JP2002237270A - Charged particle beam deflector and charged particle beam defect inspection device and method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged particle beam deflector allowing the generation of a uniform electric field and the correction of the track of a secondary beam while minimizing the distortion of an image to be formed on a detection plane, and a charged particle beam defect inspection device and method using the same. SOLUTION: The beam deflector A comprises eight electrodes 71-78 arranged at equal spaces on a circumference in such a manner that an angle α made between two adjacent electrodes from a circumferential center O is equal to an angle β made between the electrodes from the circumferential center O, power supplies 71a-78a for applying voltage to the electrodes 71-78 and a bema deflector control part 79 for controlling the power supplies 71a-78a. A deflection field generation control system 79a, a first uniform field generation control system 79b and a second uniform field generation control system 79c are used for controlling values for voltage to be distributed to the electrodes 71-78 to make an electric field to be generated in the circumference uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle beam deflecting device for generating an electric field by applying a voltage to an electrode and deflecting a charged particle beam such as an electron beam or an ion beam. The present invention relates to a charged particle beam defect inspection apparatus and method for observing an object surface such as a liquid crystal substrate and inspecting defects, and a semiconductor element.

[0002]

2. Description of the Related Art A semiconductor device has a fine pattern formed on the surface of a semiconductor substrate by using a planar technique. However, as the size of the semiconductor device becomes smaller and the integration becomes higher, the pattern becomes finer. I have. Such a defect inspection apparatus used for observing the surface state of a semiconductor element and inspecting defects requires a detection sensitivity of, for example, 0.1 μm. In order to satisfy such a demand for higher detection sensitivity and higher inspection speed, a charged particle beam microscope using a charged particle beam such as a scanning electron microscope has been used as a charged particle beam defect inspection apparatus. In particular, low-energy electron beams do not damage semiconductor elements due to ion plantation or the like and reduce the effect of charging an insulator, and are thus widely used for pattern inspection of semiconductor elements.

[0003] Conventionally, as a charged particle beam defect inspection apparatus using an electron beam, for example, Japanese Patent Application Laid-Open No. H11-13505 has been proposed.
No. 6 is known. FIG.
1 schematically shows the inspection of the surface state of a semiconductor device using such a conventional charged particle beam defect inspection apparatus. An electron beam as a charged particle beam is generated by an electron gun 100 as a charged particle source, and as a primary beam,
It is transported by a primary optical system (not shown) in the direction of the arrow (a) in the figure. When the primary beam enters the Wien filter 200, the primary beam is deflected in the direction of the arrow (b) in the figure, passes through the objective optical system 300, and irradiates the surface of a sample 400 such as a semiconductor device. Thus, secondary electrons, reflected electrons, and backscattered electrons are obtained from the sample 400. Since the generation probability of secondary electrons depends on the physical properties of the object surface, the secondary electrons are transferred as a secondary beam for surface inspection by the objective optical system 300 and the Wien filter 200 in the direction indicated by the arrow (c) in the figure. Then, an image is formed on the detection surface 600a of the detection device 600 by the secondary optical system 500.

