomes a probe after an oxidation step.

The end portion 280 of the silicon nitride film 112
Residual silicon having a (111) plane exposed from the substrate is also formed on the (100) plane of the intermediate silicon oxide film 104 and the etched surface 12.
The triangular pyramid shape is formed from the surface surrounded by the silicon oxide film wall 128 on the fourth side. Since the triangular pyramid projections 284 protrude in parallel with the lever base portion 120, the subsequent measurement is performed. There is no problem above.

Next, as shown in FIG. 7, a silicon oxide film 132 is formed on the surfaces of the probe base 130 and the lever base 120 having a triangular pyramid shape by a thermal diffusion furnace. In FIG. 7, the silicon oxide film 132 is formed by removing the silicon oxide wall 128 in the previous step; however, the silicon oxide film 132 may be formed without removing the silicon oxide wall 128.

As shown in FIG. 8, the first silicon substrate 1
The second support portion 136 is formed by performing a wet anisotropic etching process on 02 from the back surface.

Finally, as shown in FIG. 9, the intermediate silicon oxide film 104 sandwiched between the first support portion 114 and the second support portion 136 by a hot phosphoric acid aqueous solution, a hydrogen fluoride aqueous solution or the like is removed. By removing all the silicon oxide film and the silicon nitride film, a cantilever 142 as a finished product is obtained.

The cantilever 142 has a lever portion 14
Numeral 0 denotes a doubly supported beam extending obliquely from the first support portion 114, and a probe portion 138 is formed at the center thereof.
As shown in FIG. 13, the probe portion 138 has a triangular pyramid-shaped tip portion, and two out of three surfaces defining the tip portion.
One is the (111) plane and (100) plane of silicon, and the remaining 1
One surface 144 is formed by artificial processing.

In the above-described manufacturing method, assuming that the design value of the width of the lever portion of the cantilever and the thickness of the second silicon substrate 106 of the bonded SOI substrate 108 are substantially equal, a silicon nitride film is formed on the surface of the second silicon substrate 106. Although the second silicon substrate 106 is formed, when the thickness of the second silicon substrate 106 is larger than the design value of the width of the lever portion, before the silicon nitride film 112 of FIG. The thickness of the portion forming the probe forming portion is adjusted by etching. At this time, the etching method may be either a dry method or a wet method. However, in consideration of a later step, wet etching is preferable in order to reduce surface roughness. In consideration of the rigidity of the first support portion 114 later, the thickness may be adjusted by wet anisotropic etching so that the (111) plane is formed in connection with the lever portion.

As shown in FIG. 9, the cantilever 142 manufactured by the manufacturing method of the present embodiment has a lever portion 140 made of single-crystal silicon having a doubly-supported beam shape. A conical probe portion 138 is formed. The lever 140 is supported by the first support 114, and the first support 114 is supported by the second support 136 via the silicon oxide film 104. The surface 286 of the lever 140 opposite to the probe 138 is the first surface 286.
And a groove is formed in the normal direction of the surface 286.

As shown in FIG. 14, the cantilever of the present embodiment stands up almost perpendicular to the surface of the sample for measurement. The change in the displacement of the probe part 138 due to the change in the unevenness of the sample surface is directly transferred to the vertical movement of the surface 286 of the lever part 140. At this time, the light of the optical displacement sensor is applied to the surface 286 of the lever portion 140 through the groove of the first support portion 114 to detect the displacement. Alternatively, the displacement may be detected by once reflecting off the surface 286 of the second support portion 136 on the first support portion 114 side and then irradiating the surface 290 of the lever portion 140. As the optical displacement sensor, an interference type displacement sensor using an optical fiber is used.

Here, since the cantilever of this embodiment has a doubly supported beam shape, the displacement of the probe 138 becomes the displacement of the surface 286 of the lever 140 as it is, and the accurate information of the sample surface is displaced upward. Conveyed to the sensor.

At this time, in the cantilever of this embodiment, as shown in FIG. 9, the supporting portion for supporting the cantilever is present only on almost one side of the surface including the lever portion and the probe, and the supporting portion is provided with the cantilever. Since the thickness becomes thinner toward the sample, the portion other than the probe is hardly in contact with the sample surface. Further, when the cantilever of the present embodiment is arranged on the sample surface as shown in FIG.
Since there is no shielding on the supporting portion side, that is, on the side where the cantilever is provided, using this space, for example,
An objective lens such as an optical microscope is disposed obliquely above the probe and the sample surface, and the tip of the probe and the sample surface are aligned while observing.

