JP6116391B2 - Electron microscope fine drive unit - Google Patents

Description

  The present invention relates to a driving mechanism (hereinafter referred to as a fine driving unit) for a diaphragm member for narrowing an electron beam and a supporting member for supporting a sample in a housing that maintains a vacuum degree inside the electron microscope and shields a stray magnetic field. In particular, in a technique for finely positioning a movable portion of a fine movement unit with a piezoelectric actuator, a new technique is provided in which the fine movement feeding accuracy, the fine movement positioning accuracy, and the durability for maintaining this accuracy are dramatically improved.

  In recent years, many techniques have been provided for finely positioning a movable portion of the fine drive unit with a piezoelectric actuator in a fine drive unit drive mechanism provided in a housing that maintains the degree of vacuum inside the electron microscope and shields stray magnetic fields. Yes.

  Several well-known electron microscope micro-drive units will be introduced. First, the electron microscope of the prior application related to the invention of the present inventor (Muranaka Shogo) has an XY-axis hollow micro-drive mechanism (sample fine movement stage), a uni-axis drive (piezoelectric actuator) on both the XY axes, and a one-side slide ( (Sliding guide) system, and the XY shaft body has a single layer structure. As the piezoelectric actuator, a micro squiggle motor manufactured by New Scale Technologies is selected and used as a suitable drive source. The structure is formed by attaching a piezo element 103 (corresponding to the piezoelectric bodies 52 and 62) to the outer four surfaces of a square columnar nut (core) 102 that is screwed into a bolt (corresponding to the spindles 53 and 63 by a screw). Is. As a result, the XY shaft body can have a simple configuration, and the occurrence of an image failure can be suppressed, and the position adjustment of the drive object arranged in the housing is performed at a speed and accuracy according to the purpose. (For example, refer to Patent Document 1).

  The above-mentioned piezoelectric actuator is a micro squeegle motor piezoelectric actuator manufactured by New Scale Technologies, but as another embodiment, the expansion and contraction of the piezoelectric element is transmitted to the driving member and engaged with the driving member with a predetermined friction force. There is an ultrasonic linear actuator that moves a driven member using a speed difference between when a piezoelectric element is extended and when it is reduced. The structure transmits the vibration of the vibrator to the driving member, and the driven member engaged with the driving member with a predetermined frictional force is utilized by utilizing a speed difference between the time when the vibrator is extended and the time when the vibrator is reduced. A drive circuit for an actuator to be moved includes a pulse generation circuit that applies a drive pulse to the vibrator, and a control circuit that controls a generated pulse of the pulse generation circuit, the control circuit including the vibration in the pulse generation circuit By generating a driving pulse having a predetermined duty frequency and a predetermined duty with respect to the resonance frequency in the child system, a pseudo speed that causes the speed difference in the engaging portion between the driving member and the driven member is generated. A sawtooth-shaped displacement vibration is generated, and the drive frequency is maintained and the drive pulse is set to the predetermined value at least one of starting, stopping, or intermittent driving of the driven member. Is intended to output a shortened pulse than the pulse width defined by Yuti (e.g., see Patent Document 2.).

  As shown in FIG. 16, the ultrasonic linear actuator has a further detailed configuration in which the vibration of the disc-shaped vibrator 1 is transmitted to the drive member of the shaft 1A penetrating through the center and supported by the shaft 1A. A frictional force composed of a thin leaf spring 2B (or a thick leaf spring 2C) whose pressing force F is finely adjusted by a male screw 2M of a screw B screwed into a predetermined V groove 2A and a female screw 2E in the middle of the portion 2. The driven member D is engaged, and the driven member D is moved by utilizing the speed difference between the forward movement and the backward movement of the shaft 1A by the vibrator 1. The ultrasonic linear actuator is also applied to a fine drive unit other than an electron microscope (for example, Non-Patent Document 1).

  Furthermore, there is a known patent in which the ultrasonic linear actuator is used as a fine drive mechanism of a microscope apparatus. The configuration includes a fixed base, a movable body supported so as to be movable with respect to the fixed base, an ultrasonic actuator that relatively moves the movable body and the fixed base, and outputs a drive signal of the ultrasonic actuator. The ultrasonic actuator drive signals at the time of fine movement are two types of burst signals having the same frequency and different phases, and the beginning and end of each of the two types of burst signals are The fine movement mechanism is characterized in that the amplitude changes with time, and at least one of the two types of burst signals has a maximum amplitude smaller than that during normal driving (see, for example, Patent Document 3).

  Republished patent WO2011 / 0334020A1   JP 2011-182577 A   Ultrasonic motor Techno Hands Co., Ltd. 6-29-34-103, Okurayama, Kohoku-ku, Yokohama 222-0037, Japan   JP 2009-27865 A

  The electron microscope disclosed in the re-published patent WO2011 / 034020A1 includes an XY-axis hollow microscope unit (a diaphragm member drive mechanism 30 and support member drive mechanisms 40 and 50), a uniaxial drive (piezoelectric actuator) and a unilateral slide (both XY axes). (Sliding guide) method, and has an advantage that an actuator can be housed in an XY-axis moving body having a single layer structure. However, since the piezo element 103 is attached to the outer four surfaces of the square columnar nut 102 that is screwed to the bolt 101, and the XY axis is a one-side drive and one-side slide system, the bolt 101 has a slight rotational vibration. It is necessary to support both ends of the bolt with a gap, and it has been pointed out that play and backlash occur between the one-side drive and the one-side slide when the bolt is reversed. Even if the initial adjustment is performed perfectly to solve the above problems, play and backlash between the one-side drive and the one-side slide are expanded with repeated use of the sample fine movement mechanism. For this reason, there is a problem that accurate microscopic observation cannot be guaranteed for a long period of time due to a phenomenon of deterioration in durability (moving characteristics and stationary characteristics) of the sample fine movement mechanism.