By the way, the secondary beam is transmitted to the secondary optical system 50.
For example, as shown by a dotted line in the drawing, the light is emitted from the secondary optical system 500 at a certain angle due to a processing accuracy of 0, an assembly error, and the like, as shown by a dotted line in the figure. Therefore, the secondary optical system 5
A charged particle beam deflector 700 is provided at a position facing the detection device 600 at the end of 00, and the trajectory is corrected in the direction of arrow (d) in the figure. The distance d from the exit pupil in the secondary optical system 500 to the charged particle beam deflecting device 700 depends on the device, but is, for example, about 30 mm, and the distance L from the charged particle beam deflecting device 700 to the detection surface 600a.
Is, for example, about 500 mm. If the trajectory of the secondary beam is not corrected by the charged particle beam deflecting device 700, the image to be formed on the optical axis is, for example, the detection surface 6
An image is formed at a position shifted by about 10 mm from the optical axis of 00a. In this case, the charged particle beam deflecting device 700 deflects the secondary beam by about 20 mrad, and corrects the trajectory of the secondary beam so that an image is formed on the optical axis. FIG. 8 shows the charged particle beam deflecting device 700 as viewed from the optical axis direction. In the figure, a charged particle beam deflector 70
0 denotes eight electrodes 711 to 711 arranged at equal intervals on the circumference.
718 and a voltage application device (not shown) for applying a voltage to each of the electrodes 711 to 718. When deflecting the electron beam as a secondary beam in, for example, the direction of arrow (e) in the figure, first, two electrodes 71 adjacent to each other are used.
1, 712, a predetermined positive voltage V is applied to the electrodes 711,
A negative voltage −V having an absolute value equal to the voltage V is applied to two electrodes 715 and 716 adjacent to each other with the center of the circumference interposed therebetween at 712.
An electric field is generated from 12 toward electrodes 715 and 716. The four electrodes 71 to which the voltage V and the voltage −V are applied
The remaining four electrodes 713, 714, 717, and 718 adjacent to 1, 712, 715, and 716 apply a voltage obtained by reducing the voltage V and the voltage −V by a predetermined ratio t, that is, apply a voltage to the electrodes 713 and 718. t × V is applied to the electrodes 714 and 717
To make the electric field for deflecting the charged particle beam uniform. The figure shows equipotential lines of the electric field generated in this way. The value of t is appropriately selected depending on the direction in which the light is to be deflected. When the light is deflected in the direction of the arrow (e), a value of about 0.4 is selected. In general,
In order to apply a voltage to a plurality of ideal point-shaped electrodes arranged on the circumference and having no size, and to generate an electric field as uniform as possible in the circumference, it is necessary to apply a voltage from the center of the circumference to the electrodes. Since it suffices to apply a voltage proportional to the cosine of the angle formed between the direction in which the charged particle beam deflects and the direction in which the
As the voltage applied to 8, an optimal value is appropriately selected according to the direction in which the charged particle beam is deflected.

[0005] In addition, for the purpose of increasing the inspection efficiency and improving the throughput, the detection device 600 includes, for example, a TDI (Ti / Ti) described in JP-A-10-197462.
me-Delay-Integration (time delay integration type) Array CCD
(Hereinafter referred to as a TDI sensor). This TD
The I-sensor has a feature that it can capture a high-resolution image in a short time as compared with a line scan CCD. In the case of a line scan CCD, an image is taken by focusing an electron beam on a sample surface, irradiating the sample with high luminance, and scanning the irradiation position. In order to perform imaging in a short time, the brightness of the electron beam must be further increased by increasing the current of the electron beam. However, since the energy of the electron beam is low, the beam diverges due to the Coulomb force and the resolution is reduced. . For this reason, if a line scan CCD is used, there is a limit in shortening the imaging time naturally, and the time during which the sample is conveyed to the imaging area and the time during removal from the imaging area is not used for imaging. Waste also exists. On the contrary,
In the case of the TDI sensor, as described later, imaging can be performed while transporting the sample, so that the imaging time is not wasted, and the sample surface is uniformly irradiated with the electron beam. Can be omitted,
In addition, the brightness is suppressed and there is no problem such as divergence of the beam due to Coulomb force.

Here, the imaging by the detection device 600 and the TDI sensor will be described with reference to FIGS. 9 and 10. FIG. 9 is a diagram illustrating the detection device 600. Detection surface 600a
The electron beam as a secondary beam imaged on the first
Incident on the MCP (Micro-Channel-Plate) 601 of
While passing through the first MCP 601 and the second MCP 602, the current amount is amplified and collides with the fluorescent screen 603. At that time, the potential at the entrance of the first MCP 601 is adjusted so that the electron beam has energy that maximizes the MCP detection efficiency. First MCP 601 and second MCP
A voltage for amplifying electrons is applied between the CPs 602, and between the second MCP 602 and the phosphor screen 603, the divergence of the electron beam emitted from the second MCP 602 due to Coulomb force and a decrease in resolution are suppressed. Therefore, an accelerating voltage is further applied. On the phosphor screen 603, electrons are converted into photons, and the output image is FOP (Fiber-Opti).
C-Plate) 604 irradiates a camera 605 equipped with a TDI sensor. Here, the FOP 604 is configured to reduce the image so that the image size on the phosphor screen 603 and the image pickup size of the camera 605 match.
FIG. 10 is a block diagram of the TDI sensor. The TDI sensor has C (1), C (2)... C (M−
1), M (M) linear CCD pixel rows arranged in a row form ROW (1), ROW (2),.
N (W (N-1) and ROW (N)) are arranged. The accumulated charges on each CCD pixel column are simultaneously transferred in the Y direction by one vertical clock signal supplied from the outside.
The data is transferred by D1 pixels. Sample 40
When the image of the sample 400 formed on the ROW (1) at a certain time moves by one pixel column in the Y direction along with the movement of the sample 400, a vertical clock signal is given in synchronization with the movement of the image. , ROW (1) are transferred to ROW (2). Then, since the same image is continuously taken, the charge of the stored image is doubled. Subsequently, when the image is further moved by one pixel in the vertical direction and a synchronous clock signal is applied, the stored image is RO
W (3), where the image charge is accumulated until tripled. ROW following the image movement
When the transfer of charges and the imaging are repeated up to (N), the result of accumulating N times image charges is serially taken out from the horizontal register as image data. The above-described operation is simultaneously performed in each of the pixel rows ROW (1) to ROW (N), and while the two-dimensional image (M pixels × N pixels) is sent in the vertical direction, the image charge accumulated in one pixel is reduced. Until N times, the accumulated image charges are taken out synchronously line by line. Thus, in the case of the detection device 600 using the TDI sensor, imaging is performed simultaneously while the sample 400 is being conveyed, and a high-resolution image is captured in a short time.