As described above, according to the cantilever of this embodiment, since the cantilever having a double-supported beam shape including the lever portion and the probe is provided on one side of the support portion, the cantilever other than the tip portion of the probe which is unnecessary for measurement is provided. Can easily avoid contact with the surface of the sample, and the position of the probe tip and the surface of the sample to be measured can be easily observed. It is possible to easily obtain information in a short time.

In addition, according to the cantilever of the present embodiment, since the portion detected by the optical displacement sensor is the surface formed directly behind the probe, the change in the displacement of the probe is directly detected by the optical displacement sensor. Since the displacement of the reflection surface directly behind the probe changes, it is possible to obtain accurate information on the unevenness of the sample surface.

In addition, according to the cantilever of this embodiment, the influence of the drag of the probe at the time of XY scanning is reduced.

Further, according to the cantilever of the present embodiment, even in the AC mode in which the cantilever is resonated for measurement, the probe only vibrates up and down because of the double-supported beam shape. Accurate AFM measurement is possible without deviation of the probe tip position.

In addition, in the cantilever of the present embodiment, the spring constant of the cantilever is determined by the lever portion 140 which extends obliquely from the first support portion 114.
For this reason, as shown in FIG. 15, the spring constant may be reduced by forming the lever portion into a shape in which obliquely extending portions are overlapped. In FIG. 15, the diagonal lever part is
Although it overlaps, more lever parts may be overlapped,
The setting of this number is selected according to the designer's intention.

Further, according to the cantilever of the present embodiment, the extension angle of the lever portion 140 from the first support portion 114 is set to 45 °, but this angle can be arbitrarily selected. To make it softer than the spring constant of
This angle may be set smaller than 45 °.

For example, the angle may be set to 0 ° as shown in FIG. Also in the case of this cantilever, the intermediate oxide film 104 between the cantilever portion and the second support portion 136 is removed by removing the silicon oxide film in the final step of this embodiment.
Therefore, the displacement direction of the probe, that is, the vertical movement of the probe is not hindered.

The characteristics of the cantilever include, for example, a length of 100 μm, a width of 5 μm, a thickness of 0.4 μm, a resonance frequency of about 2 MHz, and a spring constant of 1 N / m or less. Similarly to the embodiment, the shape can be arbitrarily changed depending on a measurement sample or a measurement method.

In addition, according to the manufacturing method described above, the thickness of the lever portion can be easily reduced by the photolithography of FIG. 3, dry etching, and oxidation of FIGS. A cantilever suitable for SPM measurement for high-speed scanning used for observing a change or the like can be easily manufactured.

Further, in the cantilever 142 manufactured by the manufacturing method of the present embodiment, as shown in FIG. 13, the probe portion 138 has a triangular pyramid-shaped tip, and three tips defining the tip are provided. Two of the faces are silicon (111)
The surface and the (100) surface, and the remaining one surface 144 is formed by artificial processing. Therefore, the radius of curvature of the tip of the probe part 138 is caused by the step of forming the surface 144 on the support part side. This surface 144 is defined by the etching surface 126 of the probe forming part 122 formed in the step of FIG.

As shown in FIG. 10, the etching surface 126 of the probe forming portion 122 formed in the step of FIG. 3 is a flat surface formed by photolithography and dry etching. Therefore, the roughness of the etching surface 126 generated by the dry etching determines the radius of curvature of the tip of the probe 138.

Generally, the surface roughness by dry etching is 1
Since it is 0 nm or less, as shown in FIG. 12, when the (111) plane of silicon is exposed to form the probe base 130, the radius of curvature of the tip of the probe base 130 is already It is 10 nm or less. Therefore, the radius of curvature of the probe 138 formed through the subsequent oxidation step is stably sharpened to 10 nm or less.

As shown in FIG. 10, the aspect ratio of the probe portion 138 includes a surface including <110> and perpendicular to the (100) plane (this is a surface opposite to the later formed probe portion 138). (Parallel to 286) is determined by the inclination θ of the etching surface 126 of the probe forming portion 122. Including <110> (1
The inclination θ of the etched surface 126 with respect to the plane orthogonal to the (00) plane is a design parameter that can be arbitrarily selected by the maker of the cantilever.

Therefore, in the above-described embodiment, θ = 7
Although the probe portion 138 having an apex angle of 20 ° is formed by selecting 0 °, a probe portion having a higher aspect ratio can be formed by selecting an even larger value for θ.

