Abstract:
Conventionally, defect data outputted by an inspection system comprised only characteristic quantitative data, such as coordinate data, area, and projected length, and only the coordinate data for moving to a defect location could be utilized effectively. By contrast, the present invention, by using image data in addition to characteristic quantitative data as the defect data for an inspection system, enables the retrieval of image data via an outside results confirmation system. Further, in the case of defect data of a plurality of substrates, it is enabled to display a defect image during inspection by the fact that similar defects are retrieved via images and retrieval results are displayed as trends makes it possible to display a defect image during inspection by searching similar defects on images and displaying them as a trend, designating a substrate on the trend, thereby displaying the defect map thereof and designating a defect on the defect map.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention is related to a manufacturing system for a substrate having a circuit pattern, such as a semiconductor device or liquid crystal display, and more particularly to the technology for inspecting a substrate pattern during fabrication.  
         [0003]     2. Description of the Related Art  
         [0004]     Conventional optical or electron beam pattern inspection systems are described in Japanese Patent Laid-open No. H5-258703 and Japanese Patent Laid-open No. H11-160247.  
         [0005]      FIG. 1  shows the constitution disclosed in Japanese Patent Laid-open No. H5-258703 as an example of an electron beam pattern inspection system. An electron beam  2  from an electron beam source  1  is deflected in the X direction by a deflector  3 , and is irradiated onto a target substrate  5  via an object lens  4  while a stage  6  is simultaneously made to move continuously in the Y direction, and a secondary electron  7  from the target substrate  5  is detected by a detector  8 , the detected signal is converted from analog to digital by an analog-to-digital (A/D) converter  9 , and, as a digital image, is compared by an image processing circuit  10  to a digital image of a place that can be expected to be the same as the original, a place that differs is detected as a pattern defect  11 , and the location of the defect is established.  
         [0006]      FIG. 2  shows the constitution disclosed in Japanese Patent Laid-open No. H11-160247 as an example of an optical inspection system. A light from a light source  21  is irradiated onto a target substrate  5  via an object lens  22 , and a reflected light is detected by an image sensor  23  at that time. By repeatedly detecting the reflected light while a stage  6  moves at a constant speed, an image is detected as a detected image  24 , and stored in memory  25 . [This detected image  24 ] is compared against a memory  25 -stored image  27 , which can be expected to be the same pattern as the detected image  24 , and if the patterns are identical, the detected image  24  is determined to be a normal portion, but if the patterns differ, this difference is detected as a pattern defect  11 , and the defect location is established.  
         [0007]     As an example,  FIG. 3  shows a layout of when a target substrate  5  is a wafer  31 . Dies  32 , which are ultimately cut apart to yield individual products of the same variety, are formed on wafer  31 . Stage  6  is moved along a scanning line  33 , and an image of the stripe region  34  is detected. When the present detection location A is  35 , an image of detection location B  36  in memory  25  is extracted as a stored image  27 , and the two images are compared. Thereby, detection location A  35  is compared against a pattern that can be expected to be an identical pattern. Here, memory  25  possesses capacity capable of holding an image that can be expected to be an identical pattern, that is used repeatedly in a ring shape to form an actual circuit.  
         [0008]     In case of the both inspection systems, to confirm the results of the inspection, the inspected data was outputted to a review system. Thereafter, the wafer was transferred to and set on a table of the review system to review defects detected by the inspection system. In the review system, the defect to be reviewed was placed in a viewing field of the review system by using the inspected data outputted from the inspection system. Then visually observing the image to judging whether or not it was an actual defect or to infer what could have caused it. In these reviewing method, a vast amounts of image data acquired by the inspection were not effectively used.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention is constituted such that an image of a defect portion, which is similar to an image of a defect portion specified on the basis of inspection results outputted by an inspection system and the defect portion image data thereof, is retrieved, and the conditions for the occurrence of a specific mode defect, which occurred in the past, can be grasped by displaying the retrieval results so as to enable identification.  
         [0010]     A first constitution according to the present invention will be explained. A constitution that uses an electron beam will be shown here, but it is substantially identical to a constitution, which utilizes another charged particle.  
