U.S. patent application number 12/548642 was filed with the patent office on 2009-12-24 for visual inspection apparatus, visual inspection method, and peripheral edge inspection unit that can be mounted on visual inspection apparatus..
This patent application is currently assigned to OLYMPUS CORPORATION. Invention is credited to Shinichi DOSAKA, Hiroyasu HEBIISHI, Atsutoshi YOKOTA.
Application Number | 20090316143 12/548642 |
Document ID | / |
Family ID | 37307951 |
Filed Date | 2009-12-24 |
United States Patent
Application |
20090316143 |
Kind Code |
A1 |
YOKOTA; Atsutoshi ; et
al. |
December 24, 2009 |
VISUAL INSPECTION APPARATUS, VISUAL INSPECTION METHOD, AND
PERIPHERAL EDGE INSPECTION UNIT THAT CAN BE MOUNTED ON VISUAL
INSPECTION APPARATUS.
Abstract
This visual inspection apparatus has a macro-inspection section
and a micro-inspection section. In the micro-inspection section, a
inspection stage and a microscope are loaded into a loading plate.
The inspection stage can be moved in any directions of the X, Y,
and Z directions, and can also be rotated in the .theta. direction.
Moreover, a peripheral edge inspection section that acquires an
enlarged image of a peripheral edge of wafer W is fixed to the
loading plate. The peripheral edge inspection section is arranged
so as to image the peripheral edge of wafer W held by the
inspection stage.
Inventors: |
YOKOTA; Atsutoshi;
(Kamiina-gun, JP) ; HEBIISHI; Hiroyasu; (Tokyo,
JP) ; DOSAKA; Shinichi; (Tsukui-gun, JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
220 Fifth Avenue, 16TH Floor
NEW YORK
NY
10001-7708
US
|
Assignee: |
OLYMPUS CORPORATION
Tokyo
JP
|
Family ID: |
37307951 |
Appl. No.: |
12/548642 |
Filed: |
August 27, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11977880 |
Oct 26, 2007 |
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12548642 |
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PCT/JP2006/308759 |
Apr 26, 2006 |
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11977880 |
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Current U.S.
Class: |
356/237.5 |
Current CPC
Class: |
G01N 21/9503
20130101 |
Class at
Publication: |
356/237.5 |
International
Class: |
G01N 21/00 20060101
G01N021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 27, 2005 |
JP |
P2005-129403 |
Jul 11, 2005 |
JP |
P2005-202015 |
Claims
1. A visual inspection apparatus comprising: a visual inspection
section for performing visual inspection of a surface of a
workpiece; a peripheral edge inspection section that acquires an
enlarged image of a peripheral edge which includes a side part, a
chamfered part of a workpiece, and a surrounding part of front and
back surfaces of the workpiece; and a holding unit that is
configured to hold the workpiece and that is capable of moving, the
holding unit being provided in the visual inspection section;
wherein the holding unit is shared between an inspection at the
visual inspection section and an inspection at the peripheral edge
inspection section by moving between the visual inspection section
and the peripheral edge inspection section.
2. The visual inspection apparatus according to claim 1, wherein
the holding unit and the peripheral edge inspection section are
provided so as to be brought closer to and spaced apart from each
other.
3. The visual inspection apparatus according to claim 1, wherein
the peripheral edge inspection section is detachably provided in
the visual inspection section.
4. The visual inspection apparatus according to claim 1, wherein
the visual inspection section includes a micro-inspection section
that acquires an enlarged image of the surface of the workpiece,
and wherein the holding unit is shared so as to be movable between
the micro-inspection section and the peripheral edge inspection
section.
5. The visual inspection apparatus according to claim 4, further
comprising means for: (i) recording a coordinate of an observation
position when inspection is performed in one of the
micro-inspection section and the peripheral edge inspection
section, and (ii) moving the observation position to an observation
position of the other one of the micro-inspection section and the
peripheral edge inspection section based on the recorded coordinate
of the observation position when inspection is performed in the
other one of the micro-inspection section and the peripheral edge
inspection section.
6. The visual inspection apparatus according to claim 1, wherein
the holding unit and the peripheral edge inspection section are
provided on a same loading plate that is free from vibration.
7. A visual inspection method comprising: holding a workpiece by a
holding unit provided in a visual inspection section, and visually
inspecting a surface of the workpiece; bringing a peripheral edge
inspection section that acquires an enlarged image of a peripheral
edge which includes a side part, a chamfered part, and front and
back surfaces of the workpiece closer to the holding unit; and
acquiring the enlarged image of the peripheral edge of the
workpiece in a state where the holding unit is brought closer to
the peripheral edge inspection section.
8. A peripheral edge inspection unit that is mountable on a visual
inspection apparatus, the peripheral edge inspection unit
comprising: an anchor which is detachable from a visual inspection
section that performs visual inspection of a surface of a workpiece
in a state where the workpiece is movably held by a holding unit;
and an enlarged image acquisition part that is arranged so as to
face a peripheral edge which includes a side part, a chamfered
part, and front and back surfaces of the workpiece held by the
holding unit, and that is capable of acquiring an enlarged image of
the peripheral edge of the workpiece.
9. The peripheral edge inspection unit according to claim 8,
wherein the anchor and the enlarged image acquisition part are
connected via a uniaxially movable stage.
10. The visual inspection apparatus according to claim 1, wherein
the workpiece is a flat plate-like test body, and the peripheral
edge inspection section includes: (i) an observation optical system
that observes a peripheral end face of the flat plate-like test
body, and (ii) a mirror part that deflects an optical axis in the
observation optical system to make the optical axis reach the
peripheral end face of the test body, and wherein, while a
direction of view is changed by rotation of the mirror part, a
distance between the observation optical system and the peripheral
end face of the test body is kept substantially constant, and the
peripheral end face of the test body is observed.
11. The visual inspection apparatus according to claim 2, wherein
the peripheral edge inspection section is detachably provided in
the visual inspection section.
12. The visual inspection apparatus according to claim 11, wherein
the visual inspection section includes a micro-inspection section
that acquires an enlarged image of the surface of the workpiece,
and wherein the holding unit is shared so as to be movable between
the micro-inspection section and the peripheral edge inspection
section.
13. The visual inspection apparatus according to claim 12, further
comprising means for: (i) recording a coordinate of an observation
position when inspection is performed in one of the
micro-inspection section and the peripheral edge inspection
section, and (ii) moving the observation position to an observation
position of the other one of the micro-inspection section and the
peripheral edge inspection section based on the recorded coordinate
of the observation position when inspection is performed in the
other one of the micro-inspection section and the peripheral edge
inspection section.
14. The visual inspection apparatus according to claim 2, wherein
the visual inspection section includes a micro-inspection section
that acquires an enlarged image of the surface of the workpiece,
and wherein the holding unit is shared so as to be movable between
the micro-inspection section and the peripheral edge inspection
section.
15. The visual inspection apparatus according to claim 14, further
comprising means for: (i) recording a coordinate of an observation
position when inspection is performed in one of the
micro-inspection section and the peripheral edge inspection
section, and (ii) moving the observation position to an observation
position of the other one of the micro-inspection section and the
peripheral edge inspection section based on the recorded coordinate
of the observation position when inspection is performed in the
other one of the micro-inspection section and the peripheral edge
inspection section.
16. The visual inspection apparatus according to claim 3, wherein
the visual inspection section includes a micro-inspection section
that acquires an enlarged image of the surface of the workpiece,
and wherein the holding unit is shared so as to be movable between
the micro-inspection section and the peripheral edge inspection
section.
17. The visual inspection apparatus according to claim 16, further
comprising means for: (i) recording a coordinate of an observation
position when inspection is performed in one of the
micro-inspection section and the peripheral edge inspection
section, and (ii) moving the observation position to an observation
position of the other one of the micro-inspection section and the
peripheral edge inspection section based on the recorded coordinate
of the observation position when inspection is performed in the
other one of the micro-inspection section and the peripheral edge
inspection section.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a Continuation Application of
U.S. application Ser. No. 11/977,880 filed Oct. 26, 2007, which is
incorporated herein by reference and which is a Continuation of
International Application No. PCT/JP2006308759 filed Apr. 26,
2006.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a visual inspection
apparatus used to inspect the appearance of a workpiece, a visual
inspection method, and a peripheral edge inspection unit that can
be mounted on such a visual inspection apparatus and used to
inspect the peripheral edge of the workpiece.
[0004] 2. Description of Related Art
[0005] When patterns, such as circuits, on a workpiece, such as a
semiconductor wafer, are formed, a visual inspection apparatus that
inspects the existence of a defect on the surface of the workpiece
is used. As this type of visual inspection apparatus, there is an
inspection apparatus (for example, refer to Patent Document 1) that
oscillates and rotatably holds a workpiece, has a macro-inspection
section that allows an inspector to visually inspect the surface of
the workpiece (macro inspection), and a micro-inspection section
that acquires an enlarged image of the workpiece to allow
inspection (micro inspection), and that enables such macro
inspection and micro inspection by use of one apparatus.
[0006] Further, when circuits, etc. are formed on a workpiece,
warpage or internal stress may be caused in the workpiece due to
heat treatment, etc. If such warpage and internal stress become
large, the workpiece may be fractured during manufacture of the
circuits. Thus, a technique of enlarging and observing the
peripheral edge of the workpiece in advance, thereby inspecting the
existence of cracks which may becomes fractures in the future, is
known. As a visual inspection apparatus used to inspect the
peripheral edge of the workpiece (peripheral edge inspection),
there is an inspection apparatus (for example, refer to Patent
Document 2) including a support that rotatably supports a
workpiece, a peripheral edge imaging section that continuously
captures images of the peripheral edge of the workpiece, and a
peripheral edge illumination device that illuminates the peripheral
edge.
[0007] [Patent Document 1] JP-A-2004-96078
[0008] [Patent Document 2] JP-A-2003-243465
[0009] However, in order to carry out the macro inspection, micro
inspection, and peripheral edge inspection, there are problems in
that a wafer must be replaced and moved by a machine, a loader,
etc., between the visual inspection apparatus disclosed in Patent
Document 1, and the visual inspection apparatuses disclosed in
Patent Document 2, causing prolonged takt time. Further, when one
visual inspection apparatus is attached to another visual
inspection apparatus externally, transport time can be shortened.
However, replacement of a workpiece is required even in such a
case. Moreover, the installation area as the whole apparatus is not
different from when apparatuses are installed independently.
SUMMARY OF THE INVENTION
[0010] The invention has been made in view of the above
circumstances. It is therefore a main object of the invention is to
reduce takt time, miniaturize the apparatus, and simplify the
configuration of the apparatus in performing macro inspection,
micro inspection, and peripheral edge inspection.