Further, in the step of FIG. 7, the probe base portion 130 is oxidized by a heat diffusion furnace or the like, which oxidizes the probe base portion 130. The temperature at this time is 900 to 1000 ° C., preferably 95 ° C.
By setting the temperature to 0 ° C., which is lower than the temperature at which a silicon oxide film is formed by a normal semiconductor process, a sharper probe portion 138 as shown in FIG. 16 can be formed. This is because the growth speed of the silicon oxide film becomes slow in the vicinity of the tip of the probe portion 138. As a result, the silicon portion that is not oxidized, that is, the portion that eventually becomes the probe portion is sharpened toward the tip. , The radius of curvature of the tip becomes several nm or less.

Further, in the cantilever 142 manufactured by the manufacturing method of the present embodiment, as shown in FIG. 13, a triangular pyramid-shaped projection 284 protruding in a direction parallel to the surface 286 of the lever part 140 also has a probe part 138. Formed at the same time.
Among the above-described manufacturing methods, as shown in FIG.
Although the inclination α of the etching surface 124 with respect to 10> is set to 45 ° for convenience, an angle which does not hinder SPM measurement using the probe 138 is sufficient, and is not limited to the set angle of the present embodiment. .

As shown in FIG. 17, by shifting the end 280 of the silicon nitride film 112, the etching surface 1
By making V 24 a surface bent in a V shape, FIG.
As shown in FIG. 8, the length of the protrusion 284 may be shortened.

In addition, in the manufacturing method of the present embodiment, patterning for forming the protrusion 284 is performed in order to form the (111) plane constituting the probe portion 138 neatly. As long as there is no influence, the shape other than the protrusion may be formed by changing the shape of the edge 280 of the mask when the probe base portion 130 shown in FIG. 11 is manufactured.

In the cantilever 142 manufactured by the manufacturing method of this embodiment, as shown in FIG. 13, the thickness 290 of the lever portion 140 supporting the probe 138 is
It is preferable that the tip of the probe portion 138 has a sufficient thickness so that the surface 286 of the lever portion is not curved by the force received from the sample surface.

As described above, the tip of the probe portion 138 is defined by the (111) and (100) surfaces of silicon and the surface 144 that can be processed artificially. 122 is defined by the etched surface 126. In addition, the shape of the etching surface 126 can be arbitrarily selected. Therefore, by changing the shape of the etching surface 126, it is possible to produce a probe portion having a shape different from the probe portion 138 shown in FIG.

Hereinafter, a modified example of the etched surface and a probe formed based on the etched surface of the modified example will be described.

In the first modification, as shown in FIG.
The etching surface 126 ′ of the probe forming part 122 is <110>
A plane 126a having an inclination θ with respect to a plane perpendicular to the ((100)) plane, and a plane having an inclination φ (> θ) with respect to a plane perpendicular to the ((100)) plane, including <110>. 126b.

When the above-described manufacturing method is similarly applied to the etching surface 126 ′ having such a shape, a silicon oxide wall bent in the middle reflecting the shape of the etching surface 126 ′ is formed, and The base portion has a shape in which a triangular pyramid having an aspect ratio higher than that of a truncated triangular pyramid is provided at the tip.

As a result, as shown in FIG. 20, a probe portion 138 'having a tip portion having a shape in which a triangular pyramid having a higher aspect ratio than the truncated triangular pyramid is continuous is obtained. The tip of the probe 138 'is located between the (100) plane of silicon and the plane 1
44 ′, and the surface 144 ′ is
<110> reflecting the shape of the etched surface 126 ′ of FIG.
A plane 144a having an inclination θ with respect to a plane perpendicular to the ((100)) plane, and a plane having an inclination φ (> θ) with respect to a plane perpendicular to the ((100)) plane, including <110> 144b.

The probe portion 138 'having this shape can realize an improvement in the aspect ratio of the tip and an increase in the height dimension without substantially reducing the overall rigidity and strength.

In the simple triangular pyramid-shaped probe portion 138 as shown in FIG. 13, if the value of the inclination θ is increased to improve the aspect ratio or the height of the tip, it is inevitable. The rigidity and strength of the entire probe are reduced. Therefore, the upper limit of the aspect ratio and height of the tip of the probe 138 is determined by the purpose of use of the probe and the rigidity and strength of the material (single crystal silicon).

