JP2011187191A - Device and method of inspecting circuit pattern - Google Patents

Abstract

An object of the present invention is to efficiently monitor the defect occurrence frequency and characteristic likelihood of an ROI region with high sensitivity.
In synchronization with the continuous movement of the stage, a plurality of electron beams arranged in a matrix are thinned out in the stage movement direction and irradiated onto the circuit pattern, and secondary electrons generated are acquired and acquired in the same region. By averaging the images, a high SN image is acquired at high speed, and a defect in the circuit pattern is determined from the acquired image. By acquiring a thinned image instead of an adjacent region when moving the stage and moving in the vertical direction, the defect occurrence frequency and characteristic likelihood of only the ROI region or the entire circuit pattern are efficiently monitored.
[Selection] Figure 1

Description

  The present invention relates to a charged particle beam apparatus and an inspection method for inspecting a substrate on which a circuit pattern is formed, such as a semiconductor substrate of a semiconductor device or a deflection array substrate of a liquid crystal display, using a charged particle beam as an inspection sample. . In this specification, the description is limited to the inspection of a semiconductor wafer, but it goes without saying that the present invention can be similarly applied to a substrate on which another circuit pattern is formed, such as a semiconductor device or a liquid crystal substrate.

  An example of a conventional electron beam pattern inspection apparatus is described in JP-A-5-258703. The electron beam inspection system irradiates the wafer to be inspected with an electron beam, detects the secondary electrons generated, and scans the electron beam in synchronization with the stage movement, thereby secondary electrons of the circuit pattern on the wafer. An image is obtained, and the detected image is compared with an eyelid reference image having the same pattern, and a place having a large difference is determined as a defect. By analyzing the distribution of detected defects on the wafer statistically or by analyzing the shape and characteristics of the detected defects in detail, problems at the time of manufacturing the wafer in which the defect has occurred are analyzed.

  In such an electron beam pattern inspection apparatus, speed of processing a sample, that is, improvement of inspection speed and improvement of defect detection sensitivity are both important issues. Is a conflicting issue. Several approaches have been proposed to overcome these challenges. For example, there are a method for devising image processing, a method for increasing the parallelism of image detection, and a method for devising a sampling method on a wafer.

  As a technique for devising image processing, for example, as described in Non-Patent Document 1, focusing on the point that the image detection speed is determined by the S / N of the image, and improving the apparent S / N, high speed There is a technique to realize a simple inspection.

  As a technique for increasing the degree of parallelism, a multi-beam type charged particle beam application apparatus having a plurality of beams has been proposed. For example, Patent Document 2 discloses that a plurality of beams formed by dividing an electron beam emitted from a single electron gun into a plurality of beams and individually focusing them by lenses arranged in an array form a single beam. A multi-beam type electron beam inspection apparatus that irradiates and scans a sample using an optical element is disclosed.

  As a technique for contriving sampling on a wafer, Non-Patent Document 2 describes that necessary defect distribution information is acquired at a low sampling rate by sampling stage movement coordinates.

JP-A-5-258703 JP 2007-317467 A

Robust Defect Detection System Using Double Reference Image Averaging for High Throughput SEM Inspection Tool In-line e-beam inspection with optimized sampling and newly developed ADC

  However, there is a demand for realization of defect monitoring that is more sensitive than the above-described prior art and that is more efficient than conventional techniques, such as defect occurrence frequency of ROI (Region of Interest) and circuit pattern characteristic likelihood. Here, the ROI is a concept for inspecting only the inspection region in which the user is interested, and is one of techniques for increasing the inspection speed. Therefore, an object of the present invention is to realize an appearance inspection method that is faster and more efficient than the conventional art. Of the above-mentioned problems, only high-sensitivity inspection, only high-speed inspection, only ROI inspection, only efficient monitoring, or multiple solutions of these items lose significance. There is no.