[0011] In order to solve the above problems, the invention provides
a visual inspection apparatus including: a visual inspection
section for performing visual inspection of the surface of a
workpiece, and a peripheral edge inspection section that acquires
an enlarged image of a peripheral edge of the workpiece. Here, a
holding unit that holds the workpiece in the visual inspection
section is shared by the visual inspection section and the
peripheral edge inspection section.
[0012] Further, the invention provides a visual inspection method
including: holding a workpiece by a holding unit and inspecting the
appearance of the surface of the workpiece; bringing a peripheral
edge inspection section that acquires an enlarged image of a
peripheral edge of the workpiece relatively close to the holding
unit; and acquiring the enlarged image of the peripheral edge of
the workpiece in a state where the holding unit is brought
relatively close to the peripheral edge inspection section.
[0013] In the invention, when visual inspection is performed, a
workpiece is held by the holding unit, and inspection is performed
while the holding unit is moved as needed. Moreover, when the
peripheral edge inspection is performed, a workpiece is rotated
while the workpiece is held by the holding unit without performing
transfer of the workpiece, and the enlarged image of a peripheral
edge of the workpiece is acquired in the peripheral edge inspection
section.
[0014] Moreover, the invention provides a peripheral edge
inspection unit mountable on the visual inspection apparatus
including: an anchor that is detachable to a visual inspection
section that allows visual inspection of the surface of a workpiece
in a state where the workpiece is movably held by a holding unit;
and an enlarged image acquisition part that is arranged so as to
face a peripheral edge of the workpiece held by the holding unit,
and is capable of acquiring an enlarged image of the peripheral
edge of the workpiece.
[0015] In the invention, it is possible to fix the anchor to a
predetermined position of the visual inspection section, thereby
performing the peripheral edge inspection, using the holding unit
of the visual inspection section. That is, visual inspection can be
performed, without transferring a workpiece carried into the visual
inspection section. Here, the peripheral edge refers to a side
part, and a chamfered part of a workpiece, and a surrounding part
of its front and back surfaces. Further, if the workpiece is a
wafer, an edge cut line portion after an unnecessary resist is
removed after application of a resist is included in the peripheral
edge.
[0016] According to the present invention, in the visual inspection
apparatus that has the visual inspection section that is used to
allow visual inspection of the surface of a workpiece, the holding
unit that holds the workpiece is shared by the visual inspection of
the surface of the workpiece, and the peripheral edge inspection
that inspects the peripheral edge of the workpiece. Thus, it is
possible to perform the visual inspection and peripheral edge
inspection while the workpiece is held by the holding unit, without
performing transfer of the workpiece. Furthermore, compared with a
case where apparatuses are configured independently, the
installation area can be made small. Moreover, since the distance
at which the workpiece is moved, and the time and effort for
transfer can be omitted, the tact time of inspection can be
reduced.
DETAILED DESCRIPTION OF THE INVENTION
[0017] FIG. 1 is a plan view showing the schematic configuration of
a visual inspection apparatus according to an embodiment of the
invention
[0018] FIG. 2 is a side view showing the schematic configuration of
the visual inspection apparatus
[0019] FIG. 3 is an exploded view illustrating attachment and
detachment of a peripheral edge inspection section FIG. 4 is a plan
view showing the schematic configuration of the visual inspection
apparatus
[0020] FIG. 5 is a side view showing the schematic configuration of
the visual inspection apparatus
[0021] FIG. 6 is a side view showing the schematic configuration of
the visual inspection apparatus
[0022] FIG. 7 is a plan view showing the schematic configuration of
the visual inspection apparatus
[0023] FIG. 8 is a view showing an exemplary configuration when a
variable direction-of-view observation apparatus of a first mode is
seen from the front of the apparatus
[0024] FIG. 9A is a view showing an exemplary configuration when
the variable direction-of-view observation apparatus of the first
mode is seen from the side of the apparatus
[0025] FIG. 9B is a view showing an exemplary configuration of a
mirror cam as seen from an arrow A1 side in FIG. 9A
[0026] FIG. 10A is a view for explaining an observable direction of
view in the variable direction-of-view observation apparatus of the
first embodiment
[0027] FIG. 10B is a view for explaining the observable direction
of view in the variable direction-of-view observation apparatus of
the first embodiment
[0028] FIG. 11 is a view showing an exemplary configuration when a
variable direction-of-view observation apparatus of a second
embodiment is seen from the front
[0029] FIG. 12A is a view showing an exemplary configuration when a
variable direction-of-view observation apparatus of a third
embodiment is seen from the front
[0030] FIG. 12B is a view showing an exemplary configuration when
the variable direction-of-view observation apparatus of the third
embodiment is seen from the back FIG. 12 C is a view showing a
cross-sectional exemplary configuration of a movable front-and-back
observation mirror as seen from an arrow C1 side in FIG. 12B;
[0031] FIG. 13A is a view for explaining the operation of the
variable direction-of-view observation apparatus of the third
embodiment
[0032] FIG. 13B is a view for explaining the operation of the
variable direction-of-view observation apparatus of the third
embodiment
[0033] FIG. 13C is a view for explaining the operation of the
variable direction-of-view observation apparatus of the third
embodiment
[0034] FIG. 13D is a view for explaining the operation of the
variable direction-of-view observation apparatus of the third
embodiment
[0035] FIG. 13E is a view for explaining the operation of the
variable direction-of-view observation apparatus of the third
embodiment
[0036] FIG. 13F is a view for explaining the operation of the
variable direction-of-view observation apparatus of the third
embodiment
[0037] FIG. 13G is a view for explaining the operation of the
variable direction-of-view observation apparatus of the third
embodiment.
REFERENCE NUMERALS
[0038] 1, 51, 71: VISUAL INSPECTION APPARATUS [0039] 10:
MICRO-INSPECTION SECTION (VISUAL INSPECTION SECTION) [0040] 11:
MICRO-INSPECTION SECTION (VISUAL INSPECTION SECTION) [0041] 12, 61:
PERIPHERAL EDGE INSPECTION SECTION (PERIPHERAL EDGE INSPECTION
UNIT) [0042] 15, 30, 72: LOADING PLATE [0043] 22: MICRO-INSPECTION
UNIT (HOLDING UNIT) [0044] 31, 74, 95: INSPECTION STAGE (HOLDING
UNIT) [0045] 36A, 79: ROTARY SHAFT [0046] 41: ANCHOR [0047] 44:
ENLARGED IMAGE ACQUISITION PART [0048] 45, 96: CONTROL DEVICE
[0049] 73: AUTOMATIC MICRO-INSPECTION SECTION (VISUAL INSPECTION
SECTION) [0050] W: WAFER (WORKPIECE) [0051] 101: BASE [0052] 101a:
MOTOR ATTACHING PLATE [0053] 102: MOTOR [0054] 103: BALL SCREW SET
[0055] 103a: BALL SCREW [0056] 103b: BALL SCREW GUIDE [0057] 104:
Z-DIRECTION MOVABLE LINEAR GUIDE [0058] 104a, 106a: RAIL [0059]
104b, 106b: CASE [0060] 105: Z-MOVABLE CARRIAGE [0061] 105a: ARM
[0062] 106: X-DIRECTION MOVABLE LINEAR GUIDE [0063] 107: X MOVABLE
PLATE [0064] 108: CAM [0065] 108a, 118a: CAM SURFACE [0066] 109,
117: CAM ROLLER [0067] 111, 120: TENSION SPRING [0068] 112: CCD
CAMERA [0069] 114: WAFER [0070] 115: ROTARY MIRROR [0071] 116:
ROTARY SHAFT [0072] 118: MIRROR CAM [0073] 119: ROTARY ARM [0074]
121a, 121b: SPRING HOOK [0075] 122: IMAGING LENS [0076] 200, 201,
202: VARIABLE DIRECTION-OF-VIEW OBSERVATION APPARATUS (PERIPHERAL
EDGE INSPECTION SECTION)
DETAILED DESCRIPTION OF THE INVENTION
[0077] The best modes for carrying out the invention will be
described in detail with reference to the accompanying
drawings.
First Embodiment
[0078] As shown in FIG. 1, a visual inspection apparatus 1 has an
inspection section 2 provided at the front (a lower part in FIG. 1)
that faces an inspector, and a loader part 3 is connected to the
back side of the inspection section 2. In the loader part 3, two
wafer carriers 4A and 4B that receive semiconductor wafers W
(hereinafter referred to as "wafer W") that are workpieces are
connected side by side. In addition, the wafer carriers 4A and 4B
can receive a plurality of wafers W at a predetermined pitch in a
vertical direction. For example, a non-inspected wafer W is
received in the wafer carrier 4A, and an inspected wafer W is
received in the wafer carrier 4B. Moreover, the wafer carriers 4A
and 4B can be independently attached to and detached from the
loader part 3.
[0079] The loader part 3 has an automated transport unit 5. The
automated transport unit 5 includes a multi-segmented robotic arm,
and a hand 5A at a tip of the robotic arm is provided with suction
holes 6 that hold wafer W by suction-clamping. This automated
transport unit 5 is configured movably and rotatably so that the
wafer W can be transported between each of the two wafer carriers
4A and 4B and a macro-inspection section 10 of the inspection
section 2.
[0080] The inspection section 2 has an the macro-inspection section
10 that is used in order for an inspector to inspect the surface of
wafer W visually and macroscopically (macro inspection), and a
micro-inspection section 11 that makes an inspection (micro
inspection) performed by acquiring an image of the surface of wafer
W as an enlarged image of a higher magnification than visual
observation, and a peripheral edge inspection section 12 that
acquires an enlarged image of a peripheral edge of wafer W is
attached to the micro-inspection section 11.
[0081] In the macro-inspection section 10, a swivel arm 16 is
rotatably and liftably provided on the loading plate 15. The swivel
arm 16 has three transport arms 18, 19, and 20 horizontally
extending equiangularly from a rotary shaft 17, and a plurality of
suction holes (wafer chuck) 21 are provided at the tip of each of
the transport arms 18, 19, and 20. These suction holes 21 are
connected to a suction device that is not shown. Moreover, the
rotation of the swivel arm 16 is controlled so that the transport
arms 18, 19, and 20 may be arranged at positions P1, P2, and P3,
respectively. The position P1 is a transfer position where wafer W
is transferred between the macro-inspection section 10 and the
loader part 3, and the position P2 is an inspection position where
macro inspection is performed. The position P3 is a transfer
position where wafer W is transferred between the macro-inspection
section 10 and the micro-inspection section 11.
[0082] In addition, a macro-inspection unit 22 is provided in the
position P2. The macro-inspection unit 22 has a base part 23 fixed
to the loading plate 15. A holder 24 that holds wafer W by
suction-clamping is provided in the base part 23 so as to be
liftable and oscillatable in the Z direction (vertical direction),
and causes the wafer W in the position P2 to rise towards an
inspector so that the wafer W can be rotated and oscillated.