On the other hand, in the probe portion 138 'as shown in FIG. 20, the portion of the truncated triangular pyramid (the portion including the surface 144a) close to the lever portion 140 increases the strength, so Increasing the aspect ratio does not significantly reduce the overall strength. Therefore, the upper limit of the aspect ratio and the height dimension of the probe section 138 ′ that can be actually realized is determined by the probe section 13 of FIG.
8 higher than that.

In the second modification, as shown in FIG.
The etched surface 126 '' of the probe forming part 122 has a <110>
A plane 126a having an inclination θ with respect to a plane perpendicular to the ((100)) plane, and a plane having an inclination φ (> θ) with respect to a plane perpendicular to the ((100)) plane, including <110>. 126b and <110>
And a plane 126c having an inclination ψ (<θ) with respect to a plane perpendicular to the ((100)) plane.

When the above-described manufacturing method is similarly applied to the etched surface 126 ″ having such a shape, a silicon oxide wall bent at a portion reflecting the shape of the etched surface 126 ″ is formed. The tip portion of the probe base has a shape in which a triangular pyramid having an aspect ratio higher than that of the truncated triangular pyramid continues at the tip of the triangular pyramid, and the apex portion is cut off obliquely.

As a result, as shown in FIG. 22, a triangular pyramid having an aspect ratio higher than that of the truncated triangular pyramid continuously
A probe portion 138 '' having a tip portion whose top portion is obliquely cut off is obtained. The tip of the probe portion 138 ″ is formed by the (111) plane, the (100) plane, and the plane 144 ″ of silicon.
The surface 144 ″ reflects the shape of the etching surface 126 ″ of the probe forming part 122 and includes a tilt angle θ with respect to a plane including <110> and perpendicular to the ((100)) plane. Plane 1 with
44a, a plane 144b including <110> and having a tilt φ (> θ) with respect to a plane perpendicular to the ((100)) plane, and a plane 144b including <110> and perpendicular to the ((100)) plane. And a plane 144c having an inclination ψ (<θ).

The probe portion 138 ″ of this shape has three vertices 146 a, 146 b, and 146 c near its tip, and is particularly suitable for applications such as measurement of a vertical wall and measurement of the bottom of a groove. I have. By increasing the inclination φ of the surface 144b and lengthening the corresponding portion, it is possible to obtain a cantilever particularly suitable for measuring the wall and bottom of a deep groove.

Further, in both the first modified example and the second modified example, in the step of FIG.
By oxidizing at 00 ° C., preferably at 950 ° C., the effect shown in FIG.
A more sharpened probe section is obtained.

As described above, according to the manufacturing method described above,
A cantilever for SPM having a probe with a small radius of curvature at the tip can be easily and stably manufactured. Therefore, it is possible to provide an SPM cantilever that enables SPM measurement with higher resolution.

In addition, since a similar probe portion can always be formed stably with high accuracy in cantilevers having various characteristics,
It is possible to provide a cantilever for SPM that does not deteriorate the resolution due to the difference in the PM measurement method and always enables the SPM measurement with high resolution.

Further, an SPM cantilever having a probe portion having a high aspect ratio can be easily and stably manufactured. Therefore, it is possible to provide an SPM cantilever that enables SPM measurement with higher resolution. The SPM cantilever having the probe portion having such a high aspect ratio is particularly suitable for a sample having a large step such as a groove of an optical disc.
Suitable for M measurement. In addition, the cantilever of the present invention can move the probe up and down almost accurately, and
Since the tip of the probe is thin, it is easy to observe the bottom of a trench or a contact hole, or a minute groove or hole having a high aspect ratio such as damascene.

In the present embodiment, the shape of the etching mask 110 for forming the second support portion 136 is rectangular. Therefore, as shown in FIG. Shoulders remain parallel.

The shape of the second support portion 136 depends on the etching mask 110 formed in the step shown in FIG. In addition, the shape of the first support portion 114 depends on the photolithography patterning in the process of FIG. Therefore, by changing the shape of the etching mask 110 and the patterning of the photolithography in the process of FIG. 3, the cantilever 142 ′ having a shape in which the shoulders of the support portions on both sides are cut off as shown in FIG. 23 can be obtained. It is possible.

When the cantilever 142 'is attached to a scanning probe microscope, the cantilever 14' shown in FIG.
2, the first support portion 114 and the second support portion 13
6 can be easily avoided from contacting the sample.

