JPH09152436A - Probe for scanning probe microscope and making thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the measurement of surface information in an area to be measured having arbitrary geometric dimensions with higher reproducibility regardless of measuring environment. SOLUTION: A probe 6 has a strip-shaped cantilever beam 10 extended from a support part 8 and a probe 12 formed at an extended end (free end) of the cantilever beam. The probe is formed roughly in a square pole, the diameter thereof reduces continuously toward an intermediate extended part P2 from a part P1 near the cantilever beam and then, increases continuously toward the tip part P3 from the intermediate extended part. The tip part P3 of the probe has a roughly asteroid shape comprising four sides. When the longitudinal direction of the cantilever beam is represented by X, among diagonal lines connecting the first to fourth intersections (protrusion parts) 14a, 14b, 14c and 14d of the four sides, the direction of the diagonal line connecting the first and third protrusion parts 14a and 14c is set within an angle range of 45 deg. to the longitudinal direction, almost parallel with the longitudinal direction preferably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe for a scanning probe microscope capable of measuring the uneven shape of trench grooves or holes formed in a semiconductor device, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a scanning probe microscope (SPM; SPM) has been used as an apparatus for observing a sample at an atomic order resolution.
canning Probe Microscope) is known and this SP
M is a general term for a scanning tunneling microscope (STM), an atomic force microscope (AFM), a magnetic force microscope (MFM), a scanning near field optical microscope (SNOM), and the like.

Among such SPMs, the AFM is an apparatus which is capable of observing an insulating sample with a resolution of atomic order and is the most popular apparatus at present (Japanese Patent Laid-Open No. 62-62-62).
130302).

Such an AFM is equipped with a cantilever having a sharpened protrusion (probe), and when the probe is brought close to the sample, it is displaced by the interaction force (atomic force) acting on the tip of the probe. The surface information of the sample can be captured three-dimensionally by, for example, optically detecting the displacement of the cantilever.

Y. Martin, CCwilliams, HKWickra
Force detection mode AFM proposed by masinghe et al.
Is configured so that the surface information of the sample can be measured without contacting the sample surface with the probe by detecting the force gradient of the attractive force acting between the probe and the sample (J. Appl.Phys.Vol.61 No.10 (1987)).

This measuring method using the attractive force detection mode AFM changes the vibration state of the cantilever that occurs when the probe approaches the sample surface in a state where the cantilever is slightly vibrated at a frequency near its resonance frequency. This is a method of three-dimensionally capturing the surface information of the sample by performing feedback control so that is constant. According to such an attractive force detection mode AFM, since it is not affected by a lateral force such as a frictional force acting along the surface direction of the sample, the surface information of the sample is measured with the probe in contact with the sample surface. Contact mode AFM (repulsive force mode AF
Compared with M), it becomes possible to measure the surface information of the sample faithfully.

However, this attractive force detection mode AFM
Has a problem that the AFM measurement in the atmosphere becomes unstable. Therefore, in recent years, in order to solve this problem, the vibration amplitude of the cantilever is set to 20 nm to 200 nm.
By controlling the feedback so that the change in the vibration state of the cantilever that occurs when the probe is lightly contacted with the sample surface in a state of being controlled in the range of nm becomes constant, the surface information of the sample is three-dimensionally A method of capturing is proposed. According to such a measuring method, since the probe is in contact with the sample surface during scanning, there is a problem that the probe is worn, but the sample surface contains water and dust. Since the vibration energy that is stronger than the meniscus force that the probe receives from the adsorption layer (contamination layer) is applied to the cantilever, stable AFM measurement can be performed in the atmosphere.

By the way, as a cantilever used in the above-described SPM, there is Albrecht (TRAlbrec
Since the proposal of a SiO ₂ (silicon dioxide) cantilever chip manufactured by applying a semiconductor IC manufacturing process by ht) etc., a cantilever manufactured by applying this semiconductor IC manufacturing process has become mainstream (Thomas R.
Albrecht Calvin F. Quate: Atomic resolution Imagin
g of a nonconductor by Atomic force Microscopy
J. Appl. Phys, 62 (1987) 2599). One of the advantages of applying this semiconductor IC manufacturing process is the micrometer (μm)
It is possible to make highly reproducible cantilevers on the order of, and another advantage is that by making multiple cantilevers at once in a batch process,
That is, the manufacturing cost can be reduced.

