JPH04196044A - Cantilever body and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent breakage of a lever daring manufacturing or measuring process thereof by providing a supporting substrate for supporting a thin film provided with its corner parts corresponding to intersections of a mesh exposed, and probes formed at corners of the film. CONSTITUTION:Since a supporting substrate 2 is formed in such a way that corner parts corresponding to intersections of a mesh are exposed and formed on one side of a thin film 3a having its external shape such as rectangle or the like regulated by a mesh and supports the thin film 3a, the corner parts 4a to 4d of the thin film 3a are freely supported in a cantilever manner so that these parts serve as cantilevers. Therefore, a cantilever body 1 having the above mentioned structure has a smaller amount of protrusion of the cantilever itself from the cantilever body 1 than that of a conventional cantilever body, so that the lever is not damaged upon division of the cantilever body 1. Further, cantilevers are formed apart form each other. Consequently, upon measurement of a specimen surface using probes 5 formed on cantilevers, even if the cantilever body 1 inclines against the specimen surface, cantilevers except one being employed are not damaged due to the contact with the specimen surface.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to an atomic force microscope (Atomic Force microscope).
BACKGROUND OF THE INVENTION Recent advances in science and technology have been remarkable, and scanning microscopes have been developed that are capable of microscopically observing two-dimensional structures on material surfaces with high accuracy.

Atomic open force microscope (c) Hereinafter, it will be abbreviated as AFM. ) is one such scanning microscope, and is expected to have a wide range of applications because it can observe non-electrically conductive material surfaces and organic molecules on a nanometer scale.

FIG. 7 is an explanatory diagram illustrating the principle of AFM.

As shown in this figure, the AFM has a leaf spring-like cantilever 72 (
car displacement i/transducer system) and this lever 72
It has a system (displacement measurement system) 73 for measuring zero bending.

Generally, between the surfaces of non-polar substances, a weak attractive force due to dispersion force acts at a long distance, and a repulsive force acts at a short distance. Since the bending of the lever 72 is proportional to the force acting on it, by measuring this bending, we can measure this weak force acting between the tip of the probe 71 and the surface 75 of the sample 74, which is within a few nm of the tip. It becomes possible to detect local forces. Furthermore, sample 74
By scanning the sample in the direction along its surface, that is, in the XYXF-plane, two-dimensional information on the force on the sample surface can be obtained. That is, the Z control signal to keep the force constant is
The drive system 76 drives the sample 74 in two directions.
While controlling in the axial direction, an XY scanning signal is applied to the same XYZ drive system 76, and the sample 74 is scanned in the XY direction by this drive system 76. This makes it possible to observe the microscopic shape of the sample surface. Here, 77 is a piezoelectric element for lever modulation, 78 is a pace, and 79 is a comparison circuit that compares the output signal from the displacement measurement system 73 with a reference value.

The actual cantilever is made of fine metal foil (wire) or SIO
It is a thin film type using a Si3N4 film or a Si3N4 film. Set the displacement detection sensitivity to 0. In order to make it possible to detect a force of 10'N (the typical magnitude of the weak attractive force), a soft spring with an elastic constant of ION/m or less must be used for the cantilever V.

However, in terms of the sweep frequency of the running system and vibration isolation, it is not possible to reduce the elastic constant of the lever and lower its resonance frequency. To satisfy these contradictory conditions,
It is necessary to make the lever as small as possible.

In light of the above, a method for manufacturing this cantilever is, for example, by forming a pattern of cantilever bodies (chips) on a wafer using the reduction exposure method used in semiconductor device manufacturing technology, and then cutting out the cantilever body according to this pattern. be.

FIG. 8 is a schematic diagram of a cantilever body (chip) manufactured by this manufacturing method. As shown in this figure, the cantilever body 80 is formed with cantilevers 81a and 81b arranged adjacent to a support 82 in the same plane, and protrudes significantly from the support 82.

Here, the cantilevers 818 and 81b have different elastic constants, and are selected depending on the sample surface to be observed.

However, the cantilever body (chip) 80 having this structure has the following problems. That is, since the cantilevers 818 and 81b are formed in a protruding shape as described above, it is extremely difficult to avoid damaging the cantilevers 818 and 81b when cutting out the cantilever chip 80. 1. Since the elastic constant of the cantilever is controlled by changing the shape of the lever, such as its thickness, it is not easy to change the design of the lever during manufacturing.

