JP2000215843A - Inspection device and inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection device and an inspection method capable of continuously taking in image information of a sample from a plurality of inspection regions arranged in the moving direction of a stage even in any moving direction of the stage. SOLUTION: The inspection device has an electron optics system 20 for forming on a specified screen an image of secondary beams emitted from a sample 28 by irradiating with electron beams the sample 28 on a movable stage 27; a projection means 22 for projecting on a specified screen an image of electron beams from the sample 28 positioned within a visual field of the electron optics system 20; deflection means 26, 36 for deflecting at least one path of electron beams and the secondary beams; an image sensor 41 for picking up an image projected on a specified screen; and a control means 43 for synchronizing the movement of the sample 28 with the deflection of the path caused by the deflection means 26, 36 to control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an inspection apparatus and an inspection method for capturing image information of a sample using an electron beam and inspecting a defective portion of the sample.

[0002]

2. Description of the Related Art With the recent increase in the degree of integration of LSIs, it is required to further increase the detection sensitivity of defects in samples such as wafers and masks. For example, in a 256 Mbit DRAM, a detection sensitivity of a defect size of 0.1 μm is required for a pattern size of 0.25 μm. Further, not only the improvement of the detection sensitivity described above, but also the speedup of the defect detection is desired.

[0003] In order to meet these demands, inspection devices using electron beams are being developed. For example, in the inspection apparatus described in JP-A-7-249393 and the inspection apparatus described in JP-A-10-197462, a stage is moved by using a rectangular beam having a rectangular beam cross section. The speed of defect detection is increased by scanning the surface of the sample.

However, in the inspection apparatus described in Japanese Patent Application Laid-Open No. 7-249393, since a sample image projected on an MCP (micro channel plate) is captured by a line CCD sensor, a rectangular beam irradiating the sample is applied to a line C.
The shape is elongated in accordance with the shape of the CD sensor. For this reason, the area of the sample image projected on the MCP becomes very small, and there has been a problem that the life of the MCP is reduced.

On the other hand, in the inspection apparatus described in Japanese Patent Application Laid-Open No. Hei 10-197462, a sample image projected on the MCP is converted to a TDI (Time Delay Integration) array CC.
In order to capture by the D sensor, the rectangular beam irradiated on the sample is shaped into a rectangle according to the shape of the TDI array CCD sensor. For this reason, the area of the sample image projected on the MCP also becomes a large rectangle, and the life of the MCP can be extended.

[0006]

The above-mentioned TD
In an inspection apparatus using an I-array CCD sensor, when capturing a sample image, a TDI array CCD sensor 90 (FIG.
In order to vertically shift the signal charges stored in each of the horizontal lines 91-1 to 91-N in 5), the sample must be moved in the vertical direction in accordance with the shift of the signal charges.

For this reason, the TDI array CCD sensor 90
In the inspection apparatus using, a sample image can be continuously captured from a plurality of inspection regions 93 to 95 arranged in the vertical direction of the sample 92 (FIG. 26) by moving the sample in the vertical direction. However, the TDI array CC
In the D sensor 90, since the direction in which the signal charge is shifted is determined in advance in the vertical direction as described above,
When the sample 92 is moved in the horizontal direction, a sample image cannot be captured.

Therefore, a plurality of inspection areas 96 to 98 arranged in the horizontal direction of the sample 92 (FIG. 27)
When capturing a sample image from each of the inspection areas 96 to 98, the stage must be moved in the vertical direction.

Then, for example, after the image capturing of the inspection area 96 is completed and before the image capturing of the adjacent inspection area 97 is started, the sample 92 is moved obliquely to set the image capturing start point of the inspection area 97. Time is required for positioning. For this reason, when sample images of the inspection areas 96 to 98 arranged in the horizontal direction are captured, the image capture of the inspection area 96 → positioning → image capture of the inspection device 97 → positioning →. Cannot be captured. As a result, the inspection efficiency decreases.

[0010] Such a problem similarly occurs in an inspection apparatus using the above-described line CCD sensor. An object of the present invention is to capture a sample image while moving a stage, and to continuously capture image information from a plurality of inspection areas arranged along the moving direction, regardless of the moving direction of the stage. It is an object of the present invention to provide an inspection apparatus and an inspection method which can perform the inspection.

[0011]

According to a first aspect of the present invention, there is provided an inspection apparatus comprising: a movable stage; irradiation means for irradiating a sample mounted on the stage with an electron beam; It has an electron optical system that forms a secondary beam generated from the sample by beam irradiation on a predetermined surface, and projects an image of the secondary beam from the sample located in the field of view of the electron optical system onto a predetermined surface. Projection means, deflecting means for deflecting at least one trajectory of the electron beam and the secondary beam, and an image sensor for capturing the image projected on a predetermined surface, based on an output signal from the image sensor The apparatus includes image capturing means for capturing corresponding image information, and control means for controlling the movement of the sample accompanying the movement of the stage and the deflection of the trajectory by the deflection means in synchronization.

As described above, according to the first aspect of the present invention,
An image of a secondary beam from a sample located in the field of view of the electron optical system is projected onto a predetermined surface, and the projected image is captured by an image sensor. Also, the trajectory of the electron beam irradiated on the sample,
At least one of the trajectories of the secondary beam generated from the sample is deflected in synchronization with the movement of the sample accompanying the movement of the stage.

Here, when the trajectory of the electron beam irradiated on the sample is deflected, the position of the irradiation area of the electron beam on the sample surface moves. Therefore, when the trajectory of the electron beam is deflected in synchronization with the movement of the sample, the electron beam can be continuously irradiated on a predetermined region of the sample. When the trajectory of the secondary beam generated from the sample is deflected, the field of view of the electron optical system moves. For this reason, if the trajectory of the secondary beam is deflected in synchronization with the movement of the sample, the projection image can be stopped on the above-described predetermined surface.

Therefore, when capturing the image information of the sample while moving the stage, at least one of the trajectories of the electron beam and the secondary beam is deflected in synchronization with the movement of the sample. , An image of the same inspection area is projected, and the sample image can be reliably captured. Further, regardless of the direction in which the stage moves, image information can be continuously taken in from a plurality of inspection areas arranged along the moving direction.

According to a second aspect of the present invention, in the inspection apparatus according to the first aspect, the irradiating means includes:
It has beam shaping means for shaping the irradiation area of the electron beam according to the shape of the imaging surface of the image sensor.
Therefore, according to the second aspect of the present invention, it is possible to efficiently irradiate the electron beam and to contribute to prevention of charge-up and contamination of the sample.

According to a third aspect of the present invention, in the inspection apparatus according to the first or second aspect, the deflecting means deflects the trajectory of the electron beam and the trajectory of the secondary beam. The control means controls the deflection of the trajectory of the electron beam by the deflecting means in synchronization with the deflection of the trajectory of the secondary beam.

Therefore, according to the third aspect of the invention, the sample image can be continuously taken in while keeping the positional relationship between the electron beam irradiation area and the field of view of the electron optical system constant. The projection image on the predetermined surface can always be stopped. (Claim 4) The invention described in claim 4 is based on claim 1
The inspection apparatus according to any one of claims 1 to 3,
The control means alternately controls the deflection means synchronized with the movement of the sample and the deflection means not synchronized with the movement of the sample.

Therefore, according to the present invention, an image is taken in from one inspection area during a period synchronized with the movement of the sample, and is moved to the next inspection area during a period not synchronized with the movement of the sample. Therefore, a large number of inspection areas on the sample can be inspected one after another, and sample images can be continuously taken. (Claim 5) Further, the invention described in claim 5 is based on claim 1
In the inspection device according to any one of claims 4 to 5,
The image sensor is constituted by a two-dimensional CCD image pickup device having a plurality of light receiving pixels arranged two-dimensionally.

Therefore, according to the fifth aspect of the present invention, the sample image formed on the imaging surface of the two-dimensional CCD imaging device can be accumulated over the shutter time. For this reason, even if the secondary beam generated from the sample is weak, clear image information can be captured. (Claim 6) The inspection method according to claim 6, wherein the moving step of moving the stage on which the sample is mounted, the irradiating step of irradiating the sample with an electron beam in a plane, and the moving of the sample in the moving step And a detection step of detecting, as a still image, a secondary beam generated from the sample irradiated in the irradiation step by an image sensor in synchronization with the above.

