JP2006105744A - Nano-wire tension test device and testing method using device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nano-wire tension test device and a testing method using this device, suitable for a tension test of a nano-dimension material. <P>SOLUTION: This nano-wire tension test device has base parts 5 and 6, a specimen fixing part 2 having first and second fixing parts 21 and 22, a first support part 23 and a towing object part 24 for fixing a specimen, a displacement amplifying part 4 having a measuring cantilever 41, and an actuator part 3 having a towing part 36, first and second towing attraction generating parts 32 and 34, a second support part 31 and a contact part 35. The first fixing part 21, the second towing attraction generating part 34, and the first and second support parts 32 and 34 are fixed to the base parts 5 an 6. An interval between the towing object part 24 and the towing part 36 is set larger than an interval between the contact part 35 and the measuring cantilever 41. The actuator part 3 pushes the measuring cantilever 41 by DC voltage impressed on first and second electrodes 38 and 39, and tows the towing object part 24. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a nanowire tensile test device for performing a uniaxial tensile test of a material having a dimension on the order of nanometers (nm) and a test method using the same.

  With the development of nanotechnology, it is expected to realize ultra-small sensors and nanomachines using materials of nanometer order dimensions (hereinafter referred to as nanodimensions) including carbon nanotubes. In designing nano-sized structures, it is necessary to evaluate the mechanical and electrical properties of nano-sized materials. For example, it is necessary to measure and evaluate the tensile properties of nano-sized linear materials (hereinafter referred to as nanowires) by tests.

  Generally, a tensile test is performed by gripping a test object (hereinafter referred to as a test piece) at two locations and applying a force in a direction that widens the distance between the gripped portions. For example, Patent Documents 1 and 2 below disclose a tensile test apparatus for a minute test piece. Patent Document 1 discloses a tensile test apparatus that attaches a measurement mark to a test piece (rubber, resin, fiber), and images the displacement of the measurement mark with two cameras while applying a tensile force to the test piece. Yes. Patent Document 2 discloses a tensile test apparatus for bonding wires of semiconductor devices (for example, wires connecting semiconductor pellets and leads).

Further, as a means for pulling the test piece, a method is known in which two comb-shaped actuators are arranged at a predetermined interval, and electrostatic attraction generated by applying a DC voltage thereto is used. In this case, the applied voltage is directly used to evaluate the force applied to the test piece.
JP-A-6-138209 JP-A-5-72088

  However, it was very difficult to perform a tensile test on nano-sized materials. None of the test apparatuses disclosed in Patent Documents 1 and 2 can test nano-sized materials. The device disclosed in Patent Document 2 targets a semiconductor bonding wire, but its diameter is on the order of μm, for example, 20 μm to 50 μm, and is applied to nanowires that are one or two orders of magnitude thinner than that. It is not possible.

  Further, in the tensile test of nanowires, the amount of elongation of the material is very small, and it is very difficult to measure the amount of displacement by the method of directly measuring the displacement of the test piece as disclosed in Patent Document 1 above. It is.

  It is also possible to reduce the size of the test device and perform a tensile test on nano-sized materials using electrostatic attraction, but simply reducing the size will cause slight vibrations in the measurement preparation stage. There is a problem that the member attached with the end of the nanowire moves due to the surrounding air current, and the test piece is damaged due to this.

  In addition, since the test method using electrostatic attraction is easily affected by the environment, for example, ambient humidity, the generated electrostatic attraction may be different even when the same device is used and the same voltage is applied. It may be inappropriate to evaluate the test results using the applied voltage directly.

  An object of the present invention is to provide a nanowire tensile test device suitable for a tensile test of a nano-sized material and a test method using the same, in order to solve the above-described problems.

  The object of the present invention is achieved by the following means.

  That is, the nanowire tensile test device (1) according to the present invention includes a base, a first fixing portion that fixes one end of the test piece, a second fixing portion that fixes the other end of the test piece, and the second fixing portion. A fixed first support portion, a test piece fixing portion having a towed portion fixed to the first support portion, a displacement amplifying portion having a measurement cantilever, and a first interval from the towed portion. It can be in contact with the arranged traction unit, the first traction force generation unit, the second traction force generation unit, the second support unit, and the displacement amplification unit that are arranged to face the first traction force generation unit with a predetermined interval. An actuator part having a contact part, wherein the first fixing part and the second traction force generating part are fixed to the base part, and the first supporting part and the second supporting part are fixed to the base part so as to be elastically deformable. The first interval is between the contact portion and the displacement amplifying portion. When a DC voltage is applied between the first traction force generation unit and the second traction force generation unit that is greater than the distance, electrostatic attraction generated between the first traction force generation unit and the second traction force generation unit When the contact portion applies a force to the displacement amplifying portion and is larger than the displacement amount of the contact portion to displace the free end of the measurement cantilever, and the voltage increases, the towing portion is applied to the towed portion. In contact with each other, the tow portion pulls the to-be-towed portion.

  The nanowire tensile test device (2) according to the present invention is the nanowire tensile test device (1), wherein one end of the measurement cantilever is fixed to the base so as to be elastically deformable, and the first traction force generating unit When a DC voltage is applied between the second traction force generating unit, the contact unit applies a force to the measurement cantilever, and the free end of the measurement cantilever and the contact unit are in contact with the measurement cantilever. The distance between the first position and the first position is about 10 to 200 times the distance between the fixed end of the measurement cantilever and the first position.