Means for solving the above problems of the present invention will be described with reference to FIG. Figure 1 is a diagram for explaining the inspection area, with the stage movement, by sharing the channel width W _c of the channel 101 a to 101 d, scanning N (N = 2) area between the scanning area A102a scanning area B102b multibeam And acquire images in parallel. Prior to image acquisition of the scanning area A 102a and the scanning area B 102b, the pre-irradiation area 103 is irradiated with an electron beam. This enables the image acquisition swath width 104W multiplied by the channel width W _c and the number of channels 101 a to 101 d. Further, an image having an image acquisition width 106 (L line) is acquired and inspected with respect to the inspection pitch 105 (P line) in the stage scanning direction. When the P dimension stage has advanced, the same area acquired in 102a is acquired in 102b, so these N images (N = 2) are added and averaged. Compared with the conventional method of scanning the entire surface with one beam, according to this image acquisition method, it is possible to expect a high speed of (P / L) × (W / W _c ) × N. By processing an image acquired at high speed, defects can be detected and a defect distribution can be obtained. Here, P / L is the inspection sampling rate in the stage moving direction, W / W _c is the parallelism improvement rate by multi-beams, N is the S / N improvement rate by addition averaging (an image according to the rate of improvement of S / N) The detection clock can be speeded up). The selection of the L dimension in the P dimension may be simple sampling at a constant pitch, or an ROI region having a high defect generation rate may be selected.

  If the inspection sampling rate is 10, the parallelism is 10, and the addition average is 2, the defect distribution can be obtained at a speed 200 times faster.

  In addition, although the effect is not constant depending on the inspection object, it is possible to charge the circuit pattern by irradiating the electron beam prior to the inspection and to increase the sensitivity of defect detection.

  Further, by combining with the stage movement coordinate sampling (about 10) described in “Problems to be Solved by the Invention”, it is possible to expect further high-speed defect distribution acquisition.

  Further, by combining with the S / N improvement method by image processing described in “Problems to be Solved by the Invention”, it is possible to expect a double speed.

  Further, even application of partial items of the solution means described here is sufficiently effective and does not depart from the spirit of the present invention.

  As a result, it is possible to realize efficient monitoring of the defect occurrence frequency and characteristic likelihood in the ROI region at a very high speed and with high sensitivity.

  According to the present invention, it is possible to provide an inspection apparatus and an inspection method for efficiently monitoring the defect occurrence frequency and characteristic likelihood in the ROI region with high sensitivity.

Explanatory drawing of the test | inspection area | region explaining the means for solving a problem. 1 is an overall configuration diagram of a first embodiment according to the present invention. Explanatory drawing of the multi-beam arrangement | positioning of 1st Example which concerns on this invention. Explanatory drawing of the thinning-out test | inspection method of 1st Example which concerns on this invention. Explanatory drawing of the addition average of 1st Example which concerns on this invention. Explanatory drawing of the defect determination method by RIA of 1st Example which concerns on this invention. Explanatory drawing of the defect determination method by the GP comparison method of 1st Example which concerns on this invention. Explanatory drawing of the test | inspection area | region of the 2nd Example which concerns on this invention. Explanatory drawing of the multi-beam arrangement | positioning of 3rd Example based on this invention. Explanatory drawing of the test | inspection area | region of the 4th Example which concerns on this invention. The whole block diagram of the 4th Example concerning the present invention. The whole block diagram of the 5th Example which concerns on this invention. Explanatory drawing of the multi-beam arrangement | positioning of 5th Example based on this invention.

Example 1
Hereinafter, a first embodiment of an inspection method and an inspection apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 2 shows the entire configuration of the circuit pattern inspection apparatus according to the first embodiment. That is, the electron gun 201 includes a cathode 202 made of a material having a low work function, an anode 203 having a high potential with respect to the cathode 202, and an electromagnetic lens 204 for superimposing a magnetic field on an acceleration electric field formed between the cathode and the anode. . In this embodiment, a Schottky cathode that can easily obtain a large current and has stable electron emission is used. In the downstream direction in which the primary electron beam 205 is extracted from the electron gun 201, as shown in FIG. 2, a collimator lens 206, an aperture array 207 having a plurality of openings arranged on the same substrate, and a lens array 208 having a plurality of openings. , A beam separator 209, an objective lens 210, a scanning deflection deflector 211, a stage 212, secondary electron detectors 213a to 213d, and the like. Further, the current limiting aperture, the primary beam center axis (optical axis) adjustment aligner, an aberration corrector, and the like are added to the electron optical system (not shown). The stage 212 moves with the wafer 214 placed thereon.

