JP2004295146A - Manipulator, probe device using it, and sample preparing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manipulator capable of improving the operation rate of a device by shortening the stop time of the device at replacing a probe, as for a manipulator for operating the probe inside a vacuum device. <P>SOLUTION: The device is provided with a vacuum guiding mechanism of taking the probe in and out of the vacuum chamber 1 of the device main body without opening the vacuum chamber 1 in the air in the case of taking the probe in and out of the vacuum chamber. Concretely, an air lock chamber 3 is arranged in the vacuum chamber 1, and the air lock chamber 3 is connected to the vacuum chamber 1 of the main body through a vacuum bellows 2. A probe holder 5 is attached to the air lock chamber 3, and the probe 4 is moved together with the air lock chamber 3 by a moving mechanism 7 arranged in the main body. The air lock chamber 3 is constituted so that the evacuation can be performed through a discharge port 9, and a space between the air lock chamber 3 and the vacuum chamber 1 is partitioned by a vacuum valve 8. A 2nd moving mechanism 10 is arranged so that the probe 4 can be moved between the air lock chamber 3 and the vacuum chamber 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a manipulator for a micro-tip in a vacuum, and particularly to a probe device for evaluating the performance of an electronic element or analyzing a failure, or a portion necessary for analysis and observation from a sample piece using a focused ion beam. The present invention relates to a sample preparation apparatus for processing and extracting only a sample.

  As a conventional method for evaluating an electronic element, there is a probe device. This is a method in which a probe is brought into contact with a position where electrical characteristics are to be measured while observing an inspection sample with an optical microscope in the atmosphere. By providing the probe with a voltage applying unit and a current measuring unit, it is possible to evaluate the current-voltage characteristics of the element and to specify a conduction failure portion. In recent years, semiconductors have been highly integrated, and techniques for evaluating electronic devices having submicron wiring have been devised. For example, as disclosed in Patent Document 1, in the above-described probe device, instead of an optical microscope, a sample is irradiated with charged particles in a vacuum, and microscopic means (such as an electron microscope or the like) for detecting secondary electrons of the sample is applied. ), The probe is brought into contact with the sample by a high-precision probe moving mechanism.

  In addition, due to the high integration of semiconductors, the necessity of analysis of extremely fine objects that cannot be measured with the resolution of a scanning electron microscope (hereinafter abbreviated as SEM) is increasing. For this reason, a transmission electron microscope (hereinafter abbreviated as TEM) having a high observation resolution has been regarded as a promising alternative to the SEM. In order to observe with a TEM, it is necessary to make the thickness of the observation portion of the sample as thin as 0.1 μm. As an example of this processing procedure, first, a strip-shaped pellet including a region to be observed is cut out from a sample such as a wafer using a dicing apparatus. A part of the pellet is irradiated with a focused ion beam (hereinafter abbreviated as FIB) to form a thin-walled part. At the time of TEM observation, the thin wall surface is irradiated with an electron beam vertically. Disadvantages of this method are that the work involved in preparing one sample is complicated, and that there is a part that cannot be analyzed because the wafer is cut. On the other hand, Patent Document 2 discloses the following method. This is a method of cutting out a sample only by FIB processing while changing the posture of the sample. Here, as a sample extracting means after cutting out, an operating needle having the same shape as the probe of the probe device described above is brought into contact with the sample, a deposition gas is supplied, and an ion beam assisted deposition film is formed, thereby performing the operation. The needle and the sample are bonded and separated from the wafer.

JP-A-9-326425

JP-A-5-52721

  However, a problem common to both the former probe device and the latter sample preparation device is deterioration of the probe tip because a probe or an operating needle (hereinafter, referred to as a probe) is brought into contact with the sample. A contact detection method is also being studied so that the deformation of the probe upon contact is a load / displacement that falls within the elastic deformation region. However, since the state of the contact surface is not always the same, for example, the surface of the sample is covered with an insulator, the probe may be pressed against the sample more than necessary due to poor contact detection of the probe. As a result, the tip of the probe is plastically deformed, and it becomes difficult to use the probe after the next time. This problem becomes more remarkable as the degree of integration of the semiconductor increases and the tip of the probe becomes thinner.