Further, a method has been proposed in which silicon nitride is used instead of SiO ₂ (silicon dioxide) to fabricate a cantilever having a sharpened probe (J. Vac.
Sci.Technol.A8 (4) 3386 1990: T.Albrecht, S.Akamine,
TECaver and CF Quate). The cantilever produced by this method has a hollow triangular shape or a rectangular shape with a length of about 50 to 200 μm and a thickness of about 0.
It is 5-1 μm. Moreover, the probe provided on this cantilever has a radius of curvature of several hundred nanometers at its tip, thus achieving high resolution.

Furthermore, Yves Martin and H. Kumar Wickramas
inghe et al. have proposed a method of measuring surface information of a sample (not shown) by a probe (not shown) having a probe 2 having a shape as shown in FIG. 4 (Appl.
y.Phys.Lett.Vol.64 No.19 (1994) P.2498-2500).

As shown in FIG. 4, the probe 2 has a substantially cylindrical shape and has a large diameter portion 2a having a diameter of 2 μm to 2.5 μm and a small diameter extending from the large diameter portion 2a. It is composed of a part 2b. The small-diameter portion 2b has a substantially boot shape, and has an extension length of about 2.8 μm and an extension tip 4a having a diameter of about 360 nm. Also, this small diameter portion 2b
A constricted portion 4b having a diameter smaller than that of the extending tip 4a is formed at a substantially central portion of the constricted portion 4b, and the constricted portion 4b has a diameter of about 210 nm.

When the shape of a trench groove or hole of a semiconductor device is measured using such a probe 2, the tip 4a of the probe is used.
Is protruding more than other parts, so this probe tip 4
a comes closest to the measurement target area. Therefore,
By scanning the tip 4a of the probe along the measurement target region, it becomes possible to measure the shape of the trench groove or hole of the semiconductor element.

It should be noted that silicon nitride, which is richer in silicon than single crystal silicon, is less likely to wear as the material of the probe 2, and in particular, the stoichiometry of silicon and nitrogen is 3 (stoichiometry). It has been reported by Matsuyama et al. That the use of pair 4 silicon nitride is more difficult to wear (Proceedings of the 55th SPSJ Academic Lecture P. 47).
3).

[0014]

[Problems to be Solved by the Invention] By the way, "Apply.Ph
ys.Lett.Vol.64 No.19 (1994) P.2498-2500 '' is described in J.Appl.Phys.Vol.61 No.10 (1987) P.4723.
Since it is a method that applies the attractive force detection mode AFM described in -4729, the AFM measurement in the atmosphere may become unstable.

In this case, the AFM measurement can be stabilized by increasing the vibration amplitude of the cantilever.
The problem of probe wear still remains. Further, when the probe wears and the shape of the probe is deformed, a new problem arises that the reproducibility of measurement data is lost. Furthermore, if the amplitude is increased to 200 nm (400 nm), for example, a new problem arises that it becomes impossible in principle to measure the shape of a groove or hole narrower than 400 nm.

The present invention has been made to solve such a problem, and an object thereof is to measure the surface information of a measurement target region having an arbitrary shape and dimension with good reproducibility regardless of the measurement environment. An object of the present invention is to provide a probe for a possible scanning probe microscope.

[0017]

In order to achieve such an object, a probe for a scanning probe microscope of the present invention comprises a supporting means and a thin plate-shaped cantilever extending from the supporting means and elastically deformable. A beam, a probe formed in the cantilever and having a substantially quadrangular prism shape or a substantially columnar shape, and a tip portion which is formed in the probe and approaches or contacts the measurement target region during scanning, The shape and dimension of the tip portion is projected and enlarged as compared with other portions.

The method for producing a probe for a scanning probe microscope according to the present invention is based on the step of forming a mask made of a predetermined material on one side of a silicon wafer having a predetermined plane orientation and the plane orientation of the silicon wafer. A step of forming a polygonal or circular opening having a predetermined size in the mask, a step of forming a hole of a predetermined shape on one surface side of the silicon wafer through the opening, and an inner peripheral surface of the hole A step of depositing a film made of a predetermined material on the silicon wafer, and after removing the mask from the silicon wafer, depositing a probe constituent member constituting the probe for the scanning probe microscope over one surface side of the silicon wafer and the inside of the hole. And a pattern having the same shape as the cantilever beam is formed on the probe constituent member based on the surface orientation of the silicon wafer. And a step of joining the supporting means on the probe constituent member on which the pattern is formed, and a step of removing the silicon wafer and the coating film so that the scanning probe microscope probe remains. .

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A probe for a scanning probe microscope according to an embodiment of the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1A and 1B, the probe 6 for the scanning probe microscope according to the present embodiment.
Is a support portion 8 made of Pyrex glass which is detachably attached to a scanning probe microscope (not shown), a strip-shaped cantilever beam 10 extending from the support portion 8 and elastically deformable, and the cantilever. The beam 12 is provided with a probe 12 formed at an extended end (hereinafter referred to as a free end).