  Further, the ultrasonic linear actuator disclosed in Japanese Patent Application Laid-Open No. 2011-182577 does not relate to the configuration of the fine drive unit (sample fine movement mechanism) in the XY-axis hollow microscope, but relates to the drive circuit of the ultrasonic actuator. Therefore, it is not clear how to finely adjust the frictional force of the three-point support of the shaft of the ultrasonic actuator, the V groove of the holding piece, and the thin plate spring. Therefore, in the configuration of the sample fine movement mechanism, fine movement feeding accuracy, fine movement positioning accuracy, and maintenance of this accuracy cannot be expected.

  Further, in the above non-patent document, the pressing force is finely adjusted by a predetermined V-groove 2A and screw 2M on the way of the holding portion 2 of the shaft 1A in the technique of finely positioning the movable portion of the fine drive unit by an ultrasonic linear actuator. The driven member D that is engaged by the frictional force composed of the thin plate spring 2B (or the thick plate spring 2C) is similar to the fine drive unit according to the present invention. However, in the configuration of the sample fine drive unit, if fine adjustment of the friction force of the three-point support of the shaft, the V-groove and the thin plate spring is executed by the screw 2M, a relatively high fine feed accuracy of the driven member is obtained at the initial stage of adjustment. Fine positioning accuracy is obtained. However, due to wear of the shaft and V-groove, the repeatability of fine feed is lowered relatively quickly, necessitating fine adjustment again. That is, in the method of finely adjusting the pressing force of the thin plate spring with an adjusting screw, the know-how in manufacturing technology for guaranteeing the fine movement feeding accuracy and fine movement positioning accuracy of the driven member and maintaining this accuracy even in a long-term repeated operation. Is not included. For this reason, the problem that the intended purpose cannot be expected as a fine drive unit of an electron microscope remains.

  Furthermore, a microscope apparatus provided with a fine movement mechanism disclosed in Japanese Patent Application Laid-Open No. 2009-27865 relates to a control apparatus that outputs a drive signal for an ultrasonic actuator. Therefore, in the configuration of the fine drive unit of the sample, it is not clear how to finely adjust the frictional force due to the three-point support of the shaft of the ultrasonic linear actuator, the V groove of the holding body, and the thin plate spring. The accuracy and maintenance of this accuracy cannot be expected.

  The present invention has been made in view of the problems of the technique for finely positioning the movable part of the fine drive unit in each of the above known examples with an ultrasonic linear actuator, and in particular, has the intended purpose as a fine drive unit of an electron microscope. In order to achieve this, we provide a new technology that dramatically improves the fine feed accuracy, fine positioning accuracy, and durability to maintain this accuracy when finely positioning the movable part of the fine drive unit with an ultrasonic linear actuator. is there.

In order to achieve the above object, a fine drive unit of an electron microscope according to claim 1 of the present invention uses an electron lens to converge an electron beam to acquire an image of a sample, and irradiates the sample with the electron beam. A microscope that houses the sample and the electron lens, maintains a degree of vacuum inside and blocks a stray magnetic field, and a first driving body of a diaphragm member that squeezes the electron beam disposed in the case Is a fine driving unit of an electron microscope that includes an ultrasonic linear actuator and feeds and controls the position of the first driving body by a pulse signal.
The first driving body includes a pair of a vibrator and a shaft connected to one side of the central position so as to house the X-axis hollow movable body and the Y-axis hollow movable body in a fixed frame, a sample holder, or a plate. The ultrasonic linear actuator is supported on opposite sides of the fixed frame, the sample holder or the plate with the vibrator and the shaft opposed to each other in the opposite direction, and the X-axis hollow movable body or the Y-axis hollow movable body at the middle part of each shaft. The hollow movable body that is held at three points by the thick V-shaped groove formed in the U-shape of the holding portions provided on both sides and the flat side of the thin-side clamping piece, and is orthogonal to each shaft that holds the hollow movable body A pair of ultrasonic linear actuators are oppositely supported in opposite directions on both side surfaces of the shaft, and at the middle of each shaft, there are three points of the V groove of the holding portion provided on both sides of another hollow movable body and the plane of the sandwiching piece Hold the X-axis hollow movable body and Y-axis Check movable body and is characterized in that it is driven on both sides in the same direction by imparting a reverse pulse signal applied to the pair of ultrasonic linear actuator.

In order to achieve the above object, a fine drive unit of an electron microscope according to claim 2 of the present invention uses an electron lens to converge an electron beam to obtain an image of a sample, and irradiates the sample with the electron beam. A microscope that houses the sample and the electron lens, maintains a degree of vacuum inside and blocks a stray magnetic field, and a second driver of a support member that supports the sample disposed in the case Is a fine drive unit of an electron microscope that includes an ultrasonic linear actuator and controls the feed and position of the second drive body by a pulse signal.
The second driving body includes a pair of a vibrator and a shaft connected to one side of the central position so as to house the X-axis hollow movable body and the Y-axis hollow movable body in a fixed frame, a sample holder, or a plate. The ultrasonic linear actuator is supported on opposite sides of the fixed frame, the sample holder or the plate with the vibrator and the shaft opposed to each other in the opposite direction, and the X-axis hollow movable body or the Y-axis hollow movable body at the middle part of each shaft. The hollow movable body that is held at three points by the thick V-shaped groove formed in the U-shape of the holding portions provided on both sides and the flat side of the thin-side clamping piece, and is orthogonal to each shaft that holds the hollow movable body A pair of ultrasonic linear actuators are oppositely supported in opposite directions on both side surfaces of the shaft, and at the middle of each shaft, there are three points of the V groove of the holding portion provided on both sides of another hollow movable body and the plane of the sandwiching piece Hold the X-axis hollow movable body and Y-axis Check movable body and is characterized in that it is driven on both sides in the same direction by imparting a reverse pulse signal applied to the pair of ultrasonic linear actuator.

