JP4989521B2 - Fine sample handling device - Google Patents

Description

  The present invention relates to a fine sample handling apparatus used for grasping and transporting a fine sample for an electron microscope.

  In semiconductor defect inspection, a defect part is cut out from a semiconductor wafer or the like by a focused ion beam (FIB), a micron-sized fine sample cut out is transported and fixed on a sample stage, and observed with a transmission electron microscope. It has been broken. Conventionally, a needle-like probe has been used for transporting the micron-sized sample. That is, first, a fine sample is adhered to the tip of the probe using a deposition gas while the tip of the probe is in contact with the fine sample, the probe is moved, and the fine sample is transported to a desired position. In this method, the tip of the probe is cut and a fine sample is separated from the probe.

  Regarding the handling of micro samples, Japanese Patent Application Laid-Open No. 2006-120391 describes a normally closed micro sample holder made by semiconductor silicon technology, in which two opposing needles are driven apart by an electrostatic actuator. ing. Japanese Patent Application Laid-Open No. 2004-283946 describes a micro gripper that is driven away by a shape memory alloy wire that contracts due to heat generated by energization.

JP 2006-120391 A JP 2004-283946 A

  In the conventional method of transporting a probe by adhering it to a fine sample, a facility for deposition is required, and an operation of sharpening the tip of the probe before use is necessary. The time required for one transfer is also about 10 minutes. Therefore, there are problems in terms of equipment, time, workability, and the like.

  Since the method described in Japanese Patent Application Laid-Open No. 2006-120391 uses an electrostatic force, a large holding force cannot be obtained. In order to generate electrostatic force effectively, it is necessary to form electrodes on the opposing surfaces, but in the semiconductor silicon process, the process of forming electrodes on the side surfaces rather than the upper and lower sides of the substrate is difficult, There's a problem. Furthermore, the stroke cannot be increased with electrostatic force. In addition, since the sample is sandwiched between the two needle-shaped bodies that are in the open state, the possibility that the sample slips and escapes increases.

  The method described in Japanese Patent Application Laid-Open No. 2004-283946 secures holding force and stroke using a shape memory alloy wire, but does not consider the method of fixing the shape memory alloy wire to the arm. It is difficult to fix a shape memory alloy wire having a thickness of about 0.1 mm to an arm downsized to 1 mm or less in order to grasp a micron-sized sample. The arm tip is opened and closed with a shape memory alloy wire that shrinks due to heat generated by energization and expands when the temperature drops due to current interruption, but it is not considered for use in a vacuum. There is a problem that it takes time for the temperature to drop and the arm tip to open.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a micro sample handling apparatus that can reliably handle micron-sized micro samples quickly, easily and without skill, and can be used even in a vacuum.

  In the present invention, a micro sample handling apparatus for handling micro samples of micron size is miniaturized according to the sample size, and is manufactured by micro processing by a semiconductor process or the like using silicon or the like as a material. A shape memory alloy wire is used as an actuator for generating an opening / closing driving force of the sample gripping portion of the fine sample handling apparatus, and the sample gripping portion is opened and closed by energizing the shape memory alloy wire. A groove is processed in the arm by a semiconductor process, and a shape memory alloy wire is laid. The laid shape memory alloy gold wire is fixed to the arm by vapor-depositing a conductive and heat-dissipating metal film. In addition, it is possible to provide a function for automatically recognizing that the sample gripping part is in contact with the object or grasping the object, and a function for preventing adsorption that is likely to occur in a micro-sized fine sample. .

  A fine sample handling apparatus according to an aspect of the present invention includes a base, a pair of arms extending from the base at a predetermined distance from each other, and a pair of arm tips extending in directions approaching each other from the pair of arms. It has a monolithic main body member manufactured by a semiconductor process, a shape memory alloy member fixed to both ends across a pair of arms, and means for energizing the shape memory alloy wire. It is preferable that the arm tip extends obliquely forward from the arm.

  This fine sample handling device can be provided with a function of detecting that the tip of the arm constituting the sample gripping portion has contacted the object. This function can be composed of means for vibrating the arm at its resonance frequency and means for detecting a change in the vibration state of the arm.

