WO2011102511A1 - 回路パターン検査装置 - Google Patents
回路パターン検査装置 Download PDFInfo
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- WO2011102511A1 WO2011102511A1 PCT/JP2011/053686 JP2011053686W WO2011102511A1 WO 2011102511 A1 WO2011102511 A1 WO 2011102511A1 JP 2011053686 W JP2011053686 W JP 2011053686W WO 2011102511 A1 WO2011102511 A1 WO 2011102511A1
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- 238000010894 electron beam technology Methods 0.000 claims abstract description 306
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
- H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/10—Measuring as part of the manufacturing process
- H01L22/12—Measuring as part of the manufacturing process for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/26—Electron or ion microscopes
- H01J2237/28—Scanning microscopes
- H01J2237/2809—Scanning microscopes characterised by the imaging problems involved
- H01J2237/2811—Large objects
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/26—Electron or ion microscopes
- H01J2237/28—Scanning microscopes
- H01J2237/2813—Scanning microscopes characterised by the application
- H01J2237/2817—Pattern inspection
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- H—ELECTRICITY
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Definitions
- the present invention relates to a defect inspection technique for a substrate having a fine circuit pattern such as a semiconductor device or a liquid crystal device, and more particularly to a defect inspection technique for a pattern on a substrate typified by a semiconductor wafer in the course of manufacturing a semiconductor device.
- a semiconductor device is manufactured by repeating a process of transferring a circuit pattern formed on a photomask on a semiconductor wafer by lithography and etching.
- the quality of the lithography process and the etching process, the generation of foreign matter, and the like greatly affect the yield of the semiconductor device. Therefore, various devices (circuit pattern inspection devices) for inspecting defects existing in the circuit pattern on the semiconductor wafer in the manufacturing process are used to detect such abnormalities and defects in the manufacturing process early or in advance. ing.
- an optical defect inspection device that irradiates a semiconductor wafer with light and compares the same kind of circuit patterns of multiple LSIs using an optical image, and a semiconductor particle is irradiated with a charged particle beam such as an electron beam.
- An electron beam type defect inspection apparatus that detects the generated secondary electrons and reflected electrons, images the signals, and detects defects has been put into practical use.
- the electron beam type defect inspection apparatus performs defect inspection by comparing SEM (scanning electron microscope) images.
- SEM scanning electron microscope
- the stage is moved stepwise and repeated, and an electron beam is scanned two-dimensionally at each stage stop position, and the stage is scanned and moved in one direction at a constant speed.
- the latter method having excellent throughput is mainly used.
- a non-patent document 1, a non-patent document 2, a patent document 1, and a patent document 2 are irradiated with an electron beam 100 times or more (10 nA or more) of a normal SEM.
- a method is disclosed in which any of the generated secondary electrons, reflected electrons, and transmitted electrons is detected, and an image formed from the signal is compared and inspected between adjacent identical patterns.
- the direction of the circuit pattern (particularly the longitudinal direction of the pattern) contained in many areas where defects are likely to occur, such as peripheral circuits near the upper and lower ends of the memory mat and peripheral circuits near the left and right edges toward the wafer Each may be different. In such a case, the optimum beam scanning direction for inspecting the corresponding area is different.
- an electron beam irradiation area called swath which will be described later, is set and a wafer image is acquired, so the degree of freedom in setting the inspection area is limited. Furthermore, since the inspection cannot be performed by changing the beam scanning direction for each inspection region, the inspection is performed in a beam scanning direction that is not optimal depending on the inspection region.
- a step-and-repeat inspection apparatus has a relatively large degree of freedom in setting an inspection region, but is not practical in terms of throughput. For this reason, the conventional circuit pattern inspection apparatus has a problem that it is difficult to efficiently inspect a region where defects are likely to occur.
- An object of the present invention is to provide a circuit pattern inspection apparatus capable of efficiently acquiring an image of an arbitrary inspection area set in a swath in a circuit pattern inspection apparatus of a stage continuous movement method.
- the above-described problem is solved by introducing two-dimensional beam deflection control in the circuit pattern inspection of the stage continuous movement method, which has been conventionally performed only for one-dimensional scanning.
- the electron beam deflection control in the first direction parallel to the moving direction of the stage and the electron beam deflection control in the second direction crossing the first direction are used in combination. It is possible to acquire an image of an arbitrary inspection area set in the swath.
- the electron beam deflection signal waveforms in the first and second directions are based on the inspection conditions (scanning conditions of the electron beam such as the size of the region to be inspected, the beam deflection frequency, the number of integrated frames, the presence / absence of pre-scanning, etc.) ).
- the image other than the inspection area may not be taken, but preferably, the deflection control of the electron beam is performed so as to obtain an image of only the set inspection area.
- the present invention it becomes possible to selectively inspect a region such as a pattern boundary of a semiconductor wafer where defects are likely to occur in the manufacturing process of the semiconductor wafer (substrate), thereby realizing efficient inspection of the semiconductor wafer. .
- FIG. 1 is a schematic diagram illustrating a configuration of a circuit pattern inspection apparatus according to a first embodiment.
- FIG. 3 is a diagram illustrating an inspection region, an X deflection signal, and a Y deflection signal in the circuit pattern inspection apparatus according to the first embodiment.
- FIG. 3 is a diagram illustrating electron beam scanning in an inspection region in the circuit pattern inspection apparatus according to the first embodiment.
- FIG. 10 is a diagram illustrating an inspection region, an X deflection signal, and a Y deflection signal in the circuit pattern inspection apparatus according to the second embodiment.
- FIG. 6 is a diagram illustrating electron beam scanning in an inspection region in the circuit pattern inspection apparatus according to the second embodiment.
- FIG. 10 is a diagram illustrating an inspection region, an X deflection signal, and a Y deflection signal in the circuit pattern inspection apparatus according to the third embodiment.
- FIG. 10 is a diagram illustrating electron beam scanning in an inspection region in the circuit pattern inspection apparatus according to the third embodiment.
- FIG. 10 is a diagram illustrating an inspection region, an X deflection signal, and a Y deflection signal in the circuit pattern inspection apparatus according to the fourth embodiment.
- FIG. 10 is a diagram illustrating electron beam scanning in an inspection region in the circuit pattern inspection apparatus according to the fourth embodiment.
- FIG. 10 is a diagram illustrating an inspection region, an X deflection signal, and a Y deflection signal in the circuit pattern inspection apparatus according to the fifth embodiment.
- FIG. 10 is a diagram illustrating an inspection region, an X deflection signal, and a Y deflection signal in the circuit pattern inspection apparatus according to the sixth embodiment.
- FIG. 15 is a diagram illustrating an inspection region, an X deflection signal, and a Y deflection signal in the circuit pattern inspection apparatus according to the seventh embodiment.
- FIG. 10 is a diagram illustrating electron beam scanning in an inspection region in the circuit pattern inspection apparatus according to the seventh embodiment.
- the moving direction of the stage is defined as the X-axis direction
- the direction perpendicular to the moving direction of the stage within the wafer surface is defined as the Y-axis direction.
- the leftward direction is the ⁇ X direction
- the rightward direction is the + X direction
- the upward direction is the + Y direction
- the downward direction is the ⁇ Y direction.
- FIG. 2A is a diagram showing a trajectory of an irradiation electron beam on a wafer.
- the irradiation electron beam 21 is applied to the wafer 22 while being continuously scanned in the Y direction by a deflector (not shown).
- the stage not shown in the figure moves in the ⁇ X direction, and the wafer 22 is moved in the ⁇ X direction as indicated by the arrow 23, so that the irradiation electron beam 21 is moved along the locus indicated by the arrow 24. 22 is irradiated.
- FIG. 2B is a diagram showing a part of the inspection area on the wafer and an X deflection signal and a Y deflection signal for scanning the irradiation electron beam.
- an area corresponding to the locus drawn by the irradiation electron beam on the wafer is called a swath.
- the single operation of the stage refers to the continuous movement of the stage from the stationary state to the longitudinal direction of the swath until the movement is finished with respect to a certain swath.
- swath irradiating a region corresponding to a swath with an electron beam
- the swath 25 includes a plurality of inspection areas 26a, 26b, and 26c.
- the X deflection signal 28 is a signal for scanning the irradiation electron beam in the X direction
- the Y deflection signal 29 is a signal for scanning the irradiation electron beam in the Y direction.
- the vertical axis of the illustrated X deflection signal and Y deflection signal corresponds to the deflection voltage of the deflector
- the horizontal axis corresponds to the position in the X direction.
- the width of the swath 25 (the length in the Y direction in the case of FIG. 2B) corresponds to the scanning width of the one-dimensional scanning of the electron beam.
- the irradiation position of the electron beam when the X deflection signal 28 and the Y deflection signal 29 are zero is on the wafer along the dotted line 27 indicating the center of the swath 25 from the ⁇ X direction to the + X direction (left side of FIG. 2B). Move to the right).
- the “irradiation position of the electron beam when the X deflection signal and the Y deflection signal are zero” that is, the projection position on the sample of the central axis (electron beam optical axis) of the electron optical column provided in the inspection apparatus. This is referred to as “electron beam reference position”.
- an X deflection signal 28 and a Y deflection signal 29 indicate the deflection signal amounts of the deflector in the X direction and the Y direction corresponding to the position of the swath 25, respectively.
- the X deflection signal 28 in the direction parallel to the stage moving direction (X direction) is always zero in one swath. Therefore, the irradiation electron beam is deflected only by the Y deflection signal 29 in the direction perpendicular to the stage moving direction (Y direction), and continuously scans the wafer.
- the relationship between the stage speed and the deflection speed of the irradiation electron beam will be described.
- the irradiation electron beam makes one round trip in the scanning direction of the one-dimensional scanning (the Y direction in FIG. 2B), That is, it is only necessary to move the stage by the length of one scanning line in the stage moving direction (that is, one pixel) during the time required for scanning one scanning line.