  Speaking of the latter sample preparation apparatus alone, the probe tip must be cut off when the probe tip is bonded to the sample and the sample is separated from the wafer, and then another sample is prepared and extracted. This cutting can be performed with the FIB, and the cut surface can be sharpened with the FIB. However, only flat processing is performed, resulting in a wedge-shaped probe that is thick in the thickness direction. Therefore, there is a limit for repeated use.

  For these reasons, the probe is a consumable item in any device and needs to be replaced quite frequently. By the way, the manipulator for moving the probe attached to these devices has a mechanical unit and a probe integrated with each other, and it is necessary to open the vacuum chamber to the atmosphere and remove it from the main body when replacing the probe. Therefore, it takes a long time to start up the vacuum after the replacement, which causes a reduction in the operation rate of the apparatus.

  In order to solve the above problems, the following means are used.

  There is provided a vacuum introduction mechanism that can be used when the probe is taken in and out of the vacuum chamber that is the apparatus main body without opening the vacuum chamber to the atmosphere. Specifically, an airlock chamber is provided in the vacuum chamber, and the airlock chamber is connected to a vacuum chamber of the main body by a flexible vacuum bellows. The member holding the probe is attached to the airlock chamber, and the probe can be moved together with the airlock chamber by a moving mechanism provided in the main body. The airlock chamber has a structure capable of evacuating, and the airlock chamber and the vacuum chamber are separated by a vacuum valve. A second moving mechanism is provided so that the probe can move between the airlock chamber and the vacuum chamber.

  According to the present invention, it is not necessary to open the vacuum chamber to the atmosphere when the probe is moved in and out of the vacuum chamber of the main body, so that the operation rate of the apparatus can be improved.

  Hereinafter, the present invention will be described with reference to examples.

  FIG. 1 is a schematic configuration diagram of a manipulator showing an embodiment of the present invention. In the figure, an airlock chamber 3 connected by a vacuum bellows 2 is provided in a vacuum chamber 1 which is a main body of the apparatus. The probe holder 5 on which the probe 4 is mounted is fixed to the airlock chamber 3 via a vacuum seal 6, and the three-axis moving mechanisms 7 a, 7 b, 7 c provided in the vacuum chamber 1 provide a probe together with the airlock chamber 3. 4 movements are possible. The partition between the air lock chamber 3 and the vacuum chamber 1 is constituted by a vacuum valve 8 that can be opened and closed, and the exhaust port 9 is connected to a vacuum pump 11 via a three-way valve 12. By switching the three-way valve 12, the air lock chamber 3 can be evacuated / released to the atmosphere. The exhaust port 9 is provided with a vacuum gauge 13 for measuring the pressure in the air lock chamber 3. If the pressure does not fall within a certain set value, the vacuum valve 8 does not open. I have. The probe holder 5 is provided with a uniaxial moving mechanism 10 so that the probe 4 can move between the airlock chamber 3 and the vacuum chamber 1.

  Here, the operation of the present embodiment will be described. When exchanging the probe 4, as shown in FIG. 2A, the probe holder 5 is retracted using the moving mechanism 10, and the vacuum valve 8 is closed. Thereby, the air lock chamber 3 becomes a separate space from the main body vacuum chamber 1. Here, air is introduced into the air lock chamber 3 from the exhaust port 9 to make the inside of the air lock chamber 3 atmospheric pressure. Thereafter, the probe holder 5 is removed from the airlock chamber 3, and the probe 4 is replaced after the state shown in FIG. After the replacement, the probe holder 5 is attached to the airlock chamber 3 in the reverse order, and the airlock chamber 3 is evacuated. After confirming that the pressure difference between the air lock chamber 3 and the vacuum chamber 1 has become small, the vacuum valve 8 is opened. The probe holder 3 is introduced into the vacuum chamber 1 by the moving mechanism 10. To operate the probe 4 at a desired position, the airlock chamber 3 is moved together with the three-axis moving mechanisms 7a, 7b, 7c. Thus, the probe can be replaced without exposing the vacuum chamber to the atmosphere.