Therefore, according to the present invention, a stable still image is detected by detecting the secondary beam image formed by the secondary beam from the sample in synchronization with the movement of the sample. can do. Further, a still image can be detected without repeating the movement and stop of the sample, and the inspection time can be reduced.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) First, a first embodiment will be described. The first embodiment corresponds to claims 1 to 6. The inspection apparatus 10 according to the first embodiment includes a primary column 21, a secondary column 22, and a chamber 23, as shown in FIG. Primary column 21
It is attached obliquely to the side surface of the secondary column 22. A chamber 23 is attached to a lower part of the secondary column 22. These primary column 21 and secondary column 2
2. The chamber 23 is connected to an evacuation system (not shown), and is evacuated by a vacuum pump of the evacuation system.
The internal vacuum is maintained.

Here, the primary column 21 and the secondary column 22
And the configuration of the chamber 23 will be described in order. [Primary Column] Inside the primary column 21, an electron gun 24 for emitting an electron beam is arranged. This electron gun 2
As the cathode 4, lanthanum hexabolite (LaB ₆ ) capable of extracting a large current with a rectangular cathode is used.

In the interior of the primary column 21, a primary optical system 25 and a primary deflector 2 are placed on the optical axis of an electron beam (hereinafter, referred to as “primary beam”) emitted from an electron gun 24.
6 are arranged. As the primary optical system 25, a quadrupole (or octupole) electrostatic lens (or electromagnetic lens) having an asymmetric rotation axis can be used. In the first embodiment, a three-stage electrostatic lens 25a is used. , 25b, 25c (FIG. 3)
Reference) will be described.

Each of the electrostatic lenses 25a, 25b and 25c is composed of four cylindrical rods 1 to 4 as shown in FIG. 2 (a), and opposing electrodes (1 and 3, 2 and 4) are equipotential. And opposite voltage characteristics (+ V to 1 and 3)
-Vq) is given to q, 2 and 4. Such electrostatic lenses 25a, 25b, and 25c can cause convergence and divergence on the long axis (X axis) and the short axis (Y axis) of the rectangular cathode, respectively, similarly to a so-called cylindrical lens. Therefore, each of the electrostatic lenses 25a, 25b, 25c
By optimizing the lens conditions described above, the cross section of the primary beam can be formed into an arbitrary shape without losing outgoing electrons. FIG. 2A shows a case where the cross section of the primary beam is rectangular.

The primary deflector 26 (FIG. 1) may be an electrostatic deflector or an electromagnetic deflector. In the first embodiment, as shown in FIG. An example of an electrostatic deflector configured with two electrodes 5 to 8 and capable of biaxial deflection will be described. By changing the applied voltage V1 to the electrodes 6, 8, the trajectory of the primary beam can be deflected along the X axis. Further, the applied voltage V to the electrodes 5 and 7
By changing 1, the trajectory of the primary beam can be deflected along the Y axis.

Further, in the primary column 21 (FIG. 1), a primary column control unit 45 for controlling the lens voltage of the primary optical system 25 and a deflector control unit 47 for controlling the voltage applied to the primary deflector 26. It is connected. These primary column control unit 45 and deflector control unit 47
Are connected to the CPU 43.

[Chamber] A stage 27 is provided inside the chamber 23 as shown in FIG.
A sample 28 is placed on the stage 27. Stage 2
7 is movable in the XY directions. On stage 27,
A predetermined retarding voltage (described later) is applied.

In the chamber 23, the stage 27 is
A stage control unit 49 that drives in the direction is connected to a laser interferometer unit 50 that outputs a stage movement signal according to the moving direction and the moving amount of the stage 27. Further, the stage control unit 49 and the laser interferometer unit 50 are connected to the CPU 43. [Secondary Column] Inside the secondary column 22, as shown in FIG. 1, a cathode lens 29, a numerical aperture 30, and a Vienna lens are placed on the optical axis of a secondary beam (described later) generated from the sample 28. Filter 31, second lens 3
2, field aperture 33, third lens 34, fourth
The lens 35, the secondary deflector 36, and the detector 37 are arranged.

The cathode lens 29 is usually composed of a plurality of electrodes. Here, as shown in FIG. 3, a configuration example of three electrodes 29a, 29b, and 29c will be described. In this case, under the cathode lens 29 (sample 28)
A voltage can be applied to the first electrode 29a and the second electrode 29b from the side) and the third electrode 29c can be set to zero potential to function as a lens.

The numerical aperture 30 (FIG. 1) is equivalent to an aperture stop and determines the aperture angle of the cathode lens 29. The shape is a metal (Mo or the like) thin film plate having a circular hole. The opening of the new mechanical aperture 30 is the cathode lens 2.
Nine focus positions are arranged. For this reason,
The numerical aperture 30 and the cathode lens 29 constitute a telecentric electron optical system.

The Wien filter 31 is a deflector acting as an electromagnetic prism, and has a Wien condition (E = vB.
Note that v represents the velocity of the charged particles, E represents an electric field, B represents a magnetic field, and E⊥B. ), Only the charged particles (for example, the secondary beam) satisfy the above conditions, and the trajectories of the other charged particles (for example, the primary beam) can be bent. Second lens 3
The second lens 34, the fourth lens 35, and the fourth lens 35 are all rotational axis symmetrical lenses called unipotential lenses or Einzel lenses, each of which includes three electrodes (see FIG. 5). Each lens is usually
The lens action is controlled by setting one electrode to zero potential and changing the voltage applied to the center electrode.

A field aperture 33 is arranged between the second lens 32 and the third lens 34 (FIG. 1). The field aperture 33 limits the field of view to a necessary range, similarly to the field stop of the optical microscope. Here, the above-described cathode lens 29, new mechanical aperture 30, Wien filter 31, second lens 32,
The field aperture 33, the third lens 34, and the fourth lens 35 will be collectively referred to as the secondary optical system 20.

The secondary deflector 36 is the primary deflector 2 described above.
6 (FIG. 2 (b)) is a biaxially deflectable electrostatic deflector composed of four independent electrodes 5 to 8;
By changing the applied voltage V2 to 8, the trajectory of the secondary beam can be deflected along the X axis. Also,
By changing the applied voltage V2 to the electrodes 5 and 7,
The trajectory of the secondary beam can be deflected along the Y axis.

The detector 37 (FIG. 1) includes an MCP 38 for accelerating and multiplying electrons and a fluorescent screen 39 for converting electrons to light.
And an optical relay lens (FOP) 40 having an optical relay lens (not shown), and a two-dimensional CCD sensor 41 for capturing an optical image. 2D CC
The D sensor 41 has a plurality of light receiving pixels arranged two-dimensionally. The detector 37 includes the image processing unit 4
2 are connected.

Further, in the secondary column 22, the respective lens voltages of the cathode lens 29, the second lens 32, the third lens 34, and the fourth lens 35 are controlled, and the electromagnetic field applied to the Wien filter 31 is controlled. A secondary column control unit 46 and a deflector control unit 48 for controlling a voltage applied to the secondary deflector 36 are connected. These secondary column control unit 46 and deflector control unit 4
8. The image processing unit 42 is connected to the CPU 43.

Note that the CPU 43 has a C for displaying an image.
RT44 is connected. Next, the trajectories of the primary beam and the secondary beam in the inspection apparatus 10 configured as described above will be described in order. [Primary Beam] The primary beam from the electron gun 24 is accelerated by the accelerating voltage of the electron gun 24 and, as shown in FIG. 3, is subjected to the lens action of the primary optical system 25 and the deflection action of the primary deflector 26 to form a Wien filter. The light is incident on the center of 31. FIG. 3 shows the trajectories of the electrons emitted in the X-direction section and the electrons emitted in the Y-direction section of the rectangular cathode.

