JP3941816B2 - Microsample processing observation method and apparatus - Google Patents

Description

The present invention researches and develops electronic devices such as semiconductor devices, liquid crystal devices, magnetic heads, and micro devices that require observation and analysis of not only the surface of the object to be observed but also the internal cross section close to the surface. The present invention relates to an apparatus system used as an observation / analysis / evaluation means in manufacturing and manufacturing.

In the manufacture of semiconductor devices such as dynamic random access memory, semiconductor devices such as microprocessors and semiconductor lasers, and electronic components such as magnetic heads,
Product characteristics are inspected during or during the manufacturing process for product quality control. In the inspection, measurement of manufacturing dimensions, inspection of circuit pattern defects, and analysis of foreign matter are performed. For this reason, various means are prepared and used.

In particular, when there is an abnormal part inside the product, the conventional focused ion beam (Focused Ion
Beam: FIB) An opportunity to use a microfabrication observation apparatus combining an electron microscope and an electron microscope is increasing. This apparatus is disclosed in Patent Document 1.

A schematic configuration of the same type of apparatus will be described with reference to FIG. A focused ion beam apparatus having a scanning electron microscope function has a vacuum sample chamber 60, and includes a focused ion beam optical system 31, an FIB irradiation, which includes an ion source 1, an ion beam scanning deflector 3, a lens 2, and the like. A secondary particle detector 6 for detecting secondary electrons and secondary ions emitted from the sample by a sample 6, a sample table 24 on which a wafer 21 such as a semiconductor wafer or a semiconductor chip is placed, and the like are arranged. Further, a scanning electron microscope optical system 41 including an electron gun 7 that emits an electron beam, an electron beam lens 9, an electron beam scanning deflector 10, and the like is installed.

Next, the operation of this apparatus will be described. First, the ions emitted from the ion source 1 are irradiated onto the wafer 21 through the lens 31. FIB4 has a diameter of a few nanometers to 1 on the sample.
It is bundled to about a micrometer. When the FIB 4 is irradiated onto the wafer 21, the constituent atoms on the sample surface are released into the vacuum by a sputtering phenomenon. Therefore, by scanning the FIB 4 using the ion beam scanning deflector 3, processing from the micrometer level to the submicrometer level can be performed. Therefore, the wafer 21 as a sample in FIG.
Is placed on the sample stage 24 inside the apparatus, and the observation point p1 designated by the coordinate value is located. Then, the observation point is irradiated with FIB 4 to dig a slot, and an internal cross section s1 of the observation point shown in FIG. 15 is created. . An outer surface and an inner wall surface of the created slot are observed with a scanning electron microscope function by electron beam irradiation, or analyzed appropriately by the analyzer 51. Note that in a conventional microfabrication observation apparatus used in a wafer process, a focused ion beam optical system and an electron beam optical system are arranged so that both beam axes intersect at an observation site on the sample surface.

Recently, a method has been devised in which a micro-sample cut out of a micron-order region including the observation site is taken out of the processing observation device, transferred to a separately prepared device, and further processed into an optimal shape for observation and analysis. It's being used. This method is disclosed in Patent Document 2.

In this method, as shown in FIG. 17, first, the posture of the sample 102 is maintained so that the FIB 4 irradiates at a right angle to the surface of the sample 102, the FIB 4 is scanned in a rectangular shape on the sample, and a required depth is formed on the sample surface. The square hole 107 is formed (FIG. 17A). Next, the sample 102 is inclined to form the bottom hole 108. The inclination angle of the sample 102 is changed by a sample table (not shown) (FIG. 17B). The posture of the sample 102 is changed, the sample 102 is set so that the surface of the sample 102 is perpendicular to the FIB 4 again, and a notch groove 109 is formed (FIG. 17C).
. A manipulator (not shown) is driven, and the tip of the probe 72 at the tip of the manipulator
The sample 102 is brought into contact with the portion to be separated (FIG. 17 (d)). The deposition gas 105 is supplied from the gas nozzle 110 and the FIB 4 is locally irradiated to the region including the tip of the probe 72 to form an ion beam assisted deposition film (hereinafter abbreviated as the deposition film 104). A separation portion of the sample 102 in contact with the tip of the probe 72 is connected by a deposition film 104 (FIG. 17).
(E)). The remaining part is cut out with FIB 4 (FIG. 17 (f)), and a micro sample 12, which is a separated sample, is cut out from the sample 102. The separated sample 12 cut out is supported by the connected probe 72 (FIG. 17 (g)). When this micro sample 12 is processed with FIB 4 and the region to be observed is wall processed, a TEM sample (not shown) is obtained. The above is a method for separating a micro sample including a desired analysis region from a sample such as a wafer by using FIB processing and a micro sample transport means. The micro sample separated by this method can be taken out of the micro processing apparatus and introduced into various observation / analysis apparatuses for analysis. However, it cannot be used if you do not want to expose the sample to the atmosphere. Moreover, since a separate device is required, an increase in equipment cost and installation space is inevitable.

JP 11-260307 A JP 05-52721 A

  The conventional methods described above have the following problems.

Problem (1) In order to observe the hole groove cross section of the sample formed by FIB processing, the hole groove inner wall cross section is observed from an oblique direction by inclining the sample stage. In this case, the tilt angle adjustment range of the sample stage is limited due to the structural distance caused by the working distance of the FIB apparatus, the presence of the objective lens, or the size of the sample stage, and the tilt cannot be increased beyond that. . Accordingly, vertical observation of the groove inner wall cross section is impossible. However, vertical cross-section observation is indispensable for confirmation of processing characteristics such as dry etching, flattening, and thin film formation in the process development of semiconductor device manufacturing, etc., but the apparatus of the above-mentioned known example cannot cope with it.