  FIG. 3 is a detailed sectional view of a manipulator showing another embodiment of the present invention. 4 is a plan view of FIG. 3, FIG. 5 is a cross-sectional view taken along the line AA of FIG. 3, and FIG. 6 is a cross-sectional view of the probe holder. In the figure, a base flange 32 is fixed to a vacuum chamber 31 which is an apparatus main body by using a vacuum seal 33. The air lock chamber 34 is connected to the base flange 32 via a vacuum bellows 35, and a vacuum valve 37 is provided on an end face of the air lock chamber 34. The opening and closing of the vacuum valve 37 is performed by rotating a cylindrical valve opening and closing mechanism 38 formed in the air lock chamber 34. In the air lock chamber 34, an exhaust pipe 39 is attached to the base flange 32 via a vacuum bellows 40 and communicates with an exhaust port 41. As a result, the air in the air lock chamber 34 is exhausted (or leaked). A base (Y) 43 is attached to the base flange 32 via a Y-axis linear guide 42. At both ends, a Y-axis linear actuator 44 fixed to the base flange 32 and a preload pressing spring 45a are provided to move the base (Y) 43 in the Y-axis direction. Similarly, a base (Z) 47 is attached to the base (Y) 43 via a Z-axis linear guide 46. The base (Y) 43 is fixed by a Z-axis linear actuator 48 fixed to the base (Y) 43 and a preload pressing spring 45b. , In the Z-axis direction. The base (X) 50 is moved along the X-axis linear guide 49 in the X-axis direction. At this time, the output of the X-axis linear actuator 51 is inverted using the lever 55. Since the air lock chamber 32 and the probe holder 54 on which the probe 36 is mounted are fixed to the base (X) 50, the linear actuators 44, 48, 51 of each axis are driven so that the probe 36 You can move. The position of the probe 36 is grasped by the output values of the encoders 52a, 52b, 52c of each axis, and highly accurate position control is possible. The probe holder 54 is provided with a shaft vacuum seal 53 so as to be movable along the axis of the airlock chamber 32 while maintaining a vacuum. A leaf spring-like conductive plate 56 is in contact with the tip of the probe holder 54 for power supply. The conductive plate 56 is connected to a current introducing terminal 58 provided on the base flange 32 by a conductive wire 57. Thus, power can be supplied to the probe. The reason why a leaf spring is used as the power supply member is to realize stable power supply by reducing the contact resistance and to suppress the generation of vibration at the distal end of the probe holder 54 by applying a load to the distal end of the probe holder 54 in one direction. That's why.

  As shown in FIG. 6A, the probe holder 54 has a double structure of a rod 59 to which the probe 36 is attached and an outer cylinder 60, and is vacuum-sealed by an O-ring 61. The rod 59 moves linearly and rotationally with respect to the outer cylinder 60 by operating the knob 62. The position of the rod 59 is fixed by the stopper 63, so that the tip of the probe can be stored and protected. At the tip of the probe holder 54, a probe socket 66 having six leaf springs 64 arranged in the radial direction is provided. Since the probe 36 is fixed by the leaf spring 64, the probe 36 can be inserted and removed, and the probe 36 can be easily removed without using screws or the like. Since the probe 36 is electrically insulated from the rod 59 by the insulating material 65, power can be supplied by the contact of the conductive plate 56 described above.