Moreover, an illumination device (not shown) that illuminates wafer
W in the position P2 is provided above the swivel arm 16. The
illumination device is configured by, for example, a light source,
and an optical system that can switch between irradiating a wafer W
with illumination light as scattered light and irradiating the
wafer W with the illumination light as condensed light. Further, a
position detecting sensor 50 that make an alignment of a wafer W is
provided in the position P3. This position detecting sensor 50
detects the position of a notch of the wafer W and any positional
deviation of the center of the wafer W by rotating the wafer W
while being placed on a rotating stage 36. If any positional
deviation is detected, the position of the rotating stage 36 is
corrected with the wafer W being lifted by the transport arms 18,
19, and 20 so that the rotation center of the rotating stage 36 and
the rotation center of wafer W may coincide with each other, and
thereafter, the transport arms 18, 19, and 20 are lowered to allow
high-precision alignment.
[0083] As shown in FIGS. 1 and 2, the micro-inspection section 11
is installed on a loading plate 30 the vibration of which is
removed by an appropriate vibration removal mechanism, and has an
inspection stage 31 that is a holding unit that holds the wafer W,
and a microscope 32 that observes the wafer W on the inspection
stage 31. In the inspection stage 31, an X-axis slider 33 that is
movable in the X direction shown in FIG. 1, and a Y-axis slider 34
that is movable in the Y direction are arranged so as to be stacked
vertically. A Z-axis stage 35 that is movable in the Z direction is
provided on the Y-axis slider 34. The Z-axis stage 35 is provided
with the rotating stage 36 as a rotating mechanism that is
rotatable in the .theta. direction. As shown in FIG. 2, the
rotating stage 36 has a rotary shaft 36A connected with a motor
that is not shown, and a holder 36B on a disk is fixed to an upper
end of the rotary shaft 36A. The external diameter of the holder
36B is smaller than the external diameter of wafer W, and a central
portion of the holder is provided with a suction hole (not shown)
for sucking wafer W. The suction hole is connected to a suction
device that is not shown.
[0084] Moreover, in the micro-inspection section 11, the peripheral
edge inspection section 12 is fixed to a front side part of the
loading plate 30. The peripheral edge inspection section has three
enlarged image acquisition parts each including an imaging optical
system, an imaging device, such as a CCD, etc., and captures an
image of the peripheral edge of the wafer from its top, side, and
bottom surface sides. Then, the captured image is displayed on a
display unit 60, and is observed and inspected by an inspector. The
peripheral edge inspection section 12 is located at a position that
does not become obstructive when the surface of the wafer W is
observed by the microscope 32 of the micro-inspection section 11,
i.e., outside a micro-inspection region A shown by an imaginary
line so as not to interfere with the wafer W at the time of
micro-inspection. As shown in FIG. 3, the peripheral edge
inspection section 12 is a peripheral edge inspection unit that can
be freely detached and attached separately from the loading plate
30, and has an anchor 41 fixed to screw holes 30A of the loading
plate 30 with bolts 40. A base part 42 extends in the Z direction
from the anchor 41. A recessed part 43 is formed in this base part
42 so as to allow entrance of the peripheral edge of the wafer W.
An enlarged image acquisition part 44 including a microscope that
is a magnifying optical system, and a CCD (Charged Coupled Device)
is provided in the recessed part. The enlarged image acquisition
part 44 has an enlarged image acquisition part 44A that observes
the upper surface (surface) of the peripheral edge of the wafer W
from above, an enlarged image acquisition part 44B that observes
the peripheral edge of the wafer W from the side, and an enlarged
image acquisition part 44C that observes the lower surface (rear
surface) of the peripheral edge of the wafer W from below. In
addition, if the enlarged image acquisition part 44 has a
configuration that can acquire an image, it will not be limited to
the CCD. Further, the peripheral edge inspection sections 12 may
have various configurations, such as a single-eye type including
one enlarged image acquisition part 44 in a movable manner, and a
five-eye type in which two enlarged image acquisition parts 44 are
added so as to sandwich the enlarged image acquisition part 44B
from the right and left. As an example of the single-eye type may
include, a configuration in which the direction of an optical axis
is fixed, a microscope and a mirror that are movable relative to
one another in the XYZ directions are included, and the mirror and
the microscope are moved so as to keep the distance between the
microscope and the part of an object to be observed always constant
may be mentioned. This concrete configuration will be described
below as a second modified example. Moreover, as another example of
the single-eye type, a configuration in which only one enlarged
image acquisition part 44 of the peripheral edge inspection section
12 of FIG. 3 is included, and an end of the wafer W rotates about
the center thereof may be mentioned.
[0085] Also, as shown in FIG. 2, the inspection stage 31 and the
peripheral edge inspection section 12 are connected to a control
device 45. The control device 45 includes a CPU (Central Processing
Unit), a memory, etc., and controls the whole visual inspection
apparatus 1. In addition to these, the macro-inspection section 10,
the automated transport unit 5, and a display device (not shown),
such as a display, are also connected to the control device 45.
[0086] Next, the operation of the present embodiment will be
described.
[0087] First, the wafer carrier 4A that has received the wafer W to
be inspected, and the empty wafer carrier 4B is mounted on the
loader part 3. The automated transport unit 5 takes out one wafer W
from the wafer carrier 4A, and transfers the wafer to the transport
arm 18 in the position P1 of the macro-inspection section 10. The
swivel arm 16 rotates with the wafer W being held by
suction-clamping by the transport arm 18, and moves the wafer W to
the position P2. Here, after the wafer W is held and raised by the
macro-inspection unit 22 after the suction of the transport arm 18
is released, the wafer W is made to rise, rotate, and oscillate by
an oscillating mechanism.
[0088] When the surface of the wafer W has been irradiated with the
illumination light from an illumination device, and the existence
of a defect, or the state of the defect has been visually checked,
the wafer W is lowered, and is again held by suction-clamping by
the transport arm 18. In addition, at this time, the transport arm
20 is arranged in the position P1 by the rotation of the swivel arm
16. In this case, the following wafer W is placed on the transport
arm 20 by the automated transport unit 5.
[0089] Next, the swivel arm 16 is rotated to move the wafer W in
the position P2 to the position P3, and to move the wafer W in the
position P1 to the position P2. Since the inspection stage 31
stands by in the position P3, the wafer W is transferred from the
transport arm 18 to the holder 36B of the inspection stage 31. In
addition, at this time, macro inspection is performed on the
following wafer W that has moved to the position P2, similarly to
the above. Further, still another wafer W is placed on the
transport arm 19 that has moved to the position P1.
[0090] In the micro-inspection section 11, alignment of the wafer W
is made in the position P2 on the rotating stage 36 of the
inspection stage 31, the control device 45 makes the inspection
stage 31 move, thereby making the part of the wafer W to be
inspected move into the field of view of an objective lens 32A
(refer to FIG. 2) of the microscope 32. An enlarged image acquired
by the microscope 32 is visually checked as an inspector looks into
an eyepiece that is not shown. Here, if an imaging device is
installed in the microscope 32, inspection may be performed,
visually observing the display unit 60. When micro inspection has
been performed on all objects to be inspected while the inspection
stage 31 is moved, the control device 45 makes the inspection stage
31 move obliquely forward in the XY direction as shown by the arrow
B, thereby bringing the inspection stage 31 closer to the
peripheral edge inspection section 12 and further making the
peripheral edge of the wafer W enter the recessed part 43 of the
peripheral edge inspection section 12 while adjusting the height of
the stage.
[0091] In the peripheral edge inspection section 12, for example,
an image of the surface of the peripheral edge of the wafer W is
acquired by the upper enlarged image acquisition part 44A, and the
acquired image processed by the control device 45, is output to the
display unit 60. In this case, the control device 45 makes the
rotary shaft 36A of the inspection stage 31 rotate, thereby making
the wafer W rotate in the .theta. direction at a predetermined
speed. When the existence/non-existence of a scratch, etc. has been
checked by performing single-around inspection of the peripheral
edge of the wafer W in this way, then the peripheral edge
inspection is performed similarly to the above by acquiring the
images of the side surface and rear surface of the peripheral edge
of the wafer W in order by the enlarged image acquisition part 44B
and the enlarged image acquisition part 44C. In addition, the
enlarged image acquisition parts 44A, 44B, and 44C may be operated
at a same time, thereby simultaneously performing the inspections
from three directions. Further, it is desirable that the inspection
of the peripheral edge is automatically performed by image
processing. For example, the luminance information of the
peripheral edge of a good wafer W, and the luminance information of
a wafer to be inspected that is acquired in advance may be compared
with each other. Further, since the luminance of a peripheral edge
of only one wafer W becomes constant except a notch, a portion the
change of luminance of which has exceeded a fixed value may be
extracted as a defect.
[0092] When the peripheral edge inspection has been completed, the
inspection stage 31 is spaced apart from the peripheral edge
inspection section 12, and is returned to the position P3 that is a
transfer position, and is transferred to the transport arm 18 that
stands by in the position P3. The swivel arm 16 rotates the
transport arms 18, 19, and 20, and returns an inspected wafer W to
the position P1. The automated transport unit 5 carries out the
inspected wafer W, and receives the wafer W in the wafer carrier
4B. A non-inspected wafer W is newly transferred to the transport
arm 18 in the position P1 that has become empty. Further, the next
wafer W on which macro inspection has been performed in the
position P2 is carried into the inspection stage 31 in the position
P3. Then, when all wafers W as objects to be inspected within the
wafer carrier 4A are inspected similarly to the above, the wafer
carriers 4A and 4B are detached, and then the next wafer carriers
to be inspected are mounted.
[0093] In addition, in this visual inspection apparatus 1, the
shift to peripheral edge inspection is made after micro inspection
is completed. However, the shift to micro inspection or peripheral
edge inspection may be made with any timing by control of the
control device 45. Moreover, only micro inspection and peripheral
edge inspection may be performed without performing macro
inspection, or only macro inspection and peripheral edge inspection
may be performed without performing micro inspection.
[0094] According to the present embodiment, when visual inspection
of the wafer W is performed, the peripheral edge inspection section
12 is attached to the micro-inspection section 11, and the
inspection stage 31 of the micro-inspection section 11 is used for
both the micro inspection and the peripheral edge inspection. Thus,
the installation area of the apparatus can be made small. Moreover,
the peripheral edge inspection can be performed without
transferring the wafer W from the micro inspection, and the
traveling distance of the inspection stage 31 can also be
significantly reduced compared with the case where separate devices
are provided. Thus, the takt time required for inspection can be
shortened.