Problem (2) Decrease in resolution due to oblique observation is a major problem. When irradiating the wafer surface with an electron beam obliquely from above and observing the cross section of the inner wall of the hole groove, the observation resolution in the direction perpendicular to the wafer surface, that is, the inner wall section of the groove hole is lowered. The reduction rate is about 15% at about 30 °, and reaches 30% at around 45 °, which is most frequently used. Recent miniaturization of semiconductor devices has reached the limit, and it is necessary to measure dimensions and shapes with an accuracy of several nanometers or less. The required observation resolution is 3 nm or less, which has entered the technical limit of the scanning electron microscope. In addition, under such a high resolution, the depth of focus becomes extremely shallow and only a range of several tens of percent of 1 μm is in focus. Therefore, the proper observation range of the device longitudinal section during oblique observation is half the required area. Less often occurs. This problem can be achieved by performing high-speed observation with focus in the entire observation region by performing vertical observation.

Problem (3) Since the observed cross section exists on the wall surface of the minute slot formed on the wafer, the number density of secondary electrons coming out of the hole is reduced as compared with the wafer surface. Therefore, the secondary electron detection efficiency is lowered, leading to a reduction in the S / N of the secondary electron image, and the accuracy of cross-sectional observation is inevitably lowered.

The miniaturization of LSI patterns is steadily progressing at a pace of 30% reduction every 2 to 3 years, and higher resolution is required for observation devices. Furthermore, even if elemental analysis (EDX analysis) is performed by measuring the surface distribution of atomic characteristic X-rays excited by irradiation with an electron beam with an X-ray detector,
Due to the expansion of the X-ray generation area due to the penetration of the electron beam into the sample, the electron beam diameter becomes 0.1 μm
Even in the following cases, the surface resolution of the analysis is about 1 μm, which is insufficient for analyzing the cross-section of the LSI element having a fine structure.

Problem (4) As an example in which cross-sectional vertical observation is indispensable, there are performance evaluations such as etching processing, groove hole embedding, and planarization processing in a wafer process. In order to accurately measure the dimension and shape of a processed cross section, conventionally, a chip size sample including a cross section to be viewed from a wafer is determined and observed with a general-purpose scanning electron microscope or the like. However, with the progress of miniaturization of devices and the increase in diameter of wafers, the work of accurately breaking at the position where the element circuit pattern is desired to be observed is very difficult, and there have been failures. On the other hand, due to insufficient supply capacity of evaluation wafers and price increases, evaluation sample preparation is not allowed to fail.

Problem (5) Although the method disclosed in Patent Document 2 can ensure a sufficient level of accuracy of observation and analysis, such as resolution, a sample is manufactured in a conventional apparatus, and this is taken out of the apparatus and prepared separately. Since it needs to be introduced into the analyzer, there is a problem that the time required from taking out a minute sample to processing / observation / analysis is several hours. In addition, in the case where the sample is deteriorated due to oxidation or moisture absorption when exposed to the atmosphere, it is difficult to avoid it. Cross-sectional observation of semiconductor devices has recently become important as a useful inspection method during semiconductor manufacturing, and the processing capacity in that case is currently expected to be observed and analyzed at 2 to 3 or more locations per hour. There is a trend that requires processing. In response to this demand, the problem that the processing capacity of the conventional method is extremely low has not been solved.

In view of the above-mentioned problems, the purpose of this application is to observe the internal cross-section of the target sample in a vertical cross-section, with high resolution, high accuracy, high throughput, no degradation due to atmospheric exposure, and observation / analysis without failure An object of the present invention is to provide an apparatus and a micro sample processing observation method.

  The object as described above is achieved by the following.

(1) An electron beam optical system including a focused ion beam optical system including an ion source, a lens for focusing an ion beam, and an ion beam scanning deflector, and an electron source, a lens for focusing the electron beam, and an electron beam scanning deflector. And a micro sample processing and observation apparatus comprising a detector for irradiating a sample with charged particles to detect secondary particles from the sample, and a sample stage having the sample together. And a micro sample processing and observation apparatus comprising a manipulator for extracting the micro sample and observing the extracted micro sample with the electron beam or the focused ion beam To do. This makes it possible to observe the internal cross-section of the target sample with a high yield of secondary electrons, enabling high-resolution observation, and the micro sample can be observed and analyzed in a short time because it is not taken out of the device. A processing observation apparatus can be provided.

(2) The micro sample processing and observation apparatus according to claim 1, wherein the manipulator has a function of adjusting the position and posture of the micro sample extracted from the sample.

As a result, the position of the micro sample can be moved relative to the scanning electron microscope optical system or the focused ion beam optical system, so that the micro sample can be arranged at a position where the observation resolution becomes higher. In addition, the direction of observing the internal cross section of the micro sample can be selected. For this reason, if the cross section is observed vertically, the yield of secondary electrons is also high, so that a micro sample processing observation apparatus that can observe with high resolution can be provided.

(3) The micro sample processing and observation apparatus according to claim 2, wherein the function of adjusting the position and orientation of the micro sample includes a function of changing an irradiation angle of the charged particle beam to the micro sample.

Thereby, the internal cross-section observation direction of the target sample can be freely selected. For this reason, if the cross section is observed vertically, it is possible to provide a minute sample processing observation apparatus capable of observing with high resolution the shape dimension, embedding condition, film thickness, etc. of etching and flattening, with high accuracy.

(4) A manipulator connected to the micro sample separated from the sample, a manipulator control device for driving the manipulator, and a function of changing the irradiation angle of the charged particle beam to the micro sample by driving independently of the sample stage The second sample stage is provided.
The described micro sample processing and observation apparatus. Thereby, it is possible to provide a micro sample processing and observation apparatus capable of observing and analyzing the internal cross section of the target sample with high resolution and in a short time. In addition, it is possible to separate the micro sample fixed to the second sample stage from the manipulator and fix a plurality of micro samples to the second sample stage with one manipulator, so that time for cross-sectional observation and elemental analysis can be obtained. Can be shortened. Further, by separating the micro sample from the manipulator and fixing it to the second sample stage, it is possible to share the anti-vibration mechanism of the sample stage that holds the introduced sample and the anti-vibration mechanism of the second sample stage that fixes the micro sample. it can.