  Further, the nanowire tensile test device (3) according to the present invention is the nanowire tensile test device (1), wherein the displacement amplification unit is fixed to the base so that the measurement cantilever is fixed and both ends are elastically deformable. When a direct current voltage is applied between the first traction force generation unit and the second traction force generation unit, the contact portion applies a force to substantially the center of the measurement beam, and the measurement beam is provided. The cantilever is fixed from the center of the measurement beam to a position that is 1/4 of the length of the measurement beam.

  Moreover, the nanowire tensile test device (4) according to the present invention is the nanowire tensile test device (1) to (3), wherein the spring constant of the first support portion is the spring of the second support portion. It is characterized by being larger than a constant.

  Moreover, the nanowire tensile test device (5) according to the present invention is the nanowire tensile test device (1) to (4), wherein the first support portion is a beam, and the second fixing portion and the nanowire tensile test device (5) The towed part is fixed at a central position of the first support part, the second support part is an even number of beams having one end fixed to the base part, and the towed part and the actuator part are It has a line-symmetric shape having a symmetry axis along a direction in which the to-be-towed portion is pulled, and the respective symmetry axes coincide with each other.

  The nanowire tensile test method (1) according to the present invention includes a base, a first fixing portion that fixes one end of the test piece, a second fixing portion that fixes the other end of the test piece, and the second fixing portion. A fixed first support portion, a test piece fixing portion having a towed portion fixed to the first support portion, a displacement amplifying portion having a measurement cantilever, and a first interval from the towed portion. It can be in contact with the arranged traction unit, the first traction force generation unit, the second traction force generation unit, the second support unit, and the displacement amplification unit that are arranged to face the first traction force generation unit with a predetermined interval. An actuator part having a contact part, wherein the first fixing part and the second traction force generating part are fixed to the base part, and the first supporting part and the second supporting part are fixed to the base part so as to be elastically deformable. The first interval is a distance between the contact portion and the displacement amplifying portion. Larger than the first traction force generation unit and the second traction force generation unit when a DC voltage is applied, the electrostatic attraction generated between the first traction force generation unit and the second traction force generation unit, When the contact portion applies a force to the displacement amplifying portion and displaces the free end of the measurement cantilever larger than the displacement amount of the contact portion, and the voltage increases, the traction portion contacts the towed portion. A nanowire tensile test method using a nanowire tensile test device in which the traction unit pulls the to-be-pulled portion, wherein a first DC voltage is applied between the first traction force generation unit and the second traction force generation unit. And a second step of measuring a displacement amount of a free end of the measuring cantilever, and the voltage is increased until the test piece is broken, and the first and second steps are repeated. After serial specimen was broken is characterized in that by decreasing the voltage repeating said first and second step.

The nanowire tensile test method (2) according to the present invention is the nanowire tensile test method (1), wherein one end of the measurement cantilever is fixed to the base so as to be elastically deformable, and the first traction force generation unit When a DC voltage is applied between the second traction force generating unit, the contact unit applies a force to the measurement cantilever, and the free end of the measurement cantilever and the contact unit are in contact with the measurement cantilever. The distance between the first position and the first position is about 10 times or more and about 200 times or less the distance between the fixed end of the measurement cantilever, and the displacement amplification factor α of the displacement amplification unit; A displacement amount Δ _{amp1 of the} free end measured by applying a voltage V before the test piece breaks, and a displacement amount Δ _{amp2 of the} free end measured by applying a voltage V after the test piece breaks ,in front By using the spring constant gamma _m of the measuring cantilever, and a spring constant gamma ₁ of the second supporting portion, ₌ load P _S applied to the test piece at the time of applying a voltage _{V P S (γ m + γ} 1) X ( _{Δamp2− Δamp1} ) / α, and the amount of elongation of the test piece is based on the amount of displacement of the free end at the bending point appearing in the graph showing the amount of displacement of the free end with respect to the applied voltage. It is characterized by seeking.

Further, the nanowire tensile test method (3) according to the present invention is the nanowire tensile test method (1), wherein the displacement amplifying part is fixed to the base part so that the measurement cantilever is fixed and both ends are elastically deformable. When a direct current voltage is applied between the first traction force generation unit and the second traction force generation unit, the contact portion applies a force to substantially the center of the measurement beam, and the measurement beam is provided. A cantilever is fixed from the center of the measurement beam to a position that is 1/4 of the length of the measurement beam, and the displacement amplification factor α of the displacement amplification unit and the voltage before the test piece breaks. A displacement amount Δ _{amp1 of the} free end measured by applying V, a displacement amount Δ _amp2 of the free end measured by applying a voltage V after the test piece _broke, and a spring constant γ of the measuring beam _m and the spring constant γ of the second support part With ₁ and the voltage load _{P S P S = (γ m} + γ 1) applied to the specimen when applied to _{V × (Δ amp2 -Δ amp1)} / calculated in alpha, elongation of the specimen Is obtained with reference to the amount of displacement of the free end at the bending point appearing in the graph showing the amount of displacement of the free end with respect to the applied voltage.