The primary beam that has entered the Wien filter 31 has its trajectory bent by the deflection action of the Wien filter 31 and reaches the opening of the numerical aperture 30. Here, by setting the lens voltage of the primary optical system 25, the primary beam forms an image at the aperture of the numerical aperture 30. The primary beam imaged at the aperture of the numerical aperture 30 is irradiated on the surface of the sample 28 via the cathode lens 29. Here, the new mechanical aperture 30 and the cathode lens 2
9 constitutes a telecentric electron optical system, so that the primary beam that has passed through the cathode lens 29 becomes a parallel beam, and is illuminated vertically and uniformly on the surface of the sample 28. In other words, Koehler illumination referred to by an optical microscope is realized.

The stage 27 on which the sample 28 is placed
Since the above retarding voltage is applied to
A negative electric field for the primary beam is formed between the electrode 29a of the cathode lens 29 and the surface of the sample 28. Therefore, the primary beam that has passed through the cathode lens 29 is decelerated until it reaches the surface of the sample 28, so that charge-up and destruction of the sample 28 are prevented.

Unnecessary electron beams scattered in the inspection apparatus 10 are prevented from reaching the surface of the sample 28 by the numerical aperture 30, thereby preventing charge-up and contamination of the sample 28. Incidentally, the primary beam irradiation area 24A on the sample 28 surface
Is shaped by controlling the lens voltage to the primary optical system 25, and has a substantially rectangular shape as shown in FIG. 4A in the first embodiment. This is a two-dimensional CCD
This is because it corresponds to the shape of the imaging surface of the sensor 41 (FIG. 1) (details will be described later).

Further, the position of the primary beam irradiation area 24A (FIG. 3) is determined by deflecting the trajectory of the primary beam in the XY directions by controlling the voltage V1 applied to the primary deflector 26.
The sample 28 can be moved in the XY directions on the surface. The movement of the irradiation area 24A is performed in synchronization with the movement of the sample 28 accompanying the movement of the stage 27 in the first embodiment.

That is, when the stage 27 moves, the laser interferometer unit 50 (FIG. 1) detects the moving direction and the moving amount of the stage 27, and outputs a stage moving signal corresponding to the detection result to the CPU 43. The CPU 43
The deflector control unit 47 is controlled in synchronization with the stage movement signal from the laser interferometer unit 50 to change the voltage V1 applied to the primary deflector 26.

For example, when the stage 27 has moved along the X-axis by a moving amount ΔX as shown in FIG.
The deflector control unit 47 (FIG. 1) changes the voltage V1 applied to the electrodes 6 and 8 (FIG. 2B) of the primary deflector 26.
As a result, the trajectory of the primary beam is deflected along the X-axis, and the irradiation area 24A of the primary beam on the sample 28 becomes as shown in FIG.
As shown in (2), the stage 27 moves by ΔX following the moving amount ΔX of the stage 27.

When the stage 27 has moved along the Y-axis by the moving amount ΔY as shown in FIG. 4C, the deflector control unit 47 (FIG. 1) 7 (FIG. 2 (b)). As a result, the trajectory of the primary beam is deflected along the Y axis, and the primary beam irradiation area 24A on the sample 28 follows the movement amount ΔY of the stage 27 as shown in FIG. It will move by ΔY.

As described above, the primary beam irradiation area 24 is synchronized with the movement of the sample 28 accompanying the movement of the stage 27.
By moving A, the irradiation of the primary beam on the predetermined area a of the sample 28 can be maintained. [Secondary Beam] On the other hand, when the primary beam is irradiated on the surface of the sample 28, a secondary beam composed of at least one of secondary electrons, reflected electrons, or backscattered electrons is emitted from the irradiated area 24A. appear.

This secondary beam has two-dimensional image information of the irradiation area 24A. In addition, since the primary beam is irradiated perpendicular to the sample 28 as described above, the secondary beam has a clear image without shadow. Here, sample 2
Since the above-described retarding voltage is applied to the stage 27 on which the sample 8 is placed, a positive beam with respect to the secondary beam is provided between the electrode 29a of the cathode lens 29 and the surface of the sample 28 shown in FIG. Is formed. Therefore, the secondary beam generated from the sample 28 is accelerated toward the cathode lens 29 and efficiently guided into the field of the secondary optical system 20.

The secondary beam is emitted from the cathode lens 2
9, the light passes through the numerical aperture 30 and travels straight without receiving the deflection effect of the Wien filter 31 to form an image on the field aperture 33 via the second lens 32. in this way,
By causing the secondary beam to form an image together with the second lens 32 instead of forming the image only with the cathode lens 29, the occurrence of lens aberration can be suppressed.

Further, by changing the electromagnetic field applied to the Wien filter 31, only electrons having a specific energy band (for example, secondary electrons, reflected electrons, or backscattered electrons) are selectively passed from the secondary beam. Can be done.
Then, the secondary beam having passed through the field aperture 33 is transmitted to a third lens 34 and a fourth lens 3
5, the image is formed once by the third lens 34, and then re-imaged on the detection surface of the detector 37 by the fourth lens 35.

As described above, the secondary beam generated from the sample 28 is imaged three times in total, and then enters the detector 37. Here, the third lens 34 and the fourth lens 35 may be combined to form one image (two images in total). The field aperture 33, together with the third lens 34 and the fourth lens 35 at the subsequent stage, blocks unnecessary secondary beams, thereby preventing charge-up and contamination of the detector 37. The numerical aperture 30 plays a role of suppressing the lens aberration of the second lens 32 to the fourth lens 35 in the subsequent stage with respect to the secondary beam.

As described above, the secondary beam generated from the sample 28 and imaged on the detection surface of the detector 37 is accelerated and multiplied when passing through the MCP 38 in the detector 37, and converted into light by the fluorescent screen 39. Is converted. The light from the fluorescent screen 39 is FO
An image is formed on the imaging surface of the two-dimensional CCD sensor 41 via P40.

The third lens 34 and the fourth lens 35
Is a lens for enlarging and projecting the intermediate image obtained on the field aperture 33. Therefore, sample 28
The two-dimensional image of the irradiation area 24 </ b> A on the surface is enlarged and projected on the detection surface of the detector 37. In addition, a two-dimensional image (secondary beam image) of the irradiation area 24A projected on the detection surface of the detector 37.
Is converted to an optical image on the phosphor screen 39,
The image is projected on the imaging surface of the two-dimensional CCD sensor 41 via P40. Incidentally, the FOP 40 projects the optical image by reducing it to about 1/3 in order to match the image size on the phosphor screen 39 with the image size on the two-dimensional CCD sensor 41.

Here, an area on the surface of the sample 28 corresponding to the imaging surface of the two-dimensional CCD sensor 41 is defined as an imaging area 41A.
(See FIG. 6A). Naturally, the imaging area 41A has a substantially rectangular shape according to the shape of the imaging surface of the two-dimensional CCD sensor 41. By the way, the position of the imaging area 41A is determined by the secondary deflector 36.
By deflecting the trajectory of the secondary beam in the XY directions by controlling the voltage V2 applied to (FIG. 5), it is possible to move the surface of the sample 28 in the XY directions.

The movement of the imaging area 41A is performed in synchronization with the movement of the sample 28 accompanying the movement of the stage 27 in the first embodiment. That is, as in the case of the primary beam irradiation area 24A described above, the CPU 43 (FIG. 1)
Controls the deflector control unit 48 in synchronization with the stage movement signal from the laser interferometer unit 50 to change the voltage V2 applied to the secondary deflector 36.

For example, when the stage 27 has moved along the X-axis by the moving amount ΔX as shown in FIG.
The deflector control unit 48 (FIG. 1) changes the voltage V2 applied to the electrodes 6 and 8 (FIG. 2B) constituting the secondary deflector 36. As a result, the trajectory of the secondary beam is deflected along the X axis, and the imaging area 41A on the sample 28 follows the movement amount ΔX of the stage 27, as shown in FIG.
It will move by X.

When the stage 27 moves along the Y-axis by the moving amount ΔY as shown in FIG. 6C, the deflector control unit 48 (FIG. 1) , 7 (FIG. 2 (b)). As a result, the trajectory of the secondary beam is deflected along the Y-axis, and the imaging area 41A on the sample 28 follows the movement amount ΔY of the stage 27 by ΔY as shown in FIG. Will move.