         [0011]      FIG. 4  shows the constitution. It is constituted from an electron beam source  1  for generating an electron beam  2 ; and a deflector  3  for deflecting electron beam  2 ; and an object lens  4  for converging electron beam  2  onto a target substrate  5 ; and a stage  6  for holding, scanning and positioning target substrate  5 ; and a detector  8  for detecting a secondary electron  7  from target substrate  5 ; and an A/D converter  9  for converting a detected signal from analog to digital and forming a digital image; and an image processing circuit  110  for comparing the digital image against a digital image of a location that can be expected to be substantially identical, and detecting a location that is different as a pattern defect  11 ; and defect data storing means  201  for storing defect data  200  comprising the defect location and image data of pattern defect  11 ; and data outputting means  203  for outputting stored defect data  202  to either a network or a storage medium; and inputting means  205  for inputting a defect data  202  related to a plurality of wafers, which was outputted to data transferring means  204  by data outputting means  203 ; and defect data storing means  206  for storing inputted defect data; and a defect map  207  for displaying defect location data of the wafer on a display screen and selecting means  208  for selecting specific defect on the defect map  207 ; and image displaying means  209  for displaying image data of selected defect data in an image format; search command means  210  for issuing a command for retrieving from the defect data group a defect image that is similar to a displayed image; and image retrieving means  211  for retrieving an image having image data that is similar to a displayed image.  
         [0012]     Electron beam  2  from electron beam source  1  is irradiated onto target substrate  5  via object lens  4 , and generated secondary electron  7  is detected by detector  8 . Electron beam  1  is deflected by deflector  3 , image data is formed by using stage  6  for scanning target substrate  5 , [this image data] is converted from analog to digital by A/D converter  9 , and a digital image is formed. Image processing circuit  110  compares this digital image with a digital image which is expected to be substantially identical, and detects a difference between the two images as a pattern defect  11 . Defect data  200 , comprising the defect location and image data of detected pattern defect  11 , is stored in defect data storing means  201 , and stored defect data  202  is outputted by data outputting means  203  as necessary to information transferring means  204  of either a network or a storage medium.  
         [0013]     Defect data  202  of a plurality of wafers, which is outputted from outputting means  203 , is inputted by inputting means  205  and is stored in a storing means  206 , and the defect location data of the inputted defect data is displayed in defect map  207 . When a specific defect on the defect map is selected by selecting means  208 , an image of the selected specific defect is displayed on image displaying means  209 . When a command is issued by search command means  210 , a defect image similar to the displayed image is retrieved from among the stored defect data stored in the storing means  206  by image retrieving means  211 , and the retrieval results are reflected in defect map  207 . Retrieval results can be checked as needed by issuing a command via selecting means  208 . The frequency at which similar defects occur can be checked by displaying in the time-series format shown in  FIG. 5 a  display format of defect map  207 . In accordance therewith, the image data acquired at inspection time can be utilized effectively.  
         [0014]     These and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a front view showing a simplified constitution of a conventional electron beam-type pattern inspection system;  
         [0016]      FIG. 2  is a front view showing a simplified constitution of a conventional optical-type pattern inspection system;  
         [0017]      FIG. 3  is a plan view showing a wafer layout;  
         [0018]      FIG. 4  is a block diagram showing a simplified constitution of solution means of the present invention;  
         [0019]      FIG. 5  is a graph showing occurrence frequency trends of defects;  
         [0020]      FIG. 6  is a block diagram showing the overall constitution of a pattern inspection system according to the present invention;  
         [0021]      FIG. 7  is a front view showing a simplified constitution of an inspection system according to the present invention; and  
         [0022]      FIG. 8  is a front view of a display screen showing an example of a display screen of a results confirmation system according to the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     The embodiments of the present invention will be explained hereinbelow using specific figures. The overall system will be explained first, and then the respective parts of the system will be explained.  