  According to the nanowire tensile test device according to the present invention, one end of the test piece is fixed to the pulled portion and the first support portion having a relatively small mass separated from the actuator portion having a relatively large mass. The possibility of damage to the test piece due to vibration during test preparation and changes in the surrounding airflow is reduced, making it easier to use in the test preparation stage.

  Further, by using the measuring cantilever, the amount of displacement can be increased, and the amount of extension of the test piece can be easily measured with high accuracy.

  In addition, the center of the measuring beam equipped with a measuring cantilever has a structure in which the contact part of the actuator part applies force, so that a force in a direction different from the pulling direction is not applied to the actuator part, and high-precision measurement is performed. Is possible.

  Moreover, highly accurate measurement is attained by making each part which comprises a nanowire tensile test device into a line symmetrical shape.

  In addition, by making the spring constant of the first support portion larger than the spring constant of the second support portion, it becomes easy to determine the bending point on the graph of the measurement result. Thereby, the extension amount of the test piece can be obtained more easily.

  Further, according to the nanowire tensile test method according to the present invention, the tension applied to the test piece can be obtained from the amount of displacement before and after the fracture of the test piece without using the applied voltage, and the bending of the measurement result on the graph The amount of elongation of the test piece can be determined from the difference in displacement before and after the test piece breaks after the point.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing a nanowire tensile test device according to an embodiment of the present invention. As shown in FIG. 1, the nanowire tensile test device 1 includes a base composed of an upper base 5 and a lower base 6, a test piece fixing part 2, an actuator part 3, and a displacement amplifying part 4. It is configured.

  The test piece fixing portion 2 includes a first fixing portion 21 that fixes one end of the test piece S, a second fixing portion 22 that fixes the other end, and a first support portion 23 (both ends are fixed to the upper base portion 5). In FIG. 1, it is formed as a beam) and a to-be-towed portion 24 fixed substantially at the center of the first support portion 23. FIG. 2 is an enlarged view showing the vicinity of the first fixing portion 21 and the second fixing portion 22. The upper base portion 5 and the lower base portion 6 are fixed to each other on the surface except for the region of the lower base portion 6 that faces the first support portion 23 and the pulled portion 24. That is, a minute gap (for example, about 1 μm) is provided between the first support part 23 and the to-be-towed part 24 and the lower base part 6.

  The actuator part 3 is fixed to the upper base part 5 by a second support part (four support beams in FIG. 1) 31, and includes an actuator main body 33 having a plurality of comb-shaped first traction force generating parts 32, And three electrode portions 37 each having a comb-shaped second traction force generating portion 34. Here, the three electrode portions 37 are fixed to the lower base portion 6, but a minute gap (for example, about 1 μm) is provided between the four cantilevers 21 and the actuator body 33 and the lower base portion 6. It has been. The displacement amplifying portion 4 side of the actuator body 33 is formed in a protruding shape (hereinafter, this portion is referred to as a contact portion 35), and the test piece fixing portion 2 side is connected to the towed portion 24 and a minute gap. (Hereinafter, referred to as an offset gap) and has a substantially fitting shape (hereinafter, this portion is referred to as a pulling portion 36). FIG. 3 is an enlarged plan view showing the vicinity of the pulling portion 36. A first electrode 38 and a second electrode 39 are formed on the surfaces of the upper base portion 5 and the three electrode portions 37, respectively.

The displacement amplifying unit 4 includes a measuring cantilever 41 having one end fixed to the upper base 5 and the other end being a free end T, and a scale portion 42 disposed in the vicinity of the free end T of the measuring cantilever 41. Yes. Here, a minute gap (for example, about 1 μm) is provided between the measurement cantilever 41 and the lower base 6. A small gap (hereinafter referred to as a tip gap) is provided between the actuator body 33 and the measurement cantilever 41. The tip gap interval g ₂ is smaller than the offset gap interval g ₁ (g ₂ <g ₁ ). 4 is an enlarged plan view showing the vicinity of the contact portion 35 of the actuator main body 33, and FIG. 5 is an enlarged view showing the vicinity of the free end T of the measurement cantilever 41. As shown in FIG.

  Although omitted in FIG. 1, as can be seen from FIGS. 3 and 4, a plurality of holes are formed in the actuator body 33 and the pulled part 24. This is for efficiently separating each from the lower base 6 in a manufacturing method using a semiconductor process described later, and is not indispensable.

  Details of the operation of the nanowire tensile test device will be described later, and an outline of the operation will be described here. By applying a predetermined DC voltage between the first electrode 38 and the second electrode 39, an electrostatic attractive force is generated between the first traction force generation unit 32 and the second traction force generation unit 34 facing each other. . As a result, the actuator body 33 is translated in the direction of the arrow A shown in FIG. 1, and the traction part 36 pulls the to-be-towed part 24 in the direction of the arrow A, so that tension can be applied to the test piece S. On the other hand, the contact portion 35 applies a force to the measurement cantilever 41. As a result, since the free end T of the measurement cantilever 41 is displaced larger than the displacement of the portion in contact with the contact portion 35, a minute displacement can be easily detected. Therefore, the tension applied to the test piece S and the amount of extension thereof can be obtained from the amount of displacement of the free end T of the measurement cantilever 41.