  According to the present invention, it is possible to perform the operation of grasping and releasing a fine sample with certainty. In addition, the arm tip can be opened and closed in a short time even in a vacuum. These operability are improved. Furthermore, the shape memory alloy wire can be easily fixed, and the manufacture becomes easy. Furthermore, the equipment for deposition processing becomes unnecessary, and it becomes space saving and low cost.

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

  FIG. 1 is a schematic view showing an example of a fine sample handling apparatus according to the present invention. FIG. 1A is a front view, and FIG. 1B is a side view. The fine sample handling apparatus has a pair of arms 12a and 12b extending in the same direction, typically in parallel, at a predetermined interval from the base 11. The pair of arm tip portions 13a and 13b extend obliquely forward, approach each other, and face each other with a certain distance d. The arm tip portions 13a and 13b arranged opposite to each other constitute a sample gripping portion. A shape memory alloy wire 15 is passed between the arms 12a and 12b and fixed with a metal film 14 which is a conductive material. The end of the shape memory alloy wire 15 protrudes from the end surface of the base 11. A portion constituted by the base portion 11, the arms 12 a and 12 b, the shape memory alloy wire 15 and the like is referred to as an arm portion, and the arm portion is inserted into the holder 16. The holder 16 includes a connector 17, and the end of the shape memory alloy wire 15 protruding from the end surface of the base 11 and the contact pin 18 are electrically connected. The connector 17 is connected to the power source 20 and the switch 21 through a conductive wire. The arm tip portions 13a and 13b are sharpened and are worn by gripping the sample. However, with this structure, the arm portion can be easily replaced. Here, the metal film 14 made of a conductive material is deposited and fixed by a semiconductor process, but fixing by a fixing bracket and a conductive adhesive may be considered. Further, instead of covering the entire arm portion with a conductive material, it is also conceivable that the conductive material is brought into contact with the shape memory alloy wires 15 at both ends of the arm portion, and the conductor is connected between them.

  FIG. 2 is a schematic view showing an example of a fine sample handling apparatus according to the present invention. 2A is a front view, and FIG. 2B is a side view. The difference from the example of FIG. 1 is that a shape memory alloy wire 15 is laid on the arms 12a and 12b in a groove processed by a semiconductor process, and a metal film 14 is deposited and fixed thereon by a semiconductor process. Yes. Here, the grooves are processed by a semiconductor process, but may be machined. Further, the position where the shape memory alloy wire 15 is provided may be limited by forming a protrusion such as a bank instead of the groove.

  FIG. 3 is a schematic view showing a state in which the arm portion is inserted into the holder 16, the switch 21 is closed, and the shape memory alloy wire 15 is energized. Since the resistance value of the metal film 14 is smaller than that of the shape memory alloy wire 15, current flows in the metal film 14 in the portion where the metal film 14 is deposited, and almost current flows in the shape memory alloy wire 15. Absent. Therefore, there is no self-heating and there is no change in shape. On the other hand, in the shape memory alloy wire 15 where the deposited film 14 is not deposited, a current flows and self-heats, and the shape changes in the memorized shrinking direction. As a result, the arm tips 13a and 13b approach each other and a fine sample can be gripped.

  When the switch 21 is opened to interrupt the energization of the shape memory alloy wire 15, the temperature drops and the shape changes in the extending direction. In the atmosphere, heat is transferred to the air in contact with the shape memory alloy wire 15 and the temperature immediately decreases. However, in vacuum, the heat is not easily transmitted and it takes time to decrease the temperature. However, by depositing the metal film 14, the heat of the shape memory alloy wire 15 is transferred to the metal film 14 by heat conduction, and the temperature drop is accelerated by heat radiation from the metal film 14. As a result, it is possible to shorten the time from when the current is interrupted until the shape memory alloy wire 15 is stretched and the fine sample is released.

  The arm portion of the fine sample handling apparatus composed of the base 11, the arms 12a and 12b, and the arm tips 13a and 13b is made of silicon and manufactured by the semiconductor process flow shown in FIG.