  A negative potential (hereinafter referred to as a retarding potential) is applied to the wafer 214 as described later. Although not shown, a wafer holder is interposed between the wafer 214 and the stage 212 so as to be electrically connected to the wafer, and a retarding power source 215 is connected to the wafer holder so that the wafer holder and the wafer 214 are connected to each other as desired. The voltage is applied.

  A surface electric field control electrode 216 is provided on the electron gun direction side from the wafer 214. A scanning signal generator 217 is connected to the deflector 211 for scanning deflection, and a surface electric field control power source 218 is connected to the surface electric field control electrode 216. An optical system control circuit 219 is connected to each part of the electron gun 201, the collimator lens 206, the lens array 208, the beam separator 209, the objective lens 210, the retarding power supply 215, and the surface electric field control power supply 218, and further controls the optical system. A system control unit 220 is connected to the circuit 219. A stage controller 221 is connected to the stage 212, and secondary electron detectors 213 a to 213 d and a scanning deflection deflector 211 are similarly connected to the system controller 220. The system control unit 220 includes a storage device 222, a calculation unit 223, and a defect determination unit 224, and a console device 225 is connected to the system control unit 220. Although not shown, components other than the control system and circuit system are arranged in a vacuum vessel and are operated by evacuation. Further, a mechanism for handling a cassette or a hoop for transporting a plurality of wafers 214 and a wafer transport system for placing the wafers on the stage from outside the vacuum are provided. On the stage, a reference mark 226 used for adjusting the electro-optical condition and measuring the adjustment state is provided.

  Next, wafer pattern inspection using the apparatus will be described.

  The primary beam 205 emitted from the electron source 202 is accelerated in the direction of the anode 205 while receiving a focusing action by the electromagnetic lens 204 to form a first electron source image 227 (a point at which the beam diameter is minimized). Although not shown, a diaphragm is arranged in the electron gun 201 as often seen in a general electron gun so that an electron beam in a desired current range passes through the diaphragm. If the operating conditions of the anode 203 and the electromagnetic lens 204 are changed, the current amount of the primary beam passing through the stop can be adjusted to a desired current amount. Although not shown, an aligner for correcting the optical axis of the primary electron beam is arranged between the electron gun 202 and the collimator lens 206, and the center axis of the electron beam is deviated from the diaphragm or the electron optical system. The configuration can be corrected. Using the first electron source image 227 as a light source, the collimator lens 206 arranges the primary beam substantially in parallel. In this embodiment, the collimator lens 206 is an electromagnetic lens. In this embodiment, the aperture array 207 has twelve apertures, and the primary beam is divided into twelve.

  In FIG. 2, three of these beams are shown. The divided primary beams are individually focused by the lens array 208, and a plurality of second electron source images 228a, 228b, and 228c are formed. The lens array 208 is composed of three electrodes each having a plurality of apertures, and acts as an Einzel lens for the primary beam passing through the apertures by applying a voltage to the central electrode among them. .

  The primary beams 205 individually focused by the lens array 208 pass through the beam separator 209. The beam separator 209 is used for the purpose of separating the primary beam 205 and the secondary beam 229, and in this embodiment, generates a magnetic field and an electric field orthogonal to each other in a plane substantially perpendicular to the incident direction of the primary beam. The Wien filter is used to give the deflection angle corresponding to the energy of the passing electrons. In this embodiment, the strength of the magnetic field and electric field is set so that the primary beam goes straight, and the strength of the electromagnetic field is deflected to a desired angle with respect to the secondary electron beam incident from the opposite direction. Adjust and control. The position of the beam separator 209 is arranged in accordance with the height of the second electron source images 228a, 228b, and 228c of the primary beam in order to reduce the influence in consideration of the influence of the aberration on the primary beam. Yes. The objective lens 210 is an electromagnetic lens and projects the second electron source images 228a, 228b, and 228c in a reduced scale.

