JP4367433B2 - Sample preparation method and apparatus - Google Patents

Description

  The present invention relates to a sample preparation method and apparatus for detecting and analyzing defects near the surface of a wafer.

  In the manufacture of semiconductor devices, it is required to continue to produce good products without any hesitation. Since the number of products produced is large, the occurrence of defects in a certain process directly leads to a decrease in product yield, greatly affecting profitability. However, it is rare that the product can be produced without any defective products, and some defective products are always generated. For this reason, it becomes a big subject how to detect a defect, a foreign material, and a processing defect at an early stage, and to reduce them.

  For this reason, at the manufacturing site of semiconductor devices, careful inspection is performed after a specific process or after the device is completed, and efforts are made to investigate the cause of defects and eliminate defective products. In practice, wafers and devices are extracted regularly or at a fixed number in the manufacturing process and inspected for the presence of defective parts. For example, the inspection location and inspection items in each process are determined in advance, and each wafer is constantly monitored to detect abnormalities in the manufacturing process by monitoring the inspection location, circuit pattern defects and foreign matter etc. after completion. A method for inspecting the wafer over a wide range, checking the operation, discarding the device if there is an abnormality, or pursuing the cause of the abnormality is taken.

  However, it is becoming clear that the occurrence of defects in such semiconductor devices is greatly influenced by the presence of surface defects in the wafer itself before various processes. Evaluation of the wafer surface before performing the process Has become very important.

  Defects that occur near the wafer surface include COP (Crystal Originated Particles) defects and Grown-in defects. In particular, Grown-in defects are concentrated from 0.1 to 0.3 μm in depth from the surface. Has occurred. When a device is formed on a wafer having such a defect, defective products due to dielectric breakdown of the gate oxide film and excessive junction leakage current frequently occur. For this reason, it is a sensible measure to prevent defective products from occurring frequently by measuring the number and distribution of defects over the entire surface of a wafer used for manufacturing a semiconductor device in advance and excluding wafers with abnormally many defects in advance.

  However, the existing defect density is about 1 piece / cm 2 when converted to the surface density from the surface, which is the device formation region, to a depth of about 0.5 μm, and it takes an enormous amount of time to detect defects using measuring means such as an electron microscope. Cost. In other words, it becomes a big problem to detect defects near the surface over a wide area in a short time.

  Recently, an optical shallow defect analysis device (hereinafter referred to as OSDA), which has attracted attention, is a device that overcomes the above-mentioned problems, and measures defect distribution over a wide range of wafers in a non-destructive manner in a short time. This is an effective device for wafer evaluation.

  FIG. 2 is a diagram for explaining the operating principle of the OSDA device 30. Laser light 32A and 32B (for example, wavelengths of 523 nm and 810 nm) emitted from the two types of laser light sources 31A and 31B are obliquely incident on the wafer 5 by the reflecting mirror 33 and the lens 36, and the wafer 5 is placed on the stage 7 in translation. While rotating, the laser beams 32A and 32B are scanned in a spiral manner on the wafer surface, and pulsed scattered light 35 generated from the defect 34 along with the scanning is condensed by a lens 36, and photoelectron image multiplication is performed for each wavelength. The detected coordinate information and two-wavelength signal intensities detected by the tubes 37B and 37E are recorded in the calculation processing unit 38. Further, the surface shape of the wafer 5 can be recorded by the camera 37A, and an image intensifier 37C is provided in front of the photomultiplier tube 37E via a light guide 37D for improving sensitivity. Further, a beam collimating lens 36 and a reflecting mirror 33 are installed in the middle of the optical path.

  The in-plane distribution of defects, the depth position distribution of defects, and the particle size distribution of defects can be obtained from the data stored in the calculation processing unit 38. The measurable range is about 1 μm deep from the surface, the depth resolution is about 0.1 μm, and the plane resolution is about 10 nm. Therefore, in order to analyze defects near the surface of the wafer, it is advantageous to measure the surface of the wafer in a wide range and in a short time with an OSDA apparatus and analyze in detail the desired defect of interest using an electron microscope.

  Note that more detailed explanations and measurement examples of the OSDA apparatus are described in, for example, “Applied Physics” (1997) Vol. 55, March, pages 109 to 110 (Prior Art 1).

The OSDA apparatus described above can detect the number and distribution of near-surface defects over a wide range of the wafer in a short time, but cannot clearly identify the types of defects.
Moreover, even if it was going to analyze in detail about the desired defect to pay attention using an electron microscope, it was difficult to analyze a desired defect exactly for the following problems.

(1) Problem of defect type identification Although the OSDA apparatus can obtain information such as the number and distribution of defects near the surface over a wide range of the wafer in a short time, it cannot identify the type and shape of the defect. Therefore, there is a problem in that it is impossible to pursue the cause of occurrence of a specific defect type among a plurality of types of defects and to take measures to reduce them.

(2) Problems in the preparation of a transmission electron microscope (TEM) sample Since the spatial resolution of the measurement by the OSDA device is about 10 μm, even if it is attempted to analyze the defect detected by the OSDA device with a high-resolution TEM, the sub-μm The position of the defect in the vicinity of the surface of interest of the size cannot be well identified. In particular, since the wafer surface evaluated by OSDA is a smooth surface without any marks or patterns, there is no clue to make a TEM sample even if the approximate position of the defect is revealed by OSDA.

  In addition, the conventional planar TEM observation method for observing a thin piece parallel to the wafer surface with a TEM has a large observable area, so the probability that a desired defect portion can be captured in the observation field is high, but only from the planar direction. Therefore, defects near the surface cannot be observed at different angles. For example, if the shape can be observed from the cross-sectional direction, the defect type can be accurately and accurately determined, but there is no method for producing a cross-sectional sample.

  In other words, in the prior art, it is an effective method for analyzing a near-surface defect to prepare a planar TEM sample including a specific near-surface defect and observe the TEM or STEM, but the defect position is accurately captured. There was no method for producing a planar TEM sample, and no method for producing a sample capable of observing a cross section of a defect obtained by planar TEM observation.

  Including such problems, a sample preparation method and a sample preparation apparatus capable of identifying a defect type for a desired defect at a specific position using defect position information obtained in a short time by the OSDA method have been desired. .

  In view of the above-mentioned problems, a first object of the present invention is to provide a sample preparation method capable of easily observing or analyzing a defect of interest among defects near the surface detected by defect inspection near the surface of the wafer. . A second object is to provide a sample preparation apparatus that realizes the first object.

  In order to realize the defect analysis method as the first object, the present invention provides a method or apparatus having the following configuration.

(1) A sample preparation method including a defect detection step for detecting defects near the surface of a wafer, and a marking step for applying a mark for identification near a desired surface vicinity defect among the surface vicinity defects detected by the defect detection step .

(2) a defect detection step of detecting defects near the surface of the wafer and storing coordinate information of the defects near the surface; a marking step of applying a mark for identifying a desired surface vicinity defect based on the coordinate information; By using a sample preparation method including a processing step for processing a test piece suitable for performing any of observation, measurement, or analysis on the desired near-surface defect based on the mark, a wafer is obtained. A sample is prepared that can accurately capture the defects of interest among the defects near the surface and observe the shape.