The probe 12 has a substantially rectangular prism shape,
An intermediate extension P2 is formed between the vicinity P1 of the cantilever 10 and the tip P3 of the probe 12. The diameter of the probe 12 applied to the present embodiment continuously decreases from the vicinity P1 toward the intermediate extension P2, and then decreases from the intermediate extension P2 toward the tip P3. The diameter is continuously increasing.

Further, the cantilever 1 applied to this embodiment.
0 has a length L in the longitudinal direction of about 100 μm, a width W of about 40 μm, and a thickness T of 1.2 μm. In addition, in the present embodiment, an explanation will be made by using a substantially quadrangular prism-shaped probe 12 as an example in the drawings, but according to a probe manufacturing method described later, a substantially cylindrical probe 12 may be applied. It is possible.

As shown in FIG. 1C, the probe 12 has a height H of about 3.5 μm, a diameter D1 of the tip P3 of about 0.7 μm, and a diameter D2 of the intermediate extension P2 of 0. It is 0.5 μm. Note that, due to the application of a probe manufacturing method to be described later, the tip portion P3 is formed with a portion that slightly projects along the extending direction of the probe 12 and has a sharp projecting end (FIG. 1B. ), (C)).

As shown in FIG. 1D, the tip portion P3 of the probe 12 has a substantially astroid shape composed of four sides when viewed from the upper side. Here, cantilever 10
Let X be the longitudinal direction of the intersection of the four sides 14a,
Of the diagonal lines connecting 14b, 14c, 14d (hereinafter, referred to as first to fourth protrusions), the first and third protrusions 1
The direction of the diagonal line connecting 4a and 14c is within an angle range of ± 45 ° with respect to the longitudinal direction X of the cantilever 10, preferably,
It is set to be substantially parallel to the longitudinal direction X.

According to the probe 6 for a scanning probe microscope of the present embodiment having such a configuration, the probe 12 is provided with respect to a side wall (for example, a vertical wall) such as a groove or a hole having a step of about several μm. First and third protrusions 14 of the tip portion P3 of the
By scanning while a and 14c are brought close to or in contact with each other, it is possible to measure the surface information of the side wall (that is, the measurement target region) with high accuracy and form an image.

Further, even for a region such as a corner or a corner of a groove having a step which is very difficult to measure by the conventional probe, the scanning probe microscope probe 6 of the present embodiment can be used. , An easy approach is possible.

In addition, the above-mentioned "Apply.Phys.Lett.Vol.64 No.
19 (1994) P.2498-2500 '',
The probe 12 applied to the present embodiment has the first to fourth protrusions 14a, 14b, 14 formed at the tip P3 thereof.
c and 14d are protruding laterally. For this reason, it is possible to realize high-resolution measurement for the measurement target region and stabilize the measurement in the atmosphere.

Further, according to the probe 6 for a scanning probe microscope of the present embodiment, at the time of measurement, the first and third protrusions 14a are formed in the measurement target region (for example, side walls such as grooves and holes). , 14c are controlled so that they are closest to or in contact with each other. Therefore, even when the probe 12 receives a force in the vertical direction from the side wall when the probe 6 is scanned at high speed along the X direction (see FIG. 1D), the force is applied to the first and third protrusions. Part 14
Since it only acts in the diagonal direction connecting a and 14c, the cantilever 10 is not twisted. As a result,
The probe 12 is always accurately and stably scanned in the measurement target area during the measurement.

As described above, according to the present embodiment, there is provided a probe for a scanning probe microscope capable of reproducibly measuring surface information of a measurement target region having an arbitrary shape dimension regardless of the measurement environment. It becomes possible to do.

When the probe 12 having a substantially cylindrical shape is used, the tip P3 of the probe 12 has a circular shape having a large radius with respect to the intermediate extension P2 of the probe 12. Therefore, as compared with the case of using the probe 12 having the substantially quadrangular prism shape described above, the tip portion P3 of the probe 12 having the substantially columnar shape accurately measures the surface information from any direction of the measurement target region. It becomes possible. That is, it can be said that the substantially cylindrical probe 12 can detect surface information from multiple directions regardless of the scanning direction, and can measure the surface information of the measurement target region with good reproducibility. .

Next, a method of manufacturing the probe 6 for the scanning probe microscope of the present embodiment will be described with reference to FIG. First, as the start wafer, the plane orientation (10
0) and the orientation flat 16a has a {001} orientation of the 4-inch silicon wafer 16 (FIG. 2).
(A)).