[0095] Since the peripheral edge inspection section 12 and the
inspection stage 31 are configured so that they can relatively
brought closer to or spaced apart from each other, it is possible
to prevent the wafer W, etc. and the peripheral edge inspection
section 12 from interfering with each other during micro
inspection. Moreover, since the peripheral edge inspection section
12 and the inspection stage 31 are provided on the same loading
plate 30, any deviation in the height direction becomes small, and
the height adjustment at the time of peripheral edge inspection
becomes easy. In particular, in the present embodiment, alignment
is made with precision when the wafer W is transferred to the
rotating stage 36. Thus, when wafer W is rotated and inspected in
the peripheral edge inspection section 12, any movement caused by
rotation of the wafer W in an observation position is suppressed,
and an inspection at high magnification is allowed. Further, the
position detecting sensor 50 detects the amount of deviation
between the notch position and center position of the wafer W in
the position P3. Thus, by controlling the inspection stage 31 at
the time of inspection of a peripheral edge even if replacement of
the wafer W is not performed, inspection may be performed in a
state where any eccentricity is not caused when wafer W is
rotated.
[0096] Further, the screw holes 30A that fix the peripheral edge
inspection section 12 are bored in the loading plate 30 of the
micro-inspection section 11, and the peripheral edge inspection
section 12 is configured so as to be attachable to or detachable
from the micro-inspection section 11 as a peripheral edge
inspection unit. Thus, peripheral edge inspection can be performed
only by mounting the peripheral edge inspection section 12 on a
visual inspection apparatus having the macro-inspection section 10
and the micro-inspection section 11. That is, the aforementioned
effects will be obtained even by the existing visual inspection
apparatus only by its minimum changes. Alternatively, the
peripheral edge inspection section 12 may be integrally anchored to
the loading plate 30.
[0097] In addition, a uniaxial stage that is movable horizontally
in the B direction may be provided between the anchor 41 of the
peripheral edge inspection section 12, and the base part 42 so that
the base part 42 can advance or retract in the direction of the
wafer W. Even in this case, the same effects as the above can be
obtained. Moreover, the takt time can be further reduced by moving
the peripheral edge inspection section 12 towards the inspection
stage 31. A stage that is interposed between the anchor 41 and the
base part 42 is not limited to the uniaxial stage. For example, a
biaxial stage that is movable even in a direction orthogonal to the
B direction, a triaxial stage that is movable even in the Z
direction, or a biaxial stage that is movable even in the B
direction and the Z direction may be used satisfactorily. If the
microscope 32 is configured such that the objective lens part 32A
is movable in the Z-axis direction, and the base part 42 is
configured so as to be movable in the Z direction, it becomes
unnecessary to provide the inspection stage 31 with the Z-axis
stage 35. Thus, the configuration of the inspection stage 31 can be
simplified.
[0098] Further, the above embodiment may be modified so as to have
a function to record the coordinate of an observation position when
inspection is made in either one of the micro-inspection section
and the peripheral edge inspection section and to move the
observation position to an observation position of the other
inspection section on the basis of the recorded coordinate of the
observation position when inspection is made in the other
inspection section (first modified example). That is, the first
modified example, as shown in FIGS. 1 and 2, includes an inspection
stage 95 that has a configuration similar to the inspection stage
31, and is adapted to be able to detect the coordinate of the
position of the wafer W in each axial direction of XYZ, instead of
the inspection stage 31 of the visual inspection apparatus 1 of the
above first embodiment, and includes a control device 96 that has a
configuration similar to the control device 45, and is adapted to
be able to acquire and store the coordinate information on the
position of a wafer detected by the inspection stage 95, and to
control of visual inspection apparatus 1 using the coordinate
information, instead of the control device 45.
[0099] The inspection stage 95 is mounted with, for example, a
stepping motor, serving as a power source that drives the X-axis
slider 33, the Y-axis slider 34, the Z-axis stage 35, and the
rotating stage 36, which are provided similarly to the inspection
stage 31, in their respective movement directions. Also, the
coordinate of a position to which the wafer W has been moved can be
detected on the basis of the information on the rotation angle of
this stepping motor from its reference position.
[0100] Here, such as actuators, scales, which can detect the
coordinates of a position, a servo motor, a linear scale, and a
linear motor, other than the stepping motor, etc., can be suitably
adopted as the power source of the inspection stage 95.
[0101] Next, the operation of the first modified example will be
described.
[0102] While the wafer W put on the inspection stage 95 is moved
and the peripheral edge of the wafer W is observed by the
microscope 32 as micro inspection, in order to find out a defect
and check the side surface or rear surface, the shift to peripheral
edge inspection is immediately made so that the peripheral edge of
the wafer W may be observed.
[0103] At that time, since the inspection stage 95 can detect
coordinates in each axial direction, an instruction is issued by
the operation part 70, like pushing one button, and the coordinate
information is stored in the control device 96. Then, when the
shift to peripheral edge inspection has been made from a point 97
on the optical axis of the objective lens of the microscope 32 that
is performing the micro inspection, using the coordinate
information stored in the control device 96, the inspection stage
95 is controlled by the control device 96 so that the point 97
observed by the microscope 32 can be observed as it is even by the
peripheral edge inspection section, and thereby the wafer W is
moved so that the point 97 may be located on the optical axis of
the imaging optical system of the peripheral edge inspection
section.
[0104] After the peripheral edge of the moved wafer W in various
optional positions has been observed manually by the operation part
70 or automatically by an observation method that is input and set
in advance, the shift to the original peripheral edge observation
of the wafer W by the microscope 32 is made. Specifically, the
coordinate information on the point 97 stored in the control device
96 is used to control the inspection stage 95, and the point 97
that has originally performed visual inspection of the peripheral
edge of the wafer W by the microscope 32 is moved back to a
position where it can be observed by the microscope 32.
[0105] On the contrary, when a defect is detected while the wafer W
put on the inspection stage 95 is moved and the peripheral edge of
the wafer W is observed in the peripheral edge inspection, in order
to detect and check the defect by an enlarged image, the shift to
the micro inspection by a microscope is immediately made so that
the peripheral edge of wafer W may be observed.
[0106] In this case, the coordinates of the point 97 that is
performing the peripheral edge inspection by an instruction by the
operation part 70 is detected by the inspection stage 95, and the
coordinate information is stored in the control device 96. Then,
when the shift to micro inspection by a microscope has been made,
the inspection stage 95 is controlled by the control device 96 so
that the point 97 observed by the peripheral edge inspection
section can be observed as it is even in the peripheral edge
observation of the microscope 32, and thereby the wafer W is moved
so that the point 97 may be located on the optical axis of the
microscope 32.
[0107] After the peripheral edge of the moved wafer W in various
optional positions is manually or automatically observed by the
microscope, the shift to the original peripheral edge observation
by the peripheral edge inspection section is made. Specifically,
the coordinate information on the point 97 stored in the control
device 96 is used to control the inspection stage 95, and the point
97 that has originally inspected the peripheral edge of the wafer W
by the peripheral edge inspection section is moved back to a
position where it can be observed by the peripheral edge inspection
section.
[0108] Next, the effects of the first modified example will be
described.
[0109] According to this modified example, if an attempt to observe
the peripheral edge of a wafer as well as the surface of the wafer
as it is or vice-versa is made while the wafer W put on the
inspection stage 95 is moved, and the peripheral edge of the wafer
W is observed by the microscope 32, that is, if any shift between
the visual inspection and peripheral edge inspection is made, the
coordinate information on the point that has been observed in each
inspection is stored only by pushing one button of the operation
part 70, and the wafer W is moved using the coordinate information.
Thus, in each inspection, the same observation point can be
observed. Therefore, for example, if a scratch, a crack, or the
like that runs from the surface of a wafer to the peripheral edge
and rear surface thereof is observed, the position of the scratch
or crack can be observed continuously without any positional
deviation, in the visual inspection and peripheral edge inspection
by the microscope, observation precision and observation speed can
be improved.
[0110] This makes it possible to smoothly and continuously perform
visual inspection or peripheral edge inspection of the peripheral
edge or other surfaces of the wafer W.
Second Embodiment
[0111] A second embodiment is characterized in that the peripheral
edge inspection section is provided in the macro-inspection section
in which inspection is performed by visual observation. Other
configurations and operations are the same as those of the first
embodiment.
[0112] As shown in FIG. 4, in a visual inspection apparatus 51, a
peripheral edge inspection section 61 (outer edge inspection unit)
is detachably provided in the loading plate 15 of the
macro-inspection section 10. The peripheral edge inspection section
61 has a anchor 62 fixed to the loading plate 15, a uniaxial stage
63, and a base part 42 attached to the enlarged image acquisition
part 44. The base part 42 is attached so that it can be brought
close to or spaced apart from the position P2. As shown in FIG. 5,
in an inspection position where the base part 42 is brought closest
to the position P2, the peripheral edge of the wafer W held
horizontally by the macro-inspection unit 22 enter the recessed
part 43. Further, as shown by an imaginary line, in a position when
the base part 42 is most spaced apart from the position P2, the
base part retracts from a macro-inspection region C, and will not
interfere with the rotation of the swivel arm 16, and the
oscillation of the wafer W by the macro-inspection unit 22.
[0113] Further, the macro-inspection unit 22 is a holding unit
provided with a rotating mechanism that rotates the wafer W that is
held while being oscillated, other than a lifting mechanism and an
oscillation mechanism.
[0114] If visual inspection of the wafer W is performed in the
present embodiment, the wafer W conveyed to the position P2 is held
by suction-clamping by the macro-inspection unit 22, and is then
macro-inspected. When the macro inspection has been completed, the
wafer W is held horizontally at a predetermined height, and the
peripheral edge inspection section 61 is moved to the inspection
position. Then, while the wafer W is rotated by the
macro-inspection unit 22, peripheral edge inspection is performed
similarly to the first embodiment. When the peripheral edge
inspection has been completed, the wafer W is transferred to the
transport arm 19 from the macro-inspection unit 22 after the
peripheral edge inspection section 61 retracts to a stand-by
position. Further, the swivel arm 16 is rotated to transfer the
wafer W to the position P3. From here, the wafer W is transferred
to the micro-inspection section 11 where micro inspection is
performed. When the micro inspection has been completed, the wafer
W is returned to the position P1 via the position P3, and is then
received in the wafer carrier 4B.
[0115] In addition, in this visual inspection apparatus 51, the
shift to peripheral edge inspection is made after macro inspection
is completed. However, the shift to macro inspection or peripheral
edge inspection may be preferred at any timing by control of the
control device 45. Moreover, only macro inspection and peripheral
edge inspection may be performed without performing micro
inspection, or only micro inspection and peripheral edge inspection
may be performed without performing macro inspection.