- the time required for the primary charged particle beam to scan one scanning line is equal to 1 / f where f is the deflection frequency of the deflector.
- image data for one scanning line per 1 / f time is output from a secondary electron or reflected electron detector provided in the inspection apparatus. Therefore, 1 / f is equal to the image detection time for one line, and in the stage continuous movement type inspection apparatus, the stage speed is normally set to a speed that can move by one pixel size in the time of 1 / f. .
- the upper stage speed is referred to as a normal stage speed synchronized with the beam scanning, and is represented by the symbol V 0 .
- the defects generated in the semiconductor chip tend to concentrate on a part of the area such as the edge of the memory mat. Therefore, if a location where a defect occurs is assumed in advance and only an image in a target area can be acquired and inspected, the burden of image processing can be reduced and more efficient inspection can be performed.
- the beam deflection control of this embodiment forms a basic form of beam deflection control of each embodiment described below.
- FIG. 1 is a configuration diagram of an electron beam type wafer inspection apparatus which is an example of a circuit pattern inspection apparatus according to the present embodiment.
- the main body of the electron beam type wafer inspection apparatus includes a column 1 which is an electron optical system, and an XY stage 2 on which a wafer (substrate) 8 is placed.
- the column 1 serves as an electron beam scanning unit that irradiates and scans the wafer 8 with an electron beam.
- a circuit pattern is formed on the wafer 8.
- the electron beam wafer inspection apparatus further includes a beam scanning controller 11, a stage controller 12, and an image processing unit 13.
- the column 1 includes an electron gun 3 that generates an irradiation electron beam (hereinafter also simply referred to as “electron beam”) 9, a condenser lens 4 and an objective lens 5 for converging the irradiation electron beam 9 and irradiating the wafer 8, and irradiation.
- a deflector 6 for scanning the electron beam 9 with respect to the wafer 8 and a secondary electron detector 7 for detecting secondary electrons 10 generated from the wafer 8 by the irradiation electron beam 9 are provided.
- the deflector 6 deflects the irradiation electron beam 9 in accordance with signals (X deflection signal and Y deflection signal) from the beam scanning controller 11 to scan the wafer 8.
- the XY stage 2 moves in accordance with a signal from the stage controller 12 and moves the wafer 8 relative to the column 1.
- the beam scanning controller 11 has a built-in sequencer that generates signal patterns of X deflection signals and Y deflection signals corresponding to each scanning pattern, and transmits the generated X deflection signals and Y deflection signals to the deflector 6. Control of scanning and deflection of the irradiation electron beam 9 is performed.
- the stage controller 12 transmits a signal to the XY stage 2 and controls movement of the XY stage 2.
- a signal from the secondary electron detector 7 is sent to the image processing unit 13.
- the image processing unit 13 links the signal from the secondary electron detector 7 with the position information from the beam scanning controller 11 and the stage controller 12 and executes image processing for defect detection. Specifically, the image processing unit 13 images the signal from the secondary electron detector 7 for a certain circuit pattern, compares this image with an image formed from another identical circuit pattern, and calculates the circuit from the comparison result. Detect pattern defects.
- the beam scanning controller 11, the stage controller 12, and the image processing unit 13 are controlled by the control PC.
- the control PC 14 is provided with a screen display means and a pointing device such as a mouse, and a setting screen for inputting various setting conditions for operating the apparatus is displayed on the screen display means.
- the apparatus operator sets and registers various types of information necessary for inspection, such as setting of the inspection area, via the setting screen.
- FIG. 3A is a diagram showing an example of an X deflection signal and a Y deflection signal for scanning a swath set on a wafer and an irradiation electron beam.
- the vertical axis of the X deflection signal and Y deflection signal shown in the figure is the deflection voltage.
- the horizontal axis is indicated by the X-direction position on the inspection area in order to correspond to the X-direction position of the swath, but the time information is also shown for easy understanding.
- the inspection areas 32, 33, 34, and 35 are set on the swath 31.
- the inspection areas 32, 33, 34, and 35 are assumed to be rectangular.
- the scanning speed (pixel sampling frequency) of the irradiation electron beam is constant, and the stage speed is also synchronized with the scanning speed.
- the moving direction of the stage is in the ⁇ X direction as indicated by the white arrow, and the wafer is moved from the + X direction side to the ⁇ X direction side.
- Swath 31 is executed by one operation of the stage. Since the stage moves in the ⁇ X direction, the electron beam reference position moves from the ⁇ X direction to the + X direction (left to right in FIG. 3A) on the wafer along the dotted line 36 indicating the center of the swath 31.
- Arrows in the inspection areas 32, 33, 34, and 35 indicate the scanning direction of the irradiation electron beam. In the inspection areas 32 and 34, an electron beam is scanned in the direction perpendicular to the stage movement direction (Y direction), and in the inspection areas 33 and 35, the electron beam is scanned in a direction parallel to the stage movement direction (X direction).
- the above setting of the scanning direction is merely an example, and the scanning direction can be arbitrarily set in each inspection region. For example, an electron beam may be scanned in the X direction in the inspection region 32, or an electron beam scan in the Y direction may be performed in the inspection region 35.
- the X deflection signal 37 is positive when the irradiation electron beam swings in the + X direction (right direction in FIG. 3A), and the Y deflection signal 38 is positive when the irradiation electron beam swings in the + Y direction (upward direction in FIG. 3A).
- the X deflection signal 37 is positive when the irradiation electron beam swings in the + X direction (right direction in FIG. 3A)
- the Y deflection signal 38 is positive when the irradiation electron beam swings in the + Y direction (upward direction in FIG. 3A).
- the electron beam scanning in the inspection region 32 is started.
- the inspection region 32 is set below the swath 31 (end in the ⁇ Y direction), and the scanning direction of the electron beam is set to the Y direction.
- the signal waveform of the Y deflection signal 38 is changed from a center point of the swath 31 to a scanning start point (in the inspection region 32), with a signal pattern having an amplitude such that the scanning width is the length in the Y direction of the inspection region 32.
- the signal waveform is obtained by adding the offset signal in the minus direction for the lower left corner). Since scanning in the X direction is not performed, the X deflection signal 37 is constant.
- Electron beam irradiation position at time t 2 is electron beam scanning of the examination region 32 and reaches the position X2 ends.
- FIG. 3B shows electron beam scanning in the inspection region 33.
- the electron beam is scanned in the order of arrows 39a, 39b, 39c, and 39d from the lower side of the inspection region 33.
- the electron beam scanning indicated by arrow 39a, the time t 3, the electron beam reference position is located on a position X3. Therefore, the X deflection signal 37 corresponding to the arrows 39a to 39d is monotonic in the -X direction in synchronization with the stage speed of the sawtooth waveform deflection signal having a signal amplitude corresponding to the X direction size (X4-X3) of the region 33.
- the reduced signal pattern is added.
- the rising edge of the sawtooth waveform is electron beam scanning in the + X direction, and the falling edge is back deflection in the stage movement direction ( ⁇ X direction).
- the scanning start position of the next scanning line 39b is made to coincide with the position X3 on the wafer by beam deflection (backward deflection) in the same direction as the stage moving direction.
- beam deflection in the + X direction is necessary because the stage moving distance during the beam deflection execution time in the + X direction is about one pixel size and the stage speed is slow. This is because even if the stage moves in a state where beam deflection in the direction is stopped, scanning for the size 33 in the X direction (X4 ⁇ X3) of the region 33 cannot be completed.
- Y deflection signal 37 when the scanning of the arrow 39a at time t 3 is started, Y deflection signal 37, the size of which corresponds to the location of the Y-direction of the arrow 39a (distance between the center line 36 of the swath 31 and arrow 39a) A positive offset signal is applied. Further, since the beam deflection in the Y direction is not performed during the scanning of the arrow 39a, the Y deflection signal 37 is constant while the electron beam is scanning on the arrow 39a. When the X-direction beam deflection of the arrow 39a is completed, the beam irradiation position is shifted upward in accordance with the Y coordinate position of the arrow 39b that is the next scanning line.
- the signal waveform of the Y deflection signal 37 has a stepped signal pattern as shown in FIG. 3A.
- the Y deflection signal 37 is returned to zero. If the number of scanning lines increases, the stepped signal pattern shown in FIG. 3A approaches a linear function-like signal pattern that monotonously increases or monotonously decreases.
- the inspection area 34 is scanned in the same manner as the inspection area 32 having the same scanning direction of the irradiation electron beam, and the inspection area 35 is scanned in the same manner as the inspection area 33 having the same scanning direction of the irradiation electron beam. Therefore, detailed description is omitted.
- a stage continuous circuit pattern inspection apparatus capable of inspecting an arbitrary area of a wafer can be realized.
- the description has been made on the assumption that images of the swaths 31 other than the inspection areas 32 to 35 are not acquired.
- the scanning area is acquired while acquiring images of portions other than the inspection areas. It is also possible to obtain an image of each inspection area by switching the scanning direction when the inspection area reaches each inspection area.
- the beam deflection control when the stage speed is synchronized with the beam scanning speed has been described.
- the stage speed is increased and the region not irradiated with the electron beam is skipped. If such an inspection can be performed, it is very advantageous for speeding up the inspection.
- FIG. 1 is appropriately referred to in the following description.
- FIG. 4A shows a configuration example of X deflection signals and Y deflection signals that enable swaths set on the wafer and high-speed stage movement, and also shows the arrangement of scanning lines in the inspection region shown in FIG. 4B. A schematic diagram is shown respectively.
- a plurality of inspection areas 42, 43, 44, 45 are set in the swath 41.
- the inspection area setting conditions such as arrangement and shape are the same as those in the inspection areas 32 to 35 described in the first embodiment.
- the electron beam scans in the direction perpendicular to the stage moving direction (Y direction).
- the electron beam is scanned in the direction parallel to the stage moving direction (X direction).
- the moving direction of the stage is also in the ⁇ X direction as in the first embodiment. Therefore, the wafer is moved from the + X direction side to the ⁇ X direction side.