(3) In the defect detection step in (1) or (2), the laser beam is scanned over a wide area of the wafer surface and relative to the wafer, and scattered light generated from the vicinity of the wafer surface is detected. It is a step of detecting the presence position of the surface vicinity defect by receiving light.

(4) In the step (3), a plurality of laser beams having different wavelengths are scanned relative to the wafer, and the presence positions of the defects near the surface by scattered light generated from the vicinity of the surface of the wafer. By adopting the step of detecting, defects near the wafer surface can be detected more reliably.

(5) The marking process in (1) or (2) is performed using at least one of a laser beam, an ion beam, an electron beam, and a mechanical probe.

(6) In particular, in the above (5), a process for forming a recess or a damaged region in a part of the surface of the wafer by either drawing or processing by irradiation of a focused ion beam or a projected ion beam among the ion beams, or (7) Processing to form a deposit containing components constituting the atmosphere around the sample on the sample surface by electron beam irradiation, or (8) Mechanical recess or damaged region by sharpened metal probe or diamond By using a process including a process for forming a mark, a mark for identifying a desired near-surface defect can be reliably applied.

(9) The test piece in the above (2) is processed as a test piece for observation or measurement with a transmission electron microscope or a scanning transmission electron microscope, so that the detected near-surface defects can be reliably identified. (10) In particular in (9) above, the surface to be observed or measured in the test piece is perpendicular to the surface of the wafer, or (11) the surface to be observed or measured is relative to the surface of the wafer. By making them parallel to each other, it is possible to observe the near-surface defects of interest in a multifaceted manner. Further, (12) When the test piece in (10) is manufactured by cutting the wafer with a dicing apparatus and processing with a focused ion beam, a desired test piece is obtained.

(13) The processing step in (2) includes an extraction step of extracting a micro sample including the desired near-surface defect from the wafer by a focused ion beam with reference to the mark, and an analysis sample holder for the micro sample. Attention is made without cleaving the wafer by being a process including a fixing process for transferring and fixing to a microscopic sample, and a finishing process for further processing the focused sample with the focused ion beam to make the shape easy to analyze. It is possible to produce a sample piece that includes defects near the surface.

(14) The processing step in (2) includes at least one of a step of cutting or cleaving the wafer based on the mark to make a small piece including the mark, and polishing or ion thinning the small piece from the wafer back surface. If any of the steps includes a thinning step for producing a thin piece sample having a thin piece portion substantially parallel to the wafer surface by applying any of the above, a planar sample piece including a surface near-surface defect to be noticed can be produced.

(15) In the above (14), after the thinning step, the step of obtaining a relative positional relationship between the mark and the desired surface vicinity defect by further observing the thin piece portion with a transmission electron microscope or a scanning transmission electron microscope And a step of extracting a part including the surface vicinity defect in the thin piece portion based on the positional relationship and fixing it to the sample holder for analysis, and including the surface vicinity defect on the wafer surface. By including a cross-section processing step of processing into a vertical thin piece, a cross-section sample piece that surely includes a defect near the surface of interest can be produced.

(16) In the processing step (2), the wafer is cut or cleaved with the mark as a reference to form a small piece including the mark, and at least one of polishing or ion thinning of the small piece from the wafer back surface is performed. And a relative positional relationship between the mark and the desired surface vicinity defect by observing the thin piece portion with a transmission electron microscope or a scanning transmission electron microscope. And a step involving a second marking step of applying a second mark for identifying in detail the position of a desired near-surface defect by a focused ion beam or an electron beam to the thin sample. It is possible to more accurately produce a sample piece including a near-surface defect.

(17) If the second marking step of (16) is a step using at least one of a pulse laser, a focused ion beam, a projection ion beam, and an electron beam, marking can be reliably applied to a minute portion. it can.

(18) When the second mark in the above (16) or (17) is one of a set of dots, line segments, or symbols arranged in a straight line or a lattice point, a defect originally present in the sample is identified. It is suitable for making it easy to do.

(19) In any of the above (16) to (18), the thin piece sample provided with the second mark is observed with a transmission electron microscope or a scanning transmission electron microscope. By clarifying the relative positional relationship with the second mark and including a position determining step for specifying the position where the surface vicinity defect exists, it is possible to attach a mark that can accurately distinguish a desired location.

(20) In the above (19), a cross-section for observing the near-surface defect including the desired near-surface defect from the cross-sectional direction with a transmission electron microscope or a scanning transmission electron microscope after the position determining step By a sample preparation method having a cross-section thinning step for processing into a thin piece sample, a sample piece that surely includes a target near-surface defect can be produced.

(21) Further, the analysis method of the surface vicinity defect in the semiconductor wafer includes (a) a defect detection step of detecting the surface vicinity defect of the wafer by laser beam irradiation, and (b) a memory for storing the coordinate information of the surface vicinity defect. And (c) a marking step for marking the vicinity of the surface vicinity defect of interest among the surface vicinity defects by focused ion beam (FIB) irradiation, and (d) the wafer including the defect of interest and the mark. Cleaving or cutting into small pieces, (e) thinning the small piece from the back and processing it into a thin piece sample, and (f) transmitting near-surface defects of interest on the basis of the mark. Sample preparation for identifying near-surface defects in semiconductor wafers by a method that follows the procedure of the observation process using an electron microscope or a scanning transmission electron microscope. There can be realized.

(22) In the above (21), further, (a) a second marking step of applying a more detailed second mark by a focused ion beam based on the observation result by the transmission electron microscope or the scanning transmission electron microscope And (b) an observation step of observing the sample having the second mark with a transmission electron microscope or a scanning transmission electron microscope, and c) the above-mentioned observation based on the observation with the transmission electron microscope or the scanning transmission electron microscope. A step of determining an observation region including a defect of interest; (d) a step of extracting a micro sample including the determined observation region; and (e) a cross-sectional slice including the desired near-surface defect by FIB. By a method of adding a procedure of a cross-section thinning step to process a sample and (f) a step of observing the cross-sectional thin sample with a transmission electron microscope or a scanning transmission electron microscope Sample Preparation for identifying near surface defects in the semiconductor wafer can be realized.

(23) In the above (22) or (23), among the defects obtained by the defect detection step, a desired defect is observed by a transmission electron microscope or a scanning transmission electron microscope from a direction perpendicular to the surface of the wafer and a cross-sectional direction. The near-surface defects to be observed can be observed in a multifaceted manner by the method for observing and analyzing the near-surface defects.

  Further, according to the present invention, in order to manufacture a semiconductor device with a high yield using a good wafer with few defects near the surface, the following wafer management method for selecting a good semiconductor wafer in advance is possible. .

(24) At least one of the position, number, distribution, and type of near-surface defects obtained by detecting the near-surface defects of the semiconductor wafer, the shape observation result by electron microscope observation of the near-surface defects, and the wafer A database of correlations with at least one of the occurrence position, number of occurrences, and type of failure of the formed semiconductor device is created, and the detection of defects near the surface of the semiconductor wafer is periodically performed during the manufacture of the semiconductor device. A semiconductor device manufacturing method for performing screening of the semiconductor wafer based on the detection result obtained by the inspection and the database.

