JP6487225B2 - Charged particle beam apparatus and defect inspection system - Google Patents

Description

  The present invention relates to a charged particle beam apparatus and a defect inspection system.

  In a conventional semiconductor device, a sample defect generally exists in the vicinity of the sample surface. For this reason, it was possible to observe and analyze the shape of the defect by irradiating the sample surface with an electron beam using a review SEM (review scanning electron microscope) for inspecting the defect. There is also known a method of analyzing a defect portion by separating it from a wafer (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 11-108810

  By the way, from the viewpoint of further integration of semiconductor devices, an increase in capacity, and the like, in recent years, a three-dimensional device (3D device) in which a plurality of thin films are stacked to form a device has attracted attention. Unlike a conventional two-dimensional circuit semiconductor device, a three-dimensional device is formed by stacking a plurality of circuits in the height direction (vertical direction), so that further integration and the like are possible.

  In a three-dimensional device, since a plurality of circuits are stacked in the height direction, defects exist not only near the surface of the sample but also inside the sample. Therefore, it is difficult to observe and analyze the shape of the defect even if the electron beam is irradiated from the sample surface by the review SEM. In addition, the method of separating and analyzing the defect portion with a focused ion beam (FIB) apparatus has a problem that it takes time to observe and analyze.

  The present invention provides a charged particle beam apparatus and a defect inspection system capable of observing defects inside a sample of a three-dimensional device.

  The charged particle beam apparatus according to the present invention includes a storage unit that stores a position of a defect existing inside a sample of a three-dimensional device, a sample stage that moves the sample, and a charge that processes the sample in an area including the position. A charged particle beam irradiation unit that irradiates the particle beam.

  As one aspect of the present invention, for example, the region is larger than the positional accuracy of the sample stage.

  As one aspect of the present invention, for example, the charged particle beam irradiation unit irradiates the charged particle beam from the surface side of the sample and performs etching processing from the surface to a predetermined depth.

  As one aspect of the present invention, for example, a defect inspection system comprising the above-described charged particle beam apparatus and an electron beam irradiation apparatus that irradiates the defect with an electron beam and observes the defect.

  As one aspect of the present invention, for example, a defect inspection system comprising: the above-described charged particle beam apparatus; and an electron beam irradiation apparatus that irradiates the defect with an electron beam and observes the defect. The distance from the defect to the defect is a distance through which the electron beam can be transmitted.

  As one aspect of the present invention, for example, the charged particle beam apparatus can process a cross section of the defect observed by the electron beam irradiation apparatus.

  As one aspect of the present invention, for example, the charged particle beam apparatus includes an electron beam irradiation unit that observes a cross section of the defect subjected to cross section processing.

  As described above, according to the present invention, the defect inside the three-dimensional device can be specified accurately and in a short time, and the analysis of the three-dimensional device can be performed accurately and in a short time.

BRIEF DESCRIPTION OF THE DRAWINGS The whole block diagram of the charged particle beam apparatus (composite charged particle beam apparatus) of embodiment by this invention. The whole electron beam irradiation apparatus (review SEM) block diagram of embodiment. It is a perspective view of the semiconductor wafer as a sample, (a) shows the position of the defect which exists in the inside of a semiconductor wafer, (b) shows the state where the hole was formed corresponding to the position of a defect, (c ) Is an enlarged view of a portion C in (b). It is sectional drawing of the semiconductor wafer as a sample, (a) is a figure which shows the defect which exists in a semiconductor wafer, (b) is a figure which shows the state in which the hole was formed by FIB, (c) FIG. 4 is a view showing a state in which a groove for cross-sectional observation is formed after observation of a defect D. The flowchart which shows the procedure of performing from the position specification of a defect to cross-sectional observation using the defect inspection system of this embodiment.

  Hereinafter, embodiments of the present invention will be described. FIG. 1 shows an overall configuration of a composite charged particle beam apparatus 100 as a charged particle beam apparatus of the present embodiment. The composite charged particle beam apparatus 100 includes an FIB column 1 that irradiates a focused ion beam (FIB) as a first charged particle beam and an electron beam (EB) as a second charged particle beam. EB column 2, a GIB column 3 that emits a gas ion beam (GIB) as a third charged particle beam, and a sample chamber (chamber) 40 that contains a sample S. I have.

