JP2005345220A - Device and method for sample preparation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent contamination of semi-conductor wafers for extracting a minute sample piece. <P>SOLUTION: To extract a minute sample piece 3 of a semi-conductor wafer thin film processed by a focused ion beam 2, the distal end 9 of a supporting means provided on a transfer means 7 is brought into contact with the minute sample piece 3, and the sample connected to the end making use of the interatomicbonds caused by surface activation of the contact surface is extracted. The distal end 9 of the supporting means has a cartridge function 11, and a plurality of end parts 9 made from a variety of materials corresponding to the material of the sample can be selectively used. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sample preparation method and apparatus for extracting a small sample piece for observation with an electron microscope or elemental analysis using an energy dispersive X-ray analyzer.

  The need for observation and analysis in ultra-fine regions using transmission electron microscopes, scanning electron microscopes, and energy dispersive X-ray analyzers has increased. It is used.

  As a method for producing a flat sample, a thin film sampling method described in Patent Document 1 has been established. In this method, a deposition gas source is provided near the sample, the deposition gas is formed by introducing a deposition gas at the junction between the small sample piece and the holding means, and irradiating with a focused ion beam, and the deposition film is thinned by the contact force of the deposition film. Remove the small sample piece.

Japanese Unexamined Patent Publication No. 2000-214056

When using small sample pieces for observation and analysis as described above, it is necessary to periodically supply W (CO) ₆ tungsten hexacarbonyl or C ₁₆ H ₁₀ pyrene loaded in the deposition film or in the deposition gas source. . In addition, the observation in a very fine region and the influence on the foreign matter analysis accuracy are problematic. Moreover, when taking out a micro sample piece from a semiconductor wafer etc., there exists a problem of contaminating the whole wafer by deposition.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a sample preparation method and apparatus capable of taking out a small sample piece easily and without contamination by using interatomic bonding without performing bonding by contact force of a deposition film. There is to do.

  In order to achieve the above object, the present invention provides a sample preparation method using an ion beam in a sample preparation method for taking out a small sample piece for observation or analysis from a sample such as a wafer placed on a sample stage in a vacuum atmosphere. A part of the sample is separated as a micro sample piece, the micro sample piece and the tip of the holding means are brought into contact with each other, and the micro sample piece is extracted by bonding using an interatomic bond (atomic force) between the two. It is characterized by.

  Here, before the micro sample piece and the tip of the holding means are brought into contact, activation processing of both contact surfaces by an ion beam is performed.

  The tip of the holding means is selected according to the material of the sample. The tip of the holding means is processed by an ion beam in accordance with the contact area of the minute sample piece.

  The sample preparation apparatus of the present invention is a sample preparation apparatus that extracts a small sample piece for observation or analysis from a sample such as a wafer placed on a sample stage in a vacuum atmosphere. A holding means for holding the separated micro sample piece, an ion beam control unit for activating the contact surface of the micro sample piece and the contact surface of the tip of the holding means by ion beam processing, and both the contact surfaces It is characterized in that there is provided a transport means for bringing the minute sample pieces into contact with each other by utilizing interatomic bonds and taking out the micro sample piece, and a control device therefor.

  The holding means is a cartridge that can store a plurality of tip portions, and has a structure selected from a plurality of materials such as gold, tungsten, and carbon in accordance with the material of the sample.

  Further, the control device controls the holding means to process the contact surface of the tip portion in conformity with the contact surface of the minute sample piece.

  According to the sample preparation method and apparatus of the present invention, there is no influence on the observation image and the X-ray analysis accuracy due to the formation of the deposition film, which has been a problem at the time of sample preparation, and the periodic gas source is supplied to the deposition gas source. Is also unnecessary. Further, there is an effect that a small sample piece can be taken out easily and without contamination.

  The present invention is a method and apparatus for taking out a fine sample for observation or analysis for analysis of a wafer defect portion. Embodiments of a sample preparation apparatus according to the present invention include a focused ion beam irradiation optical system, an ion beam deflection system that irradiates a focused ion beam at an arbitrary position, a holding unit that extracts a micro sample, and a position that controls the holding unit. A control system and a sample stage for moving the sample are provided. Hereinafter, an example is given and explained in detail.