(5) A manipulator connected to the micro sample separated from the introduced sample, and a manipulator control device for driving the manipulator independently from the sample stage, with the micro sample supported by the manipulator for observation 3. The apparatus for processing and observing a micro sample according to claim 2, which has a function of changing an irradiation angle of the charged particle beam to the micro sample. Thereby, it is possible to provide a micro sample processing and observation apparatus capable of observing and analyzing the internal cross section of the target sample with high resolution and in a short time. In addition, since the second sample stage for fixing the micro sample is not required, the operation for observing the cross section of the micro sample is simplified and the operation time can be shortened.

(6) An apparatus for processing and observing a micro sample according to any one of claims 1 to 5, further comprising an X-ray detector for detecting X-rays generated from the micro sample during irradiation with a charged particle beam. This
It is possible to provide a micro sample processing and observation apparatus capable of observing and analyzing an internal cross section of a target sample with high resolution and in a short time. In elemental analysis based on atomic characteristic X-ray detection at the time of charged particle beam irradiation, it is possible to avoid the expansion of the X-ray generation area due to penetration of the charged particle beam into the sample by thinning the micro sample. It becomes possible.

(7) The micro-sample processing and observation apparatus according to claim 1, further comprising a focused ion beam optical system and a mechanism for changing an inclination angle of the optical system with respect to the sample. This provides a micro sample processing and observation apparatus capable of observing and analyzing the internal cross section of the target sample with high resolution and in a short time. In particular, since the tilt angle of the optical system can be varied, various sample preparation methods and sample shapes can be realized.

(8) The micro-sample processing and observation apparatus according to claim 1, comprising two focused ion beam optical systems. This provides a micro sample processing and observation apparatus capable of observing and analyzing the internal cross section of the target sample with high resolution and in a short time. In particular, since two focused ion beam optical systems are used, sample preparation in a short time becomes possible. Further, if the structure of the sample table is not inclined, the apparatus can be downsized.

(9) A micro sample processing and observation apparatus having a function of cutting out a micro sample fully automatically. This provides a micro sample processing and observation apparatus capable of observing and analyzing the internal cross section of the target sample with high resolution and in a short time. In particular, since the burden on the operator can be reduced by automating the operation of the apparatus, it is possible to observe and analyze in a shorter time.

(10) In a vacuum apparatus, a focused ion beam is used to separate the observation target site from the surface of the relatively large introduced sample as a minute sample, and the minute sample is removed from the introduced sample by driving a manipulator; A method for processing and observing a micro sample is characterized by observing a specific portion of the micro sample with an electron beam or a focused ion beam while the micro sample is placed in a sample chamber in a vacuum atmosphere. This makes it possible to observe the internal cross-section of the target sample with a high yield of secondary electrons, enabling high-resolution observation, and removing the micro sample outside the device, so that the micro sample can be observed and analyzed in a short time A processing observation method can be provided.

(11) The microsample processing and observation method is characterized in that the shape of the microsample is a tetrahedron or a pentahedron. This provides a micro sample processing and observation method capable of observing and analyzing the internal cross section of the target sample with high resolution and in a short time. In particular, since there is little waste in processing to separate a micro sample, the micro sample can be manufactured in a short time.

(12) The micro sample processing and observation method is characterized in that the introduced sample is a semiconductor wafer having no pattern or a pattern. This provides a micro sample processing and observation method capable of observing and analyzing the internal cross section of the target sample with high resolution and in a short time. In particular, by applying it to semiconductor wafers, it can be used for semiconductor manufacturing process inspection, and contributes to the improvement of manufacturing yield by early detection of device defects and short-time quality control.

According to the present invention, it is possible to realize a micro sample processing and observation apparatus and a micro sample processing and observation method capable of performing internal observation of LSI devices and the like that are increasingly miniaturized with high resolution and high quality in a short time. Furthermore, by performing EDX analysis of a micro sample formed by thin film processing and performing high-precision elemental analysis, it is possible to provide a micro sample processing / observing apparatus with a comprehensive cross-section observation and analysis efficiency.

A configuration and operation of a micro sample processing and observation apparatus according to an embodiment of the present invention will be described.
Example 1
The apparatus configuration and operation of the first embodiment will be described with reference to FIGS. 1 and 2
3 shows the overall configuration of the apparatus, and FIG. 3 shows the configuration of the focused ion beam optical system, the scanning electron microscope optical system, and the periphery of the sample stage in detail. In the present embodiment, a wafer handling apparatus is shown among the micro sample processing and observation apparatus of the present invention. FIG. 3 shows a schematic overhead cross-section of FIG. 1, but there are some differences in the orientation and details of the device for convenience of explanation, but this is not an essential difference. In FIG. 1, a focused ion beam optical system 31 and an electron beam optical system 41 are appropriately installed above the vacuum sample chamber 60 at the center of the apparatus system. Inside the vacuum sample chamber 60, a sample stage 24 on which a wafer 21 to be a sample is placed is installed. The two optical systems 31 and 41 are adjusted so that the respective central axes intersect at one point near the surface of the wafer 21. The sample stage 24 incorporates a mechanism for moving the wafer 21 from front to back and from side to side with high accuracy, and is controlled so that a specified position on the wafer 21 is directly below the focused ion beam optical system 31. The sample stage 24 has a function of rotating, up and down, or tilting. An exhaust device (not shown) is connected to the vacuum sample chamber 60 and is controlled to an appropriate pressure. The optical systems 31 and 41 are also individually provided with an exhaust system (not shown) and maintained at an appropriate pressure. The vacuum sample chamber 60 has a wafer introduction unit 61 and a wafer transfer unit 62. A wafer transfer robot 82 and a cassette introducing means 81 are arranged adjacent to the vacuum sample chamber 60. An operation control unit 100 that controls and manages the entire apparatus and a series of processing for sample processing observation evaluation is arranged on the left side of the vacuum sample chamber 60.