- the electron beam is not irradiated to the areas other than the inspection areas 42, 43, 44, and 45. Accordingly, since the region not irradiated with the electron beam is included, the “swath” of the present embodiment is different from the conventional “swath”, and the beam is in the direction intersecting the stage moving direction (for example, Y direction in FIG. 4A).
- a deflection width a movement width of the electron beam, which is different from the scanning width
- the swath width that can be set is limited by the maximum field size of the electron optical column (maximum deflection length within the range where the off-axis aberration can be ignored), and multiple inspection areas can be created by moving the stage once.
- the optimal swath for inspection is determined by the apparatus based on the inspection area set by the apparatus operator and the set value of the beam change width. Calculated automatically.
- the stage speed is set to be higher than the normal synchronization speed (for example, V; V> V 0 ).
- the stage speed and the beam scanning speed that is, the deflection frequency of the deflector 6
- the beam deflection starts when the electron beam reference position reaches the end of each scanning area, for example, the position X1 or X3.
- the scanning start position on the inspection area coincides with the beam deflection start time.
- the stage speed and the beam scanning speed are asynchronous, and when the beam deflection start time is set in accordance with the synchronization time of the electron beam reference position and the scanning start position on the inspection area, as in FIG. 3A.
- a situation occurs in which the electron beam scanning does not end between the time when the electron beam reference position passes the left end of the inspection region and the time when the electron beam reference position passes the right end of the inspection region.
- the actual time that the electron beam actually scans the inspection region (the time obtained by dividing the total scanning distance in the inspection region by the scanning speed) is the time necessary for image acquisition and cannot be increased or decreased.
- the distance that the wafer moves during the beam scanning time is longer than the length of the inspection area in the stage movement direction because of the asynchronous high-speed stage movement. Therefore, the beam deflection start time is set forward according to the beam scanning speed, and the end time is set backward.
- the positional deviation between the electron beam reference position and the inspection region (position where the electron beam should be scanned originally) due to the shift of the start time and the end time is absorbed by beam deflection in the X direction. Beam deflection control based on this concept makes it possible to acquire an image of a necessary area while moving the stage at high speed.
- the inspection area 42 is an inspection area set so as to contact the lower end of the swath 41, and the scanning direction is the Y direction. Therefore, the beam deflection start time t 1 of the Y deflection signal 48 when scanning the inspection area 42 is set before the time t 2 when the electron beam reference position passes the left end X 2 of the inspection area 42. At this time, on the actual wafer, the electron beam reference position is present at a position X1 that is shifted to the near side ( ⁇ X direction side) from the left end X2 of the inspection region.
- the deviation between the electron beam reference position generated at this time and the right end X3 of the inspection area 42 corresponds to the deflection length (X4-X3), and the polarity is offset by superimposing an offset in the ⁇ X direction on the X deflection signal 47. It will be resolved.
- the X deflection signal 47 after the offset is superimposed at time t 1, the signal for correcting the difference between the electron beam reference position and the scanning target position within the examination region 42 is continuously added. Since the amount of positional deviation between the electron beam reference position and the position where the beam should be irradiated originally varies depending on the elapsed time between the stage speed and the beam scanning speed, the correction amount of the X deflection signal 47 is determined by inspection. As the scanning of the region 42 progresses, it decreases monotonously. Considering the distance dimension, moving the beam deflection start time forward is equivalent to starting electron beam scanning with a margin of a certain distance, but the stage speed is larger than the beam scanning speed, so the stage moves.
- the movement of the beam irradiation position due to gradually catches up with the movement of the electron beam reference position by beam scanning, and at some point the margin is exhausted and becomes zero.
- the movement of the electron beam reference position by the beam scanning is gradually separated from the movement of the beam irradiation position by the stage movement, and the electron beam reference position should be originally irradiated with the position X4 at the beam deflection end time. It is pulled away from the position X3 to the right side (rear in the stage movement direction).
- the beam deflection is controlled so that the position where the above-mentioned distance margin is exhausted (that is, the position where the beam irradiation position that should be scanned and the electron beam reference position match) is the center of the inspection region 42.
- Conditions are set. That is, on the left side of the inspection area 42, the target scan line is always on the right side of the electron beam reference position, and on the right side of the inspection area 42, the target scan line is always on the left side of the electron beam reference position. Become. Therefore, the correction amount of the X deflection signal 47 is always positive on the left side of the inspection region 42, and the correction amount of the X deflection signal 47 is always negative on the right side of the inspection region 42.
- the relative relationship between the positions X1 and X4 and the positions X2 and X3 becomes symmetric, and the timing control of the X deflection signal and the Y deflection signal becomes very simple. As a result, it is possible to easily realize the bi-directional inspection by moving the stage in the ⁇ X directions, and to optimize the inspection speed.
- the positions X1 and X4 can be calculated based on the following relationship.
- the inspection region 42 is scanned from the position X2 to the position X3 at the normal stage speed.
- the ratio ⁇ between the stage moving speed V and the normal stage speed V 0 is referred to as a stage moving speed coefficient.
- the inspection area 43 is an inspection area set so as to be in contact with the upper end portion of the swath 41, and the scanning direction is the X direction, but the basic concept of the beam deflection control is the same as in the case of the inspection area 42. .
- the beam deflection start time t 5 of the X deflection signal 47 and the Y deflection signal 48 is set before the time t 6 when the electron beam reference position passes the left end X 2 of the inspection region 43, and the X deflection signal 47 and Y beam deflection end time t 8 of the deflection signal 48 is also set to after time t 7 an electron beam reference position passes the position X7 is a right end of the inspection region 43.
- FIG. 4B schematically shows electron beam scanning in the inspection region 43.
- the electron beam is scanned in the order of arrows 49a, 49b, 49c, and 49d.
- the XY deflection signals corresponding to the arrows 49a to 49d are basically signals having a sawtooth waveform in the scanning direction and a stepped waveform in the direction intersecting the scanning direction.
- This pattern is a sawtooth waveform deflection signal having a signal amplitude corresponding to the X direction size (X7-X6) of the region 43, and a shape in which a monotonously decreasing signal pattern in the -X direction synchronized with the stage speed is added.
- the rising edge of the sawtooth waveform is electron beam scanning in the + X direction, and the falling edge is back deflection in the stage movement direction ( ⁇ X direction).
- the electron beam reference position is located at a position X5, than the left end of the inspection region 43 to the electron beam is scanned original (position X6) Only (X6-X5) is on the left. Therefore, the X deflection signal 47, at time t 5 (X6-X5) corresponding deflection voltage is added.
- the electron beam scanning indicated by the arrow 49a is performed when the X deflection signal 47 corresponding to the signal amplitude corresponding to the X direction size (X7-X6) of the region 43 rises starting from this state. Thereafter, the signal pattern falls by the amount corresponding to the signal amplitude corresponding to the return deflection, and thereafter the rise and fall are repeated continuously, whereby the electron beam scanning of the scanning lines indicated by the arrows 49b to 49d is executed.
- the Y deflection signal 48 is a stepped signal pattern having an increment in the + Y direction synchronized with the rise of the X deflection signal 47 and a horizontal component synchronized with the beam deflection time in the + X direction. Become.
- the signal rise of the X deflection signal 47 and the rise of the increment of the Y deflection signal 48 are not strictly synchronized, but may be considered to be roughly synchronized if detailed time control is ignored.
- the inspection area 44 is scanned in the same procedure as the inspection area 42 in which the scanning direction of the irradiation electron beam is the same.
- the inspection area 45 is scanned in the same procedure as the inspection area 43 in which the scanning direction of the irradiation electron beam is the same.
- the magnitude of the offset signal added to the Y deflection signal 48 is It is necessary to change according to the position of the inspection areas 44 and 45 in the Y direction.
- position information such as the positions X2, X3, X6, and X7 is an amount determined by the wafer to be inspected, and the stage movement speed coefficient ⁇ indicates how much high-speed inspection is performed. The amount is determined by the information of whether or not. Therefore, when the above beam deflection control is installed in the apparatus, information corresponding to the above positions X2, X3, X6, X7 and ⁇ (or information for calculating them) is supplied from the control PC 14 by the apparatus operator. Based on the input on the setting screen, the control information such as the positions X1, X4, X5, and X8 is calculated by the control PC.
- the beam scanning controller 11 and the stage controller 12 control the voltage and timing control of the XY deflection signal or the stage speed based on the control information of the positions X1, X4, X5, and X8 calculated by the control PC.
- the inspection apparatus realizes a circuit pattern inspection apparatus capable of significantly increasing the inspection speed as compared with the prior art while maintaining the effect of the first embodiment that an arbitrary area of a wafer can be inspected. .
- FIG. 1 is appropriately referred to in the following description.
- FIG. 5A is a diagram showing an X deflection signal and a Y deflection signal for scanning the memory mat of the wafer, its peripheral circuit region, and the irradiation electron beam.
- a chip formed on the wafer is provided with a region in which memory cells called memory mats are regularly arranged.
- a region called a peripheral circuit unit is further provided around the memory mat.
- 5A includes a memory mat 52, a peripheral circuit region 53 disposed between the upper and lower sides (Y direction) of the memory mat 52, and a peripheral circuit region 54 disposed between the left and right sides (X direction).
- a schematic diagram when swath is set is shown. It is assumed that the swath width (the length in the direction intersecting the stage moving direction) is set in advance by the operator according to the width of the memory mat via the setting screen described in the first embodiment. Further, the moving direction of the stage is the ⁇ X direction as in the first and second embodiments, and the beam scanning speed (pixel sampling frequency) is not changed while the stage is moving.
- the peripheral circuit region 54 has a longer region length in the direction perpendicular to the stage movement (Y direction) than the peripheral circuit region 53, so the time required for the electron beam to reciprocate each region is:
- the peripheral circuit area 54 is larger than the peripheral circuit area 53.