[0116] In the present embodiment, the peripheral edge inspection
section 61 is provided in the micro-inspection section 10, and the
macro-inspection unit 22 of the micro-inspection section 10 is used
for both the micro inspection and the peripheral edge inspection.
Thus, the reduced installation area of the apparatus can be
achieved. Moreover, the peripheral edge inspection can be performed
without transferring the wafer W from the macro inspection, and the
traveling distance of the peripheral edge inspection section 61 can
also be significantly reduced compared with a case where separate
devices are provided. Thus, the takt time required for inspection
can be shortened. In addition, the effect obtained by providing the
macro-inspection unit 22 and the peripheral edge inspection section
61 so that they can be brought close to or spaced apart from each
other, and the effect obtained by loading the macro-inspection unit
and the peripheral edge inspection section on the same loading
plate 15 are the same as those of the first embodiment. Moreover,
the effect obtained by configuring the peripheral edge inspection
section 61 so as to be attachable to or detachable from the
macro-inspection section 10 is the same as that of the first
embodiment.
Third Embodiment
[0117] A third embodiment is characterized in that the peripheral
edge inspection section is provided in an automatic
micro-inspection section that automatically extracts a defect by
image processing from an image captured by an imaging device.
[0118] Other configurations and operations are the same as those of
the first embodiment. As shown in FIGS. 6 and 7, a visual
inspection apparatus 71 has a loading plate 72 that is free from
vibration, and an automatic micro-inspection section 73 is
constructed in the loading plate 72. The automatic micro-inspection
section 73 has an inspection stage 74, and an illumination device
75 and an imaging section 76 fixed so as to sandwich the inspection
stage 74 in the X direction. The inspection stage 74 includes an
X-axis stage 77, a Z-axis stage 78, and a rotary shaft 79 serving
as a rotating mechanism, and a holding plate 80 that holds a wafer
by suction-clamping is fixed on the rotary shaft 79. The
illumination device 75 has a line light source that irradiates the
upper surface (surface) of the wafer W with linear illumination
light from the slanting upper side. The line light source extends
in the Y-direction orthogonal to the X-direction. Similarly, in the
imaging section 76, an optical system is arranged so as to take an
image of the linear reflected light or diffracted light that the
illumination light from the illumination device 75 has been
reflected by the upper surface of wafer W, and imaging devices are
arrayed in a line in the Y-direction in the position of the image.
Also, the optical axis of the imaging section 76 and the optical
axis of the illumination device 75 are arranged so as to intersect
each other on the upper surface of the wafer W. Also, the imaging
section 76 and the illumination device 75 have rotation axes 90 on
the lines on the wafer W that intersect each other, and are
installed in rotatable members 91 and 92. As the imaging section 76
and the illumination device 75 rotate independently, an image can
be taken at an angle suitable for various observation conditions,
such as normal reflection, or plus/minus primary/secondary
diffracted light.
[0119] Moreover, the peripheral edge inspection section 12 is fixed
to the loading plate 72. The peripheral edge inspection section 12
is provided in a position where it has retracted from a
macro-inspection region D of the wafer W shown by an imaginary
line. In addition, the movable range of the inspection stage 74 in
the X-direction is greater than the macro-inspection region D, and
is such that the peripheral edge of wafer W can enter the recessed
part 43 of the peripheral edge inspection section 12.
[0120] The operation of the present embodiment will now be
described. The inspection stage 74 is made to stand by in a
transfer position shown by a position P4, the wafer W is carried
into the transfer position by a automated transport unit that is
not shown, and the wafer W is held by suction-clamping in the
inspection stage 74. Next, as the inspection stage 74 is moved in
the X direction towards the peripheral edge inspection section 12,
the linear illumination light from the illumination device 75 is
reflected by the upper surface of wafer W, and is introduced into
the imaging section 76 for each line, whereby the image of the
whole wafer W is taken.
[0121] The control device 45 analyses a difference between an image
captured by the imaging section 76, and a good image that is
acquired in advance, and extracts as a defect a region whose
luminance difference is more than a fixed value by image
processing. Then, the position of the extracted defect, the
information on size, and the classification information in that
defects are automatically classified are registered in a storage
unit for every wafer W.
[0122] When the automatic macroscopic inspection of wafer W has
been completed, the inspection stage 74 is further moved in the
X-direction so as to approach the peripheral edge inspection
section 12, thereby making the peripheral edge of the wafer W enter
the recessed part 43 of the peripheral edge inspection section 12.
In that position, the wafer W is rotated in the .theta. direction,
and peripheral edge inspection is performed similarly to the first
embodiment. When the peripheral edge inspection has been completed,
the rotation of the wafer W is stopped, and then returned to the
position P4 where the wafer W is transferred.
[0123] In addition, in this visual inspection apparatus 71, the
shift to peripheral edge inspection is made after automatic macro
inspection is completed. However, the shift to macro inspection or
peripheral edge inspection may be made at any timing by control of
the control device 45. Further, when the automatic macroscopic
inspection has been completed, the peripheral edge inspection
section 12 may be arranged so that the peripheral edge of wafer W
may enter the recessed part 43 of the peripheral edge inspection
section 12. The illumination device 75 is arranged rotatably so
that even if the peripheral edge inspection section 12 is arranged
in such a position, such arrangement is allowed if it does not
hinder the automatic macroscopic inspection. Moreover, the
peripheral edge inspection section 12 may be configured so as to be
movable in the X direction so that the peripheral edge inspection
section 12 may be brought close to the wafer W after the completion
of the automatic macroscopic inspection.
[0124] In the present embodiment, the peripheral edge inspection
section 12 is provided in the automatic macro-inspection section
73, and the inspection stage 74 of the automatic macro-inspection
section 73 is used for both the macro inspection and the peripheral
edge inspection. Thus, the installation area of the apparatus can
be made small. Moreover, the peripheral edge inspection can be
performed without transferring the wafer W from the macro
inspection, and the traveling distance of the inspection stage 74
can also be significantly reduced compared with a case where
separate devices are provided. Thus, the takt time required for
inspection can be shortened. Particularly if the inspection stage
74 is moved to make the peripheral edge of the wafer W enter the
recessed part 43 of the peripheral edge inspection section 12, it
is possible to achieve inexpensive manufacture by only making the
inspection stage 74 extend in the X-direction. In addition, the
effect obtained by providing the inspection stage 74 and the
peripheral edge inspection section 12 so that they can be brought
close to or spaced apart from each other, and the effect obtained
by loading the inspection stage and the peripheral edge inspection
section on the same loading plate 72 are the same as those of the
first embodiment. Moreover, the effect obtained by configuring the
peripheral edge inspection section 12 so as to be attachable to or
detachable from the automatic macro-inspection section 73 is the
same as that of the first embodiment.
[0125] In addition, the invention is not limited to the above
respective embodiments, and can be applied widely.
[0126] For example, in the first embodiment, the installation
position of the peripheral edge inspection section 12 is not
limited to the position shown in FIG. 1, and may be attached to a
side edge of the loading plate 30. In this configuration, it is
possible to miniaturize a front part of the loading plate 30. Even
in this case, the peripheral edge inspection section 12 is arranged
so as to stand by in a position that does not become obstructive at
the time of micro inspection.
[0127] There may be a visual inspection apparatus including only
the micro-inspection section 11 and the peripheral edge inspection
section 12 without having the macro-inspection section 10.
Similarly, there may be a visual inspection apparatus including
only the macro-inspection section 10 and the peripheral edge
inspection section 12 without having the micro-inspection section
11. Further, there may be a visual inspection apparatus made up of
an automatic micro-inspection section 73 and the micro-inspection
section 11.
[0128] A recessed part that the peripheral edge of the wafer W can
enter may be provided in the microscope 32, and the enlarged image
acquisition part 44 may be arranged in the recessed part to form a
peripheral edge inspection section. In this case, the space of the
micro-inspection section 11 can be made much smaller. Further, as
long as an arrangement space exists, a rotating stage and a
peripheral edge inspection section may be provided in the position
P1, and may be provided in the position P3.
[0129] The workpiece is not limited to a semiconductor wafer, and
various workpieces, such as a glass substrate, may be used.
[0130] Further, a configuration including a variable
direction-of-view observation apparatus to be described below can
be adopted as the configuration of the above peripheral edge
inspection section. This variable direction-of-view observation
apparatus becomes a modified example (hereinafter referred to as a
second modified example) including a concrete configuration of the
example of the single-eye type of the above enlarged image
acquisition part 44. In the following, as an example of the above
workpiece, a wafer that is a flat plate-like test body will be
described.
[0131] First, the concept of the variable direction-of-view
observation apparatus of this modified example will be
described.
[0132] As for the variable direction-of-view observation apparatus,
for example, an example in which the device loaded into a
microscope apparatus will be described.
[0133] As an embodiment of the variable direction-of-view
observation apparatus of this modified example, an observation
apparatus is used that has a flat plate made up of a wafer, etc.
held as a test body (an observation object or a sample), and that
is disposed in the vicinity of a stage of a microscope apparatus,
which is movable and rotatable in triaxial directions orthogonal to
one another, to observe the peripheral end face of the test body.
For example, if a wafer is used as the (flat plate-like) test body,
the optical axis of an observation optical system (for example,
referred to as an imaging optical system) is arranged
perpendicularly to the principal planes of the wafer. By rotating a
rotary mirror that placed within the distance from a focus position
uniquely possessed by the imaging optical system to an objective
lens, i.e., WD (working distance), thereby changing the observation
and installation direction (direction of view) of the test body, a
mechanism that always keeps the distance between the objective lens
accompanying the change of the direction of view and the test body
at the above WD is given.
[0134] This modified example shows a basic configuration of visual
inspection apparatus in which includes an optical system turntable
(biaxial stage=ZX stage) on which an observation optical system and
a rotary mirror are loaded, a turntable that moves the rotation of
the mirror in the Z direction, and two cams that are engaged with
the turntables.
[0135] The conceptual configuration of this modified example
includes the following a, b, c, d, and e.
[0136] a. a biaxial stage that is movable in a direction (Z
direction) orthogonal to the surface of a test body and a direction
(X direction) parallel thereto;
[0137] b. a base having a driving unit that moves the biaxial stage
in the Z direction;
[0138] c. an X-direction movable plate of the stage that includes
an X-direction cam fixed to the base, a roller engaged with a cam
attached in the X-direction movable plate of the biaxial stage, and
a tension spring acting in a direction in which the base and the
X-direction movable plate (X stage) are brought close to each
other;
[0139] d. arranging on the X stage an observation (microscope)
whose optical axis is adjusted at right angles to the surface of
the test body, and a rotary mirror whose optical axis can be
arbitrarily deflected between an objective lens of the microscope
and the focus position of the lens as required; and
[0140] e. having a mirror cam fixed to the base and a roller
engaged with a cam attached to a rotary arm protruding from a
rotary shaft of the rotary mirror, arranging a tension spring in a
direction in which the roller is pressed against the cam between
the rotary arm and a bar (spring hook) provided with the X-stage,
and always making a focus on the end face of the test body by a
drive of the base, even if the position of the observation optical
system and the angle of the rotary mirror are changed by the cam,
and the direction of view is moved.