As described above, by moving the imaging area 41 A in synchronization with the movement of the sample 28 accompanying the movement of the stage 27, the correspondence between the predetermined area a of the sample 28 and the imaging surface of the two-dimensional CCD sensor 41 is obtained. Can be maintained. On the other hand, the optical image of the imaging area 41A projected on the imaging surface of the two-dimensional CCD sensor 41 is
The signal charge obtained by the photoelectric conversion is, for example, 1/3
It is output from the two-dimensional CCD sensor 41 to the image processing unit 42 (FIG. 1) every 0 seconds. Image processing unit 42
Converts the signal charge from the two-dimensional CCD sensor 41 into A / D, stores it in an internal VRAM, creates image information, and outputs it to the CPU 43. The CPU 43 displays an image corresponding to the imaging area 41A of the sample 28 on the CRT 44. Further, the CPU 43 specifies a defective portion of the sample by executing template matching or the like on the image information.

Here, the electron gun 2 of the first embodiment described above is used.
4. The primary optical system 25, the Wien filter 31, the new mechanical aperture 30, the cathode lens 29, and the primary column control unit 45 correspond to the "irradiating means" in the claims. The detection surface of the detector 37 of the first embodiment corresponds to a “predetermined surface” in the claims. Secondary optical system 20 of the first embodiment
Corresponds to “electron optical system” in the claims. The secondary optical system 20 and the secondary column control unit 46 of the first embodiment correspond to “projection means” in the claims. In the first embodiment, the primary deflector 26, the secondary deflector 36, the deflector control unit 47,
48 corresponds to the "deflecting means" in the claims. The two-dimensional CCD sensor 41 of the first embodiment corresponds to an “image sensor” in the claims. The detector 37 and the image processing unit 42 of the first embodiment correspond to “image capturing means” in the claims. The CPU 43 of the first embodiment corresponds to “control means” in the claims. The primary optical system 25 and the primary column control unit 45 in the first embodiment correspond to “beam shaping means” in the claims.

Next, the inspection apparatus 1 of the first embodiment described above
In FIG. 7, the operation when capturing the image information of the sample 28 while moving the stage 27 at a constant speed will be described with reference to FIG.
This will be described with reference to FIG. Here, in order to make the explanation easy to understand, an example in which the stage 27 moves at a constant speed along the X axis will be described.

In the first embodiment, the above-described primary beam irradiation area 24A (FIG. 4) corresponds to the imaging area 41A.
It is shaped into substantially the same shape as (FIG. 6), and the movement of the primary beam irradiation area 24A (FIG. 4) and the movement of the imaging area 41A (FIG. 6) are synchronously controlled along the X axis. Therefore, the irradiation area 24A of the primary beam and the imaging area 41A always maintain the state of being overlapped on the surface of the sample 28 (the cross-hatched portions in FIGS. 10A to 10G indicate the irradiation area 24A). And overlap of the image pickup area 41A).

Here, the voltage V1 (FIG. 7) applied to the primary deflector 26 and the voltage V2 applied to the secondary deflector 36 when synchronously controlling the movement of the irradiation area 24A and the movement of the imaging area 41A. (FIG. 8) will be specifically described. In addition,
7 and 8, the right vertical axis shows the position of the irradiation region 24A and the position of the imaging region 41A. The voltage V1 (FIG. 7) applied to the primary deflector 26 has a period TD (time t1 to t3, t4 to t6,...) That decreases at a fixed rate from a maximum value + V11 to a minimum value −V12, and a minimum value −V12. TU (time t3 to t4, t6 to t7,...) That increases at a constant rate from
It changes periodically (period T).

Among such periodic changes, the applied voltage V1
Are at the maximum value + V11, the irradiation area 24A is located at the point Xa as shown on the right vertical axis in FIG. 7 (FIGS. 10 (a), (d), (g). )). At times t3, t6,... At which the applied voltage V1 becomes the minimum value −V12, the irradiation area 24A is located at the point Xb as shown on the right vertical axis in FIG. 7 (FIG. 10).
(See also (c) and (f).)

Further, during a period TD in which the applied voltage V1 decreases at a constant rate, the irradiation area 24A moves at a constant speed from the point Xa to the point Xb. In a period TU in which the applied voltage V1 increases at a constant rate, the irradiation area 24A moves at a constant speed from the point Xb to the point Xa. On the other hand, the voltage V2 (FIG. 8) applied to the secondary deflector 36 is reduced at a constant rate from the maximum value + V21 to the minimum value -V22 (time t1 to t3, t4 to t6, time TD).
..) And a period TU (time t3 to t4, t6 to t7,
..) Are alternately repeated to periodically change (cycle T).

Among such periodic changes, the applied voltage V2
At times t1, t4, t7,... At which the value becomes the maximum value + V21, the imaging region 41A is located at the same point Xa as the irradiation region 24A described above (see also FIGS. 10A, 10D, and 10G).
Further, at time t3 when the applied voltage V2 becomes the minimum value -V22,
At t6 ..., the imaging area 41A is the irradiation area 2 described above.
It is located at the same point Xb as 4A (see also FIGS. 10 (c) and 10 (f)).

Further, during a period TD in which the applied voltage V2 decreases at a constant rate, the imaging region 41A moves at a constant speed from the point Xa to the point Xb, similarly to the above-described imaging region 24A. Further, in the period TU in which the applied voltage V2 increases at a constant rate, the imaging region 41A moves at a constant speed from the point Xb to the point Xa as in the above-described imaging region 24A.

As described above, the irradiation area 24A and the imaging area 4
1A means to periodically reciprocate between the point Xa and the point Xb while always maintaining the overlapping state (period T). At this time, the movement range ΔX1 of the irradiation area 24A and the imaging area 41A is substantially equal to the length Lx of the imaging area 41A along the X axis (see FIG. 10A).

Further, in the first embodiment, during the reciprocating movement of the irradiation area 24A and the imaging area 41A (FIGS. 7 and 8), the period TD of moving from the point Xa to the point Xb.
In, the movement is synchronized with the movement of the stage 27. Therefore, the irradiation area 24A and the imaging area 41A are both at the same speed as the speed Vx of the stage 27,
7 moves from the point Xa to the point Xb in the same direction as the moving direction of the point 7.

Since the speed Vx and the moving direction of the stage 27 are constant, the irradiation area 24A and the imaging area 41
During a period TU in which A moves from the point Xb to the point Xa, the movement of the irradiation area 24A and the imaging area 41A is in the opposite direction to the movement direction of the stage 27.
Will not be synchronized. And this period T
The movement of the irradiation area 24A and the imaging area 41A in U is performed at high speed.

Incidentally, the irradiation area 24A and the imaging area 41
In the first embodiment, the cycle T (for example, 1 second) of the reciprocating movement of A is the length Lx (see FIG. 10) of the imaging region 41A described above.
(see (a)) is defined as the time (Lx / Vx) required for the stage 27 (speed Vx) to move. Therefore,
Each time the period T of one cycle elapses, the stage 27
It will move by the length Lx. That is, FIG.
As shown in FIG. 10, the stage 27 (see also FIG. 10A) located at the point X0 at the time t1 is moved to the time t4 one cycle later.
At the point X1 separated by the length Lx (see FIG. 1).
0 (d)), and at time t7 when one cycle has elapsed further, it moves to a point X2 further away by a length Lx (see also FIG. 10 (g)).

The irradiation areas 24A, 24A,
According to the imaging area 41A and the stage 27, the stage 27
The image information of the sample 28 placed on top is taken in as follows. First, at time t1 (FIG. 10
(a)), the stage 27 is located at the point X0, and the irradiation area 2
4A, the imaging area 41A is located at the point Xa. Therefore, the point X is located on the imaging surface of the two-dimensional CCD sensor 41.
An image of the inspection area A located at a is projected.

The period TD from time t1 to time t3
(FIGS. 10A to 10C), irradiation area 24A, imaging area 41
A moves from the point Xa to the point Xb in synchronization with the movement of the stage 27, and tracks the inspection area A of the sample. Therefore, the image of the inspection area A is projected on the imaging surface of the two-dimensional CCD sensor 41 in a stopped state. The image of the inspection area A is read out every 1/30 seconds. C
A still image of the inspection area A is displayed on the RT 44 for about one second (corresponding to the cycle T).