  Here, the operation of the present embodiment will be described. When replacing the probe 36 due to breakage or wear of the tip of the probe 36, first, the knob 62 is moved straight and rotated, and the probe 36 is stored in the outer cylinder 60, as shown in FIG. Thereafter, as shown in FIG. 7A, the probe holder 54 is manually retracted, and the valve opening / closing mechanism 38 is operated to close the vacuum valve 37. As a result, the air lock chamber 34 becomes a separate space from the main body vacuum chamber 31. Here, gas, for example, air is introduced into the air lock chamber 34 from the exhaust port 41 to make the inside of the air lock chamber 34 atmospheric pressure. Thereafter, the probe holder 54 is further pulled out of the air lock chamber 34, and the knob 63 is returned to the original state as shown in FIG. 7B, and the probe 36 is replaced. Here, the probe is constituted by a needle 67 made of tungsten and a needle support member 68, and the needle 67 is fixed to the needle support member 68 by welding. For replacement of the probe 36, the probe 36 is pulled out from the probe holder 54 as shown in FIGS. 6C and 6D using tweezers or the like, and a new probe is inserted instead. After the replacement, it is only necessary to incorporate them in the reverse order. First, the probe holder 36 is inserted into the airlock chamber 34, and the inside of the airlock chamber 34 is evacuated. Until the pressure difference between the air lock chamber 34 and the vacuum chamber 31 becomes small, for example, it is confirmed that the pressure in the air lock chamber 34 has become 5 Pa or less, and the valve opening / closing mechanism 38 is operated to open the vacuum valve 37. The probe holder 54 is further manually inserted into the vacuum chamber 31. To operate the probe 36 at a desired position, the airlock chamber 34 is moved together with the three-axis linear actuators 44, 48, 51. Thereby, the probe can be easily replaced without exposing the vacuum chamber to the atmosphere. It should be noted that the apparatus is simply fixed to the vacuum chamber 31 of the apparatus main body by the base flange 32, so that the apparatus can be easily attached to and detached from the main body. For this reason, it is easy to additionally attach to the already delivered device by adjusting the size and position of the attachment flange of the main body.

  FIG. 8 is a sectional view of a probe holder on which a manipulator according to another embodiment of the present invention is mounted. In the figure, six probes 36 are radially arranged at the tip of a rod 59, and are fixed by leaf springs 64, respectively. The rod 59 is configured to be rotatable with respect to the outer cylinder 60, and the probe to be used can be selected by rotating the knob 63 at the tip of the rod 59. As a result, the frequency of pulling out the probe holder for replacement when the tip of the probe is damaged or worn is reduced to about 1/6, and the operation rate of the apparatus is further improved.

  FIG. 9 is a schematic diagram when the embodiment of the present invention is applied to a probe device. In the drawing, an electron beam 72 emitted from an electron gun 71 is shaped by an aperture 73, the spread of the electron beam 72 is controlled by a focusing lens 74, Is focused at the position. A substrate 78 such as a semiconductor wafer or a semiconductor chip is placed on the stage 77, and the position of an element to be evaluated on the substrate 78 is specified by a stage position controller 79. Each of the probes 81a, 81b, 81c mounted on the plurality of manipulators 80a, 80b, 80c is moved to the position of the evaluation element on the substrate 78 by the probe position controllers 82a, 82b, 82c which can be driven independently of the stage 77. Move. At the time of movement, the electron beam 72 is scanned by the electron beam controller 83 near the evaluation element on the substrate 78, secondary electrons from the substrate 78 are detected by the secondary electron detector 84, and the image is displayed on the display 85. Perform while displaying / observing. A power supply 86 is connected to each of the probes 81a, 81b, and 81c so that a voltage can be applied to a minute portion of the substrate 78 with which the probe 81 has contacted. At the same time, an ammeter 87 is connected so that the current flowing through each of the probes 81a, 81b, 81c can be measured. As an example of the evaluation method, a case of a MOS device formed on a wafer will be described. First, three probes are brought into contact with a source electrode, a gate electrode, and a drain electrode, respectively. Here, the source electrode is grounded using a probe, and the probe measures the relationship between the drain voltage and the drain current flowing between the source and the drain while varying the voltage of the gate electrode as a parameter. Thereby, the output characteristics of the MOS can be obtained. These operations are collectively controlled by the central processing unit 88.