  FIG. 1 is a schematic configuration showing one embodiment of a sample preparation apparatus according to the present invention. The sample preparation apparatus 1 includes an ion beam irradiation system 4 that irradiates a sample 3 with a focused ion beam 2, a secondary particle detector 5 that detects secondary electrons and secondary ions from the sample 3, and a sample 3 in a vacuum atmosphere. A sample exchanging mechanism 20 for inserting the sample 3 and a sample stage 6 on which the sample 3 is placed are provided. Incidentally, the inside from the outline of the sample preparation device 1 of FIG. 1 is configured in a vacuum atmosphere.

  Also, the conveying means 7 for extracting the finely processed fine sample piece 12, the control device 8 for bringing the conveying means 7 into contact with the fine sample piece 12, the holding means tip 9 and the activation of the fine sample processed surface An ion beam control unit 10 that performs processing is included. The conveying means 7 is constituted by a cartridge 11 and can select the holding means tip 9 made of a plurality of materials from outside the vacuum atmosphere.

  The ion beam irradiation system 4 is a well-known optical system and will not be described in detail. The focused ion beam 2 is focused and scanned on the sample surface at a [mu] m to sub- [mu] m level, and used for sample observation and processing.

  By detecting and imaging secondary electrons and secondary ions generated during observation and processing with the secondary particle detector 5, it is possible to observe the sample surface, processing region, and the like with the CRT 16. The fine sample piece 12 in the sample is processed into an arbitrary shape while observing images of the sample surface, the processed region, and the like.

  The holding means tip 9 used to take out the produced fine sample piece 12 needs to be arbitrarily processed by the focused ion beam 2 in order to make it easy to come into contact with the fine sample piece 12. For this reason, it has the front-end | tip part control function 81 as one function of the control apparatus 8, and performs the rotation control 18 and the angle control 19 of the holding | maintenance means front-end | tip part 9. FIG.

  FIG. 2 shows an example of a method for processing the tip of the holding means. The conveying means 7 has a built-in rotation mechanism and a rotation angle control mechanism, and is controlled by the tip end control function 81. (A) is a state in which the focused ion beam 2 is irradiated on the tip 9 of the holding means, and the tip 9 is needle-like processed 14 by continuously performing rotation control 18 as shown in (b). At this time, the parallelism 15 to the contact surface is adjusted. Furthermore, when the angle control 19 is performed in an arbitrary direction on the tip 9 of the holding means that has been needle-shaped as shown in (c) and the cross-section is processed into an arbitrary contact area 17 by the focused ion beam 2, as shown in (d). In addition, the holding means tip 9 can be processed in accordance with the size of the fine sample piece 12.

  When the fine sample piece 12 is taken out, the contact surface is activated by the focused ion beam 2 for the purpose of removing an oxide film or the like immediately before the fine sample piece 12 contacts the holding means tip 9 of the transport means. At the same time, the holding means tip 9 is also activated by the focused ion beam 2 to facilitate interatomic bonding with the fine sample piece 12.

  The control device 8 has a contact control function 82 and performs control for bringing the holding means tip 9 into contact with the fine sample piece 12 after the activation process. By bringing the holding means tip 9 into contact with the fine sample piece 12, the active surfaces are joined by interatomic bonds.

  As described above, by using this embodiment, it is possible to take out an arbitrary fine sample piece in the sample by the conveying means 7, and therefore, it can be used as an observation sample of a transmission electron microscope or a scanning electron microscope. .

  FIG. 3 is a schematic configuration example showing the cartridge function of the tip of the holding means. The cartridge function 11 of this embodiment can store a plurality of holding means tip portions 9 (9-1 to 9-4). The cartridge function 11 accommodates the tip 9 made of a plurality of materials such as gold, tungsten, and carbon according to the material of the sample 3 to be refined on the sample stage 6, and can be arbitrarily selected. That is, the contact control function 82 rotates the cartridge function 11 via the tip selection control mechanism 18 built in the transport means 7, selects any holding means tip 9-1 to 9-4, and selects the cartridge function 11. Pull out the tip from. The drawn holding means tip 9 is brought into contact with the fine sample piece 12 after the contact area is processed, and is joined by an interatomic bond. Thereafter, the fine sample piece 12 is extracted by being pulled back by the contact control function 82. According to the cartridge function, the tip of the holding means can be easily replaced even in a vacuum atmosphere. Note that the tip end portion 9 of the holding means may be processed in advance to a few μm.