  The fine driving unit of the electron microscope according to claim 3 of the present invention is the fine driving unit of the electron microscope according to claim 1 or 2, wherein the ultrasonic linear actuator includes a shaft made of a carbon material, The holding part on the X-axis hollow movable body side and the Y-axis hollow movable body side that always comes into contact with the surface by three-point support of the V groove of the holding part and the plane of the holding piece is composed of a component ratio Ti-6AL-4V. It is made of a titanium material, and is characterized by being subjected to ion nitriding treatment to form a hardened layer of titanium nitride TiN having a thickness of 1 to 3 μm and lapping in order to harden the holding portion.

  According to a fourth aspect of the present invention, there is provided the fine driving unit for an electron microscope according to the first or second aspect, wherein the ultrasonic linear actuator comprises a shaft made of a carbon material, The holding part on the X-axis hollow movable body side and the Y-axis hollow movable body side that always comes into contact with the surface by three-point support of the V groove of the holding part and the plane of the holding piece is composed of a component ratio Ti-6AL-4V. It is made of a titanium material, and is nickel-plated to have a plated layer of 10 to 20 μm and lapped so that the holding portion is hard-treated.

  The electron microscope fine drive unit according to claim 5 of the present invention is the electron microscope fine drive unit according to claim 1 or 2, wherein the transducer of the ultrasonic linear actuator and the free end of the shaft are connected to a fixed frame or It is characterized in that the bearing portion between the sample holder or the plate and the X-axis hollow movable body side and the Y-axis hollow movable body side is held by a resilient elastic adhesive.

  According to a sixth aspect of the present invention, there is provided a fine driving unit for an electron microscope according to the fifth aspect, wherein the elastic adhesive is, for example, an acryl-modified silicone resin.

  According to the fine driving unit of the electron microscope of the first and second aspects of the present invention, the repetition of the fine feed control and the fixed position stop control of the X-axis hollow movable body and the Y-axis hollow movable body is a pair of oppositely arranged. Since both sides are driven in the same direction by applying an inverse pulse signal to the ultrasonic linear actuator, the weight balance of each movable body is optimized and can be executed with high precision by both sides driving, and clear observation and images in an electron microscope are possible. Can record.

  Further, according to the fine driving unit of the electron microscope according to claims 3 and 4, even in a high vacuum environment in the microscope, driving with high wear resistance and easy sliding is possible for a long period of time. In terms of specific numerical values, the initial fine movement feed accuracy and fine movement positioning accuracy can be maintained for repeated reciprocating movements of 500,000 times or more. Furthermore, since the shaft made of carbon material has high self-lubricating properties and high wear resistance, it is possible to dramatically improve the fine feed accuracy, the fine positioning accuracy, and the durability that guarantees the maintenance of this accuracy.

  According to the fine drive unit of the electron microscope according to claims 5 and 6, the free end of the vibrator and the shaft in the ultrasonic linear actuator is elastic to the bearing portion of the fixed frame and the X-axis and Y-axis hollow movable body. Since it is held by the elastic adhesive, the shaft core is not shaken, and smooth fine feed control and fixed position stop control can be guaranteed over a long period of time. In addition, the durability of the ultrasonic linear actuator can be improved.

  1 is a cross-sectional view of a scanning electron microscope according to a first embodiment of the present invention.   It is an expansion | deployment perspective view of the 2nd drive body in the fine drive unit of the 1st Embodiment of this invention.   It is a bottom view of the 2nd drive body in the fine drive unit of the 1st Embodiment of this invention.   FIG. 3 is a sectional view taken along line XX of the second driving body, showing the first embodiment of the present invention.   FIG. 3 is a YY sectional view of the second driving body, showing the first embodiment of the present invention.   FIG. 2 is a cross-sectional view of a holding portion according to the first embodiment of the present invention.   FIG. 6 is a developed perspective view of a first driving body, showing a second embodiment of the present invention.   It is a component characteristic view of a 1st drive body and a 2nd drive body.   It is an expansion | deployment perspective view of 2nd Example in the 2nd drive body of this invention.   It is a top view of 2nd Example in a 2nd drive body.   It is a side view of 2nd Example in a 2nd drive body.   It is an electric drive figure of the 1st drive body and the 2nd drive body of the present invention.   FIG. 6 is a cross-sectional view of a transmission electron microscope, showing a third embodiment of the present invention.   FIG. 6 is a developed perspective view of a first driving body, showing a third embodiment of the present invention.   It is an expansion | deployment perspective view of 2nd Example of the 1st drive body used as the 3rd Embodiment of this invention.   It is sectional drawing which shows a well-known example and supports the shaft of an ultrasonic linear actuator three points with a V groove and a thin leaf | plate spring.

  Hereinafter, in the electron microscope of the present invention, each embodiment of the fine drive unit of the diaphragm member for narrowing down the electron beam and the fine drive unit of the material holder for supporting the sample will be sequentially described with reference to FIGS. .

  The scanning electron microscope 100 according to the first embodiment of the present invention is schematically shown in FIG. The scanning electron microscope 100 includes a fine drive unit (hereinafter referred to as a first drive body 20 and a second drive body fine movement 30) 20 ′ of diaphragm members 11 and 12 for narrowing an electron beam and a material holder 10 that supports a sample S. 30 ′ is used to observe a transmission secondary electron image of a thin film sample, and a sample holder 10 is fixed to the sample stage 3 with bolts 2. The sample holder 10 holds a sample S to be observed. In order to acquire the image of the sample S, the electron beam is converged using an electron lens, and the sample S is irradiated with the electron beam. The sample S is a thin film sample attached to a mesh-like grid.