  First, as shown in FIG. 5, a wire groove 19 is formed on a silicon wafer 31 by a photolithography process and an etching process (S11), and a shape memory alloy wire 15 is laid in the wire groove 19 as shown in FIG. S12). Due to the presence of the wire groove 19, even a thin shape memory alloy wire 15 of about 0.1 mm can be provided at an accurate position. Next, a metal film 14 was deposited on the arm by a photolithography process, a CVD (Chemical Vapor Deposition), and a sputtering process to fix the shape memory alloy wire 15 (S13). Next, as shown in FIG. 7, the wafer is turned over, and the outer shape 32 and the arm tip are sharpened on the back surface by a photolithography process and an etching process (S14). (S15).

  As an example, the distance d between the arm tip portions 13a and 13b is 100 μm, the thickness and width of the arms 12a and 12b are 200 μm, the length of the shape memory alloy wire 15 in the portion where the metal film 14 is not deposited is 1 mm, and the base portion The distance from 11 to the shape memory alloy wire 15 where the metal film 14 was not deposited was 2 mm, and the length of the shape memory alloy wire 15 protruding from the base 11 was 1 mm. As the shape memory alloy wire 15, a biometal fiber (registered trademark) having a diameter of 0.1 mm was used. These dimensions are merely examples, and it is extremely easy to manufacture a fine sample handling apparatus having a smaller dimension.

  When a DC power source of 10 V is used as the power source 20 and the switch 21 is closed and the shape memory alloy is energized, the shape memory alloy wire 15 is self-heated by passing a current, and the metal film 14 is not deposited. It shrinks by about 5% of the length of the shape memory alloy wire 15. As a result, the distance d between the arm tip portions 13a and 13b of the fine sample handling apparatus is reduced from 100 μm before energization to 0 μm. That is, 100 μm was obtained as the stroke of the arm tip portions 13a and 13b constituting the sample gripping portion, and the force generated at this time was 80 gf. For this reason, a fine sample having a square cross-sectional shape of about 10 μm to 100 μm cut out from the silicon wafer by FIB is securely held by being sandwiched between the arm tip portions 13a and 13b constituting the sample gripping portion. I was able to.

  As described above, in the present invention, as a method for opening and closing the sample gripping portion, a method in which the shape memory alloy is energized is used. The process of attaching the shape memory alloy wire to the arm is easy, and the sample gripping part is also opened and closed by energization, so no special operation is required. Also, the time required for opening and closing is very short and the holding force is large, so there is little risk of dropping the sample during transport.

  If the stroke required for the sample gripping part is determined depending on the size of the sample, the thickness of the arms 12a and 12b and the fixing position of the shape memory alloy wire 15 may be designed accordingly. For example, when a large stroke is required, it is more advantageous to fix the shape memory alloy wire 15 at a position near the base portion 11 than at a position near the arm tip portions 13a and 13b.

  FIG. 8 is a schematic view showing another embodiment of the fine sample handling apparatus according to the present invention. FIG. 8A is a front view, and FIG. 8B is a side view. In this embodiment, the temperature drop when the current is interrupted using the radiator 34 is accelerated.

  FIG. 9 is a schematic plan view showing another embodiment of the fine sample handling apparatus according to the present invention. In this example, two shape memory alloy wires, which are actuators for opening and closing the sample gripping part, were used. In FIG. 9A, the first shape memory alloy wire 45b is fixed at a position close to the arm tips 43a and 43b on the arm surface, and the second shape memory alloy wire 45a is not energized. The arm was fixed at a position close to the base 11 on the back surface of the arm. Biometal fiber (registered trademark) was adopted as the shape memory alloy. The shape memory alloy wires 45 a and 45 b are provided in grooves processed in the arms 42 a and 42 b and fixed by vapor deposition of the metal film 44. When the shape memory alloy wire 45a located near the base 11 is energized and contracted as shown in FIG. 9B, the shape memory alloy wire 45b located near the arm tip portions 43a and 43b is moved by the lever principle. The stroke of the arm tip portions 43a and 43b can be made larger than when contracted.

  According to the present embodiment, the distance between the arm tip portions 43a and 43b facing the sample gripping portion is set to be relatively wide, and a small stroke may be used when holding a sample with a large size. When the wire 45b is energized and a small sample is held, the second shape memory alloy wire 45a is energized to generate a large stroke. Biometal Fiber (registered trademark) is flexible and can be bent freely when it is not energized, so the movement of the arm is not obstructed by the non-energized shape memory alloy wire. Absent.