The period TU from time t3 to time t4 (FIGS. 10C to 10D), the irradiation area 24A and the imaging area 41A
Is moved at a high speed in the direction (rightward in the figure) opposite to the direction of movement of the stage 27 (leftward in the figure). Then, at time t4 (FIG. 10 (d)), the stage 27 is located at the point X1 separated from the point X0 by the length Lx, and the irradiation area 24A,
The imaging area 41A has returned to the point Xa again. Therefore, the image of the inspection area B located at the point Xa is projected on the imaging surface of the two-dimensional CCD sensor 41. Note that the inspection area B is adjacent to the inspection area A described above.

The period TD from the time t4 to the time t6 (FIGS. 10D to 10F), the irradiation area 24A and the imaging area 41A
Moves from point Xa to point Xb again in synchronization with the movement of the stage 27, and tracks the inspection area B of the sample. Therefore, the image of the inspection area B is projected on the imaging surface of the two-dimensional CCD sensor 41 in a stopped state. The image of the inspection area B is read out in the same manner as described above, and the CRT 4
4 displays a still image of the inspection area B.

The period TD from time t6 to time t7 (FIGS. 10 (f) to 10 (g)), the irradiation area 24A and the imaging area 41A
Is moved at a high speed in the direction (rightward in the figure) opposite to the direction of movement of the stage 27 (leftward in the figure).

At time t7 (FIG. 10)
(g)), the stage 27 is located at a point X2 separated from the point X1 by a length Lx, and includes the irradiation area 24A and the imaging area 41.
A has returned to point Xa again. Therefore, two-dimensional C
On the imaging surface of the CD sensor 41, an image of the inspection area C located at the point Xa is projected. Note that the inspection area C is adjacent to the inspection area B described above.

Thereafter, the image of the inspection area C is projected on the imaging surface of the two-dimensional CCD sensor 41 in a stopped state in the same manner as in the inspection areas A and B described above. The image of the inspection area C is read out in the same manner as described above, and a still image of the inspection area C is displayed on the CRT 44. Thus, when the stage 27 moves along the X axis, the irradiation area 2
By reciprocating the 4A and the imaging area 41A along the X axis, sample images are continuously taken in from the adjacent inspection areas A, B, and C (FIG. 10) arranged along the X axis. Can be.

According to the inspection apparatus 10, the stage 2
The stage 27 does not necessarily move along the X axis.
Move along the Y-axis, even if
By reciprocating the A and the imaging area 41A along the Y axis, sample images can be continuously taken in from a plurality of adjacent inspection areas arranged along the Y axis.

Further, according to the inspection apparatus 10, not only the plurality of adjacent inspection areas (for example, A to C in FIG. 10) arranged along the moving direction of the stage 27 as described above, but also, for example, FIG. As described above, the plurality of inspection areas A, which are displaced from the moving direction of the stage 27 and are arranged in a zigzag shape,
Sample images can also be continuously captured from B, C, D, and E.

In this case, each inspection area A, B, C, D, E
When the still image is captured, the movement of the stage 27, the irradiation area 24A, and the imaging area 4 are performed in the same manner as the above-described operation (see times t1 to t3, t4 to t6,... In FIGS. 7 to 10).
Synchronize with the movement of 1A. Then, after capturing a still image of a certain inspection area (for example, A), the irradiation area 24
A, the imaging area 41A is moved at a high speed in a direction (rightward in the figure) opposite to the direction of movement of the stage 27 (leftward in the figure), and in a direction perpendicular to the direction of movement of the stage 27 (upward or downward in the figure). By moving the inspection area at a high speed, the image capturing of the next inspection area (for example, B) separated from a certain inspection area (for example, A) can be started.

The amount of movement of the irradiation area 24A and the imaging area 41A during high-speed movement from a certain inspection area (for example, A) to the next inspection area (for example, B) is the same as that of a certain inspection area (for example, A) and the next inspection area. This is predetermined in accordance with the positional relationship with the region (for example, B). As described above, the period in which the irradiation region 24A and the imaging region 41A are synchronously moved in the moving direction of the stage 27 and the period in which the irradiation region 24A and the imaging region 41A are moved at high speed in accordance with the positional relationship of the inspection region are alternately repeated. Accordingly, a sample image can be continuously taken from a plurality of inspection areas A, B, C, D, and E arranged in a zigzag shape and not adjacent to each other.

Further, according to the inspection apparatus 10, for example, as shown in FIG. 12, sample images can be continuously taken in from the inspection areas A and B arranged along the direction orthogonal to the moving direction of the stage 27. Can be. In this case, the inspection area A
The high-speed movement of the irradiation area 24A and the imaging area 41A from to the inspection area B is performed in a direction orthogonal to the moving direction of the stage 27.

According to the inspection apparatus 10, for example, FIG.
Even when the stage 27 moves in an oblique direction as shown in FIG. 3, the irradiation region 24A and the imaging region 41A are obliquely moved synchronously along the moving direction of the stage, so that still images from each of the plurality of inspection regions A to G are obtained. Can be captured. Then, the irradiation area 24 is changed from a certain inspection area (for example, A) to the next inspection area (for example, B) according to the positional relationship.
A, by moving the imaging region 41A at high speed, still images can be continuously taken in from each of the inspection regions A to G.

As described above, according to the inspection apparatus 10 of the first embodiment, the moving direction of the stage 27 and the specimen 28
Regardless of the arrangement of the inspection areas, the still images can be continuously taken in from each inspection area, and the efficiency of the inspection can be improved. Therefore, as shown in FIG. 14, when it is desired to continuously capture still images from a large number of inspection areas A to T sparsely arranged in the partial area 28A of the sample 28,
The most efficient stage 2 according to the arrangement of the inspection areas A to T
7 is determined, and the stage 2 is moved along the
The image can be quickly taken in by moving the 7 smoothly.

As described above, since there is no restriction on the inspection direction of the sample 28 placed on the stage 27, the degree of freedom of the inspection is increased, and the inspection apparatus 10 is easy to use. The inspection apparatus 10 of the first embodiment is effective not only when inspecting the entire surface of the sample 28 but also when inspecting a part of the sample 28 at a relatively high magnification, such as reviewing the inspection result, and efficiently. Can be inspected.

In capturing an image of each inspection area of the sample 28 while moving the stage 27, the imaging area 41A and the irradiation area are not stopped for a period corresponding to the above-described period T (for example, 1 second). Region 24
A can display a still image corresponding to the inspection area being tracked in real time. Therefore, it is very effective when the operator wants to visually observe the sample image in the inspection area.

Further, in the above-described first embodiment, the shape of the irradiation area 24A is shaped according to the shape of the imaging surface of the two-dimensional CCD sensor 41, and is made substantially the same shape as the imaging area 41A. Only the necessary area of the sample 28 is irradiated with the primary beam. Therefore, it is possible to efficiently irradiate the primary beam. Sample 28
To prevent charge-up and contamination.

(Second Embodiment) Next, a second embodiment will be described. The second embodiment corresponds to claims 1 to 6. The second embodiment describes another mode of the image capturing operation in the inspection apparatus 10 (FIGS. 1 to 6) of the first embodiment.

Here, in order to make the description easy to understand, the case where the stage 27 moves at a constant speed along the X axis will be described as an example. Also in the second embodiment, the primary beam irradiation area 24A (FIG. 4) is shaped into substantially the same shape as the imaging area 41A (FIG. 6), and the irradiation area 24A
The movement of (FIG. 4) and the movement of the imaging area 41A (FIG. 6) are X
Synchronous control along the axis.

Therefore, the irradiation area 24A and the imaging area 4
1A means that the overlapping state is always maintained on the surface of the sample 28 (the cross-hatched portions in FIGS. 18A to 18E indicate the overlapping of the irradiation area 24A and the imaging area 41A). Now, in the image capturing operation of the second embodiment, the reciprocating range ΔX2 (FIGS. 15 and 16) of the irradiation area 24A and the imaging area 41A is changed to the moving range ΔX1 (FIGS. 7 and 8) of the first embodiment. ) Is smaller than the imaging area 4)
The main feature is that the length is about half of the length Lx of 1A (see also FIG. 18A).