  On the axis L of the scanning electron microscope 100, at a position facing the sample stage 3, an electron gun 4A that emits an electron beam toward the sample holder 10 and an electron beam emitted from the electron gun 4A are sample holders. An anode 6 that accelerates toward 10 is installed. Between the anode 6 and the sample holder 10 on the axis L, an alignment coil 1 for aligning the center line of the electron beam with the axis L, a converging lens 5 as an electron lens for converging the electron beam, and an objective lens 7, In addition, a deflection coil 8 for deflecting the electron beam is provided. On the axis L, a diaphragm member 11 is provided between the converging lens 5 and the deflection coil 8 to narrow down the electron beam converged by the converging lens 5. On the axis L, between the objective lens 7 and the sample holder 4, support members 11 and 12 for narrowing the electron beam converged by the objective lens 7 are installed. The members 11 and 12 are driven by a fine drive unit 20 ′ of the first drive body 20 serving as each drive mechanism. The sample S on the sample holder 10 is driven by the fine drive unit 30 ′ of the second drive body 30.

  The scanning electron microscope 100 controls the secondary electron detector 13 that detects secondary electrons generated from the sample holder 10 by irradiation of an electron beam that has passed through the sample S, and the entire scanning electron microscope 100. And a personal computer control device PC. On the display, a transmitted secondary electron image of the sample S is displayed.

  Sample holder 3, sample holder 10, electron gun 4A, anode 6, axis alignment coil 1, converging lens 5, objective lens 7, deflection coil 8, first driving body 20 for driving each diaphragm member 11, 12, and sample The second driver 30 that drives the sample S of the holder 10 and the secondary electron detector of the secondary electron detector 13 are housed in a housing 15 that is evacuated. An exhaust pipe 16 for evacuating the inside of the housing 15 is provided at the upper and lower portions of the housing 15, and an intermediate portion of the housing 15 is used to partition the inside of the housing 15 into an upper portion and a lower portion. A gate valve is provided. The housing 15 is made of iron or an aluminum alloy, maintains the internal vacuum, and shields the stray magnetic field. As for the sample holder 4, as shown in FIG. 2, an X axis, a Y axis, and a Z axis are set. In the Y-axis direction, the secondary electron detector 13 side is the front side, and the opposite side is the rear side. In the Z-axis direction, the electron gun 4A side is the upper side, and the opposite side is the lower side.

  As shown in FIG. 2, the fine drive unit 30 ′ of the second drive body 30 includes a rectangular parallelepiped sample holder 10 made of, for example, an aluminum alloy. A notch 4B having a V-shaped cross section is formed on the front surface of the sample holder 10, and an electron beam passage hole 4C having a circular cross section is formed in a portion protruding above the sample holder 10. On the lower surface of the sample holder 10, a screw hole 4 </ b> D for screwing a bolt through an insertion hole of the sample table 3 is formed. In the sample holder 10, the inclined surface facing the electron beam passage hole 4C is irradiated with the electron beam that has passed through the electron beam passage hole 4C to generate secondary electrons (secondary electron generation portion) 4E. It has become.

  Further, in FIG. 2, a rectangular parallelepiped fixing frame 21 made of, for example, an aluminum alloy is fixed to the upper surface of the sample holder 10. The fixed frame 21 is attached to the upper surface of the sample holder 10 via bolts 22 formed at the four corners thereof via bolts. The fixed frame 21 is formed with an electron beam passage hole 21A that faces the electron beam passage hole 4C of the sample holder 10 in the Z-axis direction, and this upper portion is widened in the radial direction. A thin film sample S is supported and fixed on the bottom surface of the widened portion of the electron beam passage hole 21A. Furthermore, a concave portion 21B having a rectangular cross section that opens to the lower side and the front side is formed on the lower surface of the fixed frame 21. The recess 21B is widened on the left and right sides, a notch 21C is formed on the right side, and a notch 21D is formed on the rear side.

As shown in FIGS. 2 to 6, a Y-axis hollow movable body 23 made of an aluminum alloy is disposed in the recess 21 </ b> B of the fixed frame 21. As shown in FIG. 3, the Y-axis hollow movable body 23 is provided with a pair of ultrasonic linear actuators 50 and 51 on opposite sides. The configuration includes each disk-shaped vibrator 25 and a shaft 26 that penetrates through the center and is connected to one side. Each of the vibrators 25 and the free end 26A of the shaft is held by filling the elastic adhesive U having elasticity in bearing portions 21E provided at four positions on the side surface of the fixed frame 21. As the elastic adhesive, for example, acrylic modified silicone resin is used. This product is Cemedine for industrial use (Super X No 8008, elastic adhesive). The main component is an acrylic modified silicone resin, which has a viscosity of 85,000 (PaS / 23 ° C.) and a density of 1,27 (g / cm ³ ). Of course, many elastic adhesives similar to the above elastic adhesives are available from various manufacturers and are commercially available.

  Further, as shown in FIG. 6, the shafts 26 of the ultrasonic linear actuators 50 and 51 are thin on the thick side A of the holding portions 28 provided on the front and rear sides of the Y-axis hollow movable body 23 in the middle. The shaft 26 is held at three points by a thick-side V-shaped groove 28A formed in a U-shape on the side B and a sandwiching piece 28B whose thin-side plane has a spring action. Thus, the Y-axis hollow movable body 23 is supported by the shaft 26 of the pair of ultrasonic linear actuators 50 and 51 with pressure applied to the groove 28A of the holding portion 28 and the flat clamping piece 28B. Friction caused by hitting works as a braking force. Then, as shown in FIG. 12, by the pulse signal E (both sides driven in the same direction by applying reverse pulse signals E1 and E2) urged to the transducers 25 of the ultrasonic linear actuators 50 and 51, It is possible to reciprocate within a predetermined range in the Y-axis direction by driving on both sides.