  FIG. 10 is a schematic plan view showing another embodiment of the fine sample handling apparatus according to the present invention. In the embodiments described so far, the sample gripping portion is open when the actuator is not driven, and the sample gripping portion is closed when the actuator is driven. In this embodiment, on the contrary, the sample gripping part is closed when the actuator is not driven as shown in FIG. 10A, and when the actuator is driven as shown in FIG. open.

  In the fine sample handling apparatus of this embodiment, a pair of arms 52a and 52b extend in the same direction, typically in parallel, at a predetermined interval from the base 51, and the tip portions 53a and 53b of the pair of arms are respectively arm arms. The sample gripping portion is configured to extend obliquely forward from 52a and 52b, approach each other, and face each other with a certain distance therebetween. The arm tip portions 53a and 53b are formed in a substantially closed shape. Support beams 56a and 56b protrude from the base 51 so as to face the side surfaces of the arms 52a and 52b, and a shape memory alloy wire 55 is fixed by a metal film 54 between the arms 52a and 52b and the protruding portions. . Also in this case, grooves for providing the shape memory alloy wire 55 are processed in the support beams 56a and 56b and the arms 52a and 52b. The shape memory alloy wire 55 generates heat and contracts when energized, and the arm tips 53a and 53b open. Therefore, it is only necessary to open the arm tip portions 53a and 53b by energizing the shape memory alloy wire 55 only when trying to grasp the fine sample or when separating the fine sample. The fine sample is held on the sample gripping portion by the restoring force of the arm deformed with the fine sample interposed therebetween. Moreover, as shown in FIG.10 (c), you may install the wire made from a shape memory alloy only between one arm and a support beam. Further, it is not always necessary to form a support beam as a fixing place for the shape memory alloy wire.

  FIG. 11 is an explanatory diagram showing an example of the shape of the arm tip portion constituting the sample gripping portion. The arm tip portions 61 and 62 of the sample gripping portion shown in FIG. 11A extend obliquely forward while being tapered. The surfaces of the arm tip portions 61 and 62 that are in contact with the sample are parallel to each other. The arm tip portions 63 and 64 of the sample gripping portion shown in FIG. 11 (b) have a larger surface in contact with the sample than in the case of FIG. 11 (a), and are suitable for holding a larger sample. The arm tip portions 65 and 66 of the sample gripping portion shown in FIG. 11C extend vertically from the respective arms.

  By configuring the sample gripping portion with the arm tip portions extending in the direction approaching each other from the arm as described above, the sample can be reliably held on the sample contact surface of the arm tip portion. A small tip size is used for applications in which a fine sample obtained by processing a part of a semiconductor wafer with FIB is picked up from the semiconductor wafer, transported to the sample stage of a transmission electron microscope, and fixed to the sample stage. A sample gripping portion having a shape as shown in FIG. 11 (b) or FIG. 11 (c) is effective.

  When the shape memory alloy wire is contracted and the sample is sandwiched by the arm tip, the arm or the arm tip is bent and deformed. In particular, the arm tip is the arm as shown in FIGS. In the case of a shape extending obliquely from the surface, the elasticity accompanying the deformation also contributes to the reliable holding of the sample. FIG. 11D shows a case where the sample gripping part is constituted by two parallel arms as a comparative example. When the fine sample 69 is sandwiched between the tips of the two parallel arms 67 and 68 and a force is applied, the tips of the arms 67 and 68 are bent and the tip is opened as shown in FIG. Force to push in the direction. As a result, the sample escapes from the sample gripping portion, and the sample cannot be held stably and reliably.

  FIG. 12 is a diagram illustrating a shape example of the sample contact surface of the sample gripping portion. FIG. 12A shows an example in which a large number of streak-like grooves are provided on the sample contact surfaces of the arm tip portions 71 and 72. By making the sample contact surface into such a jagged surface, the fine sample becomes less slippery and easier to hold. FIG. 12B shows an example in which one groove having a triangular cross section is provided on each sample contact surface of the arm tip portions 73 and 74. In this case, for example, when holding a fine sample having a rectangular parallelepiped shape, holding stability is increased by holding the sample so that the corner portion of the sample enters the groove. FIG. 12 (c) shows an example in which grooves corresponding to the dimensions of the sample to be held are provided on the sample contact surfaces of the arm tip portions 75 and 76. The figure shows an example in which two types of grooves, a small sample groove 77 and a large sample groove 78 are provided. FIG. 12D shows an example in which one shape of the arm tip is asymmetrical such as a receiving die and the other is a pushing die.