For this reason, the voltage V applied to the primary deflector 26
1 (FIG. 15) are the maximum value + V13 and the minimum value -V14 of the above-described first embodiment, respectively.
It is set to の of V12 (FIG. 7). Also, the maximum value + V2 of the voltage V2 (FIG. 16) applied to the secondary deflector 36
3, the minimum value -V24 is also set to 1/2 of the maximum value + V21, -V22 (FIG. 8) of the first embodiment.

At times t1, t3, t5,... At which the voltage V1 applied to the primary deflector 26 reaches the maximum value + V13, the voltage V2 applied to the secondary deflector 36 also increases to the maximum value + V23.
Becomes The irradiation area 24A and the imaging area 41A are both located at the point Xc.

At times t2, t4, t6,... At which the voltage V1 applied to the primary deflector 26 becomes the minimum value -V14, the voltage V2 applied to the secondary deflector 36 is also the minimum value -V24.
Becomes Then, the irradiation area 24A and the imaging area 41A are both located at the point Xd. Further, a period TD during which the applied voltages V1 and V2 decrease at a constant rate (time t1 to t2, t3
, T4,...), The irradiation area 24A, the imaging area 41
A is a point Xc from the point Xc while maintaining the overlapping state.
It moves at a constant speed toward d. The movement at this time is synchronized with the movement of the stage 27.

A period TU (time t2 to t3, t4 to t5,...) In which the applied voltages V1 and V2 increase at a constant rate.
In, the irradiation area 24A and the imaging area 41A move at a constant speed from the point Xd to the point Xc while maintaining the overlapping state. The movement at this time is a high-speed movement that is not synchronized with the movement of the stage 27. Further, in the image capturing operation of the second embodiment, the period K of the reciprocating movement (FIGS. 15 and 16) of the imaging region 24A and the imaging region 41A is:
The time required for the stage 27 (speed Vx) to move by half (Lx / 2) of the length Lx (Lx / 2) of the imaging area 41A (Lx /
(2Vx)).

Therefore, as shown in FIG. 17, the stage 27 moves by the length Lx / 2 every time the period K of one cycle elapses. According to the irradiation area 24A, the imaging area 41A, and the stage 27 controlled as described above, the image information of the sample 28 placed on the stage 27 is taken in as follows.

First, at time t1 (FIG. 18A),
The stage 27 is located at the point X0, and the irradiation area 24A and the imaging area 41A are located at the point Xc. For this reason,
On the imaging surface of the two-dimensional CCD sensor 41, an image of the inspection area A located at the point Xc is projected.

Then, the period TD between time t1 and time t2
(FIGS. 18A and 18B), irradiation area 24A, imaging area 41
A moves from the point Xc to the point Xd in synchronization with the movement of the stage 27, and tracks the inspection area A of the sample. Therefore, the image of the inspection area A is projected on the imaging surface of the two-dimensional CCD sensor 41 in a stopped state. The image of the inspection area A is read out every 1/30 seconds. C
On the RT 44, a still image of the inspection area A is displayed for about 0.5 seconds (corresponding to the cycle K).

The period TU from time t2 to time t3 (FIGS. 18B to 18C), the irradiation area 24A and the imaging area 41A
Is moved at a high speed in the direction (rightward in the figure) opposite to the direction of movement of the stage 27 (leftward in the figure). Then, at time t3 (FIG. 18 (c)), the stage 27 is located at the point X1 separated from the point X0 by the length Lx / 2, and
A, the imaging area 41A has returned to the point Xc again. Therefore, the point X is located on the imaging surface of the two-dimensional CCD sensor 41.
An image of the inspection area B located at c is projected. The inspection area B includes half of the inspection area A described above.

The period TD from time t3 to time t4 (FIGS. 18C to 18D), the irradiation area 24A and the imaging area 41A
Moves from the point Xc to the point Xd again in synchronization with the movement of the stage 27, and tracks the inspection area B of the sample 28. Therefore, the image of the inspection area B is projected on the imaging surface of the two-dimensional CCD sensor 41 in a stopped state. The image of the inspection area B is read out in the same manner as described above. CRT
At 44, a still image of the inspection area B is displayed.

The period TU from time t4 to time t5 (FIGS. 18D to 18E), the irradiation area 24A and the imaging area 41A
Is moved at a high speed in a direction opposite to the moving direction of the stage 27. Then, at time t5 (FIG. 18 (e)), the stage 27 moves to the point X separated from the point X1 by the length Lx / 2.
2, the irradiation area 24A and the imaging area 41A have returned to the point Xc again. Therefore, an image of the inspection area C located at the point Xc is projected on the imaging surface of the two-dimensional CCD sensor 41. The inspection area C includes half of the inspection area B described above.

Thereafter, the image of the inspection area C is projected on the imaging surface of the two-dimensional CCD sensor 41 in a stopped state in the same manner as in the inspection areas A and B described above. The image of the inspection area C is read out in the same manner as described above, and a still image of the inspection area C is displayed on the CRT 44. In the second embodiment, the right half of the inspection area A and the left half of the inspection area B are common, and the right half of the inspection area B and the left half of the inspection area C are common. Therefore, when the images of the inspection areas A to C are fetched and the images are connected, when the common portion is subjected to, for example, an averaging process, the S / N ratio of the images can be increased.

As described above, according to the second embodiment, in addition to the effects of the above-described first embodiment, the inspection apparatus is reduced by the reduced reciprocating range ΔX2 of the irradiation area 24A and the imaging area 41A. The effective visual field range of the primary optical system 25 and the secondary optical system 10 can be narrowed, and the device design becomes easy. (Third Embodiment) Next, a third embodiment will be described. The third embodiment is claimed in claim 1, claim 2, claim 4 or claim 4.
This corresponds to claim 6.

The third embodiment is different from the inspection apparatus 10 of the first embodiment (FIGS. 1 to 6) in that the primary deflector 26 and the deflector control unit 47 are omitted. This is to explain the operation when capturing the image information of the sample 28 while moving at a constant speed. Again, for ease of explanation, Stage 2
An example will be described in which the object 7 moves at a constant speed along the X axis.

As described above, since the primary deflector 26 and the deflector control unit 47 are not provided in the inspection apparatus of the third embodiment, the primary beam irradiation area 24A is the sample 28
Rest on a surface. The inspection device according to the third embodiment includes a secondary deflector 36 and a deflector control unit 48. Then, the same voltage V2 as in the first embodiment is applied to the secondary deflector 36 (FIG. 8).

Now, in the image capturing operation of the third embodiment, the irradiation area 24A is stopped, and the imaging area 41A is moved in the movement range ΔX1 (substantially equal to the length Lx of the imaging area 41A).
It is performed while reciprocating within (period T). here,
The shape of the irradiation region 24A is shaped according to the shape of the imaging region 41A, and in the third embodiment, as shown in FIG. 19, the imaging region 41A (FIG. 20) has a shape in which two imaging regions 41A are arranged along the X axis. It is well-formed.

Therefore, image information of the sample 28 placed on the stage 27 is taken in as follows. First, at time t1 (FIG. 21A), the stage 27 is located at the point X0, and the imaging area 41A is located at the point Xa. At this time, the irradiation area 24A and the imaging area 41A
Means an overlapping state in the inspection area A located at the point Xa (the cross-hatched portion in FIG. 21A indicates the overlap between the irradiation area 24A and the imaging area 41A). Therefore, an image of the inspection area A located at the point Xa is projected on the imaging surface of the two-dimensional CCD sensor 41.

Then, a period TD from time t1 to time t3
(FIGS. 21A to 21C), the imaging area 41A is the stage 2
7, moves from point Xa to point Xb in synchronization with the movement of 7, and tracks the inspection area A of the sample 28. Therefore, the inspection area A is provided on the imaging surface of the two-dimensional CCD sensor 41.
Is projected in a state where the image is stopped. The image of the inspection area A is read out every 1/30 seconds. In CRT44,
A still image of the inspection area A is displayed for about one second (corresponding to the cycle T).

In the period TU from time t3 to time t4 (FIGS. 21C to 21D), the imaging area 41A is moved at a high speed in the direction opposite to the moving direction of the stage 27. And time t
In FIG. 4 (FIG. 21D), the stage 27 moves to the point X0.
Is located at a point X1 away from the imaging area 4 by a length Lx.
1A has returned to point Xa again.