       Overall System  
       [0024]     The constitution of the first embodiment is shown in  FIG. 6 . This first embodiment is constituted from a server  151 , which is arranged on a network  150 , and which manages and stores various information; and an SEM (scanning electron microscope)-type pattern inspection system, an optical-type pattern inspection system, an extraneous material inspection system, a length-measuring SEM, and other such inspection systems A  152  and inspection systems B  153 , which treat a target substrate  5  as an object, and inspect patterns and measure dimensions; a review system  154  for receiving inspection results from inspection system A  152  and inspection system B  153 , positioning target substrate  5  at a specified defect location, and visually checking this specified defect; and a defect checking system  155  for receiving and checking either inspection or measurement data at inspection time. The respective parts satisfy their functionality by operating as described hereinbelow.  
         [0025]     That is, a target substrate  5  is loaded, and either a pattern inspection or an extraneous material inspection is carried out, or pattern dimensions are measured by inspection system A  152  and inspection system B  153 . Measurement results  160 , together with image data  161  of defective parts and measured portions are stored when inspection and measurement are performed, and measurement results  160  and image data  161  are outputted over network  150 . These data are stored in server  151  one time.  
         [0026]     Information of the measurement results  160  and image data  161  of a plurality of target substrate  5  stored in server  151  is transmitted to defect review system  154 , and measurement results  160  are displayed on defect confirmation system  155 . Based on the displayed results, image data  161  of a defective portion, which is similar to the image of a specific defect, is retrieved using a method, which will be explained hereinbelow, and the retrieval results are reflected on a display.  
         [0027]     A first variation of this embodiment will be explained. That is, instead of executing a search via a defect checking system  155 , a search can be executed via either inspection system A  152 , or inspection system B  153 , or server  151 , or review system  154 . Or, instead of the checking system  155 , a search server  156  which is connected to the network  150  is provided, and a search is executed by the search server  156  and only the results are displayed via a system other than defect checking system  155  or search server  156 . Further, a search can be executed by an arbitrary system without the need to provide search server  156  independently.  
       Inspection System  
       [0028]     The constitution of a SEM-type pattern inspection system is shown in  FIG. 7 . This constitution comprises an electron beam source  1  for generating an electron beam  2 ; and an electron optical system  64  having an electron gun for accelerating and extracting an electron beam  2  from electron beam source  1  by means of an electrode, and creating a virtual light source in a fixed location by means of an electrostatic or magnetic field superimposed lens, a condenser lens  60  for converging an electron beam  2  from virtual light source  40  in a fixed location, a blanking plate  104 , which is set near the convergence location, and which controls the ON/OFF of an electron beam  2  from electron gun, a deflector  105  for deflecting an electron beam  2  in the XY directions, and an object lens  4  for converging an electron beam  2  onto a target substrate  5 ; and a sample chamber  107  for maintaining a wafer  31 , which is target substrate  5 , in a vacuum; a stage  6 , on which is mounted the wafer  31 , and to which is applied a retarding voltage  108  for making it possible to detect an image of an arbitrary location; and detector  8  for detecting a secondary electron  7  from target substrate  5 ; and A/D converter  9  for converting a detected signal detected by detector  8  from analog to digital and producing a digital image; and memory  109  for storing a digital image; and an image processing circuit  110  for comparing a stored image stored in memory  109  with an A/D converted digital image, and detecting difference between the compared two images as a pattern defect  11 ; and a pattern defect storage portion  201  for storing defect data  200 , such as pattern defect  11  coordinates, projected length, area, critical threshold value DD (the threshold value at which, when the threshold value is lower than this value, a defect is detected), differential image average value, differential image distribution, maximum image difference, defect image texture, reference image texture, image of a defect portion, and a reference image having a pattern that is identical to that of the defect portion; and data outputting means  203  for outputting stored defect data  200  to either a network or a storage medium; and a system controller  100  for controlling the entire system (control lines from system controller  100  are omitted from the figure); and an operating screen  45  for performing various operations; and a keyboard (not shown), mouse (not shown)and knob (not shown) for specifying operations; and a Z sensor  113  for maintaining the focal point position of a detected digital image constant by measuring the height of a wafer  31 , and adding and controlling an offset  112  to the current value of object lens  4 ; and a loader (not shown) for loading and unloading wafers  31  inside a cassette  114  into sample chamber  107 ; and an orientation flat detector  117  (not shown) for positioning the wafer  31  using the outline shape of a wafer  31  as a reference; and an optical microscope  118  for observing a pattern on the wafer  31 ; and a standard sample  119 , which is provided on stage  6 .  