  The manipulators 80a, 80b, 80c have the same configuration as that shown in FIG. Thereby, even if the probe is broken at the time of measurement evaluation, the probe can be easily replaced, so that the operation rate of the probe device can be improved.

  Further, in the present embodiment, even with a probe device using an irradiation optical system configured by replacing the electron gun 71 with an ion source, a similar effect can be obtained by using the manipulator of the present invention.

  FIG. 10 is a schematic diagram when the embodiment of the present invention is applied to a sample preparation apparatus. In the figure, in a sample chamber 96 and a column 101 whose insides are made into a vacuum atmosphere by a vacuum pump 100, an ion beam 90 emitted from an ion source 89 is shaped by a beam limiting aperture 91, and is spread by a focusing lens 74. Is controlled, and the light is focused on a desired position on a stage 77 placed in a sample chamber by passing through a deflector 75 and an objective lens 76. The focused ion beam 90, that is, FIB, can perform precise processing of the sample 92 by sputtering the surface of the substrate 78 into a scanned shape. On the stage 77, a substrate 78 such as a semiconductor wafer or a semiconductor chip and a sample holder 93 for holding an extracted sample 92 are mounted, and a stage position controller 79 specifies a position for processing and extracting the sample. . The probe 81 mounted on the manipulator 80 is moved to an extraction position on the substrate 78 by a probe position controller 82 that can be driven independently of the stage 77. At the time of movement and processing, the FIB controller 94 scans the FIB near the extraction position of the substrate 78, detects secondary electrons from the substrate 78 by the secondary electron detector 84, and displays the image on the display 85. / Perform while observing. In extracting the sample 92, the sample 92 is cut out in a wedge shape by performing FIB processing while changing the posture of the substrate 78, and the tip of the probe 81 is brought into contact with the sample 92. The probe 81 and the sample 92 are bonded to each other by supplying a deposition gas to the contact portion by using a deposition gas source 95 and forming an ion beam assisted deposition film. Thereafter, the probe 81 is pulled up from the substrate 78 by the probe position controller 82 and moved to the position of the sample holder 93 on the stage 77. The probe 81 is lowered, and it is confirmed that the wedge tip of the sample 92 adhered to the probe 81 contacts the surface of the sample holder 93, and the side surface of the sample 92 and the sample holder 93 are adhered by the ion beam assisted deposition film. . The tip of the probe 81 is cut from the sample 92 by the FIB, and is moved to the next sample extracting position by the probe position controller 82. In this way, it is possible to transfer a desired number of samples from one substrate to one sample holder. These operations are collectively controlled by the central processing unit 88. Here, the probe 81 may be one having a sharp tip at the tip as shown in FIG. 11A, or one having the tip of the probe processed by FIB into a thin plate as shown in FIG. 11B. is there. In the latter case, it takes time to process the probe, but there is no need for fine positioning when the probe comes into contact with the substrate 78. Further, after the wedge-shaped sample 92 is cut off by the FIB, it becomes as shown in FIG. There is an advantage that it can be used repeatedly for a wider portion.

Note that the manipulator has the configuration shown in FIG. 3 as in the above-described embodiment. The air lock chamber inside the manipulator is connected to a three-way valve 98 and a vacuum pump 98 by a pipe 97, and has a structure capable of evacuating / opening the air lock chamber to the atmosphere. Thereby, even if the probe is worn or damaged, it is possible to easily replace the probe, and it is possible to improve the operation rate of the sample preparation apparatus.
In this embodiment, a sample preparation apparatus using a projected ion beam configured by replacing the deflector 75 and the objective lens 76 with a mask plate and a projection lens, or configured by replacing the ion source 89 with a laser light source. The same effect can be obtained by using the manipulator of the present invention even in a sample manufacturing apparatus using a laser beam.