  A sample preparation apparatus for realizing the above-described sample preparation method or the method for analyzing surface near-surface defects, and further the wafer management method or semiconductor device manufacturing method has the following configuration.

(25) A sample preparation device having at least a defect detection unit that detects defects near the surface of the wafer and a marking unit that marks a vicinity of a desired defect among the defects near the surface.

(26) At least attention is paid to a defect detection unit that detects defects near the surface of the wafer, a marking unit that marks a vicinity of a desired surface vicinity defect among the surface vicinity defects, and a defect detected by the defect detection unit. A sample preparation device including at least a sample processing unit that extracts a minute sample including a defect and processes the sample into a shape suitable for mounting on at least one of an analysis device, an observation device, and a measurement device.

(27) A defect detection unit for detecting defects near the surface of the wafer and a mark near the desired defect among the defects near the surface, and the vicinity of the desired surface among the defects near the surface based on the mark A sample preparation apparatus having a sample processing unit that extracts a micro sample including a defect and processes the sample into a sample piece having a shape suitable for at least one of an analysis apparatus, an observation apparatus, and a measurement apparatus.

(28) The sample processing section of (26) or (27) has a structure having sample moving means for moving the extracted micro sample to another member, so that a sample dedicated to an analysis apparatus such as a transmission electron microscope is used. The holder can be securely mounted in a vacuum atmosphere.

(29) In any one of (25) to (28), the defect detection unit and the marking unit, or the defect detection unit and the marking unit and the sample processing unit, or the defect detection unit and the sample processing unit. (30) In any one of (25) to (28) above, the defect detection unit and the marking unit, or the defect detection unit and the above By providing a transfer path for moving the wafer between the marking unit and the sample processing unit, or at least one of the defect detection unit and the sample processing unit, efficient inspection from defect inspection to marking or sample preparation it can.

(31) In any one of the above (25) to (30), by providing a calculation processing unit that stores at least the coordinate information of the defect detected by the defect detection unit, the marking unit is positioned accurately and quickly. be able to.

(32) The defect detection unit according to any one of (25) to (31) includes a laser beam irradiation unit that generates a laser to irradiate the wafer, and a light detection unit that detects scattered light from the wafer. Or (33) a plurality of laser generating means for generating lasers with different wavelengths and irradiating the wafer, and a plurality of lights for detecting scattered light from the wafer for each wavelength. If the sample preparation device has at least the detection means, the presence position of the surface vicinity defect can be accurately detected.

(34) The marking unit of any one of (25) to (32) includes at least one of a laser beam irradiation optical system, an ion beam irradiation optical system, an electron beam irradiation optical system, and a mechanical probe. Thus, a mark that can be clearly distinguished from a defect can be attached.

(35) By making the ion beam irradiation optical system of (34) either a focused ion beam irradiation unit or a projection ion beam irradiation unit, a mark that can be clearly distinguished from a defect can be attached.

(36) A near-surface defect detection device that stores defect coordinate information detected by detecting a near-surface defect on the wafer, and a micro sample piece including a desired defect is extracted from the wafer to be analyzed, observed, or measured Sample preparation device for processing into a sample piece having a shape suitable for at least one of the devices, TEM or STEM for analyzing defect shape and structure, wafer name, defect coordinates, defect distribution, sample piece name, defect image An apparatus for efficiently analyzing near-surface defects can be configured by connecting a computer storing at least one of these data to each other via a network to form a near-surface defect analysis system.

(37) A laser beam irradiation unit that generates a laser beam of at least one wavelength and irradiates the wafer, a light detection unit that detects scattered light from the wafer, and a calculation that stores coordinate information in which the scattered light is generated In a near-surface defect detection apparatus having at least a processing means, near-surface defect detection having a focused ion beam irradiation means equipped with a liquid metal ion source or a field ionization gas ion source for irradiating a part of the wafer with a focused ion beam According to the apparatus, it is possible to accurately and accurately mark the vicinity of the defect with the near-surface defect detection apparatus.

(38) A laser beam irradiating unit for generating a laser beam of at least one wavelength and irradiating the wafer, a light detecting unit for detecting scattered light from the wafer, and a calculation for storing coordinate information on which the scattered light is generated This can be realized by a near-surface defect detection apparatus having a processing means and a laser light irradiation means for a laser mark for applying a laser mark in the vicinity of the light emitting portion based on the coordinate information of the desired scattered light generating portion.

(39) In an ion beam apparatus for irradiating a part of a wafer with an ion beam, a laser beam irradiation unit for generating a laser beam of at least one wavelength and irradiating the wafer, and light for detecting scattered light from the wafer Marking in the vicinity of defects near the wafer surface detected by a focused ion beam apparatus having a detection unit and a near-surface defect detection unit having at least a calculation processing unit for storing coordinate information in which scattered light is generated Can do.

  According to the present invention, it is possible to easily mark near-surface defects detected over a wide range of a wafer, and it is possible to easily extract and thin a portion including the near-surface defects. For this reason, it is possible to analyze the noted surface vicinity defect in detail in a short time.

  The sample preparation method according to the present invention includes a defect detection step for detecting defects near the surface of the wafer, and a marking step for applying an identification mark near a desired surface vicinity defect among the surface vicinity defects detected by the defect detection step; A method including In addition, an apparatus for realizing the sample preparation method includes at least a defect detection unit that detects defects near the surface of the wafer, and a marking unit that marks the vicinity of a desired surface vicinity defect among the surface vicinity defects. To do.

<Example 1>
In this embodiment, a sample preparation method of a so-called planar TEM sample, which is a sample for TEM observation of a desired defect from the wafer surface, among the wafer defects detected by the near-surface defect detector, will be described.

  In order to produce a planar TEM sample, it is important to first mark a defect. Since the wafer surface before processing is a smooth surface without a pattern such as a wiring that serves as a mark, it is very difficult to attach an accurate mark that can identify the defect of interest. Therefore, in this method, a sample preparation method including the following marking process is used.

  First, a defect near the surface of the wafer is detected by the defect detection unit, and at least coordinate information, a distribution pattern, and the like of the obtained near-surface defect are stored in the calculation processing unit. The coordinates of the defect at this time are based on a reference position provided in advance on the wafer. Thereafter, the measured wafer is moved to the marking portion, and marking is performed based on the coordinate information of the previous defect.

The wafer to be subjected to near surface defect detection is smooth without any pattern before processing of semiconductor manufacturing. In the secondary electron image (Scanning Electron Microscopy: SEM image) obtained by electron beam scanning or the secondary electron image (Scanning Ion Microscopy: hereinafter abbreviated as SIM image) obtained by FIB scanning, the surface shape of the sample is observed. Yes, but I can't see inside the sample. In addition, it is difficult to specify the position of a defect to be noted with respect to a sample that does not have a unique pattern as a mark on the wafer surface.
In other words, even if an attempt is made to mark the vicinity of a defect near the surface, an accurate position cannot be determined from the SEM image or SIM image. In addition, the size of the defect is as small as about 0.1 μm, and marking by manual mechanical pointing has no positioning accuracy. On the other hand, since the observation by the FIB scanning can be observed at a high magnification and can be processed on the spot, if the defect coordinates are clear, the FIB can be used as a marking means.