- the stage speed is set to a speed at which the electron beam can move by one pixel size while reciprocating one scanning line. Accordingly, the stage speed that can be set for the inspection of the peripheral circuit area 54 is slower than the stage speed that can be set for the inspection of the peripheral circuit area 53.
- the stage speed is set to the slower speed, and the scanning of the peripheral circuit area 53 is performed between electron beam scans. Therefore, the stage speed must be matched with the scanning speed of the electron beam.
- this method is not preferable because the inspection speed is reduced by the waiting time.
- the scanning direction is changed (direction intersecting the longitudinal direction) according to the shape (longitudinal direction) of the peripheral circuit regions 53 and 54, and the deflection signal waveform is adapted to each peripheral circuit region.
- the scanning direction is set to the Y direction for the peripheral circuit region 53 whose longitudinal direction is the stage moving direction, and the scanning direction is set to the peripheral circuit region 54 whose longitudinal direction intersects the stage moving direction.
- the stage speed is obtained as (X5 ⁇ X1) / (T1 + T2), and the peripheral circuit region 53 is adjusted according to the time for which the electron beam reference position moves by the combined distance of the peripheral circuit region 53 and the peripheral circuit region 54.
- the electron beam scanning of the peripheral circuit region 54 is finished.
- T1 and T2 are times required to scan one of the peripheral circuit regions 53 and 54 with the irradiation electron beam, respectively.
- the stage speed is lower than the electron beam scanning speed for the peripheral circuit region 53, and the stage speed is electron beam scanning for the peripheral circuit region 54. Be faster than speed. Therefore, the same situation as in the second embodiment occurs in the peripheral circuit region 54, and the opposite situation in the second embodiment occurs in the peripheral circuit region 53. Therefore, as in the second embodiment, the beam deflection start time is moved forward and the end time is moved backward, and the beam deflection start time is moved backward for the peripheral circuit region 53.
- the inspection is executed by performing beam deflection control so that the end time is advanced.
- FIG. 5B is a diagram showing electron beam scanning of the peripheral circuit region 53 and the peripheral circuit region 54 of the memory mat 52 of the swath 51.
- the electron beam scanning of the peripheral circuit region 53 will be described.
- scanning of the peripheral circuit region 53 is started at the scanning start position X2
- the electron beam in the peripheral circuit region 53 is scanned in the order of arrows 58a, 58b, 58c, 58d, 58e, and 58f.
- the inspection apparatus When performing the scanning indicated by the arrow 58a, the inspection apparatus starts beam deflection when the electron beam reference position reaches the position X2 (time t 2 ).
- the electron beam reference position is (X2-X1) on the right side of the left end (position X1) of the peripheral circuit region 53 that should originally be irradiated with the electron beam. Accordingly, an offset signal in the minus direction is added to the X deflection signal 56 corresponding to the arrow 58a by a deflection amount corresponding to the distance of (X2-X1).
- the offset in the negative direction due to the X deflection signal 56 gradually decreases, and the offset is zero at the position where the scanning is completed up to the center of the peripheral circuit region 53. It becomes. Thereafter, the offset in the plus direction gradually increases, and a plus deflection amount corresponding to the distance (X4 ⁇ X3) is added to the X deflection signal 56 as an offset at the scanning end position X3.
- the Y deflection signal 57 is added to the sawtooth waveform signal for scanning in the Y direction in the plus direction corresponding to the scanning position in the Y direction.
- the signal is added with the offset.
- the beam deflection control similar to the arrow 58a is performed, and the other peripheral circuit region 53 is scanned.
- the electron beam reference position is (X4-X3) on the left side ( ⁇ X direction) from the left end (X4) of the peripheral circuit region 54.
- the X deflection signal 56 corresponding to the arrow 59g starts with a positive offset amount corresponding to (X4 ⁇ X3) and has a signal amplitude corresponding to the X direction size (X5 ⁇ X4) of the peripheral circuit region 54. .
- the X deflection signal 56 for the previous scanning line is equivalent to the amount of stage movement from the start of scanning indicated by the arrows 59g to 59h, which are the previous scanning lines, respectively. Starts from the minus side.
- the electron beam reference position is (X6-X5) on the right side (+ X direction) from the right end (X5) of the peripheral circuit region 54. Therefore, the scanning of the irradiation electron beam indicated by the arrow 59j starts from a negative offset amount corresponding to (X6-X4) and ends with a negative deflection amount corresponding to (X6-X5). It becomes.
- an offset signal corresponding to the scanning position in the Y direction of the electron beam indicated by the arrows 59g, 59h, 59i, and 59j is added to the Y deflection signal 57.
- the signal waveform of the Y deflection signal 57 is a stepped waveform similar to those of the first and second embodiments, but is illustrated by a straight line in FIG.
- the control PC 14 can determine the longitudinal direction of each inspection region pattern from the image (or design information) of each inspection region acquired in advance, and can determine the scanning direction based on the determination result. is there.
- the beam scanning controller 11 and the stage controller 12 control the voltage and timing control of the XY deflection signal, or the stage speed based on the control information such as the scanning direction and the positions X1, X4, X5, and X8 calculated by the control PC 14. To do.
- an inspection apparatus capable of performing inspection without waiting time without changing a control operation that causes a reduction in throughput such as changing the stage speed or changing the beam scanning speed during the inspection is realized.
- the irradiation electron beam is scanned in two directions, the X direction and the Y direction, but the scanning direction is not limited to these two directions. For example, you may scan in the direction of 45 degrees with respect to the X direction.
- FIG. 1 will be referred to as appropriate in the following description. Further, since the basic preconditions are the same as before, the same description will not be repeated.
- FIG. 6A is a diagram showing a mat peripheral portion of a memory mat of a wafer and an X deflection signal and a Y deflection signal for scanning an irradiation electron beam.
- a memory mat 62 is arranged on the wafer, and a mat outer peripheral portion 63 in the memory mat 62 is an inspection region.
- the swath 61 includes a memory mat 62 array including a mat outer periphery vicinity portion 63.
- the stage speed is determined by the following method.
- a position X6 is a position at the right end (+ X direction) of the mat outer peripheral vicinity 63, and (X9 ⁇ X6) is an interval of the memory mat 62.
- the positions X7 and X8 are determined based on the memory mat interval (X9-X6) and the width of the memory mat 62 in the X direction (X6-X2).
- ⁇ is a distance for taking a preparation time required from the end of scanning of a certain inspection area (mat outer periphery vicinity 63) to the start of scanning of the next inspection area (mat outer periphery vicinity 63). It is sufficiently smaller than the interval (X9-X6).
- the time T required to scan the entire inspection region is calculated from the size of the inspection area and the electron beam scanning conditions, and the stage speed is obtained by the calculation formula (X6-X1) / T. .
- (X9 ⁇ X8) (X2 ⁇ X1) from the repeatability of the pattern.
- FIG. 6B is a diagram showing electron beam scanning of the vicinity 63 of the outer periphery of the mat of the memory mat 62 of the swath 61.
- the electron beam scanning of the mat outer periphery vicinity portion 63 will be described with reference to FIG. 6B.
- the irradiation electron beam is scanned in the order of arrows 67a, 67b, 67c, 67d, 67e, 67f, 67g, and 67h. In this way, beam scanning is performed parallel to the mat boundary. In this case, since the number of beam scans in the entire inspection region is smaller than the beam scan perpendicular to the mat boundary, the total beam return time can be reduced to shorten the inspection time T.
- Arrows 67a and 67b indicate scanning of the peripheral portion on the left side ( ⁇ X direction side) of the memory mat 62.
- the X deflection signal 65 an offset signal for correcting the difference between the electron beam reference position and the scanning target position at the time of scanning of each irradiation electron beam is output.
- the Y deflection signal 66 a scanning signal in the Y direction is output.
- Arrows 67c and 67d indicate scanning of the peripheral portion on the lower side ( ⁇ Y direction side) of the memory mat 62.
- the X deflection signal 65 a signal obtained by adding an offset signal for correcting a difference between the electron beam reference position and the scanning target position at the time of scanning of each irradiation electron beam to the scanning signal in the X direction is output.
- the Y deflection signal 66 an offset signal corresponding to the scanning position in the Y direction is output.
- Arrows 67e and 67f indicate scanning of the peripheral portion on the upper side (+ Y direction side) of the memory mat 62.
- the X deflection signal 65 is a signal obtained by adding the scanning signal in the X direction and the offset signal.
- As the Y deflection signal 66 an offset signal corresponding to the scanning position in the Y direction is output.
- Arrows 67g and 67h indicate scanning of the peripheral portion on the right side (+ X direction side) of the memory mat 62.
- the X deflection signal 65 an offset signal for correcting the difference between the electron beam reference position and the scanning target position at the time of scanning of each irradiation electron beam is output.
- the Y deflection signal 66 a scanning signal in the Y direction is output.
- an inspection apparatus capable of further increasing the speed is realized by shortening the time required for the beam swing back.
- the irradiation electron beam is scanned in two directions of the X direction and the Y direction.
- the scanning direction is not limited to these two directions, and is the same as in the third embodiment.
- a configuration example of an inspection apparatus capable of adding frames of an image of an inspection area set during swath will be described.
- the frame integration is to acquire a plurality of images for the inspection area and integrate the obtained images. Since the S / N of the image signal is improved by integration, a high-definition image is obtained, and the accuracy of defect detection is improved. Since a plurality of images are required for the same region, it is necessary to perform scanning for the same number of times for the same inspection region.
- a stage continuous movement type inspection apparatus capable of satisfying the above constraints without changing the stage speed or changing the beam deflection frequency during the inspection will be described. For simplicity, it is assumed in the following description that the frame integration number is twice and the stage speed is a normal speed.
- the setting of the frame integration number and the stage speed is not limited to this, and the frame integration number is not limited to this. It may be three times or more, or the stage speed may be asynchronous. Further, as in the embodiment described above, FIG. 1 is appropriately cited in the description of this embodiment, and the same description is not repeated for common portions.
- each inspection area must be repeatedly scanned by the number of frames integrated without changing the stage speed or the beam deflection frequency.