Next, the wafer introduction operation of this embodiment will be outlined. When the wafer cassette 23 is placed on the table of the cassette introduction means 81 and a work start command is issued from the operation control console 100, the wafer transfer robot 82 pulls out a wafer as a sample from a designated slot in the cassette, and FIG. The orientation adjusting means 83 shown adjusts the orientation of the wafer 21 to a predetermined position. Next, the wafer 21 is placed on the mounting table 63 when the hatch 62 above the wafer introducing means 61 is opened by the wafer transfer robot 82. When the hatch 62 is closed, a narrow space is formed around the wafer to form a load lock chamber, which is evacuated by a vacuum evacuation means (not shown), and then the mounting table 63 is lowered. Next, the wafer transfer means 61
Picks up the wafer 21 of the mounting table 63 and mounts it on the sample table 24 in the center of the vacuum sample chamber 60.
The sample stage 24 is provided with means for chucking the wafer 21 as necessary to correct warpage of the wafer 21 and to prevent vibration. The coordinate value of the observation analysis position p 1 on the wafer 21 is input from the operation control unit 100, the sample stage 24 is moved, and the observation analysis position p 1 of the wafer 21 is set just below the focused ion beam optical system 31 and stopped.

Next, the process of sample processing observation evaluation will be described with reference to FIG. In the micro sample processing and observation apparatus of the present invention, the focused ion beam optical system 31 includes an ion source 1, a lens 2 for focusing an ion beam emitted from the ion source 1, an ion beam scanning deflector 3, and the like, and an electron beam. The optical system 41 includes an electron gun 7, an electron lens 9 that focuses the electron beam 8 emitted from the electron gun 7,
It comprises an electron beam scanning deflector 10. In addition, a secondary particle detector 6 for detecting a secondary particle from the wafer 21 by irradiating the wafer 21 with a focused ion beam (FIB) 4 or an electron beam 8, a movable sample stage 24 on which the wafer 21 is placed, a desired In order to specify the position of the sample, the position of the sample stage control device 25 for controlling the position of the sample stage and the tip of the probe 72 are moved to the extraction position of the micro sample, extracted, and irradiated with the focused ion beam (FIB) 4 or the electron beam 8 Then, a manipulator control device 15 for controlling the optimum position and direction for observing and evaluating a specific position of the micro sample and an X-ray detector 16 for detecting atomic characteristic X-rays excited upon irradiation with the electron beam 8.
And a deposition gas supply device 17.

Next, in this embodiment, the process of sample processing observation evaluation after wafer introduction will be outlined. First, in a state where the sample stage is lowered and the tip of the probe 72 is separated from the wafer 21, the probe 72 is moved in the horizontal direction (XY direction) with respect to the sample stage 24, and the tip of the probe 72 is set as the FIB4 scanning region. To do. The manipulator control device 15 retracts the probe 72 after storing the position coordinates.

The FIB 4 is irradiated onto the wafer 21 from the focused ion beam optical system 31, and a groove is formed so as to draw a U-shape across the observation analysis position p2 as shown in FIG. The processing area is about 5 in length
It is μm, width is about 1 μm, depth is about 3 μm, and is connected to the wafer 21 on one side. Thereafter, the sample stage 24 is tilted and processed so as to form a slope of a triangular prism with the FIB 4. However, in this state, the micro sample 22 and the wafer 21 are connected by a support portion.

Next, after returning the inclination of the sample table 24, the probe 72 at the tip of the manipulator 70 is brought into contact with the end of the micro sample 22 on the micro sample 22, and then deposition gas is deposited at the contact point 75 by irradiation with the FIB 4. Then, the probe 72 is joined and integrated with the micro sample 22. Furthermore, support part S2
Is cut with the FIB 4 to cut out the micro sample 22. The micro sample 22 is supported by the probe 72, and the observation and analysis surface p3 of the micro sample 22 has a surface and an internal cross section for the purpose of observation and analysis.
Ready to take out as

Next, as shown in FIG. 5B, the manipulator 70 is operated to lift the micro sample 22 to a height that floats from the surface of the wafer 21. If necessary, the irradiation angle of the FIB 4 is appropriately added to the micro sample 22 while being supported by the probe 72 by rotating the manipulator to form a desired observation cross section p3. As an example of this additional machining, there is a finishing process for making the observation cross section p2 formed obliquely by the taper of the beam of the FIB 4 into a truly vertical cross section. In the cross-section processing / observation performed so far, the side wall of the hole dug by FIB had to be used as the observation surface, but according to the apparatus of this embodiment, it is possible to perform additional machining after lifting. Since the processing can be performed while appropriately moving the observation target surface, it is possible to appropriately form a desired cross section.

Next, the micro sample 22 is rotated, and the manipulator 70 is moved so that the electron beam 8 of the electron beam optical system 41 is substantially perpendicularly incident on the observation cross section p <b> 3 to control the posture of the micro sample 22, and is then stopped. Thereby, the detection efficiency of the secondary electrons in the secondary particle detector 6 is the same as that in the case of observing the outermost surface of the wafer even when the sample cross section is observed. The observation conditions for p3 are very good, the reduction in resolution, which was a problem in the conventional example, can be avoided, and the angle of the observation analysis planes p2 and p3 can be adjusted to a desired angle. become able to.