Next, the silicon nitride film 1 is formed on the front and back surfaces of the silicon wafer 16 by the LP-CVD (low pressure CVD) method.
After depositing No. 8, a photosensitive resist film 20 is applied to the surface of this silicon nitride film. Subsequently, after the resist film 20 is subjected to a predetermined patterning, an opening 22 having a predetermined shape is formed in the silicon nitride film 18 by photolithography.
(In the present embodiment, one example thereof is 1.3 μm on each side.
To form a square opening). Note that in this embodiment, the opening 2 is formed so that the direction of each side is {011}.
2 is formed (see FIG. 2B).

After that, RIE etching (Reaction ion etching) is performed on the silicon wafer 16 using the silicon nitride film 18 and the resist film 20 as a mask. As a result, in the silicon wafer 16, a square pillar-shaped hole 24 is dug in a direction substantially perpendicular to the wafer surface.
Are formed (see FIG. 2B). The etching gas used in this manufacturing process is a mixed gas of CCl ₂ F ₂ and N ₂ .

Next, after removing the resist film 20, approximately 9
By performing a low temperature thermal oxidation process in a thermal oxidation furnace at 50 ° C., a silicon oxide layer 26 is grown and deposited on the silicon surface in the hole 24 exposed by the RIE etching. At this time, the silicon oxide layer 26 deposited in the hole 24
Among them, the silicon oxide layer 26 deposited in the deepest part of the hole 24 is formed with a substantially astroid-shaped bite part 26a which is bite in the circumferential direction of the hole 24 more than other parts (FIG. 2).
(C)). In this manufacturing process, the thermal oxidation treatment is performed at a temperature about 150 ° C. lower than the oxidation temperature (about 1100 ° C.) for forming a normal silicon oxide layer, so that the sharpness of the bite portion 26a is improved.

Subsequently, the silicon nitride film 18 is removed by hot phosphoric acid, and then 1.2-μm thick silicon nitride films 28a and 28b are deposited on the front and back surfaces of the silicon wafer 16 by the LP-CVD method (FIG. 2). (See (d)). As a result, the silicon nitride film 28a is deposited in the hole 24 in which the silicon oxide layer 26 is deposited so as to have the same shape as the probe 12 (see FIG. 1). Since silicon rich silicon nitride is used in this manufacturing process, the silicon nitride films 28a and 28b with less internal stress are deposited on the front and back surfaces of the silicon wafer 16.

Then, in the thermal oxidation furnace, the silicon nitride films 28a and 28b are annealed by flowing water vapor to perform thermal oxidation. After that, the silicon wafer 16 that has undergone the above-described manufacturing process is subjected to photolithography, and the cantilever needle 10 (see FIG. 1) is applied to the silicon nitride film 28a.
Pattern 30 having the same shape as the reference pattern (see FIG. 2).
(E)). In this fabrication process, pattern 3
0 is formed such that its longitudinal direction is {001}. 2 (e), the pattern 30 and the orientation flat 1 are shown.
Although only one pattern 30 is shown so that the positional relationship with 6a can be easily understood, in reality, 576 patterns 30 are formed on one silicon wafer 16.

Next, after the Pyrex glass 32 constituting the supporting portion 8 (see FIG. 1) is anodically bonded to a predetermined position of each pattern 30 (see FIG. 2 (f)), the silicon wafer 16
The silicon nitride film 28b deposited on the back surface of is etched. Then, potassium hydroxide aqueous solution (36% wt)
After the silicon wafer 16 is melted away by means of hydrofluoric acid, the silicon oxide film 26 around the silicon nitride film 28a forming the probe 12 (see FIG. 1) is dissolved away by means of hydrofluoric acid.

As a result, the probe 8 as shown in FIG. 1A is manufactured, and finally, one surface of the cantilever 10 (that is,
Aluminum is vacuum-deposited to a thickness of 80 nm on the surface opposite to the surface on which the probe 12 is formed).

This metal coating of aluminum contributes to enhancing the reflectance of light and improving the S / N ratio when the movement of the cantilever 10 is monitored by the optical displacement sensor. According to such a manufacturing method, the probe 6 having the silicon nitride probe 12 which is more excellent in wear characteristics than single crystal silicon is manufactured.

In the manufacturing method applied to this embodiment, when the RIE etching is performed on the silicon wafer 16 (see FIG. 2B), a square mask having a side of about 1.3 μm is used. Even if a circular mask having a diameter of 1.3 μm or less is used, the hole 24 after etching has a substantially quadrangular prism shape. This is because the etching rate for each plane orientation of single crystal silicon is different. Therefore, in the present embodiment, the RI with the circular mask is used.
Although it is possible to perform E etching, in this case, by appropriately selecting the plane orientation of the silicon wafer 16 and the direction of the mask, as in the above-described embodiment, the tip portion P is formed.
It is possible to manufacture the probe 12 in which 3 is projected and enlarged more than other parts.