  The FIB column 1 includes a liquid metal ion source, can form a focused ion beam with a diameter of 100 nm or less, and can process the sample S locally. The FIB column 1 can also be provided with a plasma ion source instead of the liquid metal ion source, and can be processed with a large amount of beam current, so that a large area can be processed in a short time. The GIB column 3 includes a PIG type gas ion source, and uses a focused ion beam (gas ion beam) that is not focused as much as the focused ion beam to clean the processing surface by the focused ion beam. Used in. The GIB ion source uses helium, argon, xenon, oxygen, nitrogen or the like as an ion source gas. The FIB column 1 and the GIB column 3 function as a charged particle beam irradiation unit capable of processing the sample S. On the other hand, the EB column 2 functions as an electron beam irradiation unit that observes the sample S by irradiating an electron beam for observing the sample described later.

  The composite charged particle beam apparatus 100 further includes a secondary electron detector 4 that detects secondary electrons generated from the sample S by irradiation with EB, FIB, or GIB. Moreover, you may provide the reflected electron detector which detects the reflected electron which generate | occur | produces from the sample S by irradiation of EB.

  The composite charged particle beam apparatus 100 further includes a sample holder 6 that holds and fixes the sample S and a sample stage (sample stage) 5 on which the sample holder 6 is placed. The sample stage 5 is movable in the XYZ triaxial directions (not shown). Further, the sample stage 5 can be tilted and rotated as described later. The sample holder 6 can be attached to and detached from the sample table 5. When the sample holder 6 is removed from the sample table 5, it is a normal FIB and SEM combined device.

  The composite charged particle beam apparatus 100 further includes a sample stage control unit 15. The sample stage control unit 15 controls a driving mechanism (not shown) to move the sample stage 5 in the XYZ triaxial directions. Further, the sample stage control unit 15 controls the tilt driving unit 8 to tilt the sample stage 5, and controls the rotation driving unit 10 to rotate the sample stage 5.

  The composite charged particle beam apparatus 100 further includes an FIB control unit 11, an EB control unit 12, a GIB control unit 13, an image forming unit 14, and a display unit 18. The EB control unit 12 controls EB irradiation from the EB column 2. The FIB control unit 11 controls the FIB irradiation from the FIB column 1. The GIB control unit 13 controls GIB irradiation from the GIB column 3. The image forming unit 14 forms an SEM image from the signal for scanning the EB and the secondary electron signal detected by the secondary electron detector 4. The display unit 18 can display observation images such as SEM images and various control conditions of the apparatus. The image forming unit 14 forms a SIM image from the signal for scanning the FIB and the secondary electron signal detected by the secondary electron detector 4. The display unit 18 can also display a SIM image. The image forming unit 14 forms a reflected electron image from a signal for scanning the EB and a reflected electron signal detected by the reflected electron detector. The display unit 18 can also display a reflected electron image.

  The composite charged particle beam apparatus 100 further includes an input unit 16 and a control unit 17. The operator inputs conditions relating to device control to the input unit 16. The input unit 16 transmits the input information to the control unit 17. The control unit 17 transmits control signals to the FIB control unit 11, the EB control unit 12, the GIB control unit 13, the image forming unit 14, the sample stage control unit 15, the display unit 18, and the sample holder control unit 60, and the entire apparatus. To control.

  Regarding the control of the apparatus, for example, the operator sets an irradiation area of FIB or GIB based on an observation image such as an SEM image or a SIM image displayed on the display unit 18. The operator uses the input unit 16 to input a processing frame for setting an irradiation area on the observation image displayed on the display unit 18. Further, when the operator inputs a processing start instruction to the input unit 16, an irradiation region and a processing start signal are transmitted from the control unit 17 to the FIB control unit 11 or the GIB control unit 13, and FIB from the FIB control unit 11 or The GIB controller 13 irradiates the designated irradiation area of the sample S with GIB. Thereby, FIB or GIB can be irradiated to the irradiation region input by the operator.

  Further, the composite charged particle beam apparatus 100 includes a gas gun 19 that supplies an etching gas to the vicinity of the irradiation region of the sample S on the EB, FIB, or GIB. As an etching gas, a halogen gas such as chlorine gas, fluorine-based gas (such as xenon fluoride or fluorine carbide), or iodine gas is used. By using an etching gas that reacts with the material of the sample S, gas-assisted etching by EB, FIB, or GIB can be performed. In particular, gas-assisted etching by EB can be performed without damaging the sample S by ion sputtering.