  Further, an X-axis hollow movable body 24 is arranged in the Y-axis hollow movable body 23 of the second drive body 30 as shown in FIGS. Similarly, the X-axis hollow movable body 24 is inserted through a disc-like vibrator 25 constituting a pair of ultrasonic linear actuators 52 and 53 and a shaft 26 penetrating through the center. 25 and the free ends 26A and 26A of the shaft are held by filling elastic elastic adhesives U in bearing portions 23E provided at four positions on the side surface of the Y-axis hollow movable body 23, and are supported in opposite directions. Yes. As shown in FIG. 6, each shaft 26 is formed in a U-shape of a thick side A and a thin side B in a holding portion 29 provided on both front and rear sides of the X-axis hollow movable body 24 at its middle part. The shaft 26 is held at three points by the V groove 29A on the side and the clamping piece 29B having a spring action on the thin side plane. As a result, the X-axis hollow movable body 24 is supported by the shaft 26 of the pair of ultrasonic linear actuators 52 and 53 with pressure applied to the groove 29A of the holding portion 29 and the flat clamping piece 29B. Friction due to contact acts as a braking force. Then, as shown in FIG. 12, by the pulse signal E (both sides driven in the same direction by applying the reverse pulse signals E1 and E2) biased to the transducers 25 of the ultrasonic linear actuators 52 and 53, By the pulse drive energized by each vibrator 25, it is possible to reciprocate within the predetermined range in the X-axis direction by both-side drive.

As shown in FIG. 6, the shafts of the ultrasonic linear actuators 50, 51, 52, and 53 are formed to have a diameter of about 1φ mm, and the components thereof are carbon materials that have high self-lubricity and high wear resistance. The holding portions 28 and 29 is composed of the best titanium material composed of the Ingredient ratio Ti-6AL-4V. The component analysis results of the titanium material are shown in FIG. The numerical value of each component analysis is shown by% by illustration. The holding portions 28 and 29 on the X-axis hollow movable body side and the Y-axis hollow movable body side where the shaft constantly contacts the surface by three-point support of the V-groove and the plane of the clamping piece are V The depth is about 1 mm, and the groove length is about 6 mm. In addition, the holding portions 28 and 29 are hardened on the surface to improve wear resistance. For example, a hardened layer H is formed to a film thickness of 1 to 3 μm by titanium nitride TiN whose surface hardening is enhanced by ion nitriding treatment that can treat the surface temperature at a low temperature to prevent deformation, and is finally surface-treated by lapping. Further, instead of the above ion nitriding treatment, the surface of the holding portion may be nickel-plated so that the plating layer has a thickness of 10 to 20 μm, and the holding portion may be hard-treated to be lapped.

  The shafts 26 and 26 are made of a carbon material, and the holding portions 28 and 29 and the surfaces of the sandwiching pieces 28B and 29B are formed with a hardened layer H having a film thickness of 1 to 3 μm by titanium nitride TiN, or The surface is nickel-plated so that the plating layer has a thickness of 10 to 20 μm and is surface-treated by lapping. Further, the holding pieces 28B and 29B of the holding portions 28 and 29 are sandwiched by always bringing the shafts 26 and 26 into contact with the V-groove surface with pressure by giving a spring effect. As a result, it was confirmed by repeated tests that an initial repeat accuracy guarantee could be obtained for repeated reciprocating movements of 500,000 times or more. The wiring 54 of the ultrasonic linear actuators 50, 51, 52 and 53 is connected to a control device PC of a personal computer arranged outside the scanning electron microscope 100.

  The fine driving unit 30 ′ of the second driving body 30 configured as described above is provided on the upper surface of the sample holder 10. However, as shown in FIGS. 3 to 5, the Y-axis hollow movable body 23 supported in the fixed frame 21 and the X-axis hollow movable body 24 supported in the Y-axis hollow movable body 23 are in opposite directions. In the Y-axis direction and the X-axis direction, the disk-shaped transducers 25 constituting the pair of ultrasonic linear actuators 50, 51 and 52, 53 arranged on the shaft and the shafts 26, 26 attached to one side from the center are provided. Rough reciprocation within a predetermined range, alignment movement, and fine movement alignment are performed.

  The drive circuit PD of the ultrasonic linear actuators 50, 51, 52, 53 is controlled by a programming controller or a control device PC of a personal computer as shown in FIG. That is, the power supply unit P, an oscillation unit G that transmits a pulse signal E (a reverse pulse signal composed of a positive pulse E1 and a negative pulse E2), an oscillation frequency F and a pulse signal E (reverse pulse signals E1 and E2). ) And an oscillation output unit PP, which are connected to the ultrasonic linear actuators 50, 51, 52, 53. The oscillation control unit GP controls the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 with a predetermined feed speed and feed accuracy. Of course, the drive circuit PD controls the feed speeds of the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 by the number of pulses, so that the control circuit for the ultrasonic linear actuators 50, 51, 52, 53 is provided. A commercially available set of control circuits may be used.

  The principle of operation of the ultrasonic linear actuators 50, 51, 52, 53 is that a vibrator (piezoelectric ceramic) 25 is fixed to the roots of the shafts 26, 26, and a friction body holding portion in which pressure is applied to the shafts 26, 26. The 28 and 29 V grooves 28A and 29A and the sandwiching pieces 28B and 29B are always sandwiched between the surfaces. Thus, at the time of stopping, it is held by friction and does not generate fine vibration, and there is no heat generation. In the feeding operation, the vibrator 25 vibrates the shaft in the axial direction with the pulse wave E, and the holding piece is left minutely by changing the duty ratio between the direction of the vibration and the return, or the drawing operation is performed. The movement of this minute movement is performed with respect to the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 which are controlled by the pulse wave E (E1, E2) having a high vibration frequency (ultrasonic vibration) and become ultra-compact shapes. High propulsion and holding power can be obtained.