In addition, since the micro sample 22 is observed and analyzed while being left in the sample chamber in a vacuum atmosphere without being taken out of the apparatus, the internal cross section of the target sample can be high resolution without being contaminated by foreign air exposure or adhering foreign matter. High-precision observation and analysis at the optimum angle can be realized. Moreover, observation and analysis can be performed with a high processing capacity of 2 to 3 or more locations per hour.

Furthermore, since the micro sample 22 having the observation cross section p3 can be tilted and moved by the manipulator 70 in the apparatus of the present embodiment, for example, a hole is provided in the observation cross section p2 to provide a three-dimensional fault inside the sample. It is also possible to confirm the formation state.

In the example of FIG. 3, the manipulator 70 and the electron beam optical system 41 are formed facing each other with the FIB 4 interposed therebetween. In order to reduce the processing / observation time as much as possible by reducing the number of operations of the manipulator 70 and the like, The relative angle between the manipulator 70 and the electron beam optical system 41 is FIB4.
It is desirable to form an angle close to 90 ° in a plane perpendicular to the irradiation direction. Because of this formation, the manipulator 70 only lifts the micro sample 22 from the wafer 21, rotates the probe 72 so that the observation section p2 is perpendicular to the electron beam 8, and other fine tuning operations. It is because it is sufficient to perform.

In the above description, an example in which the micro sample 22 is lifted from the wafer 21 by the manipulator 70 is used. However, the present invention is not limited to this, and the micro sample 22 is lifted by lowering the wafer 21 as a result. Also good. In this case, the sample stage 24 is provided with a Z-axis moving mechanism for moving the wafer 21 in the Z direction (the optical axis direction of the FIB 4).
According to such a configuration, it is possible to cut out and lift the micro sample 22 in a state where the optical axis of the electron beam optical system 41 is positioned at the position of the micro sample 22 in the wafer 21. In this case, the process from cutting out the micro sample 22 with the FIB 4 to observing the observation cross section p2 can be executed while confirming with an electron microscope, and can be realized without much change of the irradiation position during that time. Become.

The electron beam optical system 41 provides an electron microscope image obtained by viewing the surface of the wafer 21 from an oblique direction. If the model cross-section and the processing arrival position by the FIB 4 are superimposed on the electron microscope image, the FIB 4 is used. The cross-section processing state can be easily confirmed. To superimpose and display the planned cross section on the electron microscope image, an animation showing the cross section is superimposed on the electron microscope based on the set processing depth and the dimensions in the electron microscope image calculated from the magnification. .

Also, if the processing depth in real time is calculated based on the FIB current, acceleration voltage, sample material, etc., and the animation showing the current processing depth is superimposed on the electron microscope image, the processing progress It becomes easy to confirm. Since the electron beam optical system 41 of the apparatus of this embodiment is arranged at a bird's-eye view with respect to the wafer 21 and the electron microscope image becomes a bird's-eye view image, the above-mentioned animation is displayed in a three-dimensional manner, so that the processing status can be changed. It can be confirmed more clearly.

Further, the apparatus according to the present embodiment has a function of setting a cross-sectional processing position on a scanning ion microscope image (SIM image) formed based on secondary electrons obtained by scanning the wafer 21 with FIB. However, it is also possible to provide a sequence that automatically performs other settings and apparatus operations (drive of the sample stage and determination of the processing position by the ion beam) based on the input of the cross-sectional position and the processing depth. In this case, first, a portion to be the upper side of the observation cross section p3 is specified on the SIM image, and a processing depth (dimension in the depth direction of the observation cross section p3) is set. Based on these two settings, the formation angle of the inclined portion of the micro sample 22 and the observation analysis plane p3 are automatically determined, and the subsequent processing is automatically performed by this setting. It is also possible to provide a sequence for automatically performing the subsequent processing by setting the observation analysis plane p3 (rectangular region) on the SIM image and setting the processing depth.

In the apparatus of this embodiment, the probe 72 is provided with a fine movement mechanism (not shown) so that the observation cross section p3 is properly positioned with respect to the electron beam 8 after the micro sample 22 is lifted. For example, in the example of FIG. 4, simply rotating the probe 72 causes the micro sample 22 to rotate around the point of attachment with the probe 72, so the observation cross section p3 is only rotated about the longitudinal direction of the micro sample 22 as the rotation axis. Instead, a rotation component with the FIB 4 irradiation direction as the rotation axis is included. The probe 72 is provided with a fine movement mechanism for removing the rotation component, and the fine movement mechanism is operated at a timing different from the rotation operation in accordance with the rotation of the probe 72, whereby the electron beam 8 optical axis. It is possible to accurately position the observation cross section p3 in the vertical plane with respect to. The same effect can also be obtained by arranging the probe 72 at an angle slightly larger than 90 ° with respect to the electron beam optical system 41 in a plane perpendicular to the optical axis of the FIB 4. In this case, the effect is achieved by arranging the probe 72 with respect to the electron beam optical system 41 at a rotation component + 90 ° with the irradiation direction of the focused ion beam as the rotation axis.

The rotation component having the FIB 4 irradiation direction as the rotation axis is included because the rotation axis of the probe 72 is inclined with respect to the observation analysis plane p2 and the observation cross section p3. That is, if the probe 72 is formed so that the rotation axis is parallel to the observation analysis plane p2 and the observation cross section p3,
The above problem can be solved. Therefore, in the case of a device having a mirror structure as shown in FIG.
The rotation axis of the probe 72 may be formed parallel to the surface of the wafer 21 (perpendicular to the optical axis of the FIB 4). By bending the tip of the probe 72, the micro sample 22 can be supported even with a probe having a rotation axis parallel to the surface of the wafer 21. Further, the rotation axis of the probe 72 may be formed so as to be perpendicular to the electron beam optical system 41 so that the sample can be moved below the optical axis of the electron beam 8 by the rotation and parallel movement of the probe.