The deflector 211 for scanning deflection is constructed and installed in an electrostatic 8-pole type in the objective lens. When a signal is input to the deflector 211 by the scanning signal generator 217, the 12 primary beams passing therethrough are deflected in substantially the same direction and at substantially the same angle, and the sample wafer 214 is raster scanned. To do. At this time, the primary beam 205 is arranged on the wafer 214 so as to scan each part of the channel width W _c 101a to the channel width W _c 101d of the scanning area A 102a, the scanning area B 102b, and the pre-irradiation area 103 already shown in FIG. It has become.

  A negative potential is applied to the wafer 214 by the retarding power source 215, and an electric field for decelerating the primary beam is formed. The retarding power source 215 and the surface electric field control power source 218 are connected to the other optical elements, that is, the electron gun 201, the collimator lens 206, the lens array 208, the beam separator 209, and the objective lens 210 via the optical system control circuit 219. The system controller 220 controls the system uniformly. The stage 212 is controlled by the stage controller 221. The scanning signal generator 217 and the stage controller 221 are uniformly controlled so that the system controller 220 inspects a predetermined area on the wafer 214 for each stripe arranged in the stage moving direction. In the inspection apparatus of the present embodiment, the stage is continuously moved at the time of execution of the inspection, and the primary beam is controlled to sequentially scan the band-like region by a combination of deflection by scanning and stage movement. This band-like area is obtained by dividing a predetermined inspection area, and the entire predetermined inspection area is scanned by scanning a plurality of band-like areas.

  The 12 primary beams that have reached the surface of the wafer 214 interact with substances near the sample surface. As a result, secondary electrons such as reflected electrons, secondary electrons, and Auger electrons are generated from the sample and become twelve secondary beams 229a, 229b, and 229c. In the figure, only three lines are indicated by broken lines.

  The surface electric field control electrode 216 is an electrode for adjusting the electric field intensity near the surface of the wafer 214 and controlling the trajectory of the secondary beam 229. It is installed facing the wafer 214, and a positive potential, a negative potential, or the same potential is applied to the wafer 214 by the surface electric field control power source 218. The voltage applied to the surface electric field control electrode 216 by the surface electric field control power source 218 is adjusted to a value suitable for the type of the wafer 214 and the observation target. For example, when the generated secondary beams 229a, 229b, and 229c are to be actively returned to the surface of the wafer 214, a negative voltage is applied to the surface electric field control power source 218. Conversely, a positive voltage can be applied to the surface electric field control power source 218 so that the secondary beams 229a, 229b, and 229c do not return to the surface of the wafer 214.

  After passing through the surface electric field control electrode 216, the secondary beams 229a, 229b and 229c are subjected to the focusing action of the objective lens 210, and further, the secondary beam is deflected by the beam separator 209 having a deflection action. Separated and detected. In this embodiment, four of the twelve primary beams are used for pre-irradiation for controlling the charged state of the sample, so that only the secondary beams 229a and 229b from the scanning region A 102a and the scanning region B 102b are used as eight detectors. Detect with. In the figure, among the four detectors corresponding to the secondary beam 229a from the scanning region A102a, two detectors 213a and 213b, and among the four detectors corresponding to the secondary beam 229b from the scanning region B102b. Only two detectors 213c and 213d are shown. Signals detected by the detectors 213a, 213b, 213c, and 213d are amplified by the amplifier circuits 230a, 230b, 230c, and 230d, digitized by the A / D converter 231, and stored in the storage device 222 in the system control unit 220. Once stored as image data. Thereafter, the arithmetic operation unit 223 performs an image addition averaging operation, the defect determination unit 234 extracts an image difference, and determines the presence / absence of a defect based on the defect determination condition. The determination result is displayed on the console device 225, and the result is stored in the system control unit 220. With the above procedure, it is possible to inspect the pattern of the region to be inspected in the wafer 214 in order from the end.