  That is, the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 are driven by the oscillation output F of the oscillation unit G and the pulse signal E (reverse pulse signals E1, E2) in the drive circuit PD. That is, the ultrasonic linear actuators 50 and 52 generate a propulsive force E1 ′ that moves the holding pieces 28 and 29 to the left by the pulse signal E1, and the ultrasonic linear actuators 51 and 53 move the holding pieces 28 and 29 to the right by the pulse signal E2. A moving propulsion force E2 'is generated. However, since the respective ultrasonic linear actuators are arranged in opposite directions, the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 are independently driven on both sides in the same direction. Further, if the pulse signal E (reverse pulse signals E1, E2) is in the reverse direction, it can be reciprocated by double-sided driving. The moving speed, moving amount, and direction of the XY-axis hollow movable bodies 23 and 24 are controlled by controlling the oscillation output F and pulse signals E (reverse pulse signals E1 and E2).

  The fine drive unit 30 ′ of the second drive body 30 is directly equipped with a Y-axis hollow movable body 23 and an X-axis hollow movable body 24 on the upper surface 4A of the sample holder 10, as shown in FIGS. A second embodiment of the fine driving unit 300 ′ may be used. The fixed frame 21 is a flat plate 21 '. The configuration will be described below. First, in the X-axis hollow movable body 23, each transducer 25 of the ultrasonic linear actuators 50 and 51 and the free ends 26A and 26A of the shaft held by the holding portions 28 and 28 on both front and rear sides thereof are arranged at one corner of the upper surface 4A. The bearing 4H opened on the projecting seat 4F and the projecting seat 4G in the middle are filled with an elastic adhesive U and held. Similarly, in the Y-axis hollow movable body 24, the transducers 25 of the ultrasonic linear actuators 52 and 53 and the free ends 26A and 26A of the shaft held by the holding portion 29 on the bottom surface are the X-axis hollow movable body. The bearing 4H opened before and after the frame 23 is filled with an elastic adhesive U and held. The flat plate 21 ′ is integrally connected by a screw 60. Other configurations are the same as those of the fine drive unit 30 '.

  Next, the fine drive unit 20 ′ that is the first drive body 20 of the aperture members 11 and 12 for focusing the electron beam will be described. As shown in FIG. 7, the fine drive unit 20 ′ of the first embodiment is different from the fine drive unit 30 ′ in that a rectangular plate-like plate 4 ′ is used instead of the sample holder 10, and the fixed frame 21 is a plate. 4 'is supported by screw means. Other configurations are the same as those of the fine drive unit 30 ′, and thus the same reference numerals are given and description thereof is omitted.

  The fine drive units 20 ′, 30 ′, and 300 ′ in the scanning electron microscope 100 have the above-described configuration and operate as follows. First, the fine drive units 20 ′, 30 ′, and 300 ′ use the ultrasonic linear actuator to drive the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 supported in the Y-axis hollow movable body 23. The oscillation control unit GP of the drive circuit PD of 50, 51, 52, 53 controls the oscillation output F and the pulse signal E (reverse pulse signals E1, E2) by the oscillation unit G, and the ultrasonic linear from the oscillation output unit PP. The actuators 50, 51, 52, and 53 are controlled to feed, and the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 are controlled with a predetermined feed speed and feed accuracy. That is, the opposing ultrasonic linear actuators 50, 51 and 52, 53 are smoothly and stably driven by the reverse pulse signals E1 and E2 to move the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 without movement from side to side. The The feed rate is controlled by the pulse oscillation frequency (number of pulses).

  Hereinafter, a specific relationship between the feed speed and the feed accuracy will be described. For example, when driving the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 at an image magnification of 40 to 60 times, the ultrasonic linear actuators 50, 51, 52, 53 are connected to the Y-axis hollow movable body 23 and the X-axis hollow movable body 23. The shaft hollow movable body 24 is moved at a moving speed of 0.5 to 1 mm / s. Further, in order to drive at an image magnification of 100 to 200 times, the ultrasonic linear actuators 50, 51, 52, and 53 have a Y-axis hollow movable body 23 and an X-axis hollow movable body 24 at a moving speed of 100 to 200 μm / s. And moving at a moving speed of 5 to 10 μm / s, the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 are moved at a speed of 30000 to 50000 times. In order to drive at an image magnification, the ultrasonic linear actuators 50, 51, 52, and 53 move the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 at a moving speed of 0.5 to 3 μm / s, When driven at an image magnification exceeding 50,000 times, the ultrasonic linear actuators 50, 51, 52, 53 move the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 at a moving speed of less than 0.5 μm / s. Move .

  The shafts 26 and 26 of the ultrasonic linear actuators 50, 51, 52, and 53 in the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 are made of carbon, and the holding portions 28 and 29 and the sandwiching pieces 28B and 29B are , And is composed of a non-magnetic titanium material having a component ratio of Ti-6AL-4V. Furthermore, the holding portions 28 and 29 that always come into contact with the shaft and the three-point support have a surface formed by forming a hardened layer H with a thickness of 1 to 3 μm with titanium nitride TiN, and are surface-treated with a lapping finish. It was confirmed that the initial repeatability guarantee was obtained for repeated reciprocating movements more than once. Of course, when the surface treatment of the shafts 26 and 26 and the holding pieces 28 and 29 is nickel plating, the plating layer is 10 to 20 μm, and lapping is performed, the initial repeatability guarantee can be similarly obtained.