[0141] Although this variable direction-of-view observation
apparatus may be independently configured as an inspection
(observation) apparatus, the apparatus is attached so that it can
hold a wafer on a microscope apparatus for wafers as a test body,
and can be disposed in the vicinity of a stage of the microscope
apparatus, which is movable and rotatable in triaxial directions
orthogonal to one another, to observe the peripheral end face of a
test body held on the stage. Of course, the test body is not
limited to the wafer, as will be described below. In addition, in
the description explained below, a wafer is used as the test body,
and a planar section in the front and back surfaces of the test
body is called a principal plane. Further, the peripheral end face
of a test body mainly refers to a non-planar peripheral edge of the
front and back surfaces of a test body. Also, if chamfering, etc.
is performed by machining, or if a resist that runs into a
surrounding part of a partial rear surface called an edge cut line
of a surface from which the resist of the peripheral edge is
removed after application of a resist, the peripheral end surface
also includes the above surrounding part.
[0142] Hereinafter, a first mode (hereinafter called a first mode
for short) of this modified example will be described in
detail.
[0143] FIGS. 8, 9A and 9B show an exemplary configuration of a
first mode of a variable direction-of-view observation apparatus
200. Here, FIG. 8 is a view showing the exemplary configuration
when the variable direction-of-view observation apparatus of the
first mode is viewed from the front, FIG. 9A is a view showing the
exemplary configuration when the variable direction-of-view
observation apparatus of the first mode is viewed from the side,
and FIG. 9B is a view showing an exemplary configuration of a
mirror cam as viewed from the arrow A1 (back side of FIG. 8) in
FIG. 9A.
[0144] The configuration of this variable direction-of-view
observation apparatus 200 will be described. In addition, in the
following description, a direction that is the same direction as
the principal plane of a wafer used as a test body, and is
orthogonal to the tangential line of an end face is defined as an X
direction, and a direction that is orthogonal to the principal
plane is defined as the Z direction.
[0145] A base 101 in the present apparatus is a plate-shaped member
made of a metallic material, such as steel, aluminum, or stainless
steel. The longitudinal direction of this base 101 is arranged in a
direction orthogonal to the principal planes of the wafer 114 used
as a test body.
[0146] A motor attaching plate 101a is attached to an upper end of
the base 101 so as to project in the shape of the letter "L," and
the motor attaching plate 101a is provided with a motor 102. A
rotary shaft (not shown) of the motor 102 rotates in the X
direction by a controller that is not shown. The rotary shaft of
the motor 102 is connected with a ball screw 103a. The ball screw
103a is rotatably inserted and fitted into a ball screw guide 103b
attached to an arm 105a extending from a Z-movable carriage 105
fixed to the base 101. The ball screw 103a and the ball screw guide
103b constitute a ball screw set 103. By this configuration, the
ball screw 103a is moved by rotation of the rotary shaft of the
motor 102 so as to push up or push down the ball screw guide
103b.
[0147] Further, a rail 104a that is fixed to the Z-direction
movable carriage 105, and a case 104b that is slidably engaged with
the rail 104a and fixed to the base 101 constitute a Z-direction
movable linear guide 104.
[0148] Furthermore, a cam 108 in which a cam surface 108a that is
curved in the shape of a recess is formed is fixed to an upper part
of the base 101 via a plurality of struts. A mirror cam 118 in
which a cam surface 118a is curved in the shape of a recess that is
different from a cam surface 108a is fixed to a lower part of the
base 101 via a plurality of struts.
[0149] Moreover, a rail 106a that is fixed to the Z-direction
movable carriage 105, and a case 106b that is slidably engaged with
the rail 106a and fixed to the X movable plate 107 constitute an
X-direction movable linear guide 106. By this configuration, the
Z-direction movable carriage 105 by the X-direction movable linear
guide 106 and the X movable plate 107 by the Z-direction movable
linear guide 104 can be moved two-dimensionally in an X-Z
plane.
[0150] Further, a cam roller 109 that moves while rotating along
the cam surface 108a of the cam 108 is rotatably fixed to the X
movable plate 107. A rotary shaft 116 is rotatably provided on the
X movable plate 107. A rotary arm 119 is fixed integrally so as to
extend from the rotary shaft 116. A cam roller 117 that moves along
the cam surface 118a of the mirror cam 118 that functions as a
rotation guide part is rotatably attached to the rotary arm 119.
The rotary shaft 116 rotates by the movement of the cam roller 117
along the cam surface 118a.
[0151] A bar-shaped spring hook 121a is provided at an upper end of
the base 101 on the cam 108 side, and a spring hook 121b is
provided at the upper end of the X movable plate 107 opposite to
the spring hook 121a. A tension spring 111 is hooked to the spring
hooks 121a and 121b. The cam roller 109 acts so as to always push
against the cam 108 by the biasing force of the tension spring 111.
As shown in FIG. 9B, a tension spring 120 is hooked between a hole
of the rotary arm 119, and a spring hook 122A provided on the X
movable plate 107. The cam roller 117 acts so as to always push
against the cam surface 118a of the mirror cam 118 by the biasing
force of the tension spring 120.
[0152] Furthermore, an imaging section 123 used as an observation
optical system that has an optical axis in a direction orthogonal
to the principal plane of a wafer in a state of being mounted on a
rotary table is provided on the X movable plate 107. This imaging
section 123 is made up of an imaging lens 122, and a CCD camera 112
that receives a light image that is focused on the imaging lens
122, and that generates image signals by photoelectric conversion.
Of course, the imaging lens 122 may be a configuration made up of
an objective lens and a lens that images an infinite luminous flux
from the objective lens, like a microscope, or a single zoom lens
may be used as the imaging lens. Further, a focusing mechanism or a
zoom variable power mechanism may be electrically driven. A rotary
mirror 115 that deflects the optical axis of the imaging lens 122
exists within the WD of the imaging lens, and is bonded to the
rotary shaft 116 attached to the X movable plate 107.
[0153] The operation of the variable direction-of-view observation
apparatus 200 loaded on the microscope apparatus configured in this
way will be described.
[0154] The fact that this apparatus always comes into focus even if
the direction of view is changed to the end face of a wafer in the
following order (even if the rotary mirror is rotated) will be
described.
[0155] First, referring to FIG. 8, according to an instruction from
an inspector (observer), the motor 102 will be rotated by control
of a controller that is not shown. By this rotation, the ball screw
103a is also rotated and moved so as to push up or push down the
ball screw guide 103b. If the ball screw is moved so as to push
down the ball screw guide, the Z movable plate 105 is moved so as
to approach the wafer 114 along the guide direction of the
Z-direction movable linear guide 104.
[0156] During this decent, the Z movable plate 105 is moved
rightward along the cam surface 108a such that the cam roller 109
is pushed against the cam 108 by the biasing force of the tension
spring 111. Simultaneously with this, the rotary arm 119 is also
moved such that the cam roller 117 is pushed against the cam
surface 118a of the mirror cam 118 by the spring 120. If the cam
roller 117 is moved along the cam surface 118a, the rotary arm 119
will rotate in the clockwise direction.
[0157] That is, while the imaging lens 122 descends so as to
approach a wafer 114 along the Z direction (the direction of an
optical axis), it moves in the X direction so as to separate from
an end of the wafer 114 in the direction of a principal plane
thereof. In other words, as shown in FIG. 8, the end of the wafer
114 and the rotary shaft 116 descend at an equal distance (WD). At
this time, as the rotary arm 119 rotates in the clockwise
direction, the rotary mirror 115 also rotates in the clockwise
direction. That is, the shape of the cam surface 118a is designed
such that the optical axis of the imaging lens 122 is deflected by
the rotary mirror 115, the optical axis always coincides with the
end face of the wafer 114, and the distance WD from the imaging
lens is kept constant via the end face and the rotary mirror.
[0158] As a result, even if the angle (.theta.) at which the end
face of the wafer 114 is observed is changed, a situation where the
imaging lens 122 is always focused on the end face of the wafer can
be created. In this regard, in the present embodiment, the
direction of view that allows observation is preferably set to
about .+-.45 degrees to the principal planes of the wafer 114.
Substantially, this is because, if the deflection angle of the
rotary mirror 115 is approximately parallel to the optical axis of
the imaging lens 122, the reflecting surface (mirror surface) of
the rotary mirror 115 should be extremely increased, and therefore,
there is an actual limit to the area of the reflecting surface of
the mirror.
[0159] The reason for this will be briefly described with reference
to FIGS. 10A and 10B.
[0160] As shown in FIG. 10A, the positional relationship between
the imaging lens 122 and the rotary mirror 115
(.theta..sub.2=45.degree.) when the observation from the same
direction (.theta.=0) as the principal planes of the wafer 114 is
started is shown by a solid line, and the positional relationship
between the imaging lens 122 and the rotary mirror 115 when an end
face is observed from above is shown by a broken line.
[0161] When .theta. is .theta..sub.1, .theta..sub.2 is expressed as
.theta..sub.2=(1/2)*.theta..sub.1. Consequently when .theta.
increases, .theta..sub.2 also increases, and thus the reflecting
surface coincides with the optical axis as indicated by a
one-dotted chain line, which will hinder the observation.
Similarly, as shown in FIG. 10B, when the observation from below
the wafer 114 is made, part of the wafer 114 may enter a space
between the imaging lens 122 and the rotary mirror 115, which will
interfere with the observation.
[0162] Further to describe, the optical axis of the imaging lens
122 will be most separated from the end face of the wafer 114 when
.theta.=0. It can also be appreciated that, as .theta. becomes
large, the optical axis approaches the wafer 114. Consequently, the
mirror cam 118 is designed in consideration of these points.
[0163] As described above, according to the variable
direction-of-view observation apparatus 200 of the first mode of
this modified example, the rotary mirror 115 is moved in a
direction (Z direction) orthogonal to a principal plane with
respect to the peripheral end face in the test body 114 having two
principal planes, such as a wafer, while a substantially constant
distance is kept from the peripheral end face of the test body 114.
Therefore, the distance WD (working distance) to the peripheral end
face and the observation optical system becomes constant. As a
result, while the end face is observed (imaged), the end face of
the test body can always be focused.