Furthermore, since the cantilevers 818 and 81b are formed close to each other, when the cantilever chip 80 is used for measurement, the cantilever chip 81
If the cantilever is tilted with respect to the sample surface, anything other than the cantilever used for measurement may come into contact with the sample surface during measurement and be damaged. Therefore, cantilevers that are not used for measurement are wasted, resulting in poor production and use efficiency of cantilevers.

(Problems to be Solved by the Invention) As described above, with conventional cantilever bodies and their manufacturing methods, it is extremely difficult to manufacture them without damaging the cantilever and with flexibility in design changes. Furthermore, if the manufactured cantilever body is tilted with respect to the sample during measurement, there is a problem in that the cantilever that is not used for measurement may come into contact with the sample and be damaged.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a cantilever body that does not damage the lever during manufacturing and measurement and is flexible in design changes, and a method for manufacturing the same.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention includes a thin film having an outer shape defined by a mesh, and a corner portion corresponding to the intersection of the meshes exposed on one surface of the thin film. The present invention provides a cantilever body including a support substrate that supports the thin film and a probe formed at the corner of the thin film.

The present invention includes a rectangular thin film, a supporting substrate that supports the thin film and is formed on the back surface of the thin film by exposing the corners of the thin film, and a probe formed on the corner of the front surface of the thin film. A cantilever body is provided.

Furthermore, the present invention includes a step of forming a thin film on the surface of the substrate, a step of processing the thin film into a pattern having corners by selectively removing the thin film in a mesh pattern, and a step of forming the thin film on the substrate using the pattern as a mask. selectively removing the thin film pattern and selectively removing the substrate from the back side in a region including the intersections of the mesh to expose the corners of the thin film pattern, and moving the substrate along the mesh. A method for manufacturing a cantilever body is provided, which includes the steps of dividing the thin film pattern and providing probes at corners of the thin film pattern.

(Function) In the cantilever body according to the present invention, the support substrate is formed on one surface of a thin film having an outer shape such as a rectangle defined by a mesh, with corners corresponding to the intersections of the mesh exposed. Since the thin film is supported, the corner of the thin film is freely cantilevered, and this portion acts as a cantilever. Therefore, with the cantilever body having this structure, the protrusion of the cantilever itself from the cantilever body is tB%, 4, compared to the conventional cantilever body, so that the lever will not be damaged when the cantilever body is divided.

In addition, since the cantilevers are formed apart from each other, when measuring the sample surface using the probe formed on the cantilever, even if the cantilever body is tilted with respect to the sample surface, it is possible to The cantilever will not be damaged by contact with the sample surface.

In addition, in the method for manufacturing a cantilever according to the present invention, by selectively removing a thin film formed on the surface of a substrate in a mesh pattern, this thin film is processed into a pattern having corners, and using this pattern as a mask, the substrate is By selectively removing the substrate and selectively removing it from the back side of the substrate in areas including the intersections of the meshes, the corners of the pattern are exposed, so compared to conventional cantilever bodies, the cantilever itself is There is no protrusion from the cantilever body, so the cantilever is not damaged when dividing the substrate along the mesh. Furthermore, the elastic constant of the cantilever can be freely changed by changing the line width of the mesh, the size of the area surrounding the intersections of the mesh, and their positional relationship.
Flexibility can be provided for design changes.

In addition, in the method for manufacturing a cantilever according to the present invention, the probe is provided on the surface side of the exposed corner of the pattern, but this step is not performed in any of the above-mentioned manufacturing steps for the cantilever body. It may be done in stages.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the structure of an embodiment of a cantilever body according to the present invention. As shown in this figure, the cantilever body is chip-shaped (hereinafter referred to as cantilever chip 1). The cantilever chip 1 has a SiN film 3a having a thickness of, for example, 1 μm formed on the surface of a Si substrate 2.
3N4 membrane 3a [4 corners 4a, 4b, 4C, 4
The Si substrate 2 below d has been removed. That is, Si3N
, the film 3a is a corner part 4 a T 4 b of the Si3N4 film 3a
* 4'+'' remains in a protruding state, and this part is used as a cantilever.Furthermore, the corners 4a, 4b, 4C, 4d of the surface of the 5L3N4 film 3a
At the tips of the probes 5a, 5b, 5c, 5d, respectively
Note that an Si, N4 film 3b is also formed on the back surface of the 81 substrate 2.

This cantilever chip 1 is a cantilever 4a.