  In order to prevent the sample from adsorbing to the tip of the arm, at least the tip of the arm may be coated with an adsorption preventing material. As the adsorption preventing material, for example, if the arm tip is coated with fluorine, molybdenum disulfide, or the like by a method such as sputtering or coating, adsorption of a fine sample to the sample gripping portion can be prevented. As a method for preventing the adsorption of the sample, a method in which the electric resistance of the base or arm is reduced and grounded is also effective. In order to reduce the electric resistance of the base and the arm, it may be formed of low resistance silicon, or B or P may be implanted into the silicon so that the resistivity becomes, for example, 0.02 [Ω · cm] or less. According to the present embodiment, when the arm tip contacts the sample, the static electricity of the sample can be released and adsorption can be prevented.

  Further, a means for measuring the sample gripping force may be provided in the fine sample handling apparatus. For example, a strain gauge is formed in a portion where deformation is large when the shape memory alloy member is energized or is de-energized on the base side of the arm with respect to the portion for gripping the fine sample. The strain gauge can be formed by implanting P or B into a desired region of the Si arm to form a strain gauge based on the piezoresistance effect. By measuring the resistance change of the strain gauge with a measuring circuit such as a Wheatstone bridge circuit, the gripping force of the fine sample handling apparatus can be measured. By handling the fine sample while monitoring the gripping force, it is possible to avoid damaging the sample and to prevent the fine sample handling apparatus itself from being damaged.

  FIG. 13 is a schematic plan view showing another embodiment of the fine sample handling apparatus according to the present invention. In this embodiment, a function of detecting that the apparatus has contacted the fine sample is provided. In the fine sample handling apparatus of this embodiment, the piezoelectric element 86 is attached to the apparatus main body, and the piezoelectric element 86 is driven by the resonance frequency of the arm by the controller 87 to cause the arm to vibrate slightly. At the same time, the controller 87 monitors the vibration state of the arm from the signal obtained from the piezoelectric element. When the arm is vibrated at the resonance frequency and the apparatus is brought close to the fine sample to be grasped, the vibration state of the arm changes when the sample contact surface of the sample grasping portion comes into contact with the fine sample. When the controller 87 detects from the change in the vibration state of the arm, for example, the change in the frequency, that the sample gripping part has contacted the fine sample, the controller 87 cuts off the output to the piezoelectric element 86 and stops the vibration of the arm. Thereafter, the switch 89 is closed and the shape memory alloy wire 85 is energized, the arm tip portions 83a and 83b are closed, and the sample holding operation is started.

  When grasping a fine sample produced by the FIB apparatus, the positional relationship between the tip of the arm of the fine sample handling apparatus and the fine sample to be grasped cannot be clearly determined only by looking at the sample image of the FIB apparatus. In such a case, if the fine sample handling apparatus is operated by relying only on the sample image, the sample may not be grasped well. According to the present embodiment, since it can be confirmed that the sample contact surface of the sample gripping portion is in contact with the fine sample and then the gripping operation can be performed, the fine sample can be reliably gripped. In addition, a fine sample manufactured by the FIB apparatus is partially connected to the semiconductor wafer, and after being gripped by the fine sample handling apparatus, it is separated from the semiconductor wafer. There is no problem even if it is contacted.

  The fine sample handling apparatus shown in FIG. 10 can also have a contact detection function based on the same principle. However, in that case, the piezoelectric element is driven at the resonance frequency of the arm in a state where the shape memory alloy wire 55 is energized to open the arm tip portions 53a and 53b, and the arm is minutely vibrated. Then, the vibration state of the arm is monitored while bringing the device close to the fine sample to be gripped. When it is detected from the change in the vibration state of the arm that the sample gripping part has come into contact with the fine sample, the output to the piezoelectric element is cut off and the vibration of the arm is stopped. Thereafter, energization of the shape memory alloy wire 55 is stopped, the arm tips 53a and 53b are closed, and a fine sample is gripped.