Further, if a mechanism for transmitting the driving power from the manipulator control device 15 to a probe having a height different from that of the probe holding unit 71 and having a rotation axis parallel to the wafer 21 is provided, the micro sample 22 is enlarged. The observation cross section p3 can be aligned with the electron beam 8 without being swung.

In addition, since the micro sample 22 suspended in the probe 72 is easily affected by vibration,
When observing and analyzing in an installation environment with high magnification and a lot of vibration, the micro sample 22 is landed on a position where there is no problem on the wafer 21 or landed on a micro sample port provided in a vacant area around the wafer on the sample stage. By doing so, the vibration of the minute sample can be greatly suppressed,
Analysis becomes possible. The example shown in FIG. 18 is an example thereof, and shows an example in which the seismic resistance is improved by grounding the cut out micro sample 22 on the wafer 21. In the case of adopting such a method, it is preferable to set a sequence in advance so that the grounding position of the micro sample matches the optical axis of the electron beam 8.

In the preparation of the micro sample 22 shown in FIG. 4, the micro sample 22 was processed into a pentahedron. Thereby, in particular, there is little waste in processing for separating a micro sample, and a micro sample can be manufactured in a short time. However, although illustration is omitted, it goes without saying that the effect of the present invention can be obtained even with a tetrahedron that can minimize the machining time because of the smallest machining surface or a shape close to this.

Further, in the EDX analysis in which the electron beam 8 is scanned on the micro sample 22, if the micro sample 22 is formed thinner in the electron beam irradiation direction than the penetration distance of about 1 μm by the electron beam irradiation, the elemental analysis accuracy is improved.
(Example 2)
The configuration and operation of the micro sample processing and observation apparatus according to the second embodiment of the present invention will be described with reference to FIGS. Here, FIG. 7 shows a plan view of FIG.
For convenience of explanation, there are some differences in the orientation and details of the devices, but they are not essential. In this apparatus, a focused ion beam optical system 31 is vertically installed on the upper portion of the vacuum sample chamber 60 in the center of the apparatus system, and a second focused ion beam optical system 32 is further inclined at about 40 °. Yes. The electron beam optical system 41 is installed with an inclination of about 45 °. Three optical systems 31,
32 and 41 are adjusted so that the respective central axes intersect at one point near the surface of the wafer 21. Similarly to the apparatus of the first embodiment, a sample stage 24 on which a wafer 21 to be a sample is placed is installed in the vacuum sample chamber 60. However, although the sample stage 24 of this embodiment has functions of horizontal movement (XY), rotation, and vertical movement, the tilt function is not necessarily required.

Next, the sample preparation operation by this apparatus will be described with reference to FIG. First, the FIB 4 is irradiated onto the wafer 21 from the focused ion beam optical system 31, and the observation analysis position p2 as shown in FIG.
A groove is formed so as to draw a U-shape across. The process up to this point is the same as in the first embodiment.
Next, the slope of the triangular prism is formed by the FIB4 from the other focused ion beam optical system 32.
To process. However, in this state, the micro sample 22 and the wafer 21 are connected by a support portion. Thereafter, a micro sample is again cut out from the focused ion beam optical system 31 using the FIB 4 as in the first embodiment. That is, after the probe 72 at the tip of the probe holding portion 71 of the manipulator 70 is brought into contact with the end of the micro sample 22 on the micro sample 22, the deposition gas is deposited on the contact point 75 by irradiation of the FIB 4, and the probe 72 is made micro. The sample 22 is joined and integrated, and the support portion is cut with the FIB 4 to cut out the micro sample 22. Thereafter, the steps such as observation and analysis of the micro sample 22 are the same as those in the first embodiment.

As described above, this embodiment can perform high-resolution and high-speed observation analysis as in the first example. In the present embodiment, in particular, by using two focused ion beam optical systems, it is possible to eliminate the inclination of the sample stage. Since the tilt mechanism of the sample stage can be omitted, the positioning accuracy of the sample stage can be improved several times to 10 times or more. At the LSI device manufacturing site, in recent years, various types of wafer inspection / evaluation devices have been subjected to foreign matter inspection and defect inspection, and the characteristics and coordinate data of abnormal points on the wafer have been recorded. It has become customary to determine the designated coordinate position and perform observation analysis. Since the positioning accuracy is high, it is possible to automate the position indexing process of the observation location of the sample wafer 21 and simplify the algorithm. As a result, the required time can be greatly shortened, so that high throughput can be obtained. Furthermore, since the sample stage having no tilting mechanism is small and lightweight, high rigidity is easily obtained and the reliability is increased, higher quality observation analysis can be performed, and the apparatus can be reduced in size and cost.

In addition, by making the focused ion beam optical system 31 wait for the swing function so that the two positions of the vertical position and the tilt position are appropriately moved, the same processing as in the second embodiment can be performed without tilting the sample stage 24. Thus, the effects of the present invention can be obtained.
(Example 3)
The configuration and operation of a micro sample processing and observation apparatus according to a third embodiment of the present invention will be described with reference to FIGS. Here, FIG. 9 shows a plan view of FIG.
For convenience of explanation, there are some differences in the orientation and details of the devices, but they are not essential. In the apparatus of this embodiment, the focused ion beam optical system 33 is installed at an inclination of about 45 ° above the vacuum sample chamber 60 at the center of the apparatus system. The electron beam optical system 42 is also installed with an inclination of about 45 °. The two optical systems 33 and 42 are adjusted so that the respective central axes intersect at one point near the surface of the wafer 21. Further, as in the apparatus of the first embodiment, the vacuum sample chamber 60
A sample stage 24 is installed in the interior. As in the second embodiment, the sample stage 24 does not have a tilt function.