  Furthermore, the composite charged particle beam apparatus 100 includes a storage device 20 as a storage unit capable of storing various information and data. The storage device 20 takes various forms such as a memory, a hard disk, a storage card, and a storage disk. And in this embodiment, the memory | storage device 20 can memorize | store the position of the defect (foreign material) which exists in the inside of the sample S obtained from the outside so that it may mention later.

  In this embodiment, the FIB column 1, the EB column 2, the GIB column 3, the secondary electron detector 4, and the gas gun 19 are provided in the upper part of the sample chamber 40. The arrangement position and order of the members are not particularly limited. The internal space of the sample chamber 40 is evacuated (evacuated) by a vacuum pump described later, and the sample S held by the sample holder 6 is moved by driving the sample stage 5 in the internal space. The FIB column 1, the EB column 2, and the GIB column 3 irradiate the sample S with a focused ion beam, an electron beam, and a gas ion beam, respectively.

  FIG. 2 is an overall configuration diagram of a review SEM 200 as the electron beam irradiation apparatus of the embodiment. The review SEM 200 includes an EB column 202 that irradiates an electron beam, and a backscattered electron detector and a secondary electron detector inside the EB column 202.

  The review SEM 200 further includes an EB control unit 212, an image forming unit 214, a sample stage control unit 215, an input unit 216, a control unit 217, a display unit 218, and a storage device (storage unit) 220. The review SEM 200 also includes a sample stage (sample stage) 205 that can be moved in the XYZ triaxial directions under the control of the sample stage control unit 215.

  The review SEM 200 is a charged particle beam apparatus specialized for specimen inspection. The review SEM 200 is highly accurately linked to the position information of the defects detected by the optical defect inspection apparatus. Accordingly, for example, by moving the sample stage 205 of the review SEM 200 based on the defect position information detected by the defect inspection apparatus, the defect detected by the defect inspection apparatus can be observed by the review SEM 200 with a positional accuracy of 20 to 40 nm. . As a result, even when a large number of defects, for example, 100 or more, are present on the wafer, defects can be observed in a short time.

  On the other hand, the composite charged particle beam apparatus 100 is an apparatus for processing and observing a sample, and the sample stage 5 is provided with an inclination mechanism such as an inclination drive unit 8 in order to change the incident angle of the beam. Therefore, the positional accuracy of the sample stage 5 is generally about several μm.

  FIG. 3 is a perspective view of a semiconductor wafer W which is a specific example of the sample S, and FIG. 4 is a cross-sectional view of the semiconductor wafer W. 3A shows a position P on the surface of the semiconductor wafer W where a plurality of defects exist in the sample, and FIG. 4A shows a situation where one of these defects F exists inside the semiconductor wafer W. This corresponds to 3 (a).

  The semiconductor wafer W is configured by forming a plurality of thin films T on a substrate BP, and is a sample for producing a so-called three-dimensional device (three-dimensional semiconductor device). Each of the thin films T is processed as a circuit on one plane in the three-dimensional device, and a plurality of circuits are formed in the height direction (vertical direction in FIG. 4) when the three-dimensional device is formed. In such a semiconductor wafer W, the defect F exists not in the surface of the sample but in the sample, that is, deep in the sample as viewed from the surface of the sample. Therefore, even when a general electron beam is irradiated from the surface, the electron beam is defective. It is difficult to reach. Therefore, it is difficult to observe the shape of the defect F using an apparatus that uses an electron beam, in the embodiment, the review SEM 200.

  In order to overcome this point, in the present embodiment, the FIB processing groove is formed from the surface near the defect position P of the semiconductor wafer W using the composite charged particle beam apparatus 100. FIG. 3B shows the first groove H formed corresponding to the position P of the defect, and FIG. 3C shows an enlarged view of a portion C in FIG.

  As shown in FIG. 3A, the position P of the defect inside the semiconductor wafer W is specified by an optical defect inspection apparatus or the like using infrared light (IR). If there are many defects, the position P of each defect is specified using these devices.

  Then, the composite charged particle beam apparatus 100 that has received the information (data) on the semiconductor wafer W and the position P of the defect shows the region including the position P and its periphery from the FIB column 1 as shown in FIG. The first groove H is formed in the region by cutting (etching) with the irradiated FIB. The composite charged particle beam apparatus 100 irradiates the FIB, cuts the semiconductor wafer W from the surface side of the semiconductor wafer W in a manner such as open digging, and advances the first groove H. As shown in FIG. 3C, the first groove H is generally formed in a rectangular shape in plan view, but the shape is not particularly limited.