Here, the end surface of the first support portion 114 on the cantilever 142 side and the end surface of the second support portion 136 on the cantilever 142 side are identical.
Side end surface is cantilever 142 from the second support portion 136.
It may be protruding to the side. In this case, the probe 138 protrudes from the second support portion 136 with respect to the sample surface on which the SPM measurement is performed, and the sample surface with a larger step can be measured. Further, the shape of the first support portion 114 on the cantilever 142 side may be arbitrarily changed to a shape that avoids contact with the probe surface. In this case, there is no particular limitation as long as the rigidity of the first support portion 114 is maintained when the cantilever 142 resonates. Further, the shape of the first support portion 114 can be easily changed by changing the pattern when forming the first support portion 114 in FIG.

In order to increase the reflectance of the surface 286 of the lever portion, a step of coating the surface 286 of the lever portion with a metal film or the like may be added to the above-described manufacturing process (the steps of FIGS. 1 to 9).

A modification in which displacement of the probe 138 is detected by an optical sensor such as an optical lever system will be described below. In this modification, in the series of manufacturing methods shown in FIGS. 1 to 9, the mask of the probe forming portion formed by photolithography in the process of FIG. 3 is changed to the shape shown in FIG. As shown in (1), a cantilever having a mirror surface 401 made of a (111) plane is formed on the opposite side of the probe 138. The displacement detection by the optical sensor is performed by making light incident on the mirror surface 301.

FIG. 32 briefly shows the positional relationship between the cantilever 442 and the optical sensor 402. For example, the optical sensor 402 has a coaxial optical path of the incident light and the optical path of the reflected light, as indicated by a dashed arrow. For the optical sensor 402, for example, an optical lever method in which incident light and reflected light are coaxial, a focus detection method such as critical angle detection, an interference method, and the like can be applied. Here, the optical lever system in which the incident light and the reflected light are coaxial is, for example, a coaxial optical path for a displacement detection target, and the optical path is a λ / 4 plate or the like in front of a detector that performs displacement detection. A separable optical lever system.

In such a configuration, the displacement of the probe 138 is detected as a displacement of the mirror surface 401. FIG. 33A shows a side view of the modification, and FIG. 33B shows a schematic view of the mirror surface and the optical path. As shown in FIG. 33 (b), such an optical sensor having a coaxial optical path has an incident light La.
Are perpendicularly incident on the mirror surface 401 of the (111) plane. At this time, the angle of the incident light with respect to the measurement sample surface is 54.7 °.

Further, the optical sensor may be a general light lever optical sensor in which the optical path of incident light and the optical path of reflected light are non-coaxial. In such a general light lever optical sensor, the incident light only needs to be incident with an inclination with respect to the normal line of the mirror surface 401. As shown in FIG. 1 for mirror surface 401
It is incident at an incident angle of 0 °. In this optical lever system, a configuration is shown in which the detector is located between the laser light source and the cantilever, but the positions of the laser light source and the detector, that is, the optical paths of the incident light and the reflected light may be reversed. .

Further, the exposed surface of the second support portion 136 on the cantilever 442 side may be used as the reflection surface 303 of the optical sensor. In this case, as shown in FIG. 33B, the incident light Lc is incident, for example, parallel to the surface of the measurement sample, that is, at an incident angle of 54.7 ° on the mirror surface 301. The reflected light from the mirror surface 401 is incident on the reflecting surface 403 of the support portion of the cantilever at an incident angle of 70.6 ° and is reflected. In the configuration using the reflection surface 403, the optical path of the optical lever system can be long, so that displacement detection with higher sensitivity can be performed.

In order to detect the displacement of the probe with higher sensitivity, the cantilever may have a reflection film 404 of a metal film formed on the mirror surface 401 as shown in FIG. The reflection film 404 is provided between the steps of FIG. 7 and the step of FIG.
Are formed by adding a series of steps shown in (1).

FIGS. 34 (a) to 34 (d) show several steps immediately after the step of FIG. 7 when the mask of the step of FIG. 3 is changed to the mask shown in FIG.
It is shown in a cross section taken along line -A '. As shown in FIG. 34A, after the surface of the first support 114 on which the cantilever 442 is formed is covered with the silicon oxide film 132, FIG.
As shown in FIG. 4B, the silicon oxide film 132 on the mirror surface 401 is removed by photolithography and etching.

Next, as shown in FIG. 34C, a reflection film 404 of a metal film is formed on the mirror surface 401. afterwards,
As shown in FIG. 34D, the entire surface of the first support portion 114 including the reflective film 404 is covered with the silicon oxide film 405 again. Finally, according to the same procedure as in the above-described embodiment, a completed cantilever is obtained through the manufacturing process shown in FIG.
FIG. 35 shows a view of the vicinity of the probe of the completed cantilever viewed from the reflection film 404 side.