Next, in this embodiment, the process of sample processing observation evaluation after wafer introduction will be described with reference to FIG. First, in a state where the sample stage is lowered and the tip of the probe 72 is separated from the wafer 21, the probe 72 is moved in the horizontal direction (XY direction) with respect to the sample stage 24, and the tip of the probe 72 is set as the FIB4 scanning region. To do. After the manipulator control device 15 stores the position coordinates,
The probe 72 is retracted.

The direction of the sample stage is adjusted so that the line of intersection between the vertical plane including the optical axis of the focused ion beam optical system 33 and the upper surface of the wafer overlaps the observation cross section of the sample to be formed. Next, FIB4 is attached to wafer 21.
Is irradiated and scanned to form a vertical cross section C1 having a length and depth necessary for observation. Next, an oblique cut surface C2 intersecting with the formed cross section is formed. When the cut surface C2 is formed, the direction is determined by horizontally rotating the sample stage to a position where the slope angle can be obtained. Next, an oblique groove is formed by FIB 4 in parallel with the vertical cutting line. Further, one end C3 is cut at right angles to the groove. The processing area is
It has a length of about 5 μm, a width of about 1 μm, a depth of about 3 μm, and is connected to the wafer 21 in a cantilever state with a length of about 5 μm. Next, the probe 72 at the tip of the manipulator 70 is applied to the micro sample 22.
Is brought into contact with the end portion of the micro sample 22, and then the deposition gas is irradiated with the contact point 75 by the irradiation of the FIB 4.
The probe 72 is bonded to the micro sample 22 and integrated. Thereafter, the other end C4 that supports the micro sample with the FIB 4 is cut with the FIB 4, and the micro sample 22 is cut out. The micro sample 22 is supported by the probe 72, and the preparation for taking out the surface and the internal cross section for the purpose of observation and analysis as the observation analysis surface p3 of the micro sample 22 is completed. The subsequent processing is performed except that the orientation of the sample stage 24 needs to be appropriately adjusted when setting the orientation of the micro sample in the direction optimal for processing / observation by the focused ion beam optical system or observation by the electron beam optical system. The description is omitted since it is almost the same as the first embodiment.

As described above, this embodiment can perform high-resolution and high-speed observation analysis as in the first example. This embodiment has an advantage that a single sample ion beam optical system is tilted with respect to the sample stage, so that a minute sample can be cut out and extracted from the wafer without giving the tilt function to the sample stage. Since it is necessary to mount many devices around the optical system, space is difficult, and the total mass of these devices is large, which makes it difficult to design including securing the rigidity of the mounting board. Maintenance is also a concern. In this embodiment, the tilting mechanism of the sample stage is not required, and only one focused ion beam optical system is required. Therefore, the structure is simple, lightweight, and the cost can be reduced.
Example 4
A schematic configuration of a micro sample processing and observation apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, a second sample stage 18 and a second sample stage controller 19 for controlling the angle and height of the second sample stage are added to the basic configuration of the micro sample processing and observation apparatus shown in FIG. Is. The process from the focused ion beam optical system 31 in this embodiment to irradiating the sample with the ion beam and extracting the minute sample from the wafer is the same as in the first embodiment. In this embodiment, instead of observing and analyzing the extracted micro sample in a state supported by a manipulator, the micro sample is fixed to the second sample stage for observation and analysis.

FIG. 11 shows a state in which the micro sample 22 is fixed to the second sample stage 18. Although a member having a flat surface is used for the minute sample fixing portion of the second sample stage 18 of the present embodiment, it does not matter whether the surface is flat. The bottom surface of the micro sample is brought into contact with the second sample stage 18, the deposition gas is deposited at the contact point between the second sample stage 18 and the micro sample 22 by the FIB 4, and the assist deposit film 76 is applied to the second sample stage 18. The micro sample 22 is fixed. It should be noted that the FIB 4 irradiation angle is set to prevent inconvenience of foreign matter adsorbing to the surface of the observation cross section or destruction of the surface of the observation cross section when the micro sample 22 is created or when the deposition gas is deposited. It is also possible to create a desired observation cross section by irradiating the FIB 4 after appropriately setting the angle by operating the second sample stage so as to be parallel to the observation cross section of the micro sample.

By installing the second sample stage shown in FIG. 12, a plurality of minute samples can be handled together. By extracting the micro sample 22 from the wafer 21, fixing it to an appropriate position on the second sample table 18 beside the sample table, and repeating the operation of extracting the next micro sample 22, the wafer 21 is removed from the sample table 24.
A plurality of cross-sections can be observed and elemental analysis can be performed while being fixed to the wafer, and the distribution of the cross-sectional structure over the entire wafer 21 can be efficiently examined.

In FIG. 12, several micro samples are fixed side by side on the second sample stage 18, and the stop orientation of the sample stage 24 and the angle of the second sample stage 18 so that the micro sample 22 is at an appropriate angle with respect to the electron beam 8. If the sample observation / analysis is performed in a state in which both are adjusted, it is possible to repeatedly observe and analyze a plurality of micro samples continuously or while comparing them, so that the cross-sectional structure and element distribution over the entire wafer 21 are examined in detail and efficiently. be able to. Further, the second sample stage 18 shown in FIG. 13 can arrange a group of micro samples on the outer peripheral surface of a rotatable columnar sample stage, and can handle a larger number of micro samples at a time than in the case of FIG. it can.

Further, the micro sample 22 is attached to and removed from the designated position in the sample collection tray and is collected, and a micro sample identification means is attached, so that it is taken out again for observation and analysis when a subsequent detailed evaluation is required. It is also possible.

As described above, the secondary electron detection efficiency similar to that in the case of observing the wafer surface can be obtained in this embodiment, the angle of observation analysis can be adjusted to a desired angle including vertical observation, vacuum The observation condition of the micro sample 22 becomes very good because it can be observed while it is placed in the sample chamber in the atmosphere, etc., so that it is possible to avoid the decrease in resolution, which has been a problem in the past, and to perform an optimal and detailed observation analysis quickly. It can be performed with high efficiency. As a result, high quality observation analysis can be performed with high throughput.