When a circular mask is used and its diameter is set to 1.3 μm or more and the same manufacturing method as that of the above-described embodiment is applied, the tip portion P3 projects larger than other portions and expands. It is possible to form the substantially cylindrical probe 12.

Further, as shown in FIG. 3, even when a silicon wafer 16 having a plane orientation (100) and an orientation flat 16a having an orientation of {011} is used as a starting wafer, the same manufacturing method as described above is carried out. Then, it is possible to manufacture the probe 6 as shown in FIG.
In this case, based on the crystal orientation of silicon, the cantilever 1
By appropriately selecting the pattern 30 of 0 (see FIG. 1) and the azimuth of the opening 22, the sharpness of the tip P3 of the probe 12 can be improved.

Although silicon nitride is used as the material of the probe 12 in the present embodiment, even if a silicon compound such as silicon carbide is used, a probe having better wear characteristics than single crystal silicon can be obtained. It is possible to make. Also,
Other candidate materials include materials that are insoluble or difficult to dissolve in hydrofluoric acid.

Further, in the present embodiment, the example in which the probe 6 is formed on the cantilever 10 has been described, but if the shape of the sample surface can be detected by the probe 6 and its movement can be monitored, the both-end supported beam can be monitored. Alternatively, the probe 6 shown in this embodiment may be formed on a membrane.

[0044]

According to the present invention, it is possible to provide a probe for a scanning probe microscope capable of reproducibly measuring surface information of a measurement target region having an arbitrary shape and dimension regardless of the measurement environment. it can.

[Brief description of the drawings]

FIG. 1A is a perspective view showing an overall configuration of a probe for a scanning probe microscope according to an embodiment of the present invention,
(B) is an enlarged perspective view showing the configuration of the probe portion,
(C) is a side view of the portion shown in (b) of the same figure, (d)
Is a plan view of the portion shown in FIG.

FIGS. 2A to 2F are diagrams showing a process of manufacturing a probe for a scanning probe microscope according to an embodiment of the present invention, respectively.

FIG. 3 is a diagram showing a process of manufacturing a probe for a scanning probe microscope according to a modification of the embodiment of the invention.

FIG. 4 is a diagram showing a configuration of a probe formed on a conventional probe.

[Explanation of symbols]

6 ... Probe, 8 ... Supporting part, 10 ... Cantilever, 12 ... Probe, P1 ... Neighborhood part, P2 ... Intermediate extension part, P3 ... Tip part,
14a, 14b, 14c, 14d ... Protrusions.

Claims (3)

[Claims] 1. A support means, a thin plate-shaped cantilever extending from the support means and elastically deformable, and a probe formed on the cantilever and having a substantially quadrangular prism shape or a substantially columnar shape. The scanning is characterized in that the probe is provided with a tip portion that approaches or contacts the measurement target region during scanning, and the shape and dimension of the tip portion is projected and enlarged as compared with other portions. Probe for type probe microscope. 2. The method for manufacturing a probe for a scanning probe microscope according to claim 1, wherein a mask made of a predetermined material is formed on one surface side of a silicon wafer having a predetermined plane orientation, and the silicon is used. A step of forming a polygonal or circular opening having a predetermined dimension in the mask based on the plane orientation of the wafer; and a step of forming a hole of a predetermined shape on the one surface side of the silicon wafer through the opening, A step of depositing a coating film made of a predetermined material on the inner peripheral surface of the hole; and, after removing the mask from the silicon wafer, the probe for a scanning probe microscope is configured over one surface side of the silicon wafer and the inside of the hole. A step of depositing a probe constituent member, and a pattern having the same shape as the cantilever on the probe constituent member based on the plane orientation of the silicon wafer. A step of forming a turn, a step of joining the supporting means on the probe constituent member on which the pattern is formed, and a step of removing the silicon wafer and the coating so that the scanning probe microscope probe remains. And a manufacturing method. 3. A supporting means, a thin plate-shaped cantilever extending from the supporting means and elastically deformable, a probe formed on the cantilever and having a substantially quadrangular prism shape, and the probe. A tip portion that is formed and approaches or contacts the measurement target region during scanning, the tip portion has a substantially quadrangular shape composed of four sides, and is formed by connecting the intersection points of the four sides. A probe for a scanning probe microscope, wherein one of the diagonal lines formed is substantially parallel to the longitudinal direction of the cantilever.