  FIG. 4 is a flowchart showing one embodiment of the sample preparation method according to the present invention, and shows the procedure of the control device 8. First, the cartridge function 11 is rotated to select the holding means distal end portion 9 to be used (s101). The necessity of needle processing of the selected tip 9 is determined (s102). If necessary, the selected tip is rotated (s013), and needle processing with a focused ion beam is performed (s104).

  Next, the fine sample is processed from the sample (s105), and the contact area between the holding tip and the fine sample is set (s106). That is, the contact area of the holding means tip 9 is set according to the size of the fine sample. Then, the tip of the holding means is processed so as to have the set contact area (s107). Here, both the fine sample and the tip of the holding means are activated by the ion beam control unit 10 using the ion beam on the contact surface.

  Next, the tip of the holding means is delivered to the vicinity of the sample by the conveying means (s108), and the fine sample and the tip are joined by interatomic bonding (s109). Finally, the tip is pulled back by the conveying means (s110), and a fine sample is extracted.

  According to the present embodiment described above, since no deposition film is used for taking out a fine sample piece, contamination of the wafer can be prevented. Moreover, the troublesomeness of periodically supplying the gas source to the deposition gas source is eliminated. Further, since the tip of the holding means is processed before joining, joining with the sample strip becomes easy. Furthermore, since the cartridge structure that can change the material of the tip of the holding means in a vacuum atmosphere is employed, the holding tip according to the material of the sample can be easily selected.

The block diagram of the sample preparation apparatus by one Example of this invention. Explanatory drawing which shows the processing method before the contact of a holding | maintenance means front-end | tip part. The perspective view of the cartridge function which mounts the holding | maintenance means front-end | tip part by one Example. The flowchart of the sample preparation method by one Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Sample preparation apparatus, 2 ... Focused ion beam, 3 ... Sample, 4 ... Ion beam irradiation system, 5 ... Secondary particle detector, 6 ... Sample stage, 7 ... Conveyance means, 8 ... Control apparatus, 9, 9- DESCRIPTION OF SYMBOLS 1-9-4 ... Holding | maintenance means front-end | tip part, 10 ... Ion beam control part, 11 ... Cartridge function, 12 ... Fine sample piece, 16 ... CRT, 20 ... Sample exchange mechanism, 14 ... Needle-like process, 17 ... Contact area, 18 ... rotation control, 19 ... angle control, 81 ... tip portion control, 82 ... contact control.

Claims (8)

In a sample preparation method for taking out a small sample piece for observation or analysis from a sample such as a wafer placed on a sample stage in a vacuum atmosphere,
A part of the sample is separated as a micro sample piece using an ion beam, the micro sample piece is brought into contact with the tip of the holding means, and the micro sample piece is extracted by bonding using an atomic bond between the two. A method for preparing a sample.   2. The sample preparation method according to claim 1, wherein an activation process of both contact surfaces by an ion beam is performed before contacting the minute sample piece and the tip of the holding means.   3. The sample preparation method according to claim 1 or 2, wherein the tip of the holding means is selected according to the material of the sample.   4. The sample preparation method according to claim 1, wherein the tip of the holding means is processed by an ion beam in accordance with a contact area of the minute sample piece. In a sample preparation device that extracts minute sample pieces for observation or analysis from a sample such as a wafer placed on a sample stage in a vacuum atmosphere,
A holding means for holding a micro sample piece separated from the sample by using an ion beam, and an ion beam control unit for activating the contact surface of the micro sample piece and the contact surface of the tip of the holding means by ion beam processing A sample preparation apparatus comprising: a conveying unit that brings both of the contact surfaces into contact with each other and joins them using an interatomic bond to take out the minute sample piece; and a control device therefor.   6. The cartridge according to claim 5, wherein the holding means is a cartridge capable of storing a plurality of tip portions, and has a structure selected from a plurality of materials such as gold, tungsten, and carbon according to the material of the sample. Sample preparation device.   6. The sample preparation apparatus according to claim 5, wherein the control device controls the holding unit to process the contact surface of the tip portion in conformity with the contact surface of the minute sample piece. The micro sample piece extracted from the sample according to claim 5, is used as a sample for observation with a transmission electron microscope or a scanning electron microscope, or for elemental analysis with an energy dispersive X-ray analyzer. Sample preparation device.

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