- the basic idea for realizing this is the same as in the second embodiment, and the beam deflection start time is set forward in accordance with the beam scanning speed, and the end time is set backward.
- the beam deflection control of this embodiment will be described with reference to FIG.
- FIG. 7 is a diagram showing an X deflection signal and a Y deflection signal for scanning a wafer inspection region and an irradiation electron beam.
- the swath 71 is set to include a plurality of inspection areas 72, 73, 74, and 75.
- the electron beam scanning directions of the inspection regions 72, 73, 74, and 75 are as indicated by arrows, respectively.
- the electron beam reference position is located at the position X1, it is located than the position X2 to be scanned original (X2-X1) only the left (-X direction).
- the X deflection signal 77 is added with a plus direction signal for correcting the positional deviation of (X2-X1).
- a continuous signal for correcting the difference between the electron beam reference position and the scanning target position in the inspection area 72 is added to the X deflection signal 77, and at the same time, scanning in the Y direction is performed by the Y deflection signal 78 having a sawtooth waveform. Is called.
- the inspection area 72 is continuously scanned as described above.
- the Y deflection signal 78 in the inspection area 72 is set below the swath 71 (end in the ⁇ Y direction), it is a signal obtained by adding a negative offset to the continuous scanning signal.
- the X deflection signal 77 is shifted to the minus side by an amount corresponding to the width (X4-X2) of the region 72 in the stage moving direction. . Thereafter, scanning is continuously performed again while adding a signal for correcting the difference between the electron beam reference position and the scanning target position in the inspection area 72 to the X deflection signal 77, and the right end (+ X of the inspection area 72 is detected at position X5. The second end of the region 72 is completed.
- the scanning start position X6 is located on the left side ( ⁇ X direction) by (X7 ⁇ X6) from the left end (X7) of the inspection region 73. Therefore, the X deflection signal 77 is a deflection signal started from the plus direction by a deflection amount corresponding to (X7 ⁇ X6), and has a signal amplitude corresponding to the X direction size (X9 ⁇ X7) of the region 73. At this time, a positive signal is applied to the Y deflection signal 78 so that the lower end (end in the ⁇ Y direction) of the inspection area 73 on the upper side (+ Y direction side) of the swath 71 is scanned.
- the scanning start position of the X deflection signal 77 is shifted to the minus side in accordance with the stage movement amount, and the inspection area 73 is scanned while increasing the positive signal applied to the Y deflection signal 78.
- the upper end (the end in the + Y direction) of the inspection area 73 is scanned at a position X8 that is the midpoint of the X direction, and the first scan of the inspection area 73 is completed.
- the Y deflection signal 78 is shifted to the negative side by an amount corresponding to the width of the inspection region 73 in the Y direction.
- Scanning by the X deflection signal 77 is performed.
- the scanning start position of the X deflection signal 77 is shifted to the minus side again in accordance with the amount of stage movement, and the inspection region 73 is scanned while increasing the plus signal applied to the Y deflection signal 78.
- the second scan of the inspection area 73 is completed.
- the inspection areas 74 and 75 may be scanned in the same manner as the inspection areas 72 and 73. However, it is necessary to change the magnitude of the offset signal added to the Y deflection signal 78 in accordance with the position of the inspection areas 74 and 75 in the swath 71 in the Y direction.
- the scan start time margin time t 2 -t 1 to t 7 -t 6
- the scan end time margin time t 5 -t 4 to t 10 -t9 6
- stage speed can be set higher than the normal speed using the configuration of this embodiment. That is, a margin between the beam deflection start position and the end position in consideration of the stage speed ratio ⁇ to the stage speed normal speed is set for each area equally divided by the frame integration number in the same manner as in the second embodiment. Thereby, it is possible to realize a circuit pattern inspection apparatus having the advantages of both high image quality by frame integration and inspection speed by high-speed stage movement.
- the inspection area position information (X2, X4, X7, X9) and stage speed information (speed coefficient ⁇ ) input by the apparatus operator via the setting screen of the control PC 14 are used.
- control information such as positions X1, X5, X6, and X10 is calculated by the control PC 14 based on (information for calculating ⁇ ).
- the beam scanning controller 11 and the stage controller 12 control the voltage and timing control of the XY deflection signal or the stage speed based on the control information of the positions X1, X5, X6, and X10 calculated by the control PC.
- Pre-scan refers to scanning an electron beam before irradiation with an image-acquisition electron beam for the purpose of neutralizing an inspection region or forming a desired charged potential.
- the size of the scanning region at the time of executing the pre-scan is often set larger than the size of the inspection region.
- FIG. 1 is appropriately cited, and the same description will not be repeated for common portions. For simplicity, it is assumed that the stage speed is constant at the normal speed during scanning.
- FIG. 8 is a diagram showing an X deflection signal 87 and a Y deflection signal 88 for scanning the inspection area of the wafer and the irradiation electron beam.
- the swath 81 is set to include a plurality of inspection areas 82, 83, 84, 85 similar to the arrangement shown in FIG. 3, FIG. 4, or FIG.
- the scanning direction in the inspection area 82 is the Y direction, and a pre-scan area indicated by a dotted line is set around the inspection area 82.
- the pre-scan area is originally set not only in the Y direction but also in the X direction, in order to simplify the description, FIG. 8 shows that the pre-scan area is provided only in the Y direction.
- the electron beam scanning of each inspection area is executed in the sequence of pre-scan ⁇ scanning for a predetermined waiting time ⁇ main scan (electron beam scanning for image acquisition). That is, the pre-scan and the scan stop are executed while the electron beam reference position exists on the left side of the inspection area 82, and the main scan is executed while the electron beam reference position exists on the right side of the inspection area 82.
- different waveforms such as amplitude, inclination, or rise timing are different between pre-scanning and main scanning.
- the first XY deflection signal and the second XY deflection signal having the same are used.
- the pre-scan of the inspection area 82 is started when the electron beam reference position is at the position X1 (time t 1 ) and is completed at the time of the position X3 (time t 3 ).
- X deflection signal 87 is positive deflection voltage corresponding to the position deviation correction amount of the position X2 to be scanned original At time t 1 (X2-X1) is set.
- the electron beam reference position is at the position X3, but the scan line that should be scanned with the electron beam is the right end (position X5) of the inspection region 82, and the electron beam reference position is still higher than the original scan line.
- the X deflection signal 87 at the end of the pre-scan is also set to a positive deflection voltage corresponding to the positional deviation correction amount (X5-X3) between the positions X5 and X3.
- a deflection signal having a sawtooth waveform is applied to the deflector 6 during the pre-scan.
- the amplitude of the pre-scan is set sufficiently larger (for example, twice) than the size of the inspection region 82. Therefore, the signal amplitude of the sawtooth waveform is twice the signal amplitude of the sawtooth waveform during the main scan corresponding to the scan width of the pre-scan area.
- the electron beam reference position exists at position X 3, and the electron beam irradiation position exists at the lower right corner of the region 82.
- a waiting time sequence is started at time t 3 , irradiation electrons are blanked, and the X deflection signal 87 is shifted in the minus direction by (X4 ⁇ X2), and the electron beam irradiation position is at the left end of the inspection region 82. Returned. Blanking is performed because there is a possibility that the charging condition of the wafer may change when a beam is irradiated onto a fixed portion on the wafer during the waiting time.
- the blanking of the irradiated electrons are released, the electron beam scanning for image acquisition is started.
- the time t electron beam reference position at 4 time points is in position X4, although located than the original scanning line position X2 (X4-X2) just right (+ X direction), previously minus at time t 3 Since it is shifted by a minute, the electron beam irradiation position exists at X2.
- scanning in the Y direction is performed while adding a signal for correcting the difference between the electron beam reference position and the scanning target position in the inspection area 82 to the X deflection signal 87, thereby continuously scanning the inspection area 82.
- the signal waveform of the Y deflection signal 88 is a sawtooth waveform as usual.
- the right end (the end in the + X direction) of the inspection area 82 is scanned at the position X6 (time t 6 ), and the entire inspection area 82 is scanned.
- the scanning direction in the inspection area 83 is the X direction, and a pre-scan area indicated by a dotted line is set around the inspection area 83.
- FIG. 8 shows a prescan area only in the X direction.
- Prescanning the examination region 83 begins at time t 7, the pre-scanning of the inspection area 83 is completed at the position X9 (time t 9).
- X deflection signal waveform at time t 7 is the amount of amplitude value corresponding to the position deviation correction amount of the position X7 and X8 (X8-X7), then depending on the area size of the pre-scan area until time t 9 Followed by a signal pattern with a sawtooth waveform of different amplitude.
- the X deflection signal 87 has a deflection amount corresponding to (X10 ⁇ X8).
- the deflection signal starts from the minus direction and has a signal amplitude corresponding to the X direction size (X11 ⁇ X8) of the inspection region 83.
- a positive signal is added to the Y deflection signal 88 so that the lower end (end in the ⁇ Y direction) of the inspection area 83 on the upper side (+ Y direction side) of the swath 81 is scanned.
- the scanning start position of the X deflection signal 87 is shifted to the minus side in accordance with the stage movement amount, and the inspection area 83 is scanned while increasing the plus signal added to the Y deflection signal 88 to the position X11.
- the upper end (end in the + Y direction) of the inspection area 83 is scanned, and the entire scanning of the inspection area 83 is completed.
- the inspection areas 84 and 85 are scanned in the same manner as the inspection areas 82 and 83, respectively. However, it is necessary to change the magnitude of the offset signal added to the Y deflection signal 88 in accordance with the position of the inspection areas 84 and 85 in the swath 81 in the Y direction.
- the inspection area position information (X2, X5, X8, X11) and prescan area information input by the apparatus operator via the setting screen of the control PC 14 are used.
- the control information such as the positions X1, X5, X6, and X10 is calculated by the control PC.