  FIG. 4B shows a state in which the first groove H is formed by FIB, and corresponds to FIG. The first groove H is dug up to a predetermined depth from the surface of the semiconductor wafer W. In particular, the depth D1 of the first groove H allows the electron beam irradiated to the first groove H to reach the defect F. It is set to a certain degree. That is, in this example, the electron beam can penetrate at least over the length of the electron beam penetration length L1 from the bottom of the first groove H having the predetermined depth D1 to the lowest part of the defect F.

  In order to prevent the defect F from being cut by mistake, it is desirable that the depth D1 of the first groove H is set smaller than the depth D2 up to the uppermost position of the defect F. After the first groove H is formed, the review SEM 200 that has received the semiconductor wafer W irradiates the defect F with an electron beam through the first groove H, thereby observing the entire shape of the defect F in detail. be able to.

  In addition, the size of the region to be processed of the sample, in this example, the width L2 of the first groove H is set to be larger than the positional accuracy of the sample stage 5 of the composite charged particle beam apparatus 100. With such a setting, even if the position of the sample stage 5 and thus the sample S is slightly shifted due to the sample stage movement error, the first groove H is formed so as to be surely overlapped with the defect F when viewed from the surface side. That is, the semiconductor wafer W can be accurately processed so that the defect F can be observed by the review SEM 200 by the composite charged particle beam apparatus 100. Therefore, the irradiated electron beam always reaches the entire portion of the defect F through the first groove H, and the entire shape of the defect F can be observed in detail.

  Further, in the present embodiment, when analyzing the defect F in more detail, after the observation of the shape of the defect F by the review SEM 200, the FIB of the composite charged particle beam apparatus 100 is used again as shown in FIG. Two grooves G are formed, and the cross section of the defect F is observed using the electron beam from the EB column (electron beam irradiation unit) 2 of the composite charged particle beam apparatus 100. By forming the second groove G, the property of the defect F can be analyzed in more detail. Moreover, the defect F is analyzed in more detail by repeatedly slicing and observing the defect F to obtain an observation image inside the defect F and three-dimensional reconstruction of the observation image acquired thereby. can do. It is also possible to produce a thin piece sample including the defect F by FIB processing and observe the thin piece sample by TEM. By producing a thin sample, the defect F can be analyzed with high resolution.

  When gallium (Ga) is used for the FIB ion source used for forming the first groove H and the second groove G, the Ga implantation damage in the cross section of the formed defect F is measured from the GIB column 3. Can be removed by irradiation with a gaseous ion beam.

  FIG. 5 shows a procedure from defect position specification to cross-sectional observation using a defect inspection system including a composite charged particle beam apparatus (charged particle beam apparatus) 100 and a review SEM (electron beam irradiation apparatus) 200 of this embodiment. FIG.

  First, a sample S (for example, a semiconductor wafer) to be inspected whose defect position is detected by an operator using an optical defect inspection apparatus or the like is transferred to the charged particle beam apparatus 100. Also, defect position information is transferred from the optical defect inspection apparatus or the like to the charged particle beam apparatus 100, and the charged particle beam apparatus 100 identifies the position of the defect in the sample S based on the defect position information and moves the sample stage 5. . (Step S1). Next, the operator irradiates the surface of the sample S with FIB from the FIB column (charged particle beam irradiation unit) 1 to form the first groove H as shown in FIGS. 3 (b) and 4 (b). Etching is performed (step S2). When there are a plurality of defects in the sample, the first grooves H may be formed for some of the defects, but if the first grooves H are continuously formed for all the defects in this step, the following Since the first groove H is formed for all defects observed in the review SEM 200 in the step, the work efficiency is good.

  Next, the operator conveys the sample S in which the first groove H is formed to the review SEM 200. Also, defect position information is transferred from the optical defect inspection apparatus or the like to the review SEM 200, and the review SEM 200 identifies the position of the defect of the sample S with high position accuracy based on the defect position information, and moves the sample stage 205. Then, an electron beam is irradiated from the EB column 202 onto the defect below the first groove H, and the shape of the defect is observed (step S3). Although the process may be terminated here, the sample S is transported to the composite charged particle beam apparatus 100 again when further detailed analysis is required. Then, as shown in FIG. 4C, the FIB barrel 1 is irradiated with FIB onto the first groove H to perform cross-section processing for exposing the cross section of the defect F (step S4). Further, in the composite charged particle beam apparatus 100, the cross section of the defect F is observed by irradiating the processed cross section with an electron beam from the EB column (electron beam irradiation section) 2. Thereby, the property of the defect F can be analyzed in more detail (step S5).