Next, setting of the scanning region A 102a, the scanning region B 102b, and the pre-irradiation region 103 will be described with reference to FIG. FIG. 3A is an explanatory diagram in which relevant portions of the electron optical system are extracted. FIG. 3B shows an inspection area on the wafer 214 (an arrow indicates beam scanning, a black circle indicates a scanning area, and a white circle indicates a pre-irradiation area. 3 (c) shows the aperture array 207, and FIG. 3 (d) shows the arrangement of the secondary electron detector 213 (in the figure, the black circle indicates the secondary beam position, and the square indicates the external electron detector 213 dimensions). ing. In the electron optical system, a plurality of second cathode images 228 are formed by the lens array 208 constituted by the corresponding electrostatic lenses in the aperture array 207 and projected onto the wafer 214 by the objective lens 210. A plurality of secondary beams 229 generated from the wafer 214 are imaged at the second cathode image position by the objective lens 210 and detected by the corresponding secondary electron detector 213. Therefore, the scanning area A 102 a and the scanning area B 102 b are similar to the area on the aperture array 207, the lens array 208, the secondary electron detector 213, and the wafer 214. The scanning area A 102 a, the scanning area B 102 b, and the pre-irradiation area 103 are similar to the aperture array 207, the lens array 208, and the area on the wafer 214. The inspection pitch 105 is set by the function of adjusting the magnification of the objective lens 210 in accordance with the region settings of the scanning region A 102a, the scanning region B 102b, and the pre-irradiation region 103. The channel width W _c and swath width W are automatically determined according to the set inspection pitch 105.

Next, the image acquisition operation will be described with reference to FIG. FIG. 4 is an explanatory diagram of stage movement and beam deflection at the time of image acquisition, comparing the case of acquiring with a general method and the case of acquiring an image with the high-speed method of this embodiment. In a general method, the stage 212 is driven at a constant speed V ₀ (speed at which the stage 212 moves by the size of one line in the time required to acquire an image of one line) (401a), and an image is displayed at the center position of the visual field dimension M. The deflector 211 is scanned when the end of the acquisition width L enters, and the deflector 211 is scanned when the position where the next line is to be detected. Similarly, the image acquisition width 106L in the inspection pitch 105P is scanned. Get only minutes of images. Even at the end of the image acquisition width 106L, an image is acquired at the center of the visual field (401b). On the other hand, the high-speed method drives the stage at a constant speed V (= V ₀ × P / L times). When the start point of the image acquisition width 106L enters the edge of the field of view, the beam is scanned (402a), and when one image acquisition is completed, an image of the next line is acquired. By repeating this, the image acquisition width 106L is acquired. An image is acquired. At the end of the image acquisition width 106L, an image is acquired at a position (402b) different from the start point. When the L dimension is 0.1 times the P dimension, an image can be acquired 10 times faster than a general method.

Next, the operation of the calculation unit 223 will be described with reference to FIG. FIG. 5 is a diagram showing the scanning area A 102 a, the scanning area B 102 b, and the pre-irradiation area 103 with the time t on the horizontal axis and the X coordinate on the vertical axis. Focusing on a specific coordinate X ₀ , a beam is irradiated in the order of the pre-irradiation region 103, the scanning region A 102a, and the scanning region B 102b, and the secondary beams 229b and 229c generated from the scanning region A 102a and the scanning region B 102b are respectively secondary electrons. Detectors 213a and 213c (and secondary channels are detected by secondary electron detectors 213b and 213d). The time for the secondary electron detectors 213a and 213c to detect the same coordinate has a fixed delay time 501. In addition, since the distance between the scanning area A 102a and the scanning area B 102b is not necessarily an integer multiple of the pixel size, interpolation and interpolation is performed by linear, spline, lanczos function, etc., and the dimension below the pixel is corrected and averaged. .

  Next, the operation of the defect determination unit 224 will be described. Defect determination is an actual pattern comparison method that compares images that should be the same, an averaged image is generated from one image using repeatability, and a detected image is compared with the averaged image RIA (Reference Image Averaging ) Method, a GP (Golden Pattern) is calculated from a plurality of images acquired in advance, and a GP comparison method is used for comparing the acquired image with the GP. The actual pattern comparison method uses the same die image to compare adjacent die images, and uses the same memory cell pattern to compare adjacent cell patterns. Since it is well known that there is a cell comparison method, the description is omitted.