  The marking unit has a sample stage on which the wafer is placed, and the sample stage can be moved so that the designated coordinates can be output within the field of view with the reference position of the wafer as the origin. The same reference position on the wafer is used as the origin at the time of defect detection and at the time of marking, but even if the method of setting the coordinates at the time of defect detection and the method of setting the coordinates of the marking part are different, By determining a coordinate conversion method for the coordinate system and incorporating it into a computer, mutual coordinate information can be shared.

  FIG. 3 shows an example in which the surface of the wafer 5 is marked by FIB. FIG. 3 (a) is an example in which marks are arranged in a mesh shape, and the interval between the marks 41a is about 5 μm, the line width is about 0.1 μm, and is composed of 10 vertical and horizontal lines (FIG. 3 (a) is a part thereof) . FIG. 3B is an example of marking with grid-point dots 41b. The marking pattern may be a short line segment 41c as shown in FIG. 3C or a set of appropriate symbols 41d as shown in FIG.

  When observing a SIM image, the surface vicinity defect 42A of interest cannot be observed, but exists inside the region 42 in the vicinity of the mark. This region 42 is a region determined by the spatial resolution of the near-surface defect inspection section. In short, if the mark 41 applied to the sample surface is an artificial shape or arrangement, it can be clearly distinguished from a defect.

  The mark is formed at a predetermined coordinate with a minute current FIB. This is because when the FIB current is large, the damaged region of the sample becomes large, and when the wafer is processed into a thin piece thereafter, there is a high possibility of damaging the sample and damaging the original surface vicinity defect 42A to be observed. . In the region 42 of the extent shown in this embodiment, the mark 41 and the near-surface defect 42A of interest can be observed in the same field of view by TEM observation at a low magnification. The mark 41 can be sufficiently identified by TEM observation even with shallow processing that causes light damage to the surface of the wafer 5 with a low current FIB.

Further, as shown in FIG. 4, a large large mark 43 that can be identified by an optical microscope is also formed.
FIG. 4 shows an example of the positional relationship of the mark 41 for indicating the relative position between the large mark 43 for the optical microscope and the defect. The large mark 43 serves as a mark when the wafer 5 is cut into small pieces 5A, and may have a size of several tens of μm. Further, the large mark 43 itself can be clearly confirmed by the way of reflection of light with an optical microscope only by forming a concave portion having an appropriate depth in the sample.

  Next, the wafer 5 is cut to about 1 mm square using a diamond cutter, a dicing saw or the like so that the mark 41 and the large mark 43 are included, and the middle of the large mark 43 is approximately at the center of the small piece 5A. Next, the small piece 5A obtained by cutting is fixed to a polishing jig with the wafer surface side as an adhesive surface. There are various types of the above-mentioned polishing jigs. Basically, a polishing jig equipped with a device that can measure the size of μm order, such as a micrometer head, is used to adjust the flatness of the sample to the polishing plate. The sample is pressed and polished from the back surface to prepare a polished sample having a thickness of about 10 μm.

  Next, the polishing sample removed from the polishing jig is fixed to a single-hole mesh and mounted on an ion thinning apparatus. In ion thinning, while the single-hole mesh is rotated, argon ions are obliquely irradiated to only the back surface, and the polished sample is further thinned. In ion thinning, ion irradiation is usually performed from the front and back surfaces of a sample, but since the purpose of this example is to observe defects near the surface, ion irradiation from the surface side is not performed. Finally, the vicinity of the center where the mark 41 is present is thinned to about 100 nm or less to obtain a planar TEM sample 5B.

  This flat TEM sample 5B is mounted on a TEM stage together with a single hole mesh and subjected to TEM analysis. In the observation of the planar TEM sample 5B, a wide area of several tens of μm square can be observed at a low magnification at a time, and the FIB processed marks 41 having an artificial shape and arrangement can be easily found. The surface near-surface defect 42A to be noticed can be identified with reference to the mark 41, and TEM observation can be performed at a high magnification from the plane direction.

  As described above, the sample preparation method according to the present invention is a sample preparation method in which a mark is marked by FIB at or near the coordinates obtained by defect detection, and a defect to be noticed can be definitely found with reference to the mark.

  In the present embodiment, the FIB is used as a method for applying a mark. However, marking using ablation of the wafer surface by pulsed laser beam irradiation may be used. Further, impurities such as carbon contained in the atmosphere in the vicinity of the sample may be deposited on the wafer by electron beam irradiation to form marks, and pressing or scratching with a mechanical metal probe or diamond probe that is driven with high accuracy. It is good also as a mark by. Both methods are suitable because they can be distinguished from defects in TEM observation. As described above, the sample preparation method of the present invention can surely observe the defect of interest from the plane direction among the defects obtained by detecting defects near the surface, so that the defect can be analyzed efficiently and definitely. it can.

  In the above embodiment, the defect detection unit and the marking unit are configured separately, and the target sample is transferred from the defect detection unit to the marking unit. However, as the device configuration, the defect detection unit and the marking unit are separately provided. It is not limited to the structure to perform, You may mark in the place which performed the defect detection.

<Example 2>
The present example is a sample preparation method for TEM observation of a near-surface defect of interest detected by TEM observation of the planar TEM sample prepared in Example 1, also from the cross-sectional direction. This method will be described as a step continued from the first embodiment.

  FIG. 5A is a planar TEM image 44 of the planar TEM sample 5B, where the mark 41c and the near-surface defect 42A can be confirmed, and the approximate relative positional relationship between the mark 41c and the near-surface defect 42A is known. First, a plurality of regions from the low magnification image to the high magnification image of the planar TEM image 44 including the surface vicinity defect 42A of interest described above are stored in a computer or left on a recording paper such as a photograph. At this time, it is important that the reference mark 41c is within the same screen as the surface vicinity defect 42A. Preferably, when a plurality of marks 41c are included in the image, it is very easy to locate the surface vicinity defect 42A of interest.

  Next, the planar TEM sample 5B observed by the TEM is moved to the sample preparation apparatus while being mounted on the mesh, and an operation of extracting a micro sample of μm level including the surface vicinity defect 42A of interest from the planar TEM sample 5B is performed. In order to extract a micro sample including a target defect from the planar TEM sample 5B, the position of the target portion must be accurately grasped.

  In the marks described above, the interval between the marks is large and the positional relationship with the target defect can be accurately grasped. Therefore, in order to accurately identify the position of the defect, a planar TEM image is used as shown in FIG. Based on the above, a finer marking is performed again (hereinafter, the mark here is referred to as a second mark 46).

  The shape of the second mark 46 may be the same pattern as illustrated in FIG. 3, but the overall dimension is further reduced. As a specific example of dimensions, short line segments having a width of about 0.05 μm and a length of 0.3 μm, which are much smaller than the previous mark 41c, are arranged on four sides at intervals of 0.5 μm. In order to make the second mark 46 to be formed as small as possible, the FIB current is made as small as possible and the irradiation time is made as short as possible. Even if the mark does not penetrate the thin piece, it remains as an artificially arranged damaged region and can be easily distinguished from a defect due to the artificial shape.