         [0029]     The operation of the inspection system will be explained. When an inspection is started by a command from a user, stage  6  moves and the region to-be-inspected of the wafer  31  mounted on the stage  6  is to the scanning start position. A wafer-specific offset measured beforehand is added and set in offset  112 , Z sensor  113  is made operative, stage  6  scans in the Y direction along scanning line  33  shown in  FIG. 3 , deflector  105  scans in the X direction in synchronization with the scan of the stage, the voltage of blanking plate  104  is shut off at effective scanning time, and an electron beam  2  is irradiated onto wafer  31  and scanning is performed. Either a reflected electron or a secondary electron generated from wafer  31  is detected by detector  8 , a digital image of stripe region  34  is produced by A/D converter  9 , and then stored in memory  109  and inputted in image processing circuit  110  in parallel. Upon termination of the scan of stage  6 , Z sensor  54  is made inoperative.  
         [0030]     An inspection of all required regions is done by repeating the scan of the stage  6 . When the detection is carried out in the location A  35  (Refer to  FIG. 3 ), image processing circuit  110  compares a detected image of the location A  35  with an image of detection location B  36  (Refer to  FIG. 3 ) stored in memory  109 , and extracts a discrepancy between both images as a pattern defect  11 , and stores the image of detection location A  36  in defect data storage means  201 . Defect data  200 , such as extracted pattern defect  11  coordinates, projected length, area, critical threshold value DD (the threshold value at which, when the threshold value is lower than this value, a defect is detected), differential image average value, differential image distribution, maximum image difference, defect image texture, reference image texture, and image data, is stored in defect data storage means  201 . And from data outputting means  203  is outputted as needed to data transferring means  204 , which is either a network or an MO (magneto-optical disk), CDR (compact disk—recordable), DVD (digital video disk), FD (floppy disk) or other storage medium.  
       Results Confirmation System  
       [0031]     Outputted defect data  202  is inputted via inputting means  205  of results confirmation system  155  either via a network or from a storage medium, and defect location data from among the inputted defect data is displayed on defect map  207 . When a specific item on the defect map is selected by selecting means  208 , image data of the defect data is displayed in image format on image displaying means  209 . When a command is issued by search command means  210 , a defect image similar to the display image is retrieved by image retrieving means  211  from among the defect data group, and retrieval results are reflected on defect map  207 . Retrieval results can be checked as needed by issuing a command via selecting means  208 . The frequency at which similar defects occur can be checked by displaying in the time-series format shown in  FIG. 5 a  display format of defect map  207 . In accordance therewith, the image data acquired at inspection time can be utilized effectively.  
         [0032]     An example of a display screen of results confirmation system  155  is shown in  FIG. 8 . The location on a substrate (wafer) of each detected defect is displayed on map display portion  55 , which corresponds to defect map  207  of  FIG. 4 .  
         [0033]     Further, an image of a defect specified from among the defects displayed on the map display portion is displayed on image display portion  56 , which corresponds to image displaying means  209  of  FIG. 4 . Specifying a defect for displaying this image is done by operating a mouse operation command button  140 . That is, a current location symbol  59  is displayed on the screen by using the mouse operation command button  140  to select the selection mode  145  from among a selection mode  145  and a zooming mode  146 , the current location display  59  is moved with the mouse (not shown in the figure), and the image of a defect that [a user] wishes to see is displayed on image display portion  56  by clicking on the location of the defect to be viewed.  
         [0034]     Further, when the zooming mode  146  is selected with the mouse operation command button  140 , a display on map display portion  55  of the distribution of defects on a substrate can be either enlarged or reduced.  
         [0035]     According to the present invention, an image of a defect portion, which is similar to an image of a defect portion specified on the basis of inspection results outputted by an inspection system and the defect portion image data thereof, is retrieved, and the conditions for the occurrence of a specific mode defect, which occurred in the past, can be grasped by displaying the retrieval results so as to enable identification. Further, [the present invention] is characterized in that it enables the provision of functions for sounding an alarm in response to a future specific mode-generated defect by setting retrieval conditions in the inspection system.  
         [0036]     The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.