  The fine sample handling apparatus of the present invention can be used as a fine sample transport means required in an electron microscope, a focused ion beam apparatus, or the like. Further, in the production of a micromachine or the like, it can also be used for mounting or assembling micro parts.

The schematic diagram which shows one Example of the fine sample handling apparatus by this invention. The schematic diagram which shows the other Example of this invention. The figure which shows a state when it supplies with electricity to a shape memory alloy. Manufacturing flow of the arm part. The schematic diagram which shows the state which carried out the groove process to the wafer. The schematic diagram which shows the state which vapor-deposited the metal film on the wafer. The schematic diagram which shows the state which carried out the external shape process to the wafer. The schematic diagram which shows the other Example of this invention. The schematic diagram which shows the other Example of this invention. The schematic diagram which shows the other Example of this invention. The schematic diagram which shows the other Example of this invention. The schematic diagram which shows the other Example of this invention. The schematic diagram which shows the other Example of this invention.

Explanation of symbols

11: Base 12a, 12b: Arm 13a, 13b: Arm tip 14: Metal film 15: Shape memory alloy wire 16: Holder 17: Connector 18: Contact spring 19: Groove 20: Power supply 21: Switch 31: Wafer 32: External groove 34: radiator 41: base 42a, 42b: arm 43a, 43b: arm tip 44: metal film 45a, 45b: shape memory alloy wire 51: base 52a, 52b: arm 53a, 53b: arm tip 54 : Metal film 55: Shape memory alloy wires 56a, 56b: Support beams 61, 62, 63, 64, 65, 66, 67, 68: Arm tip 69: Fine sample 71, 72: Arm tips 82a, 82b: Arm 85: Shape memory alloy wire 86: Piezoelectric element 87: Controller 88: Power supply 89: Switch

Claims (11)

The base,
A pair of arms extending a predetermined distance from the base;
A shape memory alloy material laid on the pair of arms;
Means for energizing the shape memory alloy material,
The shape memory alloy material has a first part disposed on the pair of arms and a second part passed between the pair of arms,
Fine sample handling apparatus characterized by contacting the conductive member to the first part before Symbol shape memory alloy material. The base,
A pair of arms extending a predetermined distance from the base;
A shape memory alloy wire laid on the pair of arms;
Means for energizing the shape memory alloy wire ,
Grooves for laying the shape memory alloy wire before Symbol arm or, to prepare a projection,
The shape memory alloy wire has a first portion arranged in the groove or the protrusion of the pair of arms, and a second portion passed between the pair of arms,
A fine sample handling apparatus , wherein a conductive material is brought into contact with the first portion of the shape memory alloy wire . The base,
A pair of arms extending a predetermined distance from the base;
A shape memory alloy wire passed to the pair of arms;
Means for energizing the shape memory alloy wire,
Contacting a conductive material to the shape memory alloy wire laid on the arm;
The tip of the shape memory alloy wire protrudes from the end surface of the base,
A connector capable of being electrically connected to a shape memory alloy wire protruding from the end face of the base is provided, and a tip portion from the base to the arm is detachable. Sample handling device.   2. The fine sample handling apparatus according to claim 1, wherein the conductive material has a heat dissipation effect.   2. The fine sample handling apparatus according to claim 1, further comprising a heat dissipating piece thermally connected to the shape memory alloy material. In fine sample handling apparatus according to claim 2, before Symbol shape memory alloy wire of the fine sample handling device by the first portion of the conductive film is characterized in that fixed to the arm. The fine sample handling apparatus according to any one of claims 1 to 6 , wherein means for vibrating the arm, means for detecting that the tip of the arm is in contact with an object from a change in a vibration state of the arm, A fine sample handling apparatus comprising: The fine sample handling device according to any one of claims 1 to 7 , wherein an adsorption preventing material is coated on tip ends of the pair of arms. The fine sample handling apparatus according to any one of claims 1 to 6 , wherein the resistance of the base is reduced and the base is grounded. The fine sample handling apparatus according to any one of claims 1 to 6 , wherein the surfaces of the pair of arm tips that contact the fine sample have a shape corresponding to the fine sample to be handled. Handling device. In fine sample handling apparatus according to any one of claims 1-10, when energized in said shape memory alloy member of the base, or to the formation of the strain gauge on a portion deformed is greater when deenergized A fine sample handling device.

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