  Further, in the present embodiment, when the probe 81 is made of glass or a polymer material, the sample 92 is extracted using an electrostatic force without forming an ion beam assisted deposition film. For this reason, the tip of the probe 81 is not cut, but the same effect can be obtained by using the manipulator of the present invention for replacement in case of breakage due to an accident.

1 is a schematic configuration diagram for explaining a manipulator according to an embodiment of the present invention. It is a schematic structure figure for explaining operation of a manipulator showing an example of the present invention. FIG. 4 is a detailed sectional view of a manipulator showing another embodiment of the present invention. FIG. 4 is a plan view of a manipulator according to the embodiment of FIG. 3 of the present invention. FIG. 4 is a sectional view taken along the line AA of the manipulator according to the embodiment of FIG. 3 of the present invention. FIG. 4 is a sectional view of a probe holder mounted on the manipulator according to the embodiment of FIG. 3 of the present invention. FIG. 4 is a diagram for explaining an operation of the manipulator which is the embodiment of FIG. 3 of the present invention. It is sectional drawing of the probe holder mounted in the manipulator which is another Example of this invention. FIG. 6 is a schematic configuration diagram of a probe device showing another embodiment of the present invention. FIG. 4 is a schematic configuration diagram of a sample preparation apparatus showing another embodiment of the present invention. FIG. 11 is a schematic view showing a probe tip shape in the sample preparation apparatus according to the embodiment of FIG. 10 of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 ... Vacuum chamber, 2 ... Vacuum bellows, 3 ... Air lock chamber, 4 ... Probe, 5 ... Probe holder, 6 ... Vacuum seal, 7 ... 3-axis moving mechanism, 8 ... Vacuum valve, 9 ... Exhaust port, 10 ... 1 Shaft moving mechanism, 11: vacuum pump, 12: three-way valve, 13: vacuum gauge, 31: vacuum chamber, 32: base flange, 33: vacuum seal, 34: air lock chamber, 35: vacuum bellows, 36: probe, 37 ... Vacuum valve, 38 ... Valve opening / closing mechanism, 39 ... Exhaust pipe, 40 ... Vacuum bellows, 41 ... Exhaust port, 42 ... Y axis linear guide, 43 ... Base (Y), 44 ... Y axis linear actuator, 45 ... Prestressing spring, 46 ... Z-axis linear guide, 47 ... Base (Z), 48 ... Z-axis linear actuator, 49 ... X-axis linear guide, 50 ... Base (X), 5 ... X-axis linear actuator, 52 ... Encoder, 53 ... Vacuum seal, 54 ... Probe holder, 55 ... Lever, 56 ... Conductive plate, 57 ... Conducting wire, 58 ... Current introduction terminal, 59 ... Rod, 60 ... Outer cylinder, 61 ... O-ring, 62 ... knob, 63 ... stopper, 64 ... leaf spring, 65 ... insulating material, 66 ... socket, 67 ... needle, 68 ... needle support member, 71 ... electron gun, 72 ... electron beam, 73 ... aperture 74: focusing lens, 75: deflector, 76: objective lens, 77: stage, 78: substrate, 79: stage position controller, 80: manipulator, 81: probe, 82: probe position controller, 83: electron beam controller, 84 ... Secondary electron detector, 85 ... Display, 86 ... Power supply, 87 ... Ammeter, 88 ... Central processing unit, 89 ... Ion source, 90 ... On-beam, 91: beam limiting aperture, 92: sample, 93: sample holder, 94: FIB controller, 95: deposit gas source, 96: sample chamber, 97: piping, 98: three-way valve, 99: vacuum pump, 100: vacuum pump , 101 ... column.

Claims (1)

A manipulator comprising a needle-like member and a moving means for moving the needle-like member in a vacuum container, wherein the needle-like member is inserted into and removed from the vacuum container without opening the vacuum container to the atmosphere. A manipulator comprising a vacuum introducing means capable of performing the following.

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