As described above, in this embodiment, the mirror surface 401 of the silicon (111) surface is provided on the opposite side of the probe, in other words, on the back side of the probe at the position where the probe of the lever portion is formed.
Is provided, the optical displacement sensor can be easily arranged. In addition, a metal reflective film 4 is formed on the mirror surface 401.
The sensitivity of the optical displacement sensor is improved by forming 04.

Similarly, also in this embodiment, since the reflection film for detecting the displacement by the optical displacement sensor is formed on the back side of the probe, the change in displacement of the probe is directly detected by the optical displacement sensor. Performs accurate displacement detection of the probe,
As a result, accurate SPM measurement of irregularities on the sample surface becomes possible.

Hereinafter, an integrated AFM sensor having a built-in displacement sensor manufactured by applying the above-described manufacturing method will be described.

FIG. 24 shows an integrated AFM sensor incorporating a displacement sensor using a strain resistance layer. This integrated AFM sensor is manufactured by adding the steps of ion implantation and forming the aluminum electrode 310 to the above-described manufacturing method.
The strain resistance layer 302 formed by ion implantation is formed on the surface of the cantilever 142 and the first support 114, and can be brought into contact with an external circuit by the aluminum electrode 310. In the embodiment shown in FIG. 24, an n-type strain resistance layer 302 is formed by implanting phosphorus or arsenic into a P-type silicon substrate. For this reason, the inclination of the lever portion 140 extending from the first support portion 114 is
45 ° to <110>. In other words, the direction of the lever portion is <100>, and the n-type strain resistance layer 3
The direction with the highest sensitivity of 02 is selected as the lever portion.

This integrated type AFM sensor has a probe section 13
8 The lever portion 140 is distorted by the force received at the tip, and the resistance value of the strain resistance layer 302 on the surface of the lever portion 140 changes.
The amount of current flowing between the aluminum electrodes 310 is detected, and the amount of change is detected. The change in the amount of current is used as a change in the displacement of the probe to image the surface irregularities.

In the integrated type AFM sensor according to the present embodiment, the displacement sensor can be easily incorporated by adding only two steps to the above-mentioned cantilever manufacturing method.

In addition, the integrated type AFM sensor of this embodiment has a built-in sensor for detecting the displacement of the probe. For this reason, even in a micro cantilever suitable for high-speed scanning SPM measurement used when observing a time change of a measurement sample, displacement measurement of a smaller cantilever can be performed without concern for the light intensity of the optical displacement sensor. Will be possible.

In the integrated type AFM sensor of this embodiment, the strain resistance layer is formed by ion implantation, but the SOI having the high concentration n-type silicon in the second silicon substrate is used.
A substrate may be prepared and manufactured.

In addition, in the integrated type AFM sensor of this embodiment, the n-type strain resistance layer 302 is used.
As shown in FIG. 25, a p-type strain resistance layer 304 may be formed by implanting boron or the like into an n-type silicon substrate. In the case where the p-type strain resistance layer 304 is formed, the sensitivity can be further improved by forming the lever portion of the cantilever 142 along the <110> direction as shown in FIG. In the modification shown in FIG. 25 as well, an SOI substrate having high-concentration p-type silicon as the second silicon substrate may be prepared and manufactured.

Further, in the integrated type AFM sensor of the present embodiment, it is easy to provide all the modified examples of the above-mentioned probe portion as the probe of the cantilever by the above-mentioned manufacturing method.

Hereinafter, the fabrication of a cantilever suitable for vertical wall measurement, which can be fabricated by applying the above-described integrated AFM sensor, will be described.

In the cantilever manufactured by the above-described manufacturing method, the shape of the probe portion and the periphery of the probe are formed by two crystal planes of silicon, (111) plane and (100) plane, and by artificial processing. Are defined by two aspects. By changing the two surfaces formed by these artificial processes, it is possible to produce a cantilever having a completely different shape from the above-described probe and having a probe portion suitable for vertical wall measurement.

FIG. 26 shows a cantilever provided with a probe suitable for vertical wall measurement. In the drawings, members equivalent to those already described are denoted by the same reference numerals.