  Next, the RIA method will be described with reference to FIG. The wafer 214 has a memory mat 601. Depending on which area of the memory mat 601, the area A (602) where there is repetition in the XY direction, the place B (603) where there is repetition only in the X direction, only in the Y direction There is a place C (604) where there is repetition, and there is a place D where there is no repeatability other than these, and by adding and averaging the repetition patterns in the XY directions, one high SN image is generated, and the high SN images are arranged. XY-RIA 606 for creating a reference image that is a high SN image of only the normal part is averaged by repeating the repeating patterns in the Y direction to generate a high SN image of one column, and the high SN image is arranged by arranging the high SN images. Y-RIA 607 for creating a reference image that is an SN image, an average of repeating patterns in the X direction is generated to generate a single row of high SN images, and the normal portion is obtained by arranging the high SN images Select the X-RIA608 to create a reference image is Minodaka SN image, it generates a reference image in any way, to compare the generated reference image and detected image. The GP comparison method will be described with reference to FIG. The GP comparison can be applied to the defect determination of the region 605 having no repeatability such as the corner (D) of the memory mat 601 shown in FIG. A plurality of (in this case, four) images 701a to 701d acquired in advance are registered and averaged to create a GP image 702. The detected image 703 is aligned with the GP image, a difference is detected, and a difference image is obtained. 704 is calculated, and it is determined that the difference is a certain area or more.

  According to the present embodiment, extremely high-speed image acquisition / inspection can be realized by a synergistic effect of acquiring images in parallel using a plurality of beams and thinning out images in the stage moving direction.

  Further, according to the present embodiment, since a plurality of beams are arranged in a direction perpendicular to the stage scanning direction, it is efficient to set an area when thinning out the image in the stage moving direction.

  In addition, according to the present embodiment, since the entire surface of the memory mat portion can be determined using the RIA method or the GP comparison method, the SN of the reference image is very good, so that even if the image detection clock is set to a high speed, a high defect is obtained. Judgment performance can be obtained, and high-speed inspection is possible.

  Further, according to the present embodiment, the inspection can be performed immediately after the pre-irradiation region is irradiated with the electron beam, and stable charging can be realized immediately after the inspection start end or the region having a large gap between the inspection regions. .

  Further, according to the present embodiment, the inspection pitch can be controlled by controlling the magnification of the objective lens, and thinning out in the stage scanning direction can be efficiently realized.

Next, a second embodiment of the present invention will be described with reference to FIG. Figure 8 is a diagram for explaining the inspection area of the first variant, with the stage movement, the channel width W _c only one channel 101a, the scan area A 102, scans the scanning area B102b multibeam, the image in parallel The images acquired in the scanning area A 102a and the scanning area B 102b are averaged. Prior to image acquisition of the scanning area A 102a and the scanning area B 102b, the pre-irradiation area 103 is irradiated with an electron beam. This enables image acquisition is equal to the channel width W _c of 101a swath width 104W. In addition, the entire surface image is acquired and inspected in the stage scanning direction. Compared with the conventional method of scanning the entire surface with one beam, according to the present image acquisition method, it is possible to expect N (N = 2) times faster. Further, it is not necessary to set the inspection pitch P105 in the stage moving direction.

  According to the present embodiment, the inspection pitch P105 can be arbitrarily changed, and conditions can be easily set.

  Next, a third embodiment will be described with reference to FIG. FIG. 9A is an explanatory diagram in which relevant portions of the electron optical system are extracted, and FIG. 9B shows an inspection area on the wafer 214 (beam scanning with an arrow, scanning area with a black circle, and pre-irradiation area with a white circle). 9 (c) shows the aperture array 207, and FIG. 9 (d) shows the arrangement of the secondary electron detector 213 (in the figure, the black circle indicates the secondary beam position, and the square indicates the secondary electron detector 213 external dimensions). ing. The pre-irradiation area 103 needs to be in front of the image acquisition area. If the stage movement direction is only one direction, it may be on one side, but in order to move the stage in both directions, a beam mask 901 is added, and the arrangement of the pre-irradiation region 213 is switched according to the stage movement direction. Of course, the position of the pre-irradiation region 213 may be switched by an arbitrary method such as addition of a beam deflector.

  According to the present embodiment, even if the stage moving direction is the UP direction or the DOWN direction, it is possible to acquire and inspect images under the same conditions by simply switching the pre-irradiation area.