At this time, the irradiation area 24A and the imaging area 41
A is in a state of being overlapped in the inspection area B located at the point Xa (cross-hatched portion in FIG. 21D). Therefore, an image of the inspection area B located at the point Xa is projected on the imaging surface of the two-dimensional CCD sensor 41.
Note that the inspection area B is adjacent to the inspection area A described above.

During the period TD from time t4 to time t6 (FIGS. 21 (d) to (f)), the imaging area 41A is set to the stage 2 again.
7 moves from point Xa to point Xb in synchronization with the movement of 7, and tracks the inspection area B of the sample 28. Therefore, the inspection area B is provided on the imaging surface of the two-dimensional CCD sensor 41.
Is projected in a state where the image is stopped. The image of the inspection area B is read out in the same manner as described above, and a still image of the inspection area B is displayed on the CRT 44.

In the period TD from time t6 to time t7 (FIGS. 21F to 21G), the imaging area 41A is moved at a high speed in the direction opposite to the direction in which the stage 27 moves. And time t
7 (FIG. 21 (g)), the stage 27 moves to the point X1.
Is located at a point X2 that is a distance Lx away from the
1A has returned to point Xa again.

At this time, the irradiation area 24A and the imaging area 41
A is a state of overlap (the cross-hatched portion in FIG. 21 (g)) in the inspection area C located at the point Xa. Therefore, an image of the inspection area C located at the point Xa is projected on the imaging surface of the two-dimensional CCD sensor 41.
Note that the inspection area C is adjacent to the inspection area B described above.

Thereafter, the image of the inspection area C is projected on the imaging surface of the two-dimensional CCD sensor 41 in a stopped state in the same manner as in the inspection area A and the inspection area B described above. The image of the inspection area C is read out in the same manner as described above, and a still image of the inspection area C is obtained on the CRT 44. As explained above,
According to the third embodiment, in addition to the effects of the first embodiment, the primary deflector 26 and the deflector control unit 4
7, the configuration of the inspection apparatus 10 is simplified.

In the third embodiment, the example in which the primary beam irradiation area 24A is elongated along the X axis has been described. This is because the stage 27 is assumed to move in the X direction. When the movement in the Y direction or the oblique movement is assumed, the irradiation area 24A is also set in the movement direction.
Need to be spread out. Further, in the above-described third embodiment, an example in which the shape of the irradiation area 24A is elongated two times has been described. 2, the shape of the irradiation area 24 </ b> A
What is necessary is just to shape A into 1.5 times the shape along the X-axis.

Further, in the third embodiment described above, the shape of the irradiation area 24A is shaped according to the shape of the imaging surface of the two-dimensional CCD sensor 41, so that the irradiation area 24A corresponds to the entire moving range of the imaging area 41A. Thus, only the region of the sample 28 necessary for capturing an image is irradiated with the primary beam.
Therefore, it is possible to efficiently irradiate the primary beam. Further, it can contribute to prevention of charge-up and contamination of the sample 28.

(Fourth Embodiment) Next, a fourth embodiment will be described. The fourth embodiment is described in claim 1, claim 2,
This corresponds to claims 4 and 5. In the fourth embodiment,
In the inspection apparatus having the configuration in which the secondary deflector 36 and the deflector control unit 48 are omitted from the inspection apparatus 10 (FIGS. 1 to 6) of the first embodiment, the sample 28 is moved while the stage 27 is moved at a constant speed. This is an explanation of the operation when the image information is taken in.

Here, in order to make the description easy to understand, the case where the stage 27 moves at a constant speed along the X axis will be described as an example. As described above, since the inspection device of the fourth embodiment is not provided with the secondary deflector 36 and the deflector control unit 48, the imaging area 41A is stationary on the surface of the sample 28. The inspection device according to the fourth embodiment includes a primary deflector 2
6 and a deflector control unit 47 are provided. Then, the same voltage V1 as in the above-described second embodiment is applied to the primary deflector 26 (FIG. 15).

The image capturing operation of the fourth embodiment is performed while the imaging area 41A is stationary and the irradiation area 24A is reciprocated within the movement range ΔX2 (substantially equal to half the length Lx of the imaging area 41A). (Period K). Here, the shape of the irradiation region 24A is shaped in accordance with the shape of the imaging region 41A. In the fourth embodiment, as shown in FIG. 22, the imaging region 41A (FIG. 23) is divided by 1 / X along the X axis.
It is shaped into a doubled shape.

Therefore, image information of the sample 28 placed on the stage 27 is taken in as follows. First, at time t1 (FIG. 24A), the stage 27 is located at the point X0, and the irradiation area 24A is located at the point Xc. At this time, the irradiation area 24A and the imaging area 41A
Means that the inspection area A located at the point Xc overlaps (the cross-hatched portion in FIG. 24A indicates the overlap between the irradiation area 24A and the imaging area 41A). Therefore, an image of the inspection area A located at the point Xc is projected on the imaging surface of the two-dimensional CCD sensor 41.

Then, a period TD from time t1 to time t2
(FIGS. 24 (a) and (b)), the irradiation area 24A is the stage 2
7 moves from point Xc to point Xd in synchronization with the movement of 7, and tracks the inspection area A of the sample 28. Therefore, the inspection area A is provided on the imaging surface of the two-dimensional CCD sensor 41.
Is projected. The image of the inspection area A is displayed on the stage 2
7 moves on the imaging surface in accordance with the movement of 7. The image in the inspection area A is read out every 1/30 seconds. The image of the inspection area A is displayed on the CRT 44 for about 0.5 seconds (corresponding to the cycle K).

During a period TU from time t2 to time t3 (FIGS. 24B to 24C), the irradiation area 24A is moved at a high speed in the direction opposite to the direction in which the stage 27 moves. And time t
3 (FIG. 24 (c)), the stage 27 moves to the point X0.
The irradiation area 24A is located at a point X1 which is separated from the point by a length Lx / 2, and the irradiation area 24A has returned to the point Xc again.

At this time, the irradiation area 24A and the imaging area 41
A is in a state of being overlapped in the inspection area B located at the point Xc (cross-hatched portion in FIG. 24C). Therefore, an image of the inspection area B located at the point Xc is projected on the imaging surface of the two-dimensional CCD sensor 41.
Note that the inspection area B is adjacent to the inspection area A described above.

During the period TD from time t3 to time t4 (FIGS. 24 (c) to (d)), the irradiation area 24A is again set in the stage 2
7, moves from point Xc to point Xd in synchronization with the movement of No. 7 and tracks the inspection area B of the sample 28. Therefore, the inspection area B is provided on the imaging surface of the two-dimensional CCD sensor 41.
Is projected. The image of the inspection area B is also in the stage 2
7 moves on the imaging surface in accordance with the movement of 7. The image of the inspection area B is read out in the same manner as described above, and the image of the inspection area B is displayed on the CRT 44.

During a period TU from time t4 to time t5 (FIGS. 24D to 24E), the irradiation area 24A is moved at a high speed in a direction opposite to the moving direction of the stage 27. And time t
5 (FIG. 24 (e)), the stage 27 moves to the point X1.
The irradiation area 24A is located at a point X2 which is separated from the point by a length Lx / 2, and returns to the point Xc again.

At this time, the irradiation area 24A and the imaging area 41
A is in a state of being overlapped in the inspection area C located at the point Xc (cross-hatched portion in FIG. 24E). Therefore, the inspection area C located at the point Xc is projected on the imaging surface of the two-dimensional CCD sensor 41. Note that the inspection area C is adjacent to the inspection area B described above. Thereafter, the image of the inspection area C is changed to the two-dimensional CCD sensor 41 in the same manner as in the inspection area A and the inspection area B described above.
Is projected on the imaging surface of the. The image of the inspection area C also moves on the imaging surface in accordance with the movement of the stage 27. The image of the inspection area C is read out in the same manner as described above, and the CRT 44
Then, an image of the inspection area C is obtained.