  Next, an example of a manufacturing method will be briefly described. The nanowire tensile test device can be manufactured by using, for example, an SOI wafer and applying a semiconductor process thereto. That is, Cr is vapor-deposited on an SOI wafer (for example, the thickness of the active layer is about 35 μm), a mask pattern for forming each part is formed, and dry etching is performed by reactive ion etching (Deep-RIE). Thereafter, sacrificial layer etching with HF is performed to separate the actuator main body 33, the four support beams 31, the pulled portion 24, the beam 23, and the measurement cantilever 41 from the silicon substrate (lower base portion 6). Finally, an Au thin film electrode (first and second electrodes 38, 39) is formed on the upper base 5 and the electrode part 37 by selective vapor deposition. Through these steps, the nanowire tensile test device 1 in which the actuator body 33, the four support beams 31, the to-be-towed portion 24, the beam 23, and the measurement cantilever 41 are integrated with the upper base portion 5 can be formed. . Moreover, when carbon nanowire is used as the test piece S, for example, the test piece S may be formed by FIB-CVD so that both ends are positioned on the first and second fixing portions 21 and 22. Since these steps are well known in the semiconductor process, detailed description is omitted here.

  Next, a tensile test method using the nanowire tensile test device 1 will be described. Among them, the operation of the nanowire tensile test device 1 will be described in detail.

FIG. 6 is a diagram for explaining a tensile test method using the nanowire tensile test device 1. In this test method, as shown in FIG. 6, the nanowire tensile test device 1, the power source 7 that applies a DC voltage to the electrodes of the nanowire tensile test device 1, and the free end T of the measurement cantilever 41 are imaged. For this purpose, an optical microscope 8 and a CCD camera 9 and a computer 10 for recording digital data of an image captured by the CCD camera 9 are used. In FIG. 6, the nanowire tensile test device 1 placed on the sample stage of the entity or the optical microscope 8 is shown in an enlarged manner.
(First stage)
First, a DC voltage is applied from the power source 7 between the first electrode 38 and the second electrode 39 (see FIG. 1) of the nanowire tensile test device 1 while gradually increasing the voltage value. As a result, an electrostatic attractive force is generated between the opposing comb-shaped first traction force generation unit 32 and the second traction force generation unit 34, and the actuator body 33 is translated in the direction of arrow A shown in FIG. The contact portion 35 moves in the direction of arrow A, but is not in contact with the measurement cantilever 41 at this stage. Further, since the offset gap interval g ₁ is larger than the tip gap interval g ₂ , the traction portion 36 is not in contact with the to-be-driven portion 24. FIG. 7 is a graph showing the relationship between the voltage V (horizontal axis) applied between the first and second electrodes 38 and 39 and the displacement amount Δ _amp (vertical axis) of the free end T of the measurement cantilever 41. is there. In this first stage, as shown in FIG. 7, even when the voltage V is increased, the displacement amount Δ _amp = 0. In this first stage, the electrostatic attractive force generated by the voltage V is balanced with the restoring force due to the displacement of the four support beams 31.

The displacement amount Δ _amp of the free end T is obtained by imaging the vicinity of the free end T with the CCD camera 9 every time the voltage V is increased, and the positions of the free end and the scale portion 42 on the image captured by the computer 10. Seek from relationship.
(Second stage)
When the voltage V is increased after the first stage, the contact portion 35 comes into contact with the measurement cantilever 41. Thereafter, when the voltage V is further increased, the contact portion 35 applies a force to the measurement cantilever 41 and the measurement cantilever 41 is deformed. Since the offset gap interval g ₁ is larger than the tip gap interval g ₂ , the towing unit 36 is not in contact with the to-be-towed unit 24 even in the second stage. Therefore, in this second stage, the electrostatic attraction generated by the voltage V is balanced with the restoring force due to the displacement of the measuring cantilever 41 and the resultant force due to the displacement of the four supporting beams 31. Since the electrostatic attractive force is proportional to the square of the voltage V, the second stage graph is a quadratic curve as shown in FIG.

FIG. 8 is a diagram showing how the measurement cantilever 41 is deformed. As shown in FIG. 8, the distance L _m2 between the free end and the portion in contact with the contact portion 35 is smaller than the distance L _m1 between the fixed end of the measurement cantilever 41 and the portion in contact with the contact portion 35. Since it is designed to be large, the displacement amount Δ _amp of the free end T is larger than the displacement amount Δ _{m of the} portion in contact with the contact portion 35. The displacement amount Δ _amp of the free end T can be obtained from Equation 1 from the displacement amount Δ _{m of the} portion with which the contact portion 35 contacts.
_{Δ amp ≒ Δ m × {1} + 1.5 × (L m2 / L m1)} ··· ( Equation 1)
For _example, if the ratio _L m2 _{/ L m1} about 60 of _{L m @ 2} and _{L m1,} delta _{# 038} is about 91 times the delta _m. As L _m2 / L _m1 increases, the displacement amplification factor also increases. However, it is not preferable that L _m1 is too small, and L _m2 and L _m1 are appropriately determined in consideration of the material of the measurement cantilever 41. Can do. For example, L _m2 / L _m1 is preferably about 10 or more and about 200 or less.