Next, a fourth embodiment will be described with reference to FIGS. Figure 10 is a diagram for explaining the inspection area of the present embodiment, as the stage movement, by sharing the channel width W _c of the channel 101 a to 101 d, and scanning the scanning area A102a multibeam acquires an image in parallel . Prior to the image acquisition of the scanning area A 102a, the pre-irradiation area 103 is irradiated with an electron beam. This enables the image acquisition swath width 104W multiplied by the channel width W _c and the number of channels 101 a to 101 d. Further, an image having an image acquisition width 106 (L line) is acquired and inspected with respect to the inspection pitch 105 (P line) in the stage scanning direction. Compared with the conventional method of scanning the entire surface with one beam, according to this image acquisition method, it is possible to expect a high speed of (P / L) × (W / W _c ). By processing images acquired at high speed, defects can be detected and defect distribution can be obtained. Here, P / L is the inspection sampling rate in the stage moving direction, and W / W _c is the parallelism improvement rate by the multi-beam. The selection of the L dimension in the P dimension can be a simple sampling with a constant pitch, or an ROI region with a high defect occurrence rate can be selected. FIG. 11 shows the overall configuration of the circuit pattern inspection apparatus. Only differences from the first embodiment will be described. Since the scanning area B102b of the scanning area A102a and the scanning area B102b shown in FIG. 1 is not necessary, the corresponding aperture array 207 and lens array 208, secondary electron detector 213c, secondary electron detector 213d, and amplifier circuit 230c. , An amplifying circuit 230d is not provided, and a pre-irradiation position adjusting electrode 1101 for deflecting the position of the second cathode image 228b corresponding to the pre-irradiation region 103 is added. Along with this, an operation related to image addition becomes unnecessary. Further, the position of the pre-irradiation region 103 can be adjusted by applying a voltage to the pre-irradiation position adjusting electrode 1101. Thereby, the magnification adjustment of the objective lens 210 according to the change of the inspection pitch P105 in the stage moving direction becomes unnecessary, and only the adjustment of the position of the pre-irradiation region 103 by applying a voltage to the pre-irradiation position adjustment electrode 901 is sufficient.

  The difference effect between the present embodiment and the first embodiment is characterized in that the inspection pitch P105 can be arbitrarily changed because conditions of the images at the same position are not added and the conditions can be easily set.

  Next, a fifth embodiment will be described with reference to FIGS. FIG. 12 shows an overall configuration diagram of this embodiment. The difference from the first embodiment is that an aperture array switcher 1201 for switching between the aperture array 207 and the lens array 208 is added to form a secondary electron detector array 1202 incorporating a detector and an amplifier. When adjusting the positions of the scanning region A 102a, the scanning region B 102b, and the pre-irradiation region 103, the aperture array switcher 1201 switches the aperture array 207 and the lens array 208 to those having different dimensions. Since the secondary beam position on the sensor changes, the secondary electron detector used for image acquisition is also switched. Although the mechanical aperture array switcher 1201 has been described, any means capable of changing the position and number of the second cathode image equivalently by changing the applied voltage, such as an electrostatic shifter, has the same effect.

  According to the present embodiment, since the number and position of the scanning area A, the scanning area B, and the pre-irradiation area can be freely changed, the optimum setting can be made for each of the different types of inspection target wafers 214. is there.

  As described above, according to the present invention, it is possible to provide an inspection apparatus and an inspection method for efficiently monitoring the defect occurrence frequency and characteristic likelihood in the ROI region with high sensitivity.