In the fine drive units 20 ′, 30 ′, and 300 ′, the initial repeat accuracy is guaranteed even after repeated reciprocating movements of 500,000 times or more. Therefore, the fine drive units 20 ′, 30 ′, and 300 in the scanning electron microscope 100 are guaranteed. Many merits of ´ were confirmed.
In the following, the merit of action in detail is listed.
(1) The speed reducer, high torque (high thrust), and light weight of the shaft in the ultrasonic linear actuator can be achieved without a reduction gear. (2) Even when no current is applied, the holding force is high and no heat is generated. (3) Full stop and no vibration by friction force when stopping. (4) High response (due to vibration operation) with direct mechanism. (5) Simple, small number of parts, lightweight and downsized. (6) Since it is composed of a non-magnetic material (titanium material), it can be driven even in a strong magnetic field environment in a microscope. (7) Since the titanium material does not cause a potential difference, it does not cause electrolytic corrosion. (8) It can also deal with vacuum space (−6 Pascals). (9) Due to the high wear resistance and self-lubricating property of the shaft (carbon material), it becomes easy to slip and can also be used as a guide. (10) Further, the drive side and the shaft tip are resin-fixed with an elastic adhesive to provide a double-supported structure that absorbs the vibration of the core blur. (11) The drive body can be used for both the dual-supporting action and the double-sided driving action by the shafts of the ultrasonic linear actuators arranged on both sides. Space can be saved. (12) The ultrasonic linear actuators on both sides can be simultaneously driven with one drive source pulse, and smooth movement is possible with no left-right variation movement.

The effects of the fine drive units 20 ′, 30 ′, and 300 ′ will be described.
According to the fine driving unit of the electron microscope of the present invention, the fine movement feed control and the fixed position stop control of the Y-axis hollow movable body 23 and the X-axis hollow movable body 24 are repeated in a pair of ultrasonic linear actuators arranged in opposite directions. Since both sides are driven by the reverse pulse signals E1 and E2 to be applied, the weight balance of each movable body is optimized, and the both sides can be executed with high accuracy, and clear observation and images can be recorded. Also, according to the fine driving unit of the electron microscope, the holding piece on the hollow movable body side is made of a non-magnetic titanium material having a component ratio of Ti-6AL-4V, so that it has high wear resistance even in a high vacuum environment in the microscope. Therefore, it is possible to drive while being easy to slip and maintaining a high guide property for a long period of time.

  Further, according to the micro-drive units 20 ′, 30 ′, and 300 ′ of the electron microscope, a self-lubricating carbon material shaft is used, and the titanium material holding portion that constantly contacts the surface with a pressure by three-point support, Since the hardened layer H made of titanium nitride TiN has a film thickness of 1 to 3 μm to make a hard surface, or the surface of the holding portion is nickel-plated to make the plated layer 10 to 20 μm, and lapping is performed, 500,000 The initial accuracy can be maintained with respect to repeated reciprocating movements more than once. Further, according to the fine drive unit, the driving side of the ultrasonic linear actuator and the free end of the shaft are held by the resin material of the elastic adhesive provided on the bearing portion of the fixed frame and the hollow movable body. Can be absorbed and smooth fine feed control and fixed position stop control can be guaranteed for a long time. In addition, the durability of the ultrasonic linear actuator can be improved.

  The fine drive units 20 ′, 30 ′, and 300 ′ of the electron microscope of the present invention can be implemented in the fine drive unit 40 ′ of the transmission electron microscope 200 shown in FIG. The transmission electron microscope 200 includes a fine drive unit 40 ′ serving as a drive mechanism for a support member that supports the sample S to be observed in the fixed frame 21. The configuration of the third embodiment is shown in FIG. 14, and the same components as those of the fine drive unit 20 ′ in the scanning electron microscope 100 of FIG.

  The transmission electron microscope 200 includes, on the axis L, a fine drive unit 40 ′ having a material S on the lower side of the electron gun 4 A that emits an electron beam through the converging lens 6, and a fine drive just below the fine drive unit 40 ′. Units 20 'are arranged in two stages. Further, a fine drive unit 20 ′ is provided below the deflection coil 9, and a projection lens 73 that projects an electron beam image from the intermediate lens 72 onto the fluorescent plate 71 is installed. The fluorescent image generated on the fluorescent plate 71 is picked up by a camera or the like, and the transmitted secondary electron image of the sample S is displayed on the display of the control device PC. An exhaust pipe 16 for evacuating the inside is provided at the bottom of the transmission electron microscope 200.

  Further, as shown in FIG. 15, the fine drive unit 40 ′ of the transmission electron microscope 200 includes a Y-axis hollow movable body 23 and an X-axis hollow movable body 24 on the upper surface 4A of a rectangular plate-shaped plate 4 ′. A second embodiment of the fine drive unit 400 ′ that is directly equipped may be used. The configuration will be described below. First, in the X-axis hollow movable body 23, each transducer 25 of the ultrasonic linear actuators 50 and 51 and the free ends 26A and 26A of the shaft held by the holding portions 28 and 28 on both front and rear sides thereof are arranged at one corner of the upper surface 4A. The bearing 4H opened on the projecting seat 4F and the projecting seat 4G in the middle are filled with an elastic adhesive U and held. Similarly, in the Y-axis hollow movable body 24, the transducers 25 of the ultrasonic linear actuators 52 and 53 and the free ends 26A and 26A of the shaft held by the holding portion 29 on the bottom surface are shown in FIG. Similarly, the elastic adhesive U is filled and held in the bearing portion 23 </ b> H opened before and after the frame of the X-axis hollow movable body 23. The flat plate 21 ′ is integrally connected by a screw 60. Other configurations are the same as those of the fine drive unit 40 '.

  The fine drive units 40 ′ and 400 ′ in the transmission electron microscope 200 are configured as described above, and operate in the same manner as the fine drive units 20 ′, 30 ′, and 300 ′ of the scanning electron microscope 100. Moreover, since the effect which accompanies this is the same effect as fine drive unit 20 ', 30', 300 'of the scanning electron microscope 100, description is abbreviate | omitted.

  Although the present invention has been described in the embodiment of the fine driving unit of various electron microscopes, the fine movement feeding accuracy and fine movement positioning accuracy of each fine driving unit and the maintenance of this accuracy are improved. Application to the fine drive unit is possible.