  When the planar TEM sample 5B provided with the second mark 46 is again planarly observed with a TEM, the position of the near-surface defect 42A is further determined from the relative positional relationship with the second mark 46 as shown in FIG. 5 (b). I understand in detail. This TEM image is stored in a computer or left on a recording paper such as a photograph, and based on this, a minute region including the surface vicinity defect 42A of interest in the marking portion is extracted from the planar TEM sample, and the surface vicinity defect 42A TEM sample for cross-sectional observation can be formed.

  Hereinafter, extraction of the sample 5C including the surface vicinity defect 42A of interest will be described in detail with reference to FIG.

  First, based on the TEM image in which the preceding second mark 46 and the target near-surface defect 42A are in the same field of view, a position specifying mark king 61 is provided for recognizing the position of the near-surface defect 42A by surface observation. . Specifically, as shown in FIG. 6B, the FIB 62 is used to process an arrangement that sandwiches the surface vicinity defect 42A. The position specifying mark 61 also has a mark portion 61 'having a narrow line width in order to realize more precise processing alignment. In this example, four line segment marks were applied by FIB irradiation at intervals of 5 μm and 1 μm across the observation region.

  Next, as shown in FIG. 6C, a protective film 63 for protecting the sample is formed so as to cover the line segment connecting the two position specifying marks 61. The protective film 63 is formed by forming a metal film in the scanning region by scanning the FIB 62 in a rectangular shape while supplying a deposition gas. In this embodiment, a tungsten film having a width of about 2 μm, a length of 14 μm, and a height of about 1 μm is formed. However, the protective film 63 is not limited to tungsten, and may be formed of a carbon film, a platinum film, a silicon film, or the like.

  Next, the micro sample extraction process is started. As shown in FIG. 6D, the cantilever 65 can be formed by making a U-shaped cut by the FIB 62 so as to surround the protective film 63. As an example of dimensions, the width is approximately 4 μm, the length is 18 μm, and the sample thickness is 0.1 μm.

Next, as shown in FIG. 6E, the probe 66 is brought into contact with the cantilever 65.
The probe 66 is fixed to the tip of the transfer means for the micro sample, and the drive section (not shown) of the transfer means is provided with a probe in order to avoid damage to the cantilever 65 and the probe 66 due to careless pressing of the probe 66. It has a function of stopping driving in the + Z direction when 66 touches the sample. After the probe 66 is contacted, in order to fix the probe 66 to the cantilever 65, a deposition film 67 is formed in an area of about 2 μm square including the tip of the probe 66 with the probe 66 in contact with the cantilever 65. The deposition film 67 is formed by the same method as the protective film 63 and may be the same component. In this way, the probe 66 and the cantilever 65 (sample to be extracted) can be connected (FIG. 6 (f)).

  Thereafter, as shown in FIG. 6G, the support portion 68 of the cantilever 65 is irradiated with FIB 62 and sputtered to cut the cantilever 65. After cutting, when the probe 66 is gradually raised, the minute thin piece sample 5C can be separated and extracted from the original flat TEM sample 5B as shown in FIG. 6 (h).

  The processing procedure for making a cross-sectional TEM sample for viewing the defect 42A from the cross-sectional direction will be described below with reference to FIG.

  First, as shown in FIG. 7A, the micro thin sample 5C extracted is stopped in a state where it is lifted from the flat TEM sample 5B, and the sample stage is relatively moved so that the sample holder 70 is directly below the micro thin sample 5C. Then, as shown in FIG. 7B, the probe 66 is lowered to bring the minute thin piece sample 5C into contact with the sample holder 70. When the minute thin piece sample 5C comes into contact with the sample holder 70, the descent of the probe 66 is automatically stopped. Is done.

  Next, in order to fix the minute thin piece sample 5 </ b> C to the sample holder 70, a deposition film 71 is formed so as to straddle the minute thin piece sample 5 </ b> C and the sample holder 70. The deposition film 71 in the present embodiment has a size of about 2 μm square on the end in the longitudinal direction of the minute thin piece sample 5C (FIG. 7C). Thereafter, the deposition film 67 is irradiated with the FIB 62 to separate the probe 66 from the minute thin sample 5C, and the probe 66 is further kept away from the sample holder 70 in order to prevent the probe 66 from being damaged. Further, in order to securely fix the minute thin piece sample 5C to the sample holder 70, a deposition film 71 'of about 2 μm square is also formed on the other end side in the longitudinal direction of the minute thin piece sample 70 (FIG. 7D).

  Next, the FIB 62 is irradiated to the minute thin piece sample 5 </ b> C fixed to the sample holder 70, and the side surface is removed together with the sample holder 70 to form the recess 72. In the present embodiment, the opening of the recess 72 is about 10 μm, the depth is about 2 μm, and the depth is about 3 μm (FIG. 7E). Further, the recess 72 'is processed on the opposite side surface so that a thin wall having a thickness of about 0.1 μm remains in the central portion (FIG. 7 (f)).

  FIG. 7G is a cross-sectional sample of the completed thin piece sample, which is a cross-sectional sample of the minute thin piece sample 5C including the near-surface defect 42A (not shown) noted by the upper portion 74 of the central thin wall portion 73. It is a thin wire having a length of about 0.1 μm, a width of about 0.1 μm, and a length of about 10 μm. For reference, the direction of the incident electron beam at the time of TEM observation is indicated by an arrow 75. In this way, the electron beam is incident on the surface of the minute thin sample almost in parallel.

  In this way, a sample for observing the near-surface defect 42A from the cross-sectional direction could be created by the procedure shown in FIGS. According to the method of the present embodiment, it is possible to position a defective portion with high accuracy. In addition, since all these steps can be performed in a vacuum atmosphere, processing can be performed with almost no unnecessary fine powder adhesion.

  The cross-sectional sample prepared as described above is introduced into a TEM. Since the subsequent TEM observation technique is well known, the description thereof is omitted here.

  Thus, the three-dimensional structure of the surface vicinity defect 42A to which attention is paid can be estimated by complexly interpreting the planar TEM image and the sectional TEM image obtained by the sectional TEM observation of the attention portion. For example, in the case of this example, if the defect image is a square in the planar TEM observation and a rhombus in the cross-sectional TEM observation, the defect can be interpreted as an octahedral structure by interpreting both TEM images in a composite manner. As described above, even if the defect structure is difficult to interpret by only TEM observation of only the plane or the cross section, the structure can be accurately interpreted by observing the same defect from 90 ° different directions.

  In addition to the FIB, the marking method may use a stencil mask provided with a mark-shaped opening pattern in advance, and a plurality of mark patterns may be formed at once by a projected ion beam. In particular, since a fixed ion pattern can be applied to the projection ion beam regardless of the size of the observation field of view, it is possible to perform marking with a similar number and arrangement of marks even for a high magnification field of view.

<Example 3>
The present embodiment is an embodiment relating to a sample preparation apparatus for realizing the sample preparation method.

  FIG. 1 is a plan view for explaining an overall schematic configuration of an embodiment of a sample preparation apparatus according to the present invention. The sample preparation device 1 has a structure in which a defect detection unit 2 and a marking unit 3 are connected via a wafer handling unit 4. The marking unit 3 includes a load lock chamber 16 for introducing the wafer 5 into the vacuum container. The wafer handling unit 4 is a mechanism for taking the wafer 5 into and out of the defect detection unit 2 and the marking unit 3, and includes a telescopic arm 4A and a rotation mechanism 4B.