1 is an overall apparatus configuration of an embodiment of the present invention. 1 is a plan view of the overall configuration of an apparatus according to an embodiment of the present invention. The apparatus detailed structure of one Example of this invention. The example of the micro sample processing method of this invention. The example of the micro sample observation method of this invention. The whole apparatus structure of the 2nd Example of this invention. The top view with the whole apparatus structure of the 2nd Example of this invention. The whole apparatus structure of the 3rd Example of this invention. The top view with the whole apparatus structure of the 3rd Example of this invention. The apparatus detailed structure of 4th Example of this invention. The principal part detail drawing of 4th Example of this invention. The principal part detail drawing of 4th Example of this invention. The principal part detail drawing of 4th Example of this invention. Conventional processing method. Conventional observation method. The schematic block diagram of the conventional apparatus. Conventional micro sample preparation method. The example of the micro sample observation method of this invention. The example of the micro sample observation method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ion source, 2 ... Lens, 3 ... Ion beam scanning deflector, 4 ... Focused ion beam (FIB), 5 ... Central control display apparatus, 6 ... Secondary electron detector, 7 ... Electron gun, 8 ... Electron beam , 9 ... Electron lens, 10 ... Electron beam scanning deflector, 14 ... Manipulator, 15 ... Manipulator control device, 16 ... X-ray detector, 17 ... Deposition gas supply device, 18 ... Second sample stage,
19 ... second sample stage control device, 21 ... wafer, 22 ... micro sample, 23 ... cassette, 24 ...
Sample stage 25 ... Sample stage controller, 31 ... Focused ion beam optical system, 32 ... Focused ion beam optical system, 41 ... Electron beam optical system, 51 ... Analyzer, 60 ... Vacuum sample chamber, 61 ... Wafer transfer means, 62 ... hatch, 63 ... mounting table, 70 ... manipulator, 71 ... probe holder, 72 ... probe, 75 ... assist deposit film, 81 ... cassette introduction means, 82 ... wafer transfer robot, 83 ... orientation adjustment means, 90 ... gas Introducing pipe, 100 ... operation control unit, 101 ... sample, 105 ... sedimentary gas, 107 ... square hole, 108 ... bottom hole, 109 ... crevice groove, 110 ... gas nozzle, p1 ... observation location, p2 ... observation analysis plane, p3: Observation analysis plane,
s1 ... internal cross section, s2 ... support part.

Claims (15)

A method for observing and processing a micro sample in a sample chamber,
A sample placed on a sample stage placed in the sample chamber is irradiated with an ion beam to extract a micro sample,
Fixing the minute sample to an irradiation angle changing means for changing an irradiation angle of the ion beam and electron beam to the minute sample;
Irradiating an ion beam to the minute sample fixed to the irradiation angle changing means, forming an observation cross section,
Change the irradiation angle of the electron beam to the minute sample by the irradiation angle changing means so that the observation cross section becomes an angle substantially perpendicular to the electron beam,
A method of irradiating the minute sample fixed to the irradiation angle changing means with an electron beam and measuring the observation cross section. In the micro sample processing observation method according to claim 1,
The method for observing and processing a micro sample, wherein the irradiation angle changing means includes a manipulator capable of supporting the micro sample. In the micro sample processing observation method according to claim 1,
The method for processing and observing a micro sample, wherein the irradiation angle changing means includes a second sample stage on which the micro sample can be placed. A method for observing and processing a micro sample in a sample chamber,
A sample placed on a sample stage placed in the sample chamber is irradiated with an ion beam to extract a micro sample,
The micro sample is fixed to a second sample stage which is arranged in the sample chamber and changes the irradiation angle of the ion beam and the electron beam to the micro sample,
Irradiating the micro sample fixed to the second sample stage with an ion beam to form an observation cross section;
The irradiation angle of the electron beam to the minute sample is changed by the second sample stage so that the observation cross section becomes an angle substantially perpendicular to the electron beam,
A method of measuring the observation cross section by irradiating the minute sample fixed to the second sample stage with an electron beam. In the micro sample processing observation method according to claim 4,
A micro sample processing observation method, wherein the sample is an electronic device. In the micro sample processing observation method according to claim 4,
A micro sample processing observation method, wherein the sample is a micro device. In the micro sample processing observation method according to claim 1-6,
A method for processing and observing a micro sample, wherein the micro sample is supported by a manipulator. In the micro sample processing observation method according to claim 1-6,
A method for processing and observing a micro sample, wherein the micro sample is supported by a probe. In the micro sample processing observation method according to claim 3-8,
A method for processing and observing a micro sample, wherein the angle of the second sample stage is controlled by a second sample stage controller. In the claims 1-9 micro sample processing and observation method according,
The method for observing and processing a micro sample, wherein the second sample stage can fix a plurality of the micro samples. In the claims 3-10 micro sample processing and observation method according,
The method for observing and processing a micro sample, wherein the second sample stage is a rotatable columnar shape. In the claims 1-11 micro sample processing and observation method according,
The method for processing and observing a minute sample, wherein the shape of the minute sample is a pentahedron. In the claims 1-11 micro sample processing and observation method according,
The method for processing and observing a minute sample, wherein the shape of the minute sample is a tetrahedron. In the micro sample processing observation method according to claim 1-3,
A method for processing and observing a micro sample, comprising: irradiating the micro sample fixed to the irradiation angle changing unit with an ion beam after changing the irradiation angle of the ion beam to the micro sample by the irradiation angle changing unit. . In the micro sample processing observation method according to claim 4-14,
A method for processing and observing a micro sample, comprising: irradiating the micro sample fixed to the second sample stage with an ion beam after changing an irradiation angle of the ion beam to the micro sample with the second sample stage. .

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