3 Sample stage 4 'Plate 4A Electron gun 4C Electron beam passage hole 4E Projection seat 4F Projection seat 4G Projection seat 4H Bearing portion 5 Converging lens 6 Anode 7 Objective lens 8 Deflection coil 10 Sample holder 10A Support members 11, 12 Aperture member 13 2 Secondary electron detector 15 Housing 16 Exhaust pipe 20, 40 Second drive body 30 First drive body 20 ', 30'300' Fine drive unit 40 ', 400' Fine drive unit 21 Fixed frame 21A Electron beam passage hole 21B Recess 21C, 21D Notch part 21E Bearing part 22 Hole 23 Y-axis hollow movable body 23E Bearing part 24 X-axis hollow movable body 25 Vibrator 26 Shaft 26A Shaft free end 27 Electron beam passage hole 28, 29 Holding part 28A, 29A V groove 28B, 29B Nipping pieces 50 to 53 Ultrasonic linear actuator 54 Wiring 100 Scanning electron microscope 200 Transmission electron microscope A Thick side Thin side E pulse signals E1, E2 inversion pulse signal E1 ', E2' thrust F oscillation output G oscillating unit GP oscillation control unit H hardened layer S sample PC controller P Power unit PD driving circuit PP oscillation output unit U elastic resin agent

Claims (6)

An electron microscope that converges an electron beam using an electron lens to acquire an image of the sample, and irradiates the sample with the electron beam, contains the sample and the electron lens, and maintains an internal vacuum. The first drive body of the casing that blocks the stray magnetic field and the diaphragm member that squeezes the electron beam disposed in the casing includes an ultrasonic linear actuator, and the first drive body is controlled by feeding and controlling the position by a pulse signal. In the fine drive unit of the electron microscope to be controlled,
The first driving body includes a pair of a vibrator and a shaft connected to one side of the central position so as to house the X-axis hollow movable body and the Y-axis hollow movable body in a fixed frame, a sample holder, or a plate. The ultrasonic linear actuator is supported on opposite sides of the fixed frame, the sample holder or the plate with the vibrator and the shaft opposed to each other in the opposite direction, and the X-axis hollow movable body or the Y-axis hollow movable body at the middle part of each shaft. The hollow movable body that is held at three points by the thick V-shaped groove formed in the U-shape of the holding portions provided on both sides and the flat side of the thin-side clamping piece, and is orthogonal to each shaft that holds the hollow movable body A pair of ultrasonic linear actuators are oppositely supported in opposite directions on both side surfaces of the shaft, and at the middle of each shaft, there are three points of the V groove of the holding portion provided on both sides of another hollow movable body and the plane of the sandwiching piece Hold the X-axis hollow movable body and Y-axis Sky and the movable member, the fine driving unit for an electronic microscope, characterized in that it is driven on both sides in the same direction by applying a pair of ultrasonic linear actuator in the reverse pulse signal. An electron microscope that converges an electron beam using an electron lens to acquire an image of the sample, and irradiates the sample with the electron beam, contains the sample and the electron lens, and maintains an internal vacuum. The second drive body of the housing that blocks the stray magnetic field and the support member that supports the sample disposed in the housing is provided with an ultrasonic linear actuator, and the second drive body is controlled to feed and control by the pulse signal. In the fine drive unit of the electron microscope to be controlled,
The second driving body includes a pair of a vibrator and a shaft connected to one side of the central position so as to house the X-axis hollow movable body and the Y-axis hollow movable body in a fixed frame, a sample holder, or a plate. The ultrasonic linear actuator is supported on opposite sides of the fixed frame, the sample holder or the plate with the vibrator and the shaft opposed to each other in the opposite direction, and the X-axis hollow movable body or the Y-axis hollow movable body at the middle part of each shaft. The hollow movable body that is held at three points by the thick V-shaped groove formed in the U-shape of the holding portions provided on both sides and the flat side of the thin-side clamping piece, and is orthogonal to each shaft that holds the hollow movable body A pair of ultrasonic linear actuators are oppositely supported in opposite directions on both side surfaces of the shaft, and at the middle of each shaft, there are three points of the V groove of the holding portion provided on both sides of another hollow movable body and the plane of the sandwiching piece Hold the X-axis hollow movable body and Y-axis Sky and the movable member, the fine driving unit for an electronic microscope, characterized in that it is driven on both sides in the same direction by applying a pair of ultrasonic linear actuator in the reverse pulse signal.   In the ultrasonic linear actuator, the shaft is made of a carbon material, and the shaft is always in contact with the X-axis hollow movable body side with pressure by three-point support of the V groove of the holding portion and the plane of the clamping piece, and the Y-axis. The holding portion on the side of the hollow shaft movable body is made of a titanium material having a component ratio of Ti-6AL-4V. In order to harden the holding portion, the holding portion is ion nitrided to obtain titanium nitride TiN having a hardened layer of 1 to 3 μm. 3. The fine driving unit of an electron microscope according to claim 1, wherein the fine driving unit is lapped.   In the ultrasonic linear actuator, the shaft is made of a carbon material, and the shaft is always in contact with the X-axis hollow movable body side with pressure by three-point support of the V groove of the holding portion and the plane of the clamping piece, and the Y-axis. The holding part on the shaft hollow movable body side is made of a titanium material having a component ratio of Ti-6AL-4V, and nickel plating is applied to make the holding part a hard surface, and the plating layer is 10 to 20 μm and lapped. The fine driving unit of the electron microscope according to claim 1 or 2, characterized in that.   The ultrasonic linear actuator vibrator and the free end of the shaft are held with a resilient elastic adhesive in the bearings of the fixed frame, the sample holder or the plate, and the X-axis hollow movable body side and the Y-axis hollow movable body side. The fine driving unit of the electron microscope according to claim 1 or 2, characterized in that.   6. The fine driving unit of an electron microscope according to claim 5, wherein the elastic adhesive is, for example, an acrylic modified silicon resin.

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