- the beam scanning controller 11 and the stage controller 12 control the voltage and timing control of the XY deflection signal or the stage speed based on the control information of the positions X1, X5, X6, and X10 calculated by the control PC. It is possible to combine the configuration of the present embodiment with stage acceleration, and in this case, the stage movement speed information (speed itself or speed coefficient ⁇ or ⁇ for calculating ⁇ set by the apparatus operator). Information) is used to calculate the control information of the positions X1, X5, X6, and X10.
- an arbitrary area of the wafer can be inspected, so that the inspection can be efficiently performed.
- the formation of electrification by pre-scan can produce an effect that inspection can be performed on a sample to be inspected, such as the bottom of a contact hole or a wiring pattern of a high-resistance material, which is difficult to obtain a good potential contrast in normal scanning. .
- the waiting time after the pre-scan it is possible to observe the relaxation state of the charge formed by the pre-scan.
- Example 7 of the circuit pattern inspection apparatus of this example will be described with reference to FIGS. 9A and 9B.
- This embodiment relates to beam deflection control for executing so-called helical scanning, and the scanning direction of the electron beam is continuously changed for each scanning, and the scanning length for each scanning is continuously shortened. It is possible to realize various types of electron beam scanning.
- FIG. 9 shows only two scanning lines in the same direction, but actually there are a larger number of scanning lines.
- the X deflection signal 95 is positive when the irradiation electron beam swings in the + X direction (right direction in FIG. 9A)
- the Y deflection signal 96 is positive when the irradiation electron beam swings in the + Y direction (upward direction in FIG. 9A).
- FIG. 9B is a diagram showing electron beam scanning of the inspection area 92 of the swath 91. The electron beam scanning of the inspection area 92 will be described with reference to FIG. 9B.
- the irradiation electron beam is scanned in the order of arrows 97a, 97b, 97c, 97d, 97e, 97f, 97g, and 97h.
- the electron beam scan indicated by the arrow 97b starts from the end point of the electron beam scan indicated by the arrow 97a.
- the electron beam scanning indicated by the arrow 97c is started from the end point of the electron beam scanning indicated by the arrow 97b.
- the end point of a certain electron beam scan is always the start point of the next electron beam scan. Therefore, it is not necessary to turn back the electron beam to the start position of the next electron beam scan after the electron beam scan. For this reason, the time required for the electron beam scanning of the inspection region 92 can be shortened by the amount of time required for turning back.
- the length (electron beam scanning distance) and position (electron beam scanning position) of arrows 97a, 97b, 97c, 97d, 97e, 97f, 97g, and 97h are the size (width) of the inspection region 92. And the trajectory of the electron beam scanning from the pixel size of the image of the inspection area.
- the electron beam scanning distances corresponding to the arrows 97a, 97b, 97c, 97d, 97e, 97f, 97g, and 97h are represented by the lengths of the arrows 97a, 97b, 97c, 97d, 97e, 97f, 97g, and 97h.
- an electron beam scanning deflection signal indicated by an arrow 97a is applied at the electron beam reference position X1. Since the electron beam scanning indicated by the arrow 91a is in the Y direction, a scanning signal corresponding to the length of the arrow 97a is applied to the Y deflection signal 96. The X deflection signal 95 is applied with a signal for correcting the difference between the electron beam reference position and the scanning target position.
- an electron beam scanning deflection signal indicated by an arrow 97b is applied at position X2. Since the electron beam scanning indicated by the arrow 97b is in the X direction, the scanning signal is applied to the X deflection signal 95, and the amplitude thereof is the distance obtained by subtracting the stage moving distance during the scanning time from the length of the arrow 97b. The corresponding amount. Further, since the electron beam scanning indicated by the arrow 97b is on the upper side (+ Y direction) of the swath 91, a positive offset signal corresponding to the scanning position is applied to the Y deflection signal 96.
- an electron beam scanning deflection signal indicated by arrow 97c is applied at position X3. Since the electron beam scanning indicated by the arrow 91c is downward ( ⁇ Y direction) in the Y direction, a scanning signal that changes from positive to negative is applied to the Y deflection signal 96. The X deflection signal 95 is applied with a signal for correcting the difference between the electron beam reference position and the scanning target position.
- an electron beam scanning deflection signal indicated by an arrow 97d is applied at position X4. Since the electron beam scanning indicated by the arrow 91d is leftward scanning ( ⁇ X direction) in the X direction, a scanning signal that changes from positive to negative is applied to the X deflection signal 95. The amplitude of the scanning signal is an amount corresponding to the distance obtained by adding the stage moving distance during the scanning time to the length of the arrow 97d. Further, since the electron beam scanning indicated by the arrow 97d is below the swath 91 ( ⁇ Y direction), a negative offset signal corresponding to the scanning position is applied to the Y deflection signal 96.
- an inspection apparatus capable of omitting the time required for back deflection and shortening the time required for electron beam scanning in the inspection region is realized.
- Example 8 of the circuit pattern inspection apparatus of this example will be described with reference to FIG.
- a plurality of areas separated in the direction perpendicular to the stage movement direction are used as inspection areas.
- the direction perpendicular to the stage movement direction (Y direction) )
- a signal obtained by adding the continuous scanning signal and the offset signal is added.
- FIG. 10 is a diagram showing a wafer scanning region and a continuous scanning signal 108 and an offset signal 109 for creating an X deflection signal 106, a Y deflection signal 107, and a Y deflection signal 107 for scanning an irradiation electron beam.
- the swath 101 includes a plurality of inspection areas 102, 103, and 104.
- the X deflection signal 106 is a signal for scanning the irradiation electron beam in the X direction
- the Y deflection signal 107 is a signal for scanning the irradiation electron beam in the Y direction.
- the Y deflection signal 107 is created as a signal obtained by adding the continuous scanning signal 108 and the offset signal 109.
- the continuous scanning signal 108 and the offset signal 109 are respectively applied to independent deflectors, and the irradiation electron beam is scanned with the Y deflection signal 107 by interlocking the two deflectors.
- the deflector to which the continuous scanning signal 108 is applied has a feature that the maximum deflection width is small but the responsiveness is fast compared to the deflector to which the offset signal 109 is applied.
- the stage moves in the ⁇ X direction and moves the wafer in the ⁇ X direction.
- Swath 101 is executed by one operation of the stage.
- the electron beam reference position moves on the wafer from the ⁇ X direction to the + X direction (from the left to the right in FIG. 10) along the dotted line 105 indicating the center of the swath 101.
- Arrows 102a, 102b, 102c, 103a, 103b, 103c, 104a, 104b, and 104c in the inspection regions 102, 103, and 104 indicate the scanning direction of the irradiation electron beam.
- the X deflection signal 106 is positive when the irradiation electron beam swings in the + X direction (right direction in FIG. 10)
- the Y deflection signal 107 is positive when the irradiation electron beam swings in the + Y direction (upward direction in FIG. 10).
- the scanning of the irradiation electron beam of arrows 102a, 102b, and 102c from X2 to X3 is performed while the electron beam reference position moves from X1 to X2.
- Scanning of the irradiation electron beam indicated by arrows 103a, 103b, and 103c is sequentially performed while moving, and scanning of the irradiation electron beam indicated by arrows 104a, 104b, and 104c is sequentially performed while moving from X3 to X4.
- an electron beam scanning method in the inspection area 102 will be described.
- the electron beam reference position reaches the starting point of the inspection region 102 at the position X1
- electron beam scanning in the Y direction is started.
- a continuous scanning signal having an amplitude corresponding to the width (the length in the Y direction) of the inspection region 102 is applied to the continuous scanning signal 108.
- a minus direction signal is applied to the offset signal 109.
- the Y deflection signal 107 becomes a scanning signal having a negative offset, and the irradiation electron beam indicated by the arrow 102a is scanned.
- the electron beam scanning of the arrow 102b is performed. Since the electron beam reference position at this time is on the left side of the scanning target position, a positive offset signal is applied to the X deflection signal 106. When the arrow 102c is scanned, the difference between the electron beam reference position and the scanning target position is further increased, so that a larger positive offset signal is applied to the X deflection signal 106.
- an electron beam scanning method in the inspection area 103 will be described. Scanning of the inspection region 103 is started when the electron beam reference position is X2, but when scanning with the electron beam indicated by the arrow 103a, the electron beam reference position is on the right side of the scan target position. An offset signal is applied. Subsequently, during the electronic scanning of the arrow 103b, the offset signal of the X deflection signal 106 is 0 because the electron beam reference position is at the scanning target position. Further, during the electron beam scanning indicated by the arrow 103c, a positive offset signal is applied to the X deflection signal 106 because the electron beam reference position is on the left side of the scanning target position. In addition, since the inspection area 103 is set at the center of the swath 101, the offset signal 109 becomes zero.
- an electron beam scanning method in the inspection area 104 will be described. Scanning of the inspection region 104 is started when the electron beam reference position is X3. However, when the electron beam is scanned by the arrow 104a, the electron beam reference position is on the right side of the scanning target position, and therefore the X deflection signal 106 is negative. An offset signal is applied. Although the difference between the electron beam reference position and the scanning target position gradually decreases as the scanning of the inspection region 104 progresses, the difference disappears during the electron beam scanning indicated by the arrow 104c, and the offset applied to the X deflection signal 106 at this time is 0. It becomes. Since the inspection region 104 is set at the upper portion (the end portion in the + Y direction) of the swath 101 shown in FIG. 10, a plus direction signal is applied to the offset signal 109.
- the inspection operation moves to the next inspection region.
- the next inspection region is used. It is good also as an operation to move to.
- an operation of moving to the next inspection area may be performed.
- FIG. 11A shows a die in which a memory region 1102 and a memory region 1103 are formed, and contact hole rows 1104 are formed in the memory region at a period of several microns.
- the swath 1105 is arranged over a plurality of dies, and an image in the swath is acquired.