  The movement of the wafer 5 is usually performed in a state where it is installed on the wafer tray 6. When a defect to be noticed is detected by the defect detection unit 2, the wafer 5 is transferred from the defect detection unit 2 to the marking unit 3, or the wafer 5 is unloaded from the marking unit 3 and again by the defect detection unit 2. It can also be inspected. Control of the defect detection unit 2 and the marking unit 3, and data collection and processing are performed by the calculation processing unit 15 via the signal lines 15A and 15B.

A detailed configuration of the defect detection unit 2 will be described with reference to FIG. The defect detection unit 2 is a part that measures near-surface defects on the surface of the wafer 5, and the target wafer 5 can be installed and fixed on the wafer tray 6. The wafer tray 6 is installed on a sample stage 7 that can rotate and translate at high speed.

  Laser beams 8A and 8B applied to the wafer 5 are emitted from the semiconductor excitation YAG laser 9A (wavelength 532 nm) and the semiconductor laser 9B (wavelength 810 nm). Beam collimating lenses 10A and 10B, reflectors 11A, 11'A, 11B, 11'B, and the like are arranged in each laser beam path, and can be focused on the wafer 5 at an incident angle of 75 °. The laser beams 8A and 8B rotate the wafer 5 to scan the wafer surface in a spiral shape. The beam diameter is approximately 5 μm × 25 μm.

  Further, if there is a defect near the surface as a device configuration, the condenser lens 13 for collecting the scattered light 12 generated in a pulsed manner from the defect as the laser beam is scanned, the reflectors 11C and 11′C, and the scattered light 12A and 12B for each wavelength. Photomultiplier tubes 14A and 14B for detecting the light, the position where the scattered light is generated, and the computer 15 for storing the signal intensity of two wavelengths. Based on the data obtained with such a configuration, the in-wafer distribution of defects, the depth position distribution of defects, the particle size distribution of defects, and the like can be obtained.

  On the other hand, the marking unit 3 has a structure that can be introduced into the vacuum container 17 through the load lock chamber 16 together with the wafer tray 6 on which the wafer 5 is placed (see FIG. 1). The vacuum container 17 includes an FIB irradiation unit 18 for observing and marking the wafer 5 and the like, a sample stage 19 on which the wafer 5 is placed, and a secondary particle detector 20 for detecting secondary electrons or secondary ions. . The calculation processing unit 15 is also used as the calculation processing unit 15 of the defect inspection unit 2, and controls the FIB irradiation unit 18, the sample stage 19, the secondary particle detector 20, and the like via the signal line 15B.

  The FIB irradiation unit 18 includes, for example, a liquid metal ion source, a beam limiting aperture, a focusing lens, an objective lens, and the like, and forms an ion beam emitted from the liquid metal ion source into an FIB having a diameter of about 10 nm to several 100 nm. The FIB can be scanned in various shapes depending on the voltage application method of the deflector and can be locally processed. By detecting secondary electrons or secondary ions generated from the sample at the time of FIB irradiation with the secondary particle detector 20, a SIM image or secondary ion image of the sample can be displayed on a display, which also serves as a microscope. The SIM image is stored in the calculation processing unit 15 as necessary.

  The calculation processing unit 15 can receive and process the information of the defect coordinates obtained by the defect detection unit 2, and indicates the coordinates of the defect of interest in consideration of the depth and size of the defect among the detected coordinates of the surface vicinity defect. By doing so, the sample stage 19 operates, and the defect of interest can be stopped in the field of view of the FIB. Further, by storing the mark shape in advance in the calculation processing unit 15, by giving a marking command to the calculation processing unit 15, a mark as described in the first embodiment can be attached instantaneously.

  By using such a sample preparation apparatus 1, it is possible to mark the vicinity of the target defect among the detected defects, and by analyzing the marked sample, details such as the form of the target defect can be obtained. Obviously.

In the present embodiment, the FIB irradiation unit 18 is installed as a means for applying a mark. However, instead of the FIB irradiation unit 18, a pulse laser beam such as an excimer laser is used to perform marking using ablation of the sample surface. An irradiation unit or a semiconductor laser light irradiation system may be installed, or an electron beam irradiation system may be installed in order to attach impurities contained in the atmosphere near the sample to form a mark. Also, a mechanical metal probe or diamond probe that can be driven with high precision to mark by mechanical pressing or scratching may be installed. However, in the case of a mechanical probe, a microscopic means is required, and a scanning electron microscope or the like is used in combination.
Further, a projection ion beam optical system may be used in place of the FIB irradiation optical system.
Either method is suitable for easy identification of the position of the defect because the TEM observation makes it possible to distinguish the defect from the artificial mark.

<Example 4>
With reference to FIG. 9, an apparatus for extracting a micro sample of a μm level including a target defect from defects detected by the defect inspection unit 2 and processing the sample into a sample for TEM observation from a cross-sectional direction will be described.

  The sample preparation unit 23 in FIG. 9 also serves as the marking unit 3 in FIG. 1 and has a configuration in which at least a sample transfer unit 24 for transferring a micro sample to a sample holder is added to the basic configuration of the marking unit 3 and is locally In some cases, a deposition gas source 25 for supplying a gas for forming the position film is mounted. Of course, the sample preparation section 23 can also mark the sample.

  A sample transfer control unit 24 ′ for driving the sample transfer unit 24, a deposition source control unit 25 ′ for driving the deposition gas source 25, and an FIB control unit 18 for operating the FIB irradiation unit 18 for irradiating the FIB 49. 'And a stage control unit 19' for controlling the position of the sample stage 19 are controlled by the calculation processing unit 15. Reference numeral 22 denotes a surface state of the sample 5. It is a display unit for the calculation results of the computer 15, instructions to various control devices, operation states, and the like.

  A sample holder (not shown) is a jig for mounting a sample on a sample stage of a TEM and has a structure that can be attached to and detached from a part of the wafer tray 6. The sample holder on which a micro sample is mounted is detached from the wafer tray 6 as necessary. It can be introduced into TEM, SEM, and other analysis devices. The dimension of the sample holder used in this example is a flat plate shape having a length of 2.6 mm, an upper width of 30 μm, a lower width of 200 μm, and a height of 0.7 mm (silicon wafer thickness). By using the surface or the cleaved surface, even if the extracted micro sample is fixed to the fixed surface and observed by TEM, the unevenness of the fixed surface does not hinder the electron beam irradiation. In addition, the shape and dimensions of the sample holder are not limited to this, but in order to process the TEM sample in a short time by making the fixed surface a wafer surface or a cleaved surface and making the fixed surface width as thin as possible. This is necessary to facilitate TEM observation.

  The holder cassette 27 is a jig for mounting the sample holder, and is attached to the wafer tray 6 for mounting. One or a plurality of sample holders may be mounted on one holder cassette 27. Particularly, a plurality of sample holders are convenient for attaching and detaching and managing the sample holders. Moreover, the holder cassette 27 installed in the wafer tray 6 may be plural. For example, assuming that one micro sample is mounted on one sample holder, 10 sample holders can be mounted on one holder cassette 27, and five holder cassettes 27 are mounted on the wafer tray 6. Fifty micro samples can be continuously extracted from one wafer, surface near surface defects can be efficiently extracted under various conditions, and defect analysis can be systematically performed.