Since the cantilevers 4b, 4c, and 4d do not protrude from the square chip, these cantilevers are not damaged when dividing the 81 substrate 2. Furthermore, by installing cantilevers at the four corners 4a, 4b, 4C, and 4d of the chip 1 (7), the cantilever chip 1 can be
When measuring the surface of a sample, all cantilevers other than the force/tilever used can be separated from the sample being measured, so there is no need to use unnecessary force other than the cantilever tip shown in Figure 8. There is no chance of the cantilever being damaged during measurement.

If this cantilever chip 1 is used for awns, the effect of improving the detection sensitivity of AFM can also be obtained. FIGS. 2 and 3 are explanatory diagrams for explaining this effect.

That is, when measuring the surface of a sample using this embodiment apparatus for AF'M, the displacement of the tip of the cantilever is detected by the optical lever method. In the method of detecting displacement using light, such as the original lever method, the radiation pressure of light is very small (1 mW of light is equivalent to 7 x 10 N), so the force on the lever has almost no effect. There are no limitations on force detection sensitivity or instability in operation.

In FIG. 2, the displacement of the cantilever tip of the cantilever body according to the present invention is measured using the optical lever method. As shown in this figure, the length along the four sides of the lever is r2t, and therefore the incident angle θ of light with respect to the lever can be set large. If the angle of incidence can be increased in this way, A
It becomes possible to improve the detection sensitivity of FM. Note that here, D is the thickness of the Si substrate 2.

On the other hand, in FIG. 3, the displacement of the cantilever tip of a conventional cantilever is measured by the optical lever method. In this figure, portions corresponding to those in FIG. 2 are indicated by numbers with a dash added to the number of the portion in FIG. 2. As shown in this figure, if the length of the tip of the lever 4al from the Si substrate 2' is t, it is impossible to take a longer length than this, and the thickness of the Si substrate 21 is set as shown in FIG. If D, therefore, the incident angle θ1 of light cannot be made large.

Therefore, the detection sensitivity of AFM cannot be improved.

Next, an embodiment of the method for manufacturing a cantilever body according to the present invention will be described in detail with reference to the drawings.

FIG. 4, FIG. 5, and FIG. 6 are a process cross-sectional view, a top view, and a perspective view, respectively, illustrating the method for manufacturing the cantilever chip 1 described above. In these figures, the same parts as in FIG. 1 are denoted by the same reference numerals, and detailed explanations will be omitted.

First, as shown in FIG. 4(a), 8i3N, MB2, and 3b are deposited to a thickness of about 1 μm on both sides of an 8i substrate 2 (thickness: 625 μm), which is a 5-inch wafer with a (100) orientation, by, for example, plasma CVD. to form.

Next, a resist is applied to the entire surface of the substrate 2, and this is patterned into a lattice-like band (solid line 51) as shown in FIG. 5 using lithography technology, and the resulting resist pattern is masked. Then, the Si3N4 film 3a is etched away by reactive ion etching (IE) (FIG. 4(b)).

Here, the width of the band is set so that even if the Si substrate 2 is etched, for example, with a KOH solution as described later, the tip of the 7-shaped groove does not reach the 5t3N film 3b on the other surface. That is, when the thickness of the substrate 2 is D, 2D/tan 5
Tosle less than 4.7°.

Next, a resist is applied to the other surface of the substrate 2, and lithography is used to form a square (dotted line 5) as shown in FIG.
After patterning 2), the Si3N4 film 3b is etched away by RIB using the resulting resist pattern as a mask (FIG. 4(C)).

Here, the size of the square to be patterned is determined by the protruding 81 remaining after etching the Si substrate 2, which will be described later.
It may be arbitrarily determined depending on the size of the 3N4 film 3a.

Finally, the 81 substrate 2 is placed in, for example, a KOH solution, and this substrate 2 is selectively removed. As a result, 1
On one surface, V-shaped grooves 61 are arranged in a lattice pattern, and on the other surface, grooves 62 in the shape of a truncated pyramid are formed in a row. Si3N4 film 63 (4a, 4b in FIG. 1,
4c and 4d) are in a completely free state,
This becomes a cantilever.

Since the 7-shaped groove serves as a type of perforation, by dividing the Si substrate 2 along this groove, the cantilever chip 1 can be easily made without damaging the cantilevers 4a14b, 4C, and 4d. I can do it.

In the method of the embodiment described above, by changing the line width of the lattice-like band 51, the size of the square area 52, and the positional relationship thereof, the cantilevers 4a, 4b, 4C can be adjusted.
, 4d (especially elastic constants) can be changed with good flexibility.

Note that the region shape is not limited to the above-described square, but may be other shapes such as a rectangle.