- the contact hole row 1104 is intermittently arranged in the memory region, and the length between the plurality of contact hole rows is longer than the width of the contact hole row 1104. Furthermore, there is a feature that there is no pattern between the contact hole row and the contact hole row. Therefore, it is very wasteful to acquire images between contact hole rows. Therefore, by applying the high-speed stage movement inspection method described in the second embodiment, it is possible to realize inspection with higher throughput than conventional.
- the inspection target region including the contact hole row that is, the image acquisition region 1106 is set.
- This operation is executed when the operator of the apparatus performs a pointer operation on the above setting screen.
- the above-described image acquisition area 1106 is referred to as an ROI area (Region Of Interest).
- the control PC 14 determines the ROI area width (length in the stage movement direction), the pitch with the adjacent ROI area, or the swath width based on the set ROI area size and position information. Set automatically. Further, based on the periodicity of the pattern to be inspected, such as the contact hole row 1104, the setting position of the ROI region is developed in the region including the other die to be inspected or the contact hole row, and the other die or memory region The coordinates of the ROI area are automatically set. This calculation process is also executed by the control PC 14.
- the size of the field of view (FOV: Field Of View) for acquiring an image within the swath 1105 is M.
- the size M of the FOV is several tens of ⁇ m or more
- the pattern pitch is about 5 to 10 ⁇ m
- the size M is set so that the end line of at least one ROI region and the start end of the ROI region to be scanned next fit within the FOV.
- the ROI area width (length in the stage moving direction) is L
- the pitch between ROI areas is P
- the swath width is W.
- FIG. 12 shows a comparison of the change in the primary charged particle beam irradiation position when the stage moving speed is synchronized with the beam deflection and the change in the primary charged particle beam irradiation position when not synchronized with the beam deflection.
- FIG. 12A is a diagram schematically showing the movement of the beam irradiation position when the sample to be inspected is transported at a stage moving speed synchronized with the beam deflection.
- An area 1201 indicated by a dotted line is an ROI area. The position of the ROI area at the start of scanning of the first scanning line is shown, and the area 1202 shown by the solid line shows the position of the ROI area at the end of scanning of the Nth scanning line.
- the primary charged particle beam is only scanned in the Y direction on the one-dot chain line in the figure, and the first scanning line 1205 and the Nth scanning line 1206 in the ROI region are within the range of the field of view M.
- the stage moving speed and the beam scanning speed are synchronized as described above.
- FIG. 12D is a diagram schematically showing the movement of the beam irradiation position when the sample to be inspected is transported at a stage moving speed asynchronous to the beam deflection.
- the area 1203 indicated by the dotted line indicates the position of the ROI area at the start of scanning of the first scanning line of the ROI area
- the areas 1204 and 1204 ′ indicated by solid lines indicate when the scanning of the Nth scanning line is completed. The position of the ROI area is shown.
- the Nth scanning line should be scanned depending on the moving speed of the stage.
- a line to be scanned may protrude from the field of view M.
- the Nth scan line exists at position 1207 in FIG.
- a line image (pixel signal) cannot be acquired.
- image acquisition is started when the first scanning line 1205 enters the visual field M (at the left end of the visual field M), and the Nth scanning line is within the visual field M. It is only necessary to set the stage moving speed so that the scanning is completed while it exists, that is, the Nth scanning line is on the left side of the position 1208 in FIG.
- the back deflection in the direction opposite to the stage moving direction is performed to obtain the next ROI region.
- the scanning of the primary charged particle beam can be started from the first scanning line.
- Equation 1 shows this constraint condition.
- the stage moving speed is expressed by the equation in order to capture the entire imaging region without omission. This indicates that it cannot be increased beyond the right side of 1.
- Equations 1 and 2 are easy to understand when it is assumed that a scanning skip region is set between ROI regions for acquiring images. If the length of the skip area is large, the moving speed of the stage can be increased. Conversely, if the width of the ROI region is large, it is necessary to reduce the moving speed of the stage. For this reason, the moving speed of the stage is set corresponding to the ratio between the width of the scanning area and the width of the skip area.
- Equation 1 indicates that the maximum value of the scanning skip area is M, that is, the condition that the leading edge scanning line and the trailing edge scanning line of the ROI area can exist in the same visual field area M is to scan the beam continuously. It means the upper limit of the scanning skip area.
- the beam deflection position is at the left end of the field of view M (the end opposite to the stage traveling direction). The scanning is resumed when the tip scanning line of the next ROI area enters the field of view.
- a scanning skip area larger than the field size M is set, a time during which the beam is not irradiated, that is, a waiting time until the leading scanning line of the next ROI area enters the field of view is generated.
- the inspection area that is, the inspection speed is reduced.
- the stage moving speed is expressed in the stage moving direction of the visual field size. It can also be interpreted as indicating that the length is set according to the pixel size and the number of scanning lines in the ROI region. Similarly, Equation 3 can also be interpreted as indicating that the stage moving speed is set according to the length of the scanning skip area in the stage moving direction, the pixel size, and the number of scanning lines in the ROI area.
- the stage movement control described above is executed by the stage controller 12.
- the beam deflection in the stage movement direction is used in combination with the desired inspection region.
- the beam scanning is realized.
- the irradiation position of the primary charged particle beam is changed by beam deflection in the stage moving direction or in the reverse direction.
- the stage moving speed V is asynchronous with the beam deflection, so that the beam irradiation position is originally irradiated in one ROI area. Deviation from the power scan line has occurred.
- the irradiation position of the primary charged particle beam is deflected in the same direction as the stage moving direction under the control of the beam scanning controller 11, so that the irradiation position of the beam from the position to be originally irradiated is changed. The deviation has been eliminated.
- the appropriate deflection speed is as follows. It is expressed by the following formula.
- the above-mentioned positional deviation increases as scanning is repeated from the first scanning line toward the Nth scanning line, so that the beam shift amount due to deflection also increases as scanning in the ROI region proceeds.
- FIG. 13 shows how the beam shift amount due to deflection increases as the scanning in the ROI region proceeds, in comparison with the inspection by the normal stage moving speed.
- FIG. 13A and 13B are views of a state in which an inspection region 1302 on the specimen 1301 to be inspected is set and N scanning lines are set in this region as viewed from the side.
- a hatched inspection area 1302 on the left side of FIG. A indicates that the beam irradiation has not been completed yet, and a solid inspection area 1302 on the right side of FIG. A indicates that the beam irradiation has been completed.
- the beam deflection speed and the stage moving speed are synchronized, so that a special positional deviation occurs even when only a fixed beam scanning position is scanned. Does not occur.
- the positional deviation on the first scanning line is zero, but as shown in the central diagram of FIG.
- the shift amount is M ( ⁇ -1) lines in the 1st scan line (M: 1 ⁇ M ⁇ N), and the shift is performed in the Nth last scan line as shown in the right diagram of FIG.
- the amount is N ( ⁇ -1) lines.
- the beam scanning controller 11 performs the beam deflection by the shift amount within the same ROI region, and sets the beam irradiation position as a target. It is aligned with the position.
- the position deviation of the beam irradiation in the stage moving direction increases as the scanning is repeated in the ROI region, so that the deflection distance (beam deflection angle of the deflector 6) necessary for the position deviation correction becomes large. Therefore, a deflector with a large beam deflection distance is advantageous in increasing the speed of stage movement.
- the size M of the field of view can in principle be increased up to the maximum beam deflection distance of the deflector, but is actually constrained by the condition that image quality deterioration due to off-axis aberrations and field curvature aberrations is not noticeable. Therefore, in actual operation of the apparatus, the image of the standard sample is acquired by changing the size M of the field of view, and the conditions for detecting an image with substantially the same effect such as aberration and distortion are determined. Information on the determined visual field size M is stored in the control PC 14 and is referred to by the beam controller 11 at the time of inspection.
- an inspection apparatus capable of executing the inspection of the contact hole forming process of the NAND flash memory at a much higher speed than before can be realized.
- the inspection apparatus of this embodiment can be applied not only to NAND flash memories but also to inspections of semiconductor memory devices such as NOR flash memories or DRAMs, logic ICs or drive substrates for liquid crystal displays. .
- peripheral circuit region 54 ... peripheral circuit region, 55 ... dotted line indicating the center of swath, 56 ... X deflection signal, 57 ... Y deflection signal, 58a, 58b, 58c, 58d, 58e, 58f, 59g, 59h 59i, 59j... Arrow indicating electron beam scanning, 61... Swath, 62... Memory mat, 63 .. vicinity of mat outer periphery, 64... Dotted line indicating the center of swath, 65. , 67b, 67c, 67d, 67e, 67f, 67g, 67h ... arrows indicating electron beam scanning, 71 ...
- Y deflection signal 97a, 97b, 97c, 97d, 97e, 97f, 97g, 97h ... Electron Arrow indicating line scanning, 101... Swath, 102, 103, 104... Inspection region, 102 a, 102 b, 102 c, 103 a, 103 b, 103 c, 104 a, 104 b, 104 c. Dotted lines 106, X deflection signal, 107, Y deflection signal, 108, continuous scanning signal, 109, offset signal.