101a, 101b, 101c, 101d Channel width W _c
102a Scanning area A
102b Scanning area B
103 Pre-irradiation area 104 Swath width W
105 Inspection pitch (P line)
106 Image acquisition width (L line)
201 Electron gun 202 Cathode 203 Anode 204 Electron gun lens 205 Primary beam 206 Collimator lens 207 Aperture array 208 Lens array 209 Beam separator 210 Objective lens 211 Deflector 212 Stage 213a, 213b, 213c, 213d Secondary electron detector 214 Wafer 215 Retarding power source 216 Surface electric field control electrode 217 Scanning signal generator 218 Surface electric field control power source 219 Optical system control circuit 220 System control unit 221 Stage control unit 222 Storage unit 223 Calculation unit 224 Defect determination unit 225 Console device 226 Reference mark 227 First Cathode image 228a, 228b, 228c Second cathode image 229 Secondary beam 230a, 230b, 230c, 230d Amplifier circuit 231 A / D converter 401a General Start point image acquisition position 401b General point end point image acquisition position 402a High speed method start point image acquisition position 402b High speed method end point image acquisition position 501 Delay time 601 Memory mat unit 602 XY direction repeat area 603 Y direction Repeat area 604 X-direction repeat area 605 Non-repeated area 606 XY-RIA
607 Y-RIA
608 X-RIA
701a to 701d Multiple images 702 GP image 703 Detection image 704 Difference image 901 Beam mask 1101 Pre-irradiation position adjustment electrode 1201 Aperture array switcher 1202 Secondary electron detector array

Claims (11)

  An electron beam irradiation system for irradiating an electronic circuit with a plurality of electron beams, a stage position measuring means for monitoring the continuously moving stage and its position, and a deflection system for controlling the irradiation position based on the position to be irradiated and the measured stage position And an image detection system for detecting a two-dimensional image of a plurality of partial regions along the movement by separating, detecting and AD converting a plurality of secondary electrons generated by beam irradiation, and two of the acquired partial regions A circuit pattern inspection apparatus including a defect determination unit that determines an image defect in a set region in a three-dimensional partial region image, and a console screen that displays the determined defect.   An electron beam irradiation system for irradiating an electronic circuit with a plurality of electron beams arranged to irradiate at least the same position with two or more different electron beams, and a stage position measuring means for monitoring the continuously moving stage and its position; And a deflection system that controls the irradiation position based on the position to be irradiated and the measured stage position, and an image that detects a two-dimensional image by separating, parallel detecting, and AD-converting multiple secondary electrons generated by beam irradiation A circuit pattern inspection apparatus including a detection system, a defect determination unit that determines a defect in an image of a set region in a two-dimensional partial region image of an acquired partial region, and a console screen that displays the determined defect. In the circuit pattern inspection apparatus according to claim 1 or 2,
The plurality of electron beam irradiations are arranged at the same position in the stage moving direction,
A circuit pattern inspection apparatus characterized in that images at the same position are added and averaged.   The circuit pattern inspection apparatus according to claim 3, wherein the averaging is performed after correcting a shift amount equal to or less than a pixel. The circuit pattern inspection apparatus according to claim 3,
A circuit pattern inspection apparatus that performs the averaging process using only selected images among images at the same position in a stage moving direction. The circuit pattern inspection apparatus according to claim 3,
A circuit pattern inspection apparatus, wherein the plurality of electron beam irradiations are switched according to a stage moving direction. In the circuit pattern inspection apparatus according to claim 1 or 2,
A circuit pattern inspection apparatus, wherein the plurality of electron beam irradiation positions are arranged on a line perpendicular to a stage moving direction.   The stage is continuously moved while measuring the position, and the deflection of the beam is controlled based on the stage position and the coordinates to be detected to irradiate the electronic circuit with multiple electron beams. Detecting two-dimensional images of multiple partial areas along the movement by separating and detecting electrons in parallel, AD conversion, and detecting image defects in the set areas in the acquired two-dimensional partial area images A circuit pattern inspection method comprising: determining and displaying the determined defect or transmitting a result to a server via a network.   A plurality of electron beams that irradiate at least the same position at least two different electron beams by continuously moving the stage while measuring the position and controlling the deflection of the beam based on the stage position and the coordinates to be detected. A partial area obtained by detecting a two-dimensional image by irradiating an electronic circuit, separating multiple secondary electrons generated by beam irradiation, detecting and AD converting in parallel, and averaging the images at the same location. A circuit pattern inspection method comprising: determining a defect of an image in a set region in the two-dimensional partial region image of the first and displaying the determined defect or transmitting a result to a server via a network.   10. The circuit pattern inspection method according to claim 9, wherein the total area of the plurality of partial areas is thinned to 50% or less of the area where the stage is moved.   11. The circuit pattern inspection method according to claim 9, wherein a region where an image is acquired and inspected by continuous stage movement is provided with a gap in a direction perpendicular to the stage movement.

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