In the fourth embodiment, the image projected on the imaging surface of the two-dimensional CCD sensor 41 moves on the imaging surface according to the movement of the stage 27, as described above.
Therefore, an image is captured only from a necessary area of the imaging surface of the two-dimensional CCD sensor 41, and the captured image is integrated while shifting the image capturing area in synchronization with the movement of the stage 27, so that the SN ratio is high. An image is obtained.

As described above, according to the fourth embodiment, the configuration of the inspection apparatus 10 is simplified by the omission of the secondary deflector 36 and the deflector control unit 47. In the above-described fourth embodiment, the shape of the irradiation area 24A is shaped according to the shape of the imaging surface of the two-dimensional CCD sensor 41 to be half of the imaging area 41A. Only the region will be irradiated with the primary beam. Therefore, it is possible to efficiently irradiate the primary beam. Further, it can contribute to prevention of charge-up and contamination of the sample 28.

According to the above-described fourth embodiment, an example in which the primary beam irradiation area 24A is narrowed along the X axis has been described. This is because the stage 27 is assumed to move in the X direction. When assuming the movement in the Y direction or the oblique direction of 27, it is only necessary to narrow the movement in the movement direction.

In the first to fourth embodiments described above, an example has been described in which the signal charges stored in the two-dimensional CCD sensor 41 are sequentially read out, for example, every 1/30 second. 41 to the image processing unit 42
The timing (shutter time) at which the signal charge is output is not limited to this. For example, when the light quantity on the imaging surface of the two-dimensional CCD sensor 41 is insufficient, the shutter time is set longer, the signal charges are integrated in each light receiving pixel, and then read, thereby improving the SN ratio. be able to. Note that the shutter time of the two-dimensional CCD sensor 41 can be set long up to a time corresponding to the above-described cycle T (or cycle K).

Further, in the above-described first to fourth embodiments, an example has been described in which the stage 27 is scanned at a low speed such that the cycle T is 1 second (or the cycle K is 0.5 second). (Or cycle K) can be changed according to the speed Vx of the stage 27. If the light quantity on the imaging surface of the two-dimensional CCD sensor 41 is sufficient, the period T
Inspection by high-speed scanning with a (or period K) of 1/30 second is also possible.

In the first to fourth embodiments, the two-dimensional CC in which a plurality of light receiving pixels are two-dimensionally arranged is used.
Although the example in which the sample image is captured by the D sensor 41 has been described, the sample image may be captured by an image sensor having a plurality of line CCD sensors arranged in parallel instead of such a two-dimensional CCD sensor 41. . Further, in the inspection device 10 of FIG. 1, the cathode lens 29, the Wien filter 31, and the like are shared between the time when the primary beam is irradiated on the sample and the time when the secondary beam from the sample is detected by the detector 37. Although the configuration has been described, the primary beam system that is the path of the primary beam and the secondary beam system that is the path of the secondary beam may be independent from each other, and each may have a cathode lens.

Further, in the first to fourth embodiments described above, the inspection apparatus using an electron beam has been described. However, the present invention can be applied to image alignment of an EB exposure apparatus. Further, according to the present invention, by using an image sensor having a two-dimensional CCD sensor or a plurality of line CCD sensors, it is possible to contribute to the cost reduction of the apparatus.

[0131]

As described above, according to the first to sixth aspects of the present invention, even when the stage is moved in any direction, a large number of inspections are arranged along the moving direction. Since the sample image can be continuously and efficiently taken in from the region, the inspection direction of the sample is not limited, the degree of freedom of the inspection is increased, and the inspection apparatus is easy to use.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an inspection device 10 according to a first embodiment.

2A is a diagram illustrating a configuration of a primary optical system, and FIG. 2B is a diagram illustrating a configuration of a primary deflector.

FIG. 3 is a diagram showing a trajectory of a primary beam.

FIG. 4 is a diagram illustrating an irradiation area of a primary beam.

FIG. 5 is a diagram showing a trajectory of a secondary beam.

FIG. 6 is a diagram illustrating an imaging region.

FIG. 7 is a diagram showing a voltage applied to a primary deflector in the first embodiment.

FIG. 8 is a diagram showing a voltage applied to a secondary deflector in the first embodiment.

FIG. 9 is a diagram illustrating movement of a stage according to the first embodiment.

FIG. 10 is a diagram illustrating an image capturing operation according to the first embodiment.

FIG. 11 shows a plurality of inspection areas A to zigzag arranged.
It is a figure showing E.

FIG. 12 is a diagram showing another arrangement of a plurality of inspection areas A to E.

FIG. 13 is a diagram showing a plurality of inspection areas A to G arranged along an oblique direction.

FIG. 14 is a diagram showing a large number of inspection areas A to T sparsely arranged.

FIG. 15 is a diagram showing a voltage applied to a primary deflector in a second embodiment.

FIG. 16 is a diagram showing a voltage applied to a secondary deflector in the second embodiment.

FIG. 17 is a diagram showing movement of a stage in the second embodiment.

FIG. 18 is a diagram illustrating an image capturing operation according to the second embodiment.

FIG. 19 is a diagram illustrating an irradiation area of a primary beam in a third embodiment.

FIG. 20 is a diagram illustrating an imaging region.

FIG. 21 is a diagram illustrating an image capturing operation according to the third embodiment.

FIG. 22 is a diagram illustrating an irradiation area of a primary beam in a fourth embodiment.

FIG. 23 is a diagram illustrating an imaging region.

FIG. 24 is a diagram illustrating an image capturing operation according to the fourth embodiment.

FIG. 25 is a diagram showing a schematic configuration of a TDI array CCD sensor.

FIG. 26 is a diagram illustrating a conventional sample image capturing operation.

FIG. 27 is a diagram illustrating a conventional sample image capturing operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Inspection apparatus 20 Secondary optical system 21 Primary column 22 Secondary column 23 Chamber 24 Electron gun 25 Primary optical system 26, 36 Deflector 27 Stage 28 Sample 29 Cathode lens 30 New mechanical aperture 31 Wien filter 32 Second lens 33 Field aperture 34 Third lens 35 Fourth lens 37 Detector 38 MCP 39 Phosphor screen 40 FOP 41 Two-dimensional CCD sensor 42 Image processing unit 43 CPU 44 CRT 45 Primary column control unit 46 Secondary column control unit 47, 48 Deflector control unit 49 Stage control unit 50 Laser interferometer unit

Claims (6)

[Claims] 1. A stage on which a sample is mounted and movable, an irradiation unit for irradiating the sample with an electron beam, and a secondary beam generated from the sample by the irradiation of the electron beam is imaged on a predetermined surface. Projection means for projecting an image of the secondary beam from a sample located in the field of view of the electron optical system onto the predetermined surface; and at least one of the electron beam and the secondary beam Deflecting means for deflecting the trajectory of the image, having an image sensor for capturing the image projected on the predetermined surface, and image capturing means for capturing corresponding image information based on an output signal from the image sensor; An inspection apparatus comprising: control means for controlling the movement of the sample accompanying the movement of the stage and the deflection of the trajectory by the deflection means in synchronization with each other. 2. The inspection apparatus according to claim 1, wherein the irradiation unit has a beam shaping unit that shapes an irradiation area of the electron beam according to a shape of an imaging surface of the image sensor. Inspection equipment. 3. The inspection apparatus according to claim 1, wherein the deflecting unit deflects a trajectory of the electron beam and a trajectory of the secondary beam. An inspection apparatus characterized in that the deflection of the trajectory of the electron beam and the deflection of the trajectory of the secondary beam by a deflecting means are controlled in synchronization with each other. 4. The inspection apparatus according to claim 1, wherein the control unit controls the deflection unit in synchronization with the movement of the sample and synchronizes with the movement of the sample. An inspection apparatus wherein the control of the deflecting means, which is not performed, is performed alternately. 5. The inspection device according to claim 1, wherein the image sensor is a two-dimensional CCD image sensor having a plurality of two-dimensionally arranged light receiving pixels. Inspection equipment characterized. 6. A moving step of moving a stage on which a sample is mounted, an irradiation step of irradiating the sample with an electron beam in a planar shape, and the irradiation step in synchronization with the movement of the sample in the moving step. A detection step of detecting a secondary beam generated from the irradiated sample as a still image by an image sensor.