As shown in FIG. 26, the cantilever 2
42 is the probe part 23 with respect to the surface 286 of the lever part 140.
8 extend vertically, and the tip thereof has a probe 23
A pair of terminal points 20 located on the left and right with respect to the extension direction
1 and 202. In other words, the cantilever 242 includes a pair of triangular pyramid-shaped protrusions symmetrically protruding left and right in the direction in which the probe 238 extends.
38.

The side surface of the projection of the probe portion 238 is composed of two intersecting crystal planes, ie, a (111) plane and a (100) plane, and planes 203 and 204 formed by artificial processing. Points 201 and 202 are (111) plane and (10
0) This is the intersection between the plane and the planes 203 and 204.

The probe forming section 22 for forming the probe section
The shape of No. 2 is shown in FIG. The probe forming section 222 has a value of <11
It is formed by slightly inclined surfaces 203 and 204 ahead of surfaces 226 and 224 perpendicular to the 0> direction. Face 203,2
The angle β with respect to the plane including <110> of the plane 04 and perpendicular to the (100) plane is the same. The probe forming section 222 can be easily formed by changing the patterning of photolithography in the process of FIG. Next, by removing the silicon nitride 112 in the step of FIG. 5 only at the portion sandwiched between the surfaces 203 and 204, the cantilever 24 having the probe portion 238 having two terminal points 201 and 202 at its tip is provided.
2 are produced.

Further, in the step of FIG.
By oxidizing at 000 ° C, preferably at 950 ° C,
As shown in FIG. 28, a probe portion 238 'having a pair of more sharpened end points 201' and 202 'is obtained.

FIG. 29 shows how the vertical wall is measured using the cantilever 242. In the vertical wall measurement, the cantilever 242 is connected to the two end points 201 of the probe portion 238 (238 ′).
The excitation is performed in the direction of the ridge line connecting (201 ') and 202 (202').

In addition, an integrated AFM is used for detecting a vertical wall measurement.
A sensor is used, and the strain resistance layer is p-type.

Since such a cantilever 242 has a pair of terminal points 201 (201 ') and 202 (202') protruding left and right at the tip of the thin probe portion 238 (238 '), FIG. As can be seen, it is particularly suitable for measuring vertical wall measurements.

Although several embodiments have been described in detail with reference to the drawings, the present invention is not limited to the above-described embodiments, but may be practiced without departing from the scope of the invention. Includes all implementations.

[0112]

According to the present invention, since a cantilever of a doubly supported shape including a lever portion and a probe is provided on one side of the support portion, portions other than the tip portion unnecessary for measurement can be applied to the sample surface. Contact can be easily avoided, and the position of the tip of the probe and the surface of the sample to be measured can be easily observed. To gain.

In addition, according to the present invention, since the spring constant of the cantilever can be arbitrarily softened, a probe having a high aspect ratio can be used for SPM measurement without curving the tip of the cantilever. It is possible to accurately measure grooves and holes with a high aspect ratio, such as holes and damascenes, which are becoming finer.

Further, according to the cantilever of the present invention used for SPM measurement using an optical displacement sensor for a detection system,
Because a reflective surface that detects displacement is provided directly behind the probe,
Since the displacement information of the displacement of the tip of the probe can be accurately detected, accurate SPM measurement of the sample surface is possible.

Further, according to the cantilever of the present invention for detecting displacement by strain resistance, since the strain resistor for detecting displacement of the probe is incorporated in the cantilever itself, it is possible to miniaturize the entire size of the cantilever. High-speed scanning SPM used for observing the time change of the measurement sample
Effective for measurement.

Further, since the present invention is manufactured by a batch process to which a semiconductor process is applied, cantilevers having almost the same characteristics and having a sharp tip can be simultaneously manufactured stably in large quantities.

[Brief description of the drawings]

FIG. 1 shows a first step in a method for manufacturing a cantilever according to an embodiment of the present invention.

FIG. 2 shows a second step following the step of FIG. 1 in the method of manufacturing a cantilever according to the embodiment of the present invention.

FIG. 3 shows a third step following the step in FIG. 2 in the method of manufacturing a cantilever according to the embodiment of the present invention.

FIG. 4 shows a fourth step following the step of FIG. 3 in the method of manufacturing a cantilever according to the embodiment of the present invention.

FIG. 5 shows a fifth step following the step of FIG. 4 in the method of manufacturing a cantilever according to the embodiment of the present invention.

FIG. 6 shows a sixth step following the step of FIG. 5 in the method of manufacturing a cantilever according to the embodiment of the present invention.