  The sample transfer section 24 includes a coarse movement mechanism section 24A that moves on three axes of XYZ and a fine movement mechanism section 24B that moves slightly in the Z direction, both of which are operated by the sample transfer control section 24 '. A probe 28 for extracting a minute sample is connected to the tip.

  The sample transfer unit 24 has a coarse moving mechanism 24A having a high moving speed and a large stroke, and a moving resolution of the coarse moving unit, so that the wafer 5 can be sampled quickly from an arbitrary position even when the wafer 5 has a large diameter. The fine moving part 24B having the same stroke and high moving resolution is provided, and the entire sample transfer part 24 is installed independently of the sample stage 7, and the large movement of the sampling position is shared by the movement of the sample stage.

  The coarse movement mechanism 24A is driven in the XYZ directions by a motor, a gear, a piezoelectric element, etc., and has a moving resolution of 1 μm or less with a stroke of about several mm. The Z-direction fine movement mechanism portion 24B is required to be as compact and precise as possible due to mechanical restrictions such as the distance between the objective lens and the sample. Moving resolution is achieved.

  The probe 28 used when extracting a micro sample at the front-end | tip of the fine movement mechanism part 24B is provided. However, the configuration of the sample transfer unit 24 is not limited to the configuration shown here, and the fine movement function of the Z axis may be omitted by installing a mechanism that operates with high precision for all three axes. A rotation mechanism may be added.

  Japanese Patent Laid-Open No. 5-52721 (Known Example 2) is known as a conventional technique similar to the sample transfer unit 24. According to this prior art, the transport means for transporting the separated sample is composed of three bimorph piezoelectric elements corresponding to the XYZ axes, and the position of the transport means is set on the stage from the above publication. It can be read. When the transport means is installed on the sample stage as in this conventional example, when the separation point of interest is at the center of a wafer having a diameter of, for example, 300 mm, the movement stroke of the tip of the transport means moves from the position of the transport means to the sample. Since it is much smaller than the distance to the desired location, there is a fatal problem that the transport means installed on the sample stage does not reach the separation location of interest. In the present embodiment, in order to avoid the above-described problems, it is also one of the features that the sample transport unit 24 is provided independently of the sample stage.

  The deposition gas source 25 has a structure in which an organic metal gas or the like can be injected from a nozzle 29 at the tip, and a FIB scan can be performed while injecting an organic metal gas onto a sample to form a deposition film of a gas component in the scanning region. . This deposition film serves to protect the sample surface and to bond the members together.

  The wafer as the sample 5 can be introduced onto the sample stage 19 through the load lock chamber 16 without impairing the degree of vacuum in the sample chamber.

  By using such an apparatus, it is possible to reliably process a sample for TEM observation of a target defect in a planar TEM sample, and to observe the same surface vicinity defect from two directions of a plane and a cross section. It was possible to analyze the form of near-surface defects that had many unknown points so far.

  In Example 4, the marking part and the sample preparation part are combined, but they may be separated. For example, a marking method using an electron beam is employed for the marking part, and the sample preparation part is It is good also as a structure using FIB. Further, the method for extracting a micro sample using the sample preparation portion shown here was described in detail in Example 2.

<Example 5>
In Example 3, a sample preparation device including the defect detection unit 2 and the marking unit 3 is shown. In Example 4, the sample preparation device having the sample preparation unit 23 and the defect detection unit 2 also serving as the marking unit is used. However, as shown in FIG. 10, the near-surface defect detection device 80 that exclusively detects the near-surface defect of the wafer 5 and the marking device 81 that exclusively marks the wafer 5 may be mechanically independent. In the case of the present embodiment, the coordinate system of the near-surface defect detection device 80 and the marking device 81 is made common, each coordinate information is shared, an instruction for controlling the drive system of the sample stage of each device is issued, or the wafer 5 It is assumed that the computer 82 stores the information and the network 83 is connected to each device.

  By introducing the target wafer 5 into the marking device 81 and specifying the coordinate information of the defect of interest detected by the near-surface defect detection device 80, the stage of the marking device 81 is driven to quickly identify the defect portion of interest. It can be captured within the field of view. Moreover, it is good also as a structure which can be processed continuously based on the mark shape previously registered into the computer 82. Further, the marking device 81 may also serve as a sample preparation device, and the marking device and the sample preparation device may be made independent, and the above three devices may be controlled and data collected by a common computer.

  Furthermore, the conventional focused ion beam device can irradiate the wafer with lasers with different wavelengths, incorporates a mechanism that focuses the scattered light, splits it, and sends it to the detector. The computer that stores the coordinates of the presence of both the focused ion beam control and the sample stage control makes it possible to irradiate the focused ion beam to approximately the detected surface vicinity defect.

  Furthermore, in the above-described near-surface defect detection apparatus (for example, OSDA apparatus), a sample stage can be placed in a vacuum vessel, and the vacuum vessel includes at least a focused ion beam irradiation optical system and a secondary electron detector. By installing a deposition gas supply source and providing a control system and a computer that can move the detected defect among the detected defects to the focused ion beam irradiation area on the sample stage, it is in the vicinity of the focused defect. Marks can be made by a focused ion beam.

<Example 6>
In this embodiment, a semiconductor wafer that detects defects near the surface of a semiconductor wafer at an early stage of manufacturing and determines whether the wafer can be used for manufacturing a semiconductor device based on the detection result, that is, a semiconductor that performs screening. The present invention relates to a wafer management method.

  First, a database must be created. For a large number of semiconductor wafers, a surface defect detection device is used to store at least one of the number of near-surface defects, in-plane and depth distribution, position, shape, and type in a computer. On the other hand, with respect to defects near the surface, the shape of the sample prepared by the method of the present invention described above is observed by TEM or STEM. The wafer periphery and center, the size of the defect size, etc. are stored in the computer. The correlation between the result obtained by the surface defect detection device and the shape observation result by TEM or STEM is obtained from a lot of data thus stored. For example, a tendency such as “defects distributed at a certain depth have many octahedral vacancies” is stored in the calculation processing unit as a database.

  On the other hand, prior to the manufacture of the semiconductor device, surface defects are detected for the wafer to be used. At least one of the number of near-surface defects, in-plane and depth distribution, position, shape, and type obtained at that time is stored in the calculation processing unit together with the wafer identification number. Also, the operation of the finally finished semiconductor device is confirmed by a device operation measuring device such as a prober inspection. Correlation between each of the evaluation items at the corresponding location obtained by the surface defect detection is obtained for the chip having a good operation and the chip having a defective operation. Further, for a chip that performs a defective operation, the correlation between the defect detection result, the correlation between the defect and the electron microscope observation result, and the cause of the defective operation, for example, the breakdown voltage failure of the insulating film, are stored in association with each other.

  In this way, the correlation between the surface defect detection result for many wafers, the result of electron microscope observation of the defect, the good operation of the semiconductor device, the result of the defect, and the cause of the defective part is stored in the calculation processing unit as a database. .