Abstract
Description
ディフレクタ6は、ビーム走査コントローラ11からの信号(X偏向信号とY偏向信号)に従って、照射電子線9を偏向させてウエハ8に対して走査させる。XYステージ2は、ステージコントローラ12からの信号に従って移動し、カラム1に対してウエハ8を移動させる。
簡単のため、検査領域32、33、34、35の形状は矩形であるものとする。スワス31の走査中、照射電子線の走査速度(画素サンプリング周波数)は一定であり、ステージ速度も走査速度に同期しているものとする。ステージの移動方向は、白抜き矢印で示されるように-X方向向きであり、ウエハは+X方向側から-X方向側に移動される。
従って、ビーム偏向の開始時刻をビーム走査速度にあわせて前倒しに設定し、終了時刻については逆に後ろ倒しに設定する。開始時刻と終了時刻をずらしたことによる電子線基準位置と検査領域(電子線が本来走査すべき位置)との位置ずれについては、X方向のビーム偏向により吸収する。この考え方に基づくビーム偏向制御より、ステージを高速移動させつつ必要な領域の画像を取得することが可能となる。
一方、ステージ移動速度の上限は、ROI領域の長さLと、ROI領域のステージ移動方向の配列ピッチPによっても制約を受ける。以下の数式2は、この制約条件を示す。
数式1、2は、画像を取得するROI領域の間に走査のスキップ領域が設定されたと考えると理解しやすい。スキップ領域の長さが大きければステージの移動速度をスピードアップできる。逆にROI領域の幅が大きければステージの移動速度を落とす必要がある。このため、走査領域の幅とスキップ領域の幅との比に対応してステージの移動速度が設定される。
V≦((L+S)/L)V0 ・・・ 〔数式3〕
となり、見かけ上、数式1と等しくなる。すなわち、数式1、2は、走査スキップ領域の最大値がM、すなわち、ROI領域の先端走査ラインと後端走査ラインが同一の視野領域M内に存在できる条件が連続でビームを走査するための走査スキップ領域の上限であることを意味する。走査スキップ領域がこれ以上大きい場合には、ビームを連続で走査することは出来ず、後端走査ラインを走査した後、視野Mの左端(ステージ進行方向とは逆の端部)にビーム偏向位置を振り戻し、次のROI領域の先端走査ラインが視野に入った時点で走査を再開することになる。
V-V0=ΔV=(S/L)V0 ・・・ 〔数式4〕
と変形でき、これは、ROI検査におけるステージ移動速度のV0からの増加分が、スキップ領域の長さとROI領域の長さの比または視野サイズMとROI領域の長さの比に応じて定まることを示している。またこのことから、視野領域M内へのROI領域の設定数あるいは面積を増やせば、その分ステージ移動速度も遅くしなければならないことが分かる。
この式の物理的な意味は、ビーム照射位置のステージ移動方向への相対速度を考えれば明らかで、V-U=V-(α-1)V0=V-(V/V0-1)V0=V0となることから、ステージ移動方向へのビーム照射位置移動の相対速度が同期速度に等しくなる偏向速度である。相対速度が同期速度であれば、走査ライン1本をステージ移動方向と交差する方向へ走査する間に、ビーム照射位置がステージ移動方向に1画素分移動することになるので、位置ずれを吸収できることになる。
Claims (18)
- 予め設定された電子線の移動幅とステージの連続移動とにより仮想的に形成されるスワス内で被検査領域の画像を取得することにより、基板上に形成された回路パターンを検査する回路パターン検査装置であって、
前記回路パターンが形成された基板を移動させるステージと、
前記基板に対し電子線を走査する電子線走査手段と、
前記ステージの移動を制御するステージコントローラと、
前記電子線走査手段の動作を制御するビーム走査コントローラとを備え、
前記ステージの移動方向と平行な第1の方向への電子線偏向制御と、当該第1の方向と交差する第2の方向への電子線偏向制御とを併用することにより、前記スワス内に設定される任意の被検査領域の画像を取得する回路パターン検査装置。 - 請求項1に記載の回路パターン検査装置において、
前記ステージ移動の移動速度を保持したまま前記被検査領域の画像を取得する回路パターン検査装置。 - 請求項1に記載の回路パターン検査装置において、
前記設定された被検査領域の端部に対して時間または距離のマージンを設定し、当該設定したマージン分先んじて、前記被検査領域への電子線走査を開始または終了することを特徴とする回路パターン検査装置。 - 請求項1に記載の回路パターン検査装置において、
前記ステージコントローラは、前記電子線の走査速度よりも高速に前記ステージを移動させるよう制御を行うことを特徴とする回路パターン検査装置。 - 請求項1に記載の回路パターン検査装置において、
前記被検査領域の長手方向が前記ステージ移動と平行な方向である場合には、電子線を前記第1の方向と平行な方向に走査して当該被検査領域の画像を取得し、
前記被検査領域の長手方向が前記ステージ移動と交差する方向である場合には、電子線を前記第2の方向と平行な方向に走査して当該被検査領域の画像を取得することを特徴とする回路パターン検査装置。 - 請求項1に記載の回路パターン検査装置において、
前記被検査領域の長手方向が前記ステージ移動と交差する方向である場合には、電子線を前記第1の方向と平行な方向に走査して当該被検査領域の画像を取得し、
前記被検査領域の長手方向が前記ステージ移動と平行な方向である場合には、電子線を前記第2の方向と平行な方向に走査して当該被検査領域の画像を取得することを特徴とする回路パターン検査装置。 - 請求項1に記載の回路パターン検査装置において、
同一の被検査領域に対して複数回の電子線走査を実行し、
各走査により得られる画像を積算して検査画像とすることを特徴とする回路パターン検査装置。 - 請求項1に記載の回路パターン検査装置において、
同一の被検査領域に対し、プリスキャンと本スキャンを実行することを特徴とする回路パターン検査装置。 - 請求項8に記載の回路パターン検査装置において、
前記第1の方向あるいは第2の方向への電子線の走査長を、前記プリスキャンの設定領域のサイズおよび本スキャンの設定領域のサイズに応じて設定することを特徴とする回路パターン検査装置。 - 請求項8または9に記載の回路パターン検査装置において、
前記プリスキャンと本スキャンの間に、走査を停止する待ち時間が設定されることを特徴とする回路パターン検査装置。 - 請求項1に記載の回路パターン検査装置において、
前記スワス内に設定される被検査領域に関する事前に取得された画像もしくは設計情報から前記被検査領域の長手方向を判定し、
当該判定結果に基づき、前記スワス内に設定される被検査領域内の電子線走査方向を決定する演算手段を備えることを特徴とする回路パターン検査装置 - 請求項1から11のいずれか1項に記載の回路パターン検査装置において、
第1の方向および第2の方向への電子線偏向制御を実行する走査シーケンサを備えたことを特徴とする回路パターン検査装置。 - 予め設定された電子線の移動幅とステージの連続移動とにより仮想的に形成されるスワス内で被検査領域の画像を取得することにより、基板上に形成された回路パターンを検査する回路パターン検査装置であって、
前記回路パターンが形成された基板を移動させるステージと、
前記基板に対し電子線を走査する電子線走査手段と、
前記ステージの移動を制御するステージコントローラと、
前記電子線走査手段の動作を制御するビーム走査コントローラとを備え、
前記ステージの移動方向と平行な第1の方向への電子線偏向制御と、当該第1の方向と交差する第2の方向への電子線偏向制御とを併用することにより、前記スワス内に設定される任意の被検査領域について、当該被検査領域のみの画像を取得する回路パターン検査装置。 - 所定パターンが周期的に配列されて形成された領域を備える被検査試料に対し、一次荷電粒子線を当該被検査試料が載置されたステージの移動方向と交差する方向に走査し、当該走査により前記被検査試料から発生する二次電子または反射電子を検出して得られる信号をもとに検査画像を取得し、当該検査画像を用いて前記被検査試料を検査する荷電粒子線装置において、
前記一次荷電粒子線を所定の偏向速度で走査する走査偏向器を備えた荷電粒子カラムと、
前記ステージが前記偏向速度とは非同期な速度で移動するよう制御可能なステージコントローラとを備え、
前記ステージの移動方向への一次荷電粒子線の偏向を行うことにより、前記一次荷電粒子線を所望の検査領域に走査させることを特徴とする荷電粒子線装置。 - 所定パターンが形成された領域を備える被検査試料に対し、荷電粒子線を当該被検査試料が載置されたステージの移動方向と交差する方向に走査し、当該走査により前記被検査試料から発生する二次電子または反射電子を検出して得られる信号をもとに検査画像を取得し、当該検査画像を用いて前記被検査試料を検査する荷電粒子線装置において、
当該荷電粒子線装置は、前記パターンが形成された領域の一部を検査領域、一部を検査のスキップ領域として設定する機能を備え、
更に、前記ステージの移動速度を制御するステージコントローラを備え、
当該ステージコントローラは、前記検査領域に配置される走査ラインの本数、前記検査画像の画素サイズおよび前記スキップ領域の前記ステージ移動方向の長さに応じて、前記ステージの移動速度を設定することを特徴とする荷電粒子線装置。 - 荷電粒子線を被検査試料が載置されたステージの移動方向と交差する方向に走査し、当該走査により前記被検査試料から発生する二次電子または反射電子を検出して得られる信号をもとに検査画像を取得し、当該検査画像を用いて前記被検査試料を検査する荷電粒子線装置において、
当該荷電粒子線装置は、前記被検査試料上の一部のみを検査領域として設定する機能を備え、
前記一次荷電粒子線を所定の偏向速度で走査する走査偏向器を備えた荷電粒子カラムと、
前記ステージが前記偏向速度とは非同期な速度で移動するよう制御可能なステージコントローラとを備え、
前記偏向速度に同期するステージ移動速度の前記非同期なステージ移動速度に対する比をαとし、前記検査領域に複数本の走査ラインを配置して当該検査領域の画像を取得するとき、
前記走査偏向器は、前記複数本の走査ラインのうちのN番目の走査ラインの走査時、(α-1)Nラインに相当する距離分、前記ステージの移動方向に前記一次荷電粒子線の偏向制御を行うことを特徴とする荷電粒子線装置。 - 請求項14から16のいずれか1項に記載の荷電粒子線装置において、
前記ステージコントローラは、前記検査領域に含まれる第1の領域の走査終端と、当該第1の領域よりも後に画像が取得される第2の領域の走査開始端とが、前記ステージ移動方向への前記荷電粒子線走査範囲内で収差、歪が同一とみなせる視野内に収まるように前記ステージの移動速度を設定することを特徴とする荷電粒子線装置。 - 請求項14に記載の荷電粒子線装置において、
前記走査偏向器は、前記非同期なステージ移動速度と前記偏向速度に同期するステージ移動速度との差に相当する偏向速度で、前記ステージの移動方向への一次荷電粒子線の偏向を行うことを特徴とする荷電粒子線装置。
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