FIG. 7 shows a seventh step following the step of FIG. 6 in the method of manufacturing a cantilever according to the embodiment of the present invention.

FIG. 8 shows an eighth step following the step of FIG. 7 in the method of manufacturing a cantilever according to the embodiment of the present invention.

FIG. 9 schematically shows a cantilever as a finished product obtained through the steps of FIGS.

FIG. 10 shows the shape of a probe forming portion formed in the step of FIG.

FIG. 11 is an enlarged view showing the vicinity of a probe forming portion of a silicon nitride film remaining after the step of FIG. 5;

12 shows a probe base formed in the process of FIG. 6 based on the probe forming portion having the shape shown in FIG. 10;

FIG. 13 shows a probe portion finally formed based on the probe base portion shown in FIG.

FIG. 14 shows a state in which the cantilever shown in FIG. 9 is erected substantially perpendicular to the sample surface for measurement.

FIG. 15 shows a cantilever in which the spring constant of the lever portion is reduced by changing the shape of the lever portion.

FIG. 16 shows a probe formed by performing a low-temperature thermal oxidation process in the step of FIG. 7;

FIG. 17 shows a probe base formed by shifting an end of a silicon nitride film.

FIG. 18 shows a probe portion formed based on the probe base portion shown in FIG. 17 and having a short protrusion protruding in a direction parallel to the surface of the lever portion.

FIG. 19 shows a first modification of the shape of the probe forming portion formed in the step of FIG.

20 shows a probe base formed in the process of FIG. 6 based on the probe forming portion having the shape shown in FIG. 19;

FIG. 21 shows a second modification of the shape of the probe forming portion formed in the step of FIG.

22 shows a probe base formed in the process of FIG. 6 based on the probe forming portion having the shape shown in FIG. 21.

FIG. 23 shows a cantilever in which shoulders of support portions on both sides obtained by slightly changing a manufacturing process are cut.

FIG. 24 shows an integrated AFM sensor including a displacement sensor using a strain resistance layer.

25 shows an integrated AFM sensor in which the lever portion of the cantilever extends along the <110> direction, unlike the integrated AFM sensor shown in FIG.

FIG. 26 shows a probe section suitable for vertical wall measurement.

FIG. 27 shows a probe forming part when forming the probe part shown in FIG. 26;

FIG. 28 shows a probe portion suitable for measuring a vertical wall formed by performing a low-temperature thermal oxidation process.

FIG. 29 shows a state of vertical wall measurement using a cantilever provided with the probe portion shown in FIG. 26 or FIG.

30 is (111) on the opposite side of the probe portion shown in FIG. 31.
FIG. 4 shows a modification of the mask of the probe forming portion applied in the step of FIG. 3 to form a cantilever having a reflective surface.

31 shows a cantilever having a (111) reflecting surface on the opposite side of a probe formed according to the mask shown in FIG. 30;

FIG. 32 shows an arrangement relationship between the cantilever shown in FIG. 31 and an optical sensor for detecting its displacement.

33 (a) is a side view of the cantilever shown in FIG. 32, and FIG. 33 (b) is a schematic view of the arrangement of the optical reflection surface.

FIG. 34 shows a series of several steps added immediately after the step of FIG. 7 to form a reflective film of a metal film on the mirror surface of the cantilever shown in FIG. 31.

35 is a view of the vicinity of the probe tip of the cantilever obtained through the step of FIG. 9 after the step shown in FIG. 34, as viewed from the reflective film side.

36 shows a modification of the cantilever shown in FIG. 9, and is a perspective view of the cantilever in which the extension angle of the lever portion from the first support portion is 0 °. FIG.

[Explanation of symbols]

 114 first support portion 136 second support portion 138 probe portion 140 lever portion 142 cantilever 286 surface

Claims (3)

[Claims] 1. A cantilever for a scanning probe microscope having a probe part, a doubly supported lever part and a support part, wherein the support part is provided on substantially one side of a surface including the lever part and the probe. A cantilever for a scanning probe microscope, characterized in that: 2. A cantilever for a scanning probe microscope having a probe portion, a cantilevered lever portion and a support portion, wherein a flat surface (reflection surface) for detecting displacement is provided directly behind the probe portion. The cantilever for a scanning probe microscope according to claim 1, wherein 3. The scanning probe according to claim 1, wherein in a cantilever for a scanning probe microscope having a probe portion, a lever portion, and a support portion, a displacement amount of the probe portion is detected by a strain resistance. Microscope cantilever.