  On the basis of such a database, surface defect detection is desirably performed on the total number of wafers used in manufacturing at a semiconductor device manufacturing site. At least one of the number of near-surface defects, in-plane and depth distribution, position, shape, and type obtained at this time is taken into the computer and compared with the database stored so far. When the semiconductor device manufacturing process is continued using this wafer, it is possible to roughly estimate the yield of obtaining good products per wafer. Comparing the costs associated with the production of a single wafer and the expected profits obtained from the production, it is clear that if the number and distribution of defects exceed a certain level, damage will occur if manufactured. The wafer can be screened. This screening improves the acquisition yield of the final good semiconductor device.

The top view which shows schematic structure of the sample preparation apparatus by one Example of this invention. The longitudinal cross-sectional view for demonstrating the principle of the conventional OSDA apparatus. The partial top view of the wafer surface which shows the Example of the mark king by this invention. The partial top view of the wafer surface which shows the Example of the mark king by this invention. The partial top view of the wafer surface which shows the formation process of the 2nd mark by this invention. The perspective view which shows the procedure of the process of extracting the micro sample by one Example of this invention. The perspective view which shows the procedure of the process of forming the cross section of the micro sample by one Example of this invention. The principal part perspective view which shows the structure of the defect detection part by one Example of this invention. The principal part perspective view which shows the structure of the mark detection part by one Example of this invention. The block diagram of the sample preparation apparatus by one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sample preparation apparatus, 2 ... Defect detection part, 3 ... Marking part, 4 ... Wafer handling part, 5 ... Wafer, 6 ... Wafer tray, 7 ... Sample stage, 8 ... Laser beam, 9A, 9B ... Light source, 15 ... Calculation Processing unit 16 ... Load lock chamber 17 ... Vacuum container 18 ... FIB irradiation unit 19 ... Sample stage 22 ... Display 23 ... Sample preparation unit 24 ... Sample transfer unit 27 ... Holder cassette 28 ... Probe 41 ... mark, 42A ... surface near surface defect, 44 ... plane TEM sample image, 46 ... second mark, 5A ... wafer piece, 5B ... plane TEM sample, 5C ... minute thin piece sample, 63 ... protective film, 66 ... probe, 70 ... Sample holder, 74 ... Cross-section sample.

Claims (11)

A marking step in which a plurality of marks for identifying the defect are formed by irradiating a laser beam in the vicinity of the defect detected by the defect inspection of the wafer;
An observation step for obtaining a relative positional relationship of the defect with respect to the mark;
A step of extracting from the wafer at least an ion beam processing a micro sample including the defect of the wafer based on the relative positional relationship of the defect to the mark ;
Transferring and fixing the micro sample in the same vacuum to a sample holder for observation, measurement or analysis;
And a processing step including a step of further processing the ion beam with the ion beam to finish the sample in a shape suitable for observation, measurement, or analysis. Irradiating a first laser beam to identify defects in the wafer;
A marking step of irradiating a second laser beam in the vicinity of the detected defect to form a plurality of marks for identifying the defect;
An observation step for obtaining a relative positional relationship of the defect with respect to the mark;
A step of extracting from the wafer at least by ion beam processing a micro sample containing the defect of the wafer based on the relative positional relationship of the defect to the mark, and for observing, measuring or analyzing the micro sample in the same vacuum A processing step including a step of transferring and fixing to a sample holder, and a step of further processing the ion beam with the ion beam to finish a test piece suitable for observation, measurement, or analysis. Sample preparation method. In the sample preparation method according to claim 1 or 2,
A sample preparation method, wherein the test piece is a test piece for observation, measurement, or analysis using a transmission electron microscope or a scanning transmission electron microscope. In the sample preparation method according to claim 2,
A sample preparation method, wherein coordinate information of the defect is stored in the step of identifying the defect, and the mark is formed near the defect based on the coordinate information in the processing step. In the sample preparation method according to claim 1 or 2,
A sample preparation method comprising: storing coordinate information of the mark in the marking step; and detecting the mark based on the coordinate information in the processing step. A marking portion having a laser irradiation optical system for identifying a defect of the wafer and a marking portion having a laser light irradiation portion for attaching a plurality of marks in the vicinity of the defect;
Obtaining a relative positional relationship of the defect with respect to the mark;
The wafer is irradiated with an ion beam based on the relative positional relationship of the defect with respect to the mark , and a micro sample containing the defect is separated and extracted from the wafer to perform at least one of analysis, observation, and measurement. A sample preparation apparatus comprising at least a sample processing unit that processes a test piece suitable for the above. In the sample preparation device according to claim 6 ,
The sample processing section is
An ion beam irradiation optical system that irradiates a minute region of the wafer including the defect with an ion beam;
A probe for irradiating the microscopic region with the ion beam to separate and extract a microsample from the wafer;
A sample preparation apparatus comprising at least a sample holder on which the extracted micro sample is placed. A defect inspection apparatus for detecting defects in the wafer placed on the first stage;
A marking device for attaching a plurality of marks with a laser beam in the vicinity of the detected defect on the wafer placed on the second stage;
Obtaining a relative positional relationship of the defect with respect to the mark;
Based on the relative positional relationship of the defect with respect to the mark, the wafer is irradiated with a focused ion beam, and a micro sample containing the defect is separated and extracted from the wafer in a vacuum to be analyzed, observed, or measured. In a sample preparation system comprising at least a sample preparation device for processing into a test piece suitable for performing
At least a first coordinate system of the defect detection device and a second stage of the marking device have a common coordinate system. A marking device for attaching a plurality of marks with a laser beam in the vicinity of a defect inspected for a wafer placed on a wafer tray;
Obtaining a relative positional relationship of the defect with respect to the mark;
The wafer is irradiated with a focused ion beam based on the relative positional relationship of the defect with respect to the mark , and a minute sample including the defect is separated from the wafer in vacuum, analyzed, observed, or measured. In a sample preparation system including at least a sample preparation device that processes a test piece suitable for performing
A sample preparation system characterized in that the wafer can be transferred from the marking device to the sample preparation device in a state of being placed on the wafer tray. A defect inspection apparatus for detecting defects in the wafer placed on the first stage;
A marking device for attaching a plurality of marks with a laser beam in the vicinity of the detected defect on the wafer placed on the second stage;
Obtaining a relative positional relationship of the defect with respect to the mark;
The wafer is irradiated with a focused ion beam based on the relative positional relationship of the defect with respect to the mark , and a minute sample including the defect is separated from the wafer in vacuum, analyzed, observed, or measured. In a sample preparation system including at least a sample preparation device that processes a test piece suitable for performing
The sample preparation system, wherein the defect inspection device, the marking device, and the sample preparation device are configured to perform control and data collection by a common computer. A defect inspection process for detecting defects in the wafer;
A marking step of irradiating a laser beam in the vicinity of the detected defect to form a plurality of marks for identifying the defect;
An observation step for obtaining a relative positional relationship of the defect with respect to the mark;
The wafer is irradiated with a focused ion beam based on the relative positional relationship of the defect with respect to the mark , and a minute sample including the defect is separated from the wafer in vacuum, analyzed, observed, or measured. A sample preparation process for processing into a test piece suitable for performing,
A defect analysis method comprising an analysis step of analyzing the test piece with a transmission electron microscope or a scanning transmission electron microscope.

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