For example, when the length of the test piece S is about 5 μm and is stretched by 10% due to the tension, the displacement amount of the test piece S is about 0.5 μm. This is because, in measuring cantilever 41, appearing as a displacement amount delta _m at the position where the contact portion 35 is in contact. On the other hand, if L _m2 / L _m1 = 66 is designed, the displacement amount Δ _amp of the free end T of the measurement cantilever 41 is about 100 times Δ _m , so the displacement amount of the test piece S About 0.5 μm can be amplified to about 50 μm by observing the free end of the measurement cantilever 41. This is the amount of displacement that can be directly observed by the entity or the optical microscope 8 and the CCD camera 9.
(3rd stage)
When the voltage V is further increased after the second stage, the towing unit 36 comes into contact with the to-be-towed unit 24. Thereafter, when the voltage V is increased, the towed portion 24 is pulled in the direction of arrow A by the towing portion 36, and tension is applied to the beam 23 and the test piece S. In this third stage, the electrostatic attractive force generated by the voltage V is the restoring force due to the displacement of the measuring cantilever 41, the restoring force due to the displacement of the four support beams 31, the restoring force due to the displacement of the beam 23, and the test piece S. Is balanced with the resultant tensile stress.

The quadratic curve after the second stage shown in FIG. 7 corresponds to the third stage. Here, as compared with the second stage, the restoring force due to the displacement of the beam 23 and the tensile stress of the test piece S are added to the force that opposes the electrostatic attractive force. Therefore, the point moving from the second stage to the third stage, i.e., the time when the offset gap g ₁ are in contact and the towed unit 24 and the traction unit 36 becomes 0, as shown in FIG. 7, bent on the graph It can be determined as a point. Therefore, the extension amount of the test piece S can be obtained from the difference in the displacement amount before and after the test piece breaks after the bending point. In order to make it easier to discriminate the bending point on the graph, for example, the beam 23 and the support beam 31 are arranged so that the spring constant of the beam 23 is larger than the spring constants of the four support beams 31. When the same material is used, the beam 23 may be thicker than the four support beams 31.

  Furthermore, when the voltage V is increased, the test piece S eventually breaks. At this time, since the tensile stress due to the test piece S disappears, the amount of displacement increases with respect to the electrostatic attractive force at that time. Thereafter, when the voltage V is increased or decreased, the voltage V changes as indicated by a broken line.

Before the test piece breaks (between points B to C in FIG. 7), Formula 2 is established from the balance of forces.
_{F (V) = P S +} (γ m + γ 1) × Δ amp1 / α + γ 2 g 1 ··· ( Equation 2)
Here, F is the electrostatic attraction, P _S is the tensile stress of the test piece S, gamma ₁ are four spring constant of the supporting beams 31, gamma ₂ is a spring constant of the beam 23, gamma _m is the measurement cantilever 41 The spring constant, Δ _amp1 is the amount of displacement of the free end T of the measurement cantilever 41, and g ₁ is the interval of the offset gap. Α is an amplification factor of the displacement amount by the measurement cantilever 41. For example, when L _m2 / L _m1 = 60, α is approximately 91 as described above.

Similarly, after the test piece is ruptured (between points B to D in FIG. 7), Equation 3 is established from the balance of forces.
F (V) = (γ _m + γ ₁ ) × Δ _{amp 2} / α + γ ₂ g ₁ (formula 3)
Here, each coefficient is the same as Equation 2 except that Δ _amp2 is the amount of displacement of the free end T of the measurement cantilever 41 after the test piece S is broken.

From Equation 2 and Equation 3, Equation 4 is derived.
P _S = (γ _m + γ ₁ ) × (Δ _{amp 2} −Δ _{amp 1} ) / α (Expression 4)
Here, each spring constant can be obtained from the material and shape of the measurement cantilever 41 and the beam 23. That is, if E is the Young's modulus, I _m is the secondary moment of the cross section of the measuring cantilever 41, and I ₁ , N ₁ and L ₁ are the secondary moments of the cross section, the number and the length of the supporting beam 31, respectively, γ _m = 3EI _m / (L _m1 ) ³ , γ ₁ = 12EI ₁ N ₁ / (L ₁ ) ³

Formula 3 contains no electrostatic attraction F, the spring constant can be determined by calculation, by measuring the amount of displacement can be obtained tensile stress P _S of the specimen S. Therefore, without using the voltage V used in the measurement, it is possible to obtain the tensile stress P _S of the specimen S.

  Although the case where the measurement cantilever 41 is directly subjected to the force by the contact portion 35 and the free end T is displaced has been described above, the free end T of the measurement cantilever 41 is indirectly displaced by the contact portion 35. It may be configured. As shown in FIG. 8, the measuring cantilever 41 is deformed by receiving a force by the contact portion 35, and the force received at this time is applied almost perpendicularly to the surface of the measuring cantilever 41 while the displacement is small. However, when the displacement amount of the contact portion 35 increases, the direction of the force applied by the contact portion 35 is not perpendicular to the surface of the measurement cantilever 41. As a result, the contact portion 35 is slight but the force applied by the contact portion 35 Displacement in a direction perpendicular to This can cause a reduction in measurement accuracy. In place of the configuration shown in FIG. 1, the measurement accuracy can be obtained by providing a beam whose both ends are fixed to the upper base 5 and the free end of the measurement cantilever is indirectly displaced by the contact portion 35. The cause of the decrease can be eliminated. An example is shown in FIG.