[0164] Further, since the X movable plate that is supporting the
imaging section 123 is moving in the direction of the principal
planes of the wafer 114 only to such an extent that the distance WD
is kept, the variable direction-of-view observation apparatus of
the present embodiment is miniaturized. Further, the inspection
apparatus is not necessarily made up of a single unit, and can be
disposed and used in the vicinity of a stage of a conventional
microscope apparatus that holds a test body and is movable and
rotatable in triaxial directions orthogonal to one another. Of
course, the observation apparatus can also be loaded onto other
apparatuses including a stage, without being limited to the
microscope apparatus for a wafer.
[0165] Moreover, various test bodies can be observed by suitably
focusing the curved state of the peripheral end face of the cam
surface 108a, 118a in the cam 108, 118 to the shape of a peripheral
end face of a test body to be observed. For example, the cam 108,
118 may be detachably configured so that it can be suitably
replaced according to a test body. As a result, even if the
cross-sectional shape of an end face of a test body is a
sufficiently rounded shape or a shape the corner of which is
slightly rounded, focusing in the imaging section can be made
easily.
[0166] By providing the peripheral edge inspection section 12 of
the visual inspection apparatus 1 of the above embodiment with such
a variable direction-of-view observation apparatus 200, observed
images of the end face of the wafer 114 and its front and back
surfaces following the end face are led to a microscope of the
peripheral edge inspection section 12, so that chips or cracks
generated in the end face of the wafer can be detected. Further, in
the case of inspection of a mask pattern, the edging state of a
resist film, deposition of chemical solution used for forming the
resist onto the rear surface of a wafer, etc. can be inspected.
[0167] Next, with reference to FIG. 11, an exemplary configuration
of a variable direction-of-view observation apparatus of a second
mode (hereinafter called a second mode for short) of this modified
example will be described. In addition, the constituent parts shown
in FIG. 11 equivalent to the aforementioned constituent parts shown
in FIGS. 8, 9A and 9B are denoted by the same reference numerals,
and the description thereof is omitted. While the aforementioned
first mode has a limit to the observation angle (about .+-.45
degrees), the present mode is an example in which observation is
performed right above or right below a test body. In the present
mode, observation of front and back sides of an outer peripheral
part of a test body is allowed by further providing two
front-and-back observation mirrors as shown in FIG. 11.
[0168] In this variable direction-of-view observation apparatus
201, a notch B1 is formed in the base 130, and this notch is
configured so as to allow entrance of an end of the wafer 114.
Moreover, when the end of the wafer 114 is inserted into the notch
B1, front-and-back observation mirrors 131 and 132 fixed to the
upper and lower parts, respectively, on the optical axis (direction
orthogonal to the principal plane of the wafer 114) are arranged in
the positions that recede slightly inward from the end of the
wafer.
[0169] When observation of an upper principal plane of the wafer
114 is taken as an example, the optical axis in the imaging lens
122 will become the same as an optical axis deflected by the
front-and-back observation mirror 131 if the inclinations of the
rotary mirror 115 and the front-and-back observation mirror 131 are
made equal to each other. That is, since the optical axis curved by
these front-and-back observation mirrors 131, 132 is orthogonal to
each principal plane of the wafer 114, it is consequently possible
to observe front and back sides of the outer peripheral part of the
wafer 114.
[0170] In such an arrangement, a cam surface 135a that extends so
as to make the optical axis from a front-and-back observation
mirror coincide with the optical axis of an imaging lens is
provided in a cam 135 in correspondence with the cam profile in the
aforementioned first mode. By providing the cam surface 135a, the
angle of a rotary mirror can be determined so as to make an optical
axis coincide with the optical axis of an imaging lens, in relation
to the angle of a front-and-back observation mirror. The shape of a
can surface 134a is similarly given to a cam 134 so that the sum of
L10, L11, and L12 may be equal to WD. In addition, when WD is not
completely equal to the sum due to any individual difference of the
wafer 114, etc., it is also possible to cope with this by
interposing a stop so as to give a sufficient depth of field to an
observation optical system or by installing an AF (automatic
focusing) device.
[0171] Alternatively, although a wafer is exemplified as a test
body used as an observation object by the variable
direction-of-view observation apparatus of this modified example,
the invention is not limited thereto. For example, by loading a
glass substrate used for a liquid crystal display panel onto an
inspection apparatus for the glass substrate, it is also possible
to observe an end face of the glass substrate. Furthermore, the end
face of a cut product can also be observed by attaching the product
to a metal cutting apparatus.
[0172] As described above, according to the aforementioned first
and second modes, it is possible to observe the peripheral end face
of a wafer used as a test body from a desired angle, and it is
possible to simply observe damage, such as chips or cracks
generated in the end face and front and back surfaces over the
whole outer periphery of the wafer, or adhering foreign matters,
without carrying out focusing work each time. Further, even in this
second mode, it is possible to easily attach the observation
apparatus to a microscope apparatus similarly to the aforementioned
first mode, and load it into a wafer visual inspection apparatus, a
wafer inspection apparatus, etc. Alternatively, the observation
apparatus may be provided in a substrate processing apparatus that
has rotating stages, such as an exposure apparatus, a coater, and a
developer.
[0173] Next, a variable direction-of-view observation apparatus of
a third mode (hereinafter called a third mode for short) of this
modified example will be described in detail.
[0174] In the aforementioned second mode, the front-and-back
observation mirrors 131 and 132 are fixed and are turned to a fixed
direction regardless of the angle of the rotary mirror 115.
Therefore, if low magnification observation is set when the end
face of the wafer 114 is observed by the rotary mirror 115, the
front-and-back observation mirrors 131 and 132 may enter the field
of view of observation of the rotary mirror 115. This mode is an
exemplary configuration in which, when a movable front-and-back
observation mirror is provided to observe the end face of a test
body, the observation mirror is made to remove from the field of
view of observation of the rotary mirror 115.
[0175] FIG. 12A is a view showing the exemplary configuration when
the variable direction-of-view observation apparatus of the third
mode is viewed from the front, FIG. 12B is a view showing the
exemplary configuration when the variable direction-of-view
observation apparatus of the third mode is viewed from the back,
and FIG. 12C is a view showing an exemplary configuration of a
movable front-and-back observation mirror as viewed from the arrow
C1 in FIG. 12B. In addition, the constituent parts shown in FIGS.
12A, 12B, and 12C equivalent to the aforementioned constituent
parts shown in FIGS. 8 and 9 are denoted by the same reference
numerals, and the descriptions thereof is omitted.
[0176] As shown in FIG. 12A, a variable direction-of-view
observation apparatus 202 is provided with movable front-and-back
observation mirrors 171, 172 so that, when the rotary mirror 115
observes the end face of the wafer 114, mirror surfaces 171a, 172a
may be in specified positions that have depression angles
(direction converged on the rotary mirror 115 on the basis of the
direction of an optical axis of the imaging lens 122) of arbitrary
angles .theta..sub.3, .theta..sub.4 with respect to the rotary
mirror 115 on the basis of the principal planes of the wafer 114.
The arbitrary angles .theta..sub.3, .theta..sub.4 are angles
provided to prevent the outside light (illumination light, etc.)
reflected by the wafer 114 from being reflected again by the
movable front-and-back observation mirrors 171, 172, and entering
the rotary mirror 115. The arbitrary angles .theta..sub.3,
.theta..sub.4 incline slightly with respect to the front and back
principal planes of the wafer 114, and are provided so as to have a
depression angle (an elevation angle with respect to a wafer
principal plane) with respect to the rotary mirror 115.
[0177] These movable front-and-back observation mirrors 171, 172
have the same configuration, and as shown in FIG. 12B, they are
arranged axisymmetrically to the wafer 114 (the direction of an
optical axis). Between these movable front-and-back observation
mirrors 171, 172, a driving plate 173 is provided that is fixed to
the X movable plate 107 shown in FIG. 9, and rotates any one of the
movable front-and-back observation mirrors 171, 172 along with
vertical movement of the driving plate.
[0178] Next, a configuration will be described taking the movable
front-and-back observation mirror 171 as an example.
[0179] As shown in FIG. 12C, the movable front-and-back observation
mirror 171 includes; a mirror body 182 that is rotatably attached
to the base 101 by fitting a bearing 181 thereinto, a mirror base
183 replaceably attached to the mirror body 182, a mirror 184 fixed
to a tip (the lower side in this drawing) of the mirror base 183, a
stopper part 185 provided to specify the aforementioned specified
position in the base 101, a lever part 186 that is connected and
fixed to the mirror body 182 via the bearing 181, a cam 188 that is
provided at the tip of the lever part 186 to rotate the mirror body
182 along with the vertical movement of the driving plate 173, and
a coil spring 187 that applies a biasing force that is required for
the mirror body 182 to return to a specified position.
[0180] As a configuration in which the mirror base 183 is attached
to the mirror body 182, an attachment surface m of the mirror body
182 is provided with at least two pins 189a and 189b and a screw
hole 190, and holes 191a and 191b that are fitted to the pins 189a
and 189b, and a screw hole 191c are formed in the mirror base 183,
respectively. As for the attachment, after the holes 191a and 191b
of the mirror base 183 are respectively fitted to the pins 189a and
189b of the mirror body 182, a screw 192 is screwed into the screw
hole 190 through the screw hole 191c. As such, since the mirror
base 183 has a detachable configuration, even if a mirror becomes
dirty, it can be easily cleaned.
[0181] The stopper part 185 includes a stopper column 193 fixed to
the base 101, and a stopper 194 that defines a specified position
where the lever part 186 is locked. The coil spring 187 has one end
hooked to the lever part 186, and the other end hooked to the base
101, and the biasing force of the coil spring is applied so that
the lever part 186 may always be pressed against the stopper
194.
[0182] Next, with reference to FIGS. 13A to 13G, the operation of
the movable front-and-back observation mirrors 171, 172 configured
in this way will be described. In this example of observation, the
lower surface of a wafer is observed via an end face from the upper
surface of the wafer.
[0183] FIG. 13A shows a state where the upper surface of the wafer
114 is observed from the front of the apparatus, and FIG. 7B shows
the rotational state of the movable front-and-back observation
mirrors 171, 172 viewed from the back. In this observation state,
the rotary mirror 115 is located higher than the movable
front-and-back observation mirror 172, and the cam 188 of the
movable front-and-back observation mirror 172 is pulled up by the
driving plate 173. Then, the front surface (upper principal plane)
of the wafer projected on the movable front-and-back observation
mirror 172 is projected via the rotary mirror 115 so as to run
along the optical axis of the imaging lens 122. At this time, the
movable front-and-back observation mirror 171 is in a free state,
is biased by the coil spring 187, and is held at the arbitrary
angle .theta..sub.3 so that the surface of the mirror may be in the
aforementioned specified position.
