U.S. patent application number 10/062666 was filed with the patent office on 2007-06-14 for pattern inspection method and system therefor.
Invention is credited to Munenori Fukunishi, Takashi Hiroi, Mitsunobu Isobe, Asahiro Kuni, Hiroshi Miyai, Yasuhiko Nara, Maki Tanaka, Masahiro Watanabe.
Application Number | 20070131877 10/062666 |
Document ID | / |
Family ID | 26623192 |
Filed Date | 2007-06-14 |
United States Patent
Application |
20070131877 |
Kind Code |
A9 |
Hiroi; Takashi ; et
al. |
June 14, 2007 |
Pattern inspection method and system therefor
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.
Inventors: |
Hiroi; Takashi; (Yokohama,
JP) ; Watanabe; Masahiro; (Yokohama, JP) ;
Kuni; Asahiro; (Tokyo, JP) ; Tanaka; Maki;
(Yokohama, JP) ; Fukunishi; Munenori; (Yokohama,
JP) ; Miyai; Hiroshi; (Hitachi, JP) ; Nara;
Yasuhiko; (Hitachinaka, JP) ; Isobe; Mitsunobu;
(Machida, JP) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET
SUITE 1800
ARLINGTON
VA
22209-3873
US
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20030062487 A1 |
April 3, 2003 |
|
|
Family ID: |
26623192 |
Appl. No.: |
10/062666 |
Filed: |
February 5, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09450856 |
Nov 29, 1999 |
6476913 |
|
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10062666 |
Feb 5, 2002 |
|
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Current U.S.
Class: |
250/492.2 |
Current CPC
Class: |
G06K 9/6211 20130101;
G06T 2207/30148 20130101; G06K 9/033 20130101; G01N 23/22 20130101;
G06K 2209/19 20130101; G06T 7/001 20130101 |
Class at
Publication: |
250/492.2 |
International
Class: |
G01N 23/00 20060101
G01N023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2001 |
JP |
2001-298910 |
Claims
1. A pattern inspection method, comprising the steps of:
irradiating either a charged particle or a light on a surface of a
substrate on which a pattern is formed; obtaining an image of said
substrate surface by detecting one of a reflected light, secondary
electron, reflected electron, transmitted electron, or absorbed
electron generated from said substrate as a result of the
irradiation; producing a digital image by subjecting the produced
image signal to A/D conversion; comparing the digital image with a
reference image stored in a memory, and extracting a defect
candidate; and outputting information of the extracted defect
candidate including image of the extracted defect candidate.
2. The pattern inspection method according to claim 1, further
comprising the step of displaying the outputted image of the
extracted defect candidate on a display screen.
3. The pattern inspection method according to claim 1, wherein said
information outputted at the outputting step includes data enabling
the classification of the defect.
4. The pattern inspection method according to claim 1, further
comprising the step of displaying in a map format the defect
candidate outputted at the step of outputting.
5. The pattern inspection method according to claim 4, further
comprising the step of displaying an image of a defect candidate
designated in the map displayed on the screen.
6. A pattern inspection method, comprising the steps of: detecting
a defect candidate of a pattern by using an inspecting means;
outputting an image of this detected defect candidate and data
including location information of the defect candidate via either a
storage medium or a network; and inputting said defect candidate
image and data including location information of the defect
candidate outputted via either said storage medium or said network
to processing means, and displaying the same on a screen of the
processing means.
7. The pattern inspection method according to claim 6, wherein the
defect candidate location data is displayed in map format on said
screen.
8. The pattern inspection method according to claim 6, wherein an
image of the defect candidate is displayed on said screen.
9. The pattern inspection method according to claim 8, wherein the
defect candidate, whose image is displayed on said screen, is
designated on this screen.
10. The pattern inspection method according to claim 6, further
comprising the step of changing threshold value data on said
screen, when detecting a defect candidate of said pattern using
said inspecting means.
11. The pattern inspection method according to claim 10, wherein
defect candidate location data displayed in map format is updated
and displayed in accordance with said changed threshold value
data.
12. The pattern inspection method according to claim 6, wherein, in
said step for displaying on the screen, said defect candidates are
classified using the images of defect candidates outputted via
either said storage medium or network and data comprising the
locations of these defect candidates, and location data of these
classified defect candidates is identified by classification and
displayed in map format on said screen.
13. The pattern inspection method according to claim 6, wherein, in
said step for displaying on the screen, said defect candidates are
classified using the images of defect candidates outputted via
either said storage medium or network and data comprising the
locations of these defect candidates, and location data of the
designated defect candidate from among these classified defect
candidates is displayed in map format on said screen.
14. The pattern inspection method according to claim 13, wherein
location data of defect candidates of a plurality of
classifications designated from among said classified defect
candidates is identified by said classifications and displayed in
map format on said screen.
15. The pattern inspection method according to claim 13, further
comprising the steps of processing said inputted image of said
defect candidate and data comprising the location of this defect
candidate by said processing means, and thereafter outputting
[same] via said network.
16. A pattern inspection method, comprising the steps of: imaging a
substrate on which a pattern is formed; processing an image
obtained by said imaging to detect a defect candidate of said
pattern; outputting, via a network, an image of said detected
defect candidate and data including location information of the
defect candidate while carrying out the step of imaging said
substrate and the step of detecting a defect candidate of said
pattern; and displaying, on a screen, said defect candidate image
and data including the location information of the defect candidate
outputted via this network.
17. The pattern inspection method according to claim 16, wherein
data of the location information of the defect candidate is
displayed in map format on said screen.
18. The pattern inspection method according to claim 16, wherein an
image of the defect candidate is displayed on said screen.
19. The pattern inspection method according to claim 18, wherein
the defect candidate, whose image is displayed on said screen, is
designated on the screen.
20. The pattern inspection method according to claim 16, further
comprising the step of changing threshold value data for detecting
a defect candidate of said pattern on said screen.
21. The pattern inspection method according to claim 16, wherein
the location of the defect candidate displayed in map format is
updated and displayed in accordance with said changed threshold
value data.
22. The pattern inspection method according to claim 16, wherein,
in the step for displaying on said screen, said defect candidates
are classified using the images of defect candidates and data
including location information of the defect candidates outputted
via either said storage medium or network, and identically
classified defect candidates are displayed in map format on said
screen.
23. The pattern inspection method according to claim 16, wherein,
in the step of displaying on said screen, said defect candidates
are classified using the images of defect candidates and data
including location information of the defect candidates outputted
via either said storage medium or network, and defect candidate
location data designated from among the classified defect
candidates is displayed in map format on said screen.
24. The pattern inspection method according to claim 23, wherein
plural classes of defect candidates designated from among said
classified defect candidates are displayed on said screen
discriminately from each other in the map format.
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.
* * * * *