  The beam shown in FIG. 9 (hereinafter referred to as measurement beam 43) is arranged so that the contact portion 35 can contact the center of the measurement beam 43. Further, with the total length of the measurement beam 43 being L, the measurement cantilever 41a is fixed at a position of ¼ from the center so as to be substantially perpendicular to the measurement beam 43 and parallel to each other. When the central portion is pushed by the contact portion 35, the measuring beam 43 is deformed as indicated by a broken line. As a result, the free end of the measuring cantilever 41a is also displaced as shown. Therefore, if the amount of displacement of the free end, for example, the distance between the two free ends is measured using the CCD camera 9 as described above, the amount of displacement of the contact portion 35 can be amplified and measured. . In this case, unlike the case where the measurement cantilever 41 having only one end fixed is used (see FIG. 1), the contact portion 35 does not receive a force in a direction perpendicular to the force applied by the contact portion 35. Further, when the measurement cantilever 41a is attached at a position ¼ from the center of the measurement beam 43, the stress at the surface position where the measurement cantilever 41a is attached even if the measurement beam 43 is deformed. Therefore, the measuring cantilever 41a maintains a state perpendicular to the surface of the beam in the vicinity thereof. Accordingly, the displacement amount of the contact portion 35 can be linearly amplified. Note that the measurement cantilever 41a may not be fixed to the measurement beam 43 at a right angle, or may not be parallel to each other.

  Even when the measurement cantilever 41a is not attached to a position ¼ from the center of the measurement beam 43, the position of the free end of the measurement cantilever 41a depends on the displacement amount and attachment position of the contact portion 35. Therefore, if the nonlinearity between the displacement amount of the contact portion 35 and the displacement amount of the free end is taken into consideration, the displacement amount of the contact portion 35 can be obtained from the displacement amount of the free end. FIG. 9 shows the case where the measurement beam 43 includes two measurement cantilevers 41a. However, the measurement cantilever 41a is relatively light and the deformation of the measurement beam 43 impairs the objectivity. Otherwise, only one of the measurement cantilevers 41a may be provided, and the amount of displacement of the free end thereof may be measured.

In the above nanowire tensile test device, as shown in FIG. 1, the beam 23, the towed portion 24, the support beam 31, the actuator body 33, the towing portion 36, and the measurement cantilever 41 are formed integrally with the upper base portion 5. However, the present invention is not limited to this. As described above, the nanowire tensile test device according to the present invention includes the base, the test piece fixing part 2, the actuator part 3, and the displacement amplifying part 4, and is provided between the test piece fixing part 2 and the actuator part 3. In addition, a minute gap is provided between the actuator unit 3 and the displacement amplifying unit 4, and a distance g ₁ between the test piece fixing unit 2 and the actuator unit 3 is set to be the actuator unit 3 and the displacement amplifying unit 4. It is only necessary to be larger than the distance g ₂ between the gaps (g ₁ > g ₂ ). For example, in the nanowire tensile test device formed by dividing the test piece fixing portion 2, the actuator portion 3, and the displacement amplifying portion 4 into three parts and then connecting them to the positional relationship shown in FIG. There may be. Here, g ₂ = 0, that is, at least in the case of FIG. 9, the contact portion 35 may be in contact with the measurement cantilever 41 in a state where no DC voltage is applied to the first and second electrodes 39. .

  Further, the shapes of the towed portion 24 and the towed portion 36 are not limited to the shapes in FIG. 1 and are formed so as to pull the towed portion 24 in a predetermined direction when the towed portion 36 is displaced by electrostatic attraction. It only has to be done. Further, the number of first and second traction force generating units 32 and 34 that generate electrostatic attraction, the shape thereof (the number of combs, the size and shape of the combs), the number of electrode units 37, and the like are determined by electrostatic attraction. The tension is not limited to those described above as long as tension can be applied to the test piece. Furthermore, the first and second traction force generating units 32 and 34 that generate electrostatic attractive force do not have to be comb-shaped as long as two members are arranged to face each other and can generate a desired electrostatic attractive force. Good. What is necessary is just to design suitably the shape of the part which produces an electrostatic attraction according to the material to be used, the magnitude | size of the DC voltage applied to an electrode, the shape and dimension of the actuator main body 33, etc. Further, the number of support beams 31 is not limited to four, and may be any number that can stably support the actuator body 33.

  Moreover, the contact part 35 of the actuator part 3 may not be convex. The actuator unit 3 may have a flat portion in contact with the measurement cantilever 41 or the measurement beam 43, and the measurement cantilever 41 or measurement beam 43 may include a convex portion in a portion in contact with the contact portion 35.

  As described above, the shape and size of each part constituting the nanowire tensile test device according to the present invention can be changed as appropriate, but at least the planar shape of each part constituting the test piece fixing part 2 and the actuator part 3 is a line. It is desirable that they have a symmetrical shape, and are arranged so that each target axis is the same, and the axis of symmetry is along the direction in which the actuator unit 3 is displaced by electrostatic attraction.