  As described above, in the defect inspection system of the present embodiment, the characteristics of both the composite charged particle beam apparatus 100 suitable for sample processing and the review SEM 200 suitable for shape observation are utilized. A defect inspection apparatus detects a plurality of defects, and the composite charged particle beam apparatus 100 continuously forms a groove having a width wider than the stage position error in the vicinity of the defect position on the sample. Next, in the review SEM200, the defect position is identified at high speed and accurately with high position link accuracy based on the defect position information of the defect inspection apparatus, and the defect is observed by irradiating an electron beam that can reach the defect under the groove. can do. Therefore, the defect inside the three-dimensional device can be specified accurately and in a short time, and the analysis of the three-dimensional device can be performed accurately and in a short time.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. In addition, the material, shape, dimension, numerical value, form, number, arrangement location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

1: FIB column (charged particle beam irradiation unit)
2: EB column (electron beam irradiation unit)
3: GIB column (charged particle beam irradiation unit)
4: Secondary electron detector 5: Sample stage (sample stage)
6: Sample holder 8: Tilt drive unit 10: Rotation drive unit 11: FIB control unit 12: EB control unit 13: GIB control unit 14: Image forming unit 15: Sample stage control unit 16: Input unit 17: Control unit 18: Display unit 19: Gas gun 20: Storage device (storage unit)
40: Sample chamber 100: Compound charged particle beam device (charged particle beam device)
200: Review SEM (Electron Beam Irradiator)
202: EB column 204: Secondary electron detector 205: Sample stage (sample stage)
212: EB control unit 214: Image forming unit 215: Sample stage control unit 216: Input unit 217: Control unit 218: Display unit 220: Storage device (storage unit)
S: Sample W: Semiconductor wafer H: First groove G: Second groove

Claims (10)

A storage unit for storing a position of a defect existing in the sample of the three-dimensional device;
A sample stage for moving the sample;
A charged particle beam irradiation unit configured to irradiate a charged particle beam for processing the sample in a region including the position;
A charged particle beam device comprising :
The region is a charged particle beam device in which the position accuracy of the sample stage is larger . The charged particle beam device according to claim 1 ,
The charged particle beam irradiation unit is a charged particle beam apparatus that irradiates the charged particle beam from the surface side of the sample and performs etching processing to a predetermined depth from the surface. The charged particle beam device according to claim 1 or 2,
A defect inspection system comprising: an electron beam irradiation apparatus that irradiates the defect with an electron beam and observes the defect. A charged particle beam device according to claim 2 ;
An electron beam irradiation apparatus for irradiating the defect with an electron beam and observing the defect, and a defect inspection system comprising:
The defect inspection system, wherein a distance from the predetermined depth to the defect is a distance through which the electron beam can pass. The defect inspection system according to claim 3 or 4 ,
The charged particle beam apparatus is a defect inspection system capable of processing a cross section of the defect observed by the electron beam irradiation apparatus. The defect inspection system according to claim 5 ,
The charged particle beam apparatus is a defect inspection system including an electron beam irradiation unit that observes a cross section of the defect subjected to cross section processing. A storage unit for storing a position of a defect existing in the sample of the three-dimensional device;
A sample stage for moving the sample;
A charged particle beam irradiation unit configured to irradiate a charged particle beam for processing the sample in a region including the position;
A charged particle beam device comprising:
An electron beam irradiation apparatus for irradiating the defect with an electron beam and observing the defect, and a defect inspection system comprising:
The charged particle beam irradiation unit irradiates the charged particle beam from the surface side of the sample, etches from the surface to a predetermined depth,
The defect inspection system, wherein a distance from the predetermined depth to the defect is a distance through which the electron beam can pass . The defect inspection system according to claim 7 ,
The defect inspection system in which the area is larger than the positional accuracy of the sample stage. The defect inspection system according to claim 7 or 8 ,
The charged particle beam apparatus is a defect inspection system capable of processing a cross section of the defect observed by the electron beam irradiation apparatus. The defect inspection system according to claim 9 ,
The charged particle beam apparatus is a defect inspection system including an electron beam irradiation unit that observes a cross section of the defect subjected to cross section processing.

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