Furthermore, since the cantilevers 42, 4b, and 4C14d can be constructed from a combination of straight lines and square patterns, costs such as manufacturing costs for masks used in Ringer's fibrosis can be reduced.

Next, we will discuss how to attach the probe.

For example, if it is desired to fabricate a cantilever with an integrated probe, a Si3N film 3a having protrusions forming the probes 5a, 5b, 5C, and 5d on its surface may be fabricated in advance. Also, S
After cutting out the cantilever chip 1 from the i-board 2,
Fine particles, such as diamonds, which become the probes 5a, 5b, 5c, and 5d may be attached to the surface of the Si3N4 film 3a.

Furthermore, a probe may be formed by, for example, depositing an Au thin film on the tip of the 513N4 film 3a at high temperature, and then cooling the tip to room temperature, thereby bending the tip.

Note that a magnetic material is used as the probes 5a r 5b, 5c, and 5d, and the resulting cantilever body is used as an MFM.
It is also possible to attach it to a magnetic force microscope (magnetic force microscope) and measure the sample surface.

Note that the present invention is not limited to the above embodiments.

For example, although Si is used for the substrate, it goes without saying that other materials such as quartz, Pyrex glass, etc. may be used. At this time, the etching characteristics of the substrate material (crystal planes that are easily exposed by etching, etc.) may be taken into account and the shape of the mesh may be set to an optimal pattern. For example, patterning may be performed into a polygon other than a quadrilateral, such as a triangle.

In addition, as a thin film used for the cantilever, 8 i 3
Although N4 film was used, other insulating films, such as 5in2°SiC
etc. may be used, especially when using a compound of the substrate material,
The adhesion between the thin film of the cantilever and the substrate is improved.

Furthermore, if a metal film such as Cr, Au, etc. is used and a conductor is used for the probe, a current can be passed through the cantilever. For example, by scanning the probe over the surface of the insulating film, Locations of insulation defects can be easily detected. In addition, various modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

As described in detail above, according to the present invention, the cantilever is not damaged when dividing the cantilever body, and the design of the lever can be changed with flexibility. There is no possibility that the cantilever not used for measurement will be damaged during measurement.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of an embodiment of the cantilever chip according to the present invention, and FIGS. 2 and 3 illustrate the effect of improving AFM detection sensitivity when using the force/tilever integrated according to the present invention. FIG. 4, 5, and 6 are process cross-sectional views, top views, and perspective views explaining the manufacturing method of this embodiment, respectively. FIG. 7 is an explanatory view explaining the principle of AFM, and FIG. FIG. 1 is a schematic diagram of a cantilever body (chip) manufactured by a conventional method. In the figure, 1...Cantilever chip, 2121...Si substrate, 3a, 3b, 3a', 3b' --
-Si3N4 film, 4a, 4b. 4c, 4d, 4a'--Si3N4 film 3
Four corners in a, 5a, 5b, 5C, 5
cl, 5a'-probe, 51...grid-like band, 52
...Square area, 61...Characteristic face, 62...Front of quadrangular pyramid, 03...513N4 film, 71...Tip,
72... Cantilever, 73... Displacement measurement system, 74
...Sample, 75...Surface of sample 74, 76...X
YZ drive system, 77... piezoelectric element for lever modulation, 78...
... Base, 79 ... Comparison circuit, 80 ... Cantilever body (chip), 81 a, 8 l b ... Cantilever, 82 ... Support body. Agent Patent Attorney Noriyuki ChikaFigure 2Figure 3

Claims (4)

[Claims] (1) A thin film having an outer shape defined by a mesh, a support substrate supporting the thin film, which is provided on one surface of the thin film with exposed corners corresponding to the intersections of the mesh, and the thin film and a probe formed at the corner of the cantilever body. (2) A cantilever comprising a rectangular thin film, a support substrate that supports the thin film and is formed on the back surface with the corners of the thin film exposed, and a probe formed on the corner of the front surface of the thin film. body. (3) a step of forming a thin film on the surface of the substrate; a step of processing the thin film into a pattern having corners by selectively removing the thin film in a mesh pattern; and using this pattern as a mask, the substrate is selectively removed. a step of exposing the corners of the thin film pattern by selectively removing the substrate from the back side in a region including the intersections of the mesh, and dividing the substrate along the mesh. A method for manufacturing a cantilever body, comprising the steps of: and providing a probe at a corner of the thin film pattern. (4) Claim (2) characterized in that the mesh shape is a lattice shape, and the shape of the area including the intersections of the mesh is rectangular.
) The method for manufacturing the cantilever body described in .