  The nanowire tensile test device according to the present invention may be manufactured by a manufacturing method other than the semiconductor process, and the material of each part may not be silicon.

  Further, the measurement of the amount of displacement of the free end of the measuring cantilever is not limited to a method using a substance or an optical microscope and a CCD camera, and another method may be used. For example, a method of irradiating the surface of the measuring cantilever with laser light at a certain angle and measuring the reflection angle can be used.

  Examples are shown below to further clarify the features of the present invention.

Actually, using a SOI wafer, a nanowire tensile test device was manufactured by the semiconductor process described above. The shape of the manufactured nanowire tensile test device is about 10 mm long × about 10 mm wide, the offset gap interval g ₁ is about 4 μm, the tip gap interval g ₂ is about 3 μm, and the length of the scale portion 42 is about 50 μm. The distance from the fixed end of the measurement cantilever 41 to the position where the contact portion 35 contacts is about 50 μm, the distance from the free end of the measurement cantilever 41 to the position where the contact portion 35 contacts is about 3000 μm, and the first and second traction forces are generated. The height of the portion 34 (comb portion) is about 35 μm, the width is about 4 μm, and the interval between the comb teeth is about 3 μm. Further, the distance between the first support portion 23 (beam), the actuator main body 33 and the measurement cantilever 41 and the lower base portion 6 is about 1 μm. A carbon nanowire having a length of about 5 μm and a diameter of about 100 nm was attached to the nanowire tensile test device by the FIB-CVD method, and a tensile test was performed. FIG. 10 is a graph obtained as a result.

  As can be seen from FIG. 10, a bending point is observed between the second stage and the third stage, the carbon nanowire breaks in the middle of the third stage, and the amount of displacement changes stepwise before and after that. After the test piece is broken, the displacement amount at each voltage value is larger than the displacement amount before the breakage.

  FIG. 11 is a graph showing a load-displacement curve (the vertical axis is the load and the horizontal axis is the displacement amount) of the test piece obtained from the tensile test data shown in FIG. FIG. 12 is a graph showing a stress-strain curve obtained from the same tensile test data. FIG. 12 shows that the breaking stress of the carbon nanowire having a length of about 5 μm and a diameter of about 100 nm is about 6.5 GPa and the breaking strain is about 7.7%. As described above, the nanowire tensile test device according to the present invention can perform a highly accurate uniaxial tensile test on a nano-sized material.

1 is a perspective view showing an outline of a nanowire tensile test device according to an embodiment of the present invention. It is an enlarged view near the test piece part of the nanowire tensile test device shown in FIG. FIG. 2 is an enlarged view of the vicinity of a pulling portion of the nanowire tensile test device shown in FIG. 1. It is an enlarged view of the contact part vicinity of the nanowire tensile test device shown in FIG. It is an enlarged view near the free end of the measurement cantilever of the nanowire tensile test device shown in FIG. It is a figure explaining the tensile test method using the nanowire tensile test device shown in FIG. It is a graph which shows the relationship between the voltage V (horizontal axis) applied between the 1st and 2nd electrode and displacement amount (DELTA) _amp (vertical axis) of the free end of a measurement cantilever. It is a top view which shows the mode of a deformation | transformation of the measurement cantilever. It is a top view which shows the beam of both ends fixation used instead of the measurement cantilever shown in FIG. It is a graph which shows an example of the tension test data. It is a graph which shows the load-displacement curve of the test piece calculated | required from the tensile test data shown in FIG. It is a graph which shows the stress-strain curve calculated | required from the tensile test data shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nanowire tensile test device 2 Test piece fixing | fixed part 3 Actuator part 4 Displacement amplification part 5 Upper base 6 Lower base 7 Power supply 8 Substance or optical microscope 9 CCD camera 10 Computer 21 1st fixing | fixed part 22 2nd fixing | fixed part 23 1st support Part (beam)
24 towed part 31 2nd support part (beam for support)
32 First traction force generating section 33 Actuator body 34 Second traction force generating section 35 Contact section 36 Pull section 37 Electrode section 38 First electrode 39 Second electrodes 41 and 41a Measuring cantilever 42 Scale section 43 Measuring beam S Test piece T Free end

Claims (8)