[0184] Moreover, when a peripheral end face of the wafer 114 is
observed from a direction substantially vertical to the normal line
of a surface of the wafer from the state shown in FIGS. 13A and
13B, the rotary mirror 115 is pressed down while rotating,
resulting in the observation of the end face of the wafer 114
(refer to FIGS. 13C and 13D). In the state where this end face is
observed, the cams 188, 195 of the movable front-and-back
observation mirrors 171, 172 are not in contact with the driving
plate 173, but in a free state. For this reason, the movable
front-and-back observation mirrors 171, 172 are together in a free
state, are biased by the coil spring 187, and are held at the
arbitrary angles .theta..sub.3, .theta..sub.4 so that the surface
of the mirror may be in the aforementioned specified position.
[0185] At this time, as shown in FIG. 13E, the mirror 184 of the
movable front-and-back observation mirror 171, 172 is put into
rotation, so that it cannot enter the field of view of observation
of the rotary mirror 115.
[0186] In this observation state, the rotary mirror 115 is pushed
down while rotating, and is thereby located lower than the movable
front-and-back observation mirror 171, and the cam 195 of the
movable front-and-back observation mirror 171 is pulled down by the
driving plate 173. Then, the rear surface of the wafer (lower
principal plane) projected on the movable front-and-back
observation mirror 171 is projected via the rotary mirror 115 so as
to run along the optical axis of the imaging lens 122. At this
time, the movable front-and-back observation mirror 172 is in a
free state, is biased by the coil spring 187, and is held at the
arbitrary angle .theta..sub.3 so that the surface of the mirror may
be in the aforementioned specified position (refer to FIGS. 13F and
13G).
[0187] As described above, according to this mode, by rotating one
of two movable front-and-back observation mirrors that are arranged
vertically, with movement of a rotary mirror, an observed image of
the front surface or rear surface of a test body can be guided to
the optical axis of an imaging lens by the rotated movable
front-and-back observation mirror and the rotary mirror. Further,
when the end face of a test body is observed, both the movable
front-and-back observation mirrors are retracted from a field of
view of observation. It is therefore possible to provide an easily
viewable observation image in which only the test body used as an
observation object exists within a field of view of observation.
Further, even in this third mode, it is possible to easily attach
the observation apparatus to a microscope apparatus similarly to
the aforementioned first mode, and load it into a wafer visual
inspection apparatus, a wafer inspection apparatus, etc.
[0188] In addition, the variable direction-of-view observation
apparatus 202 of this mode is made in consideration of both the
visual observation by observer's direct viewing and a monitor image
using an imaging device. However, the invention is not limited to
this third mode. For example, in the case of a configuration in
which only the monitor image is observed, observation can also be
realized by removing an image of the front-and-back observation
mirror that has entered from a picked-up observation image, or by
generating an image without fetching an image signal equivalent to
a front-and-back observation mirror from an imaging device.
[0189] Although the description of the above second modified
example has been made in conjunction with an example of the case in
which the variable direction-of-view observation apparatus of each
mode is loaded into an inspection apparatus, such as a microscope,
that is, the apparatus is included in the peripheral edge
inspection section of the visual inspection apparatus of the
invention, the variable direction-of-view observation apparatus of
each of the above modes can also be preferably used as a single
unit as an observation apparatus in which the direction of view to
a test body is variable.
[0190] The background art in this case will now be described.
[0191] For example, JP-A-9-269298 (Patent Document A), and
JP-A-2003-344307 (Patent Document B) discloses an end defect
inspection apparatus that exclusively inspects the end face of a
wafer in order to detect chips, cracks, etc. generated in the end
face.
[0192] The following problems exist in the background art.
[0193] In the aforementioned wafer edge inspection, generally, in
order to detect chips, cracks, etc. of the end face of a wafer,
detection is made by visual observation of an image that is
obtained by imaging a wafer edge over its whole outer periphery, or
by the change of a detection value that is obtained by
photoelectric conversion.
[0194] Since the end defect inspection apparatus according to
Patent Document A is configured so as to detect chips, cracks, etc.
from part of diffraction light from the end face of a wafer, it is
not possible to observe the front surface or rear surface that
leads to the end face of the wafer. Similarly, even in the defect
inspection apparatus disclosed in Patent Document 2, it is not
possible to detect chips, cracks, etc. of a front or rear surface
that leads to the end face of a wafer. Further, in both Patent
Documents A and B, it is not possible to perform observation of an
edge cut line after the resist of an edge part on the front side is
removed. Further, the same applies to a glass substrate used for a
liquid crystal display. In this case, it is necessary to perform
optimal processing while checking damage, such as chips or cracks
generated in an end of the glass substrate, an unnecessary film,
etc.
[0195] Thus, a variable direction-of-view observation apparatus
that can observe a peripheral end face of a test body (end face,
and front and rear surfaces of an outer peripheral edge following
the end face) from a desired angle has been required.
[0196] Such a variable direction-of-view observation apparatus is
provided by the following configurations.
[0197] (1) A variable direction-of-view observation apparatus
including an observation optical system that observes a peripheral
end face of a flat plate-like test body, and a mirror part that
deflects an optical axis in the observation optical system, to make
the optical axis reach the peripheral end face of the test body.
Here, while the direction of view is changed by the rotation of the
mirror part, the distance between the observation optical system
and the peripheral end face of the test body remains substantially
constant, and the peripheral end face of the test body is
observed.
[0198] (2) A visual inspection apparatus including: a base part
that is fixed in a position where the peripheral end face of a flat
plate-like test body can be observed; an observation optical system
that has an optical axis orthogonal to the surface of the test
body; a biaxial stage that supports the observation optical system,
and is movable in directions orthogonal and parallel to the surface
of the test body; a mirror part that is rotatably supported by the
biaxial stage to deflect the optical axis in the observation
optical system, to make the optical axis reach the peripheral end
face of the test body; and a rotation guide part that is provided
in the base part, abuts and biases the mirror part so as to allow
sliding of the mirror part, and rotates the mirror part so that the
optical axis in the observation optical system may be deflected and
may be made to reach the peripheral end face of the test body at
the time of movement of the orthogonal direction in the biaxial
stage. Here, while a direction of view is changed by the rotation
of the mirror part, the distance between the observation optical
system and the peripheral end face of the test body remains
substantially constant, and the peripheral end face of the test
body is observed.
[0199] (3) The visual inspection apparatus according to the above
(2), in which the base part of the variable direction-of-view
observation apparatus holds the test body, and is disposed in the
vicinity of a stage of a microscope apparatus that is movable and
rotatable in triaxial directions orthogonal to one another.
[0200] (4) The visual inspection apparatus according to the above
(2), in which the rotation guide part of the variable
direction-of-view observation apparatus includes a first cam that
is provided in the base part, and has a cam surface that is curved
so that the mirror part may have a substantially fixed spacing from
the peripheral end face of the test body during the movement in the
orthogonal direction of the biaxial stage; and a first cam roller
that slides along curving of the cam surface at the time of
movement of the orthogonal direction of the biaxial stage, and that
rotates the mirror part so that the optical axis of the observation
optical system may reach the peripheral end face of the test
body.
[0201] (5) The visual inspection apparatus according to the above
(2), in which the variable direction-of-view observation apparatus
further includes a stage guide part made up of a second cam that is
provided in the base part, and has a cam surface that is curved so
that the optical axis in the observation optical system may be
maintained in a direction orthogonal to a surface of the test body
in the rotation guide part with the movement in the parallel
direction at the time of movement of the orthogonal direction of
the biaxial stage; and a second cam roller that is provided in the
biaxial stage and slides along curving of the cam surface at the
time of movement of the orthogonal direction.
[0202] (6) The visual inspection apparatus according to the above
(2), in which the variable direction-of-view observation apparatus
is further provided with two fixed mirrors that are fixed to the
base so as to be arranged above and below the front and back
surfaces of the test body, and bends the optical axis of the
observation optical system in the direction of the peripheral end
face of the test body.
[0203] (7) The visual inspection apparatus according to the above
(2), in which the variable direction-of-view observation apparatus
is further provided with two rotary mirrors that are fixed to the
base so as to be arranged above and below the surface of the test
body, bends the optical axis of the observation optical system in
the direction of the peripheral end face of the test body, and are
set at a predetermined angle during observation from above or
below.
[0204] (8) The visual inspection apparatus according to the above
(2), in which the variable direction-of-view observation apparatus
is further provided with two rotary mirrors that are rotatably
arranged in the base so as to be arranged above and below the test
body. Here, when the upper surface or lower surface of the test
body is observed, any one of the rotary mirrors is rotated, and an
observed image of the test body enter the observation optical
system via the mirror part, and when the peripheral end face of the
test body is observed, the mirror surface of the rotary mirror is
set to have an angle of depression with respect to the rotary
mirror, and is removed from the field of view of observation in the
observation optical system.
[0205] (9) A visual inspection apparatus is an observation
apparatus loaded into a microscope apparatus that observes the
surface of a flat plate-like test body. The observation apparatus
includes: a biaxial stage that is movable in a Z direction
orthogonal to the surface of the test body, and in an X direction
parallel thereto; a base having a driving unit that moves the
biaxial stage in the Z direction; a parallel movable plate of a
stage made up of a first cam fixed to the base, a roller that is
attached to an X-direction movable plate of the biaxial stage, and
moves along the first cam, and a tension spring that acts in a
direction in which the base and the X-direction movable plate are
brought close to each other; an observation optical system of the
microscope apparatus whose optical axis is orthogonal to the
surface of the test body on the biaxial stage; a mirror part that
is arranged between an objective lens within the observation
optical system and the focusing position of the objective lens, and
is able to arbitrarily deflect the optical axis; a second cam fixed
to the base; a second roller that is attached to a rotary arm
protruding from a rotary shaft of the mirror part, and moves along
the second cam; and a tension spring that is hooked between the
rotary arm and the biaxial stage, and acts in a direction in which
the second roller is pushed against the second cam. Here wherein,
even if the position of the observation optical system and the
angle of the rotary mirror are changed according to the first and
second cams with the movement of the biaxial stage in the Z
direction, thereby arbitrarily changing the direction of view, the
distance between the objective lens and the peripheral end face of
the test body remains constant while the direction of view is
changed with respect to the peripheral end face of the test body
and the front and back surfaces following the peripheral end
face.
[0206] In the variable direction-of-view observation apparatuses
described in above (1) to (9), even if the position of the
observation optical system and the angle of the rotary mirror are
changed by the rotary guide part, thereby changing a direction of
view, observation can be made while focusing is always made on the
peripheral end face of a test body, and the principal planes (upper
and lower surfaces) following the peripheral end face. Therefore,
it is possible to provide a variable direction-of-view observation
apparatus that can observe a peripheral end face of a test body
(end face, and front and rear surfaces of an outer peripheral edge
following the end face) from a desired angle.
* * * * *