The base,
A first fixing part for fixing one end of the test piece, a second fixing part for fixing the other end of the test piece, a first support part fixed to the second fixing part, and fixed to the first support part A specimen fixing part having a towed part;
A displacement amplifying unit having a measuring cantilever;
A traction section disposed with a first interval from the to-be-towed section, a first traction force generation section, a second traction force generation section disposed opposite to the first traction force generation section with a predetermined distance, and a second A support portion, and an actuator portion having a contact portion that can come into contact with the displacement amplification portion,
The first fixing portion and the second traction force generating portion are fixed to the base portion;
The first support part and the second support part are each fixed to the base part so as to be elastically deformable,
The first interval is larger than a distance between the contact portion and the displacement amplification portion;
When a direct-current voltage is applied between the first traction force generation unit and the second traction force generation unit, the contact portion is caused by the electrostatic attraction generated between the first traction force generation unit and the second traction force generation unit. Applying a force to the displacement amplifying part, larger than the amount of displacement of the contact part, displacing the free end of the measuring cantilever,
The nanowire tensile test device, wherein when the voltage increases, the pulling unit comes into contact with the pulled unit, and the pulling unit pulls the pulled unit. One end of the measurement cantilever is fixed to the base so as to be elastically deformable,
When a DC voltage is applied between the first traction force generation unit and the second traction force generation unit, the contact unit applies a force to the measurement cantilever,
The distance between the free end of the measurement cantilever and the first position where the contact portion contacts the measurement cantilever is approximately 10 times the distance between the fixed end of the measurement cantilever and the first position. The nanowire tensile test device according to claim 1, wherein the nanowire tensile test device is about 200 times or less. The displacement amplifying unit includes a measuring beam to which the measuring cantilever is fixed and both ends are fixed to the base so as to be elastically deformable.
When a DC voltage is applied between the first traction force generation unit and the second traction force generation unit, the contact unit applies a force to substantially the center of the measurement beam,
2. The nanowire tensile test device according to claim 1, wherein the measurement cantilever is fixed at a position that is ¼ of the length of the measurement beam from the center of the measurement beam.   The nanowire tensile test device according to any one of claims 1 to 3, wherein a spring constant of the first support part is larger than a spring constant of the second support part. The first support is a beam;
The second fixing part and the towed part are fixed at a central position of the first support part;
The second support part is an even number of beams, one end of which is fixed to the base part;
The towed portion and the actuator portion have a line-symmetric shape having a symmetry axis along a direction in which the towed portion is pulled,
5. The nanowire tensile test device according to claim 1, wherein the respective symmetry axes coincide with each other. The base,
A first fixing part for fixing one end of the test piece, a second fixing part for fixing the other end of the test piece, a first support part fixed to the second fixing part, and fixed to the first support part A specimen fixing part having a towed part;
A displacement amplifying unit having a measuring cantilever;
A traction section disposed with a first interval from the to-be-towed section, a first traction force generation section, a second traction force generation section disposed opposite to the first traction force generation section with a predetermined distance, and a second A support portion, and an actuator portion having a contact portion that can come into contact with the displacement amplification portion,
The first fixing portion and the second traction force generating portion are fixed to the base portion;
The first support part and the second support part are each fixed to the base part so as to be elastically deformable,
The first interval is larger than a distance between the contact portion and the displacement amplification portion;
When a direct-current voltage is applied between the first traction force generation unit and the second traction force generation unit, the contact portion is caused by the electrostatic attraction generated between the first traction force generation unit and the second traction force generation unit. Applying a force to the displacement amplifying part, larger than the amount of displacement of the contact part, displacing the free end of the measuring cantilever,
When the voltage increases, a nanowire tensile test method using a nanowire tensile test device in which the pulling unit is in contact with the pulled unit and the pulling unit pulls the pulled unit,
A first step of applying a predetermined DC voltage between the first traction force generator and the second traction force generator;
A second step of measuring a displacement amount of the free end of the measuring cantilever,
Increase the voltage and repeat the first and second steps until the specimen breaks,
After the test piece is broken, the voltage is decreased and the first and second steps are repeated. One end of the measurement cantilever is fixed to the base so as to be elastically deformable,
When a DC voltage is applied between the first traction force generation unit and the second traction force generation unit, the contact unit applies a force to the measurement cantilever,
The distance between the free end of the measurement cantilever and the first position where the contact portion contacts the measurement cantilever is approximately 10 times the distance between the fixed end of the measurement cantilever and the first position. Above, about 200 times or less,
The displacement amplification factor α of the displacement amplification part, the displacement _{Δamp1 of the} free end measured by applying the voltage V before the test piece breaks, and the voltage V after the test piece breaks Using the measured displacement amount Δ _{amp2 of the} free end, the spring constant γ _m of the measurement cantilever, and the spring constant γ ₁ of the second support portion, the voltage V is applied to the test piece. a load _{P S} calculated by _{P S = (γ m + γ} 1) × (Δ amp2 -Δ amp1) / α,
The nanowire according to claim 6, wherein the amount of elongation of the test piece is obtained based on the amount of displacement of the free end at a bending point appearing in a graph showing the amount of displacement of the free end with respect to the applied voltage. Tensile test method. The displacement amplifying unit includes a measuring beam to which the measuring cantilever is fixed and both ends are fixed to the base so as to be elastically deformable.
When a DC voltage is applied between the first traction force generation unit and the second traction force generation unit, the contact unit applies a force to substantially the center of the measurement beam,
The measurement cantilever is fixed at a position that is 1/4 of the length of the measurement beam from the center of the measurement beam,
The displacement amplification factor α of the displacement amplification part, the displacement _{Δamp1 of the} free end measured by applying the voltage V before the test piece breaks, and the voltage V after the test piece breaks Using the measured displacement amount Δ _{amp2 of the} free end, the spring constant γ _m of the measurement beam, and the spring constant γ ₁ of the second support part, the voltage V is applied to the test piece. a load _{P S} applied determined by _{P S = (γ m + γ} 1) × (Δ amp2 -Δ amp1) / α,
7. The nanowire tension according to claim 6, wherein the amount of elongation of the test piece is obtained based on the amount of displacement of the free end at a bending point appearing in a graph showing the amount of displacement of the free end with respect to the applied voltage. Test method.

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