[0007]

However, when a TDI sensor is used as a detecting device, the following difficult problem is immediately encountered. That is, unless the image point of a certain object point on the sample on the detection surface moves accurately on the detection surface following the movement of the sample, the image charge is not accurately accumulated and the resolution is reduced. is there. More specifically, the description will be made using the above example. In order to accurately accumulate the image charges, the image charges accumulated in the l-th pixel C (l) of the pixel row ROW (k) are calculated as m in the Y direction.
Pixel C of ROW (k + m)
At the same time, the image of the sample 400 must be accurately moved on the detection surface 600a in the Y direction. When a certain object point on the sample 400 located at the midpoint P1 of the observation area as shown in FIG. 11A is formed on a point P1 ′ on the detection surface 600a as shown in FIG. 11B, The image point where this object point is formed on the sample 400 is the sample 4 in the y direction indicated by the arrow in FIG.
Along with the movement of 00 to 400 ′, ideally, the width corresponding to one pixel in the Y direction on the detection surface should be p, for example, the point P1 should move to a point moved by m × p in the Y direction from the point P1. is there. Then, from ROW (k) to ROW (k)
+ M), image charge should accumulate in pixel C (l). However, in reality, the error is detected by an error in the installation of the TDI sensor, an error in moving the sample 400, an aberration of the secondary optical system 500, and deflection of the electron beam due to an uneven electric field in the charged particle beam deflection device 700. The image on the surface 600a is distorted, and as shown in FIGS. 11A and 11B, the object point on the sample 400 moves from the midpoint P1 to the point P on the observation area.
2, the image point formed at the point P1 'moves along a change trajectory toward a point P2' deviated from an ideal point. In the figure, ΔY is a deviation amount from an ideal point in the Y direction, and ΔX is a point P2 ′ from a point P1 ′ in the X direction.
Is the maximum change amount in the change trajectory. ΔP = K1 where P is the width corresponding to one pixel in the X direction on the detection surface.
× P Moreover, represents a ΔY = K2 _m × p, further the effective radius of the point which is formed X, if each Y-direction will be expressed as r _{X 0} and _{r Y0, | r X0 | ≦} 0. 5 × P, | r _Y0 | ≦
If the condition of 0.5 × p and | K1 | ≦ 1, | K2 _m | ≦ 0.5 is not satisfied, the formed point is mixed with an adjacent pixel as it moves and is picked up. , The resolution of the image is reduced. As is clear from this example, in particular, as the number of pixels is increased in order to increase the resolution, and the imaging is performed in a wider area, the aberration in the area away from the center increases, and the image charge increases. It is difficult to satisfy the conditions required to accumulate the data accurately. This problem is generally caused by a TDI in which the imaging area is widened in the X direction.
This becomes apparent in the case of a detection device using a sensor. The width corresponding to one pixel on the detection surface of the detection device using the TDI sensor is about 16 μm. Therefore, in order not to lower the resolution of the image,
Errors in the installation of the TDI sensor, errors in the movement of the sample, aberrations in the secondary optics, image distortion on the detection surface caused by the deflection of the secondary beam due to the non-uniform electric field in the charged particle beam deflector, etc. In this case, an accuracy of a width corresponding to one pixel is required. Of particular concern is the non-uniform electric field in the charged particle beam deflector provided downstream of the secondary optics and ultimately modifying the trajectory of the secondary beam. Because it is closest to the detection surface, the angle that must be deflected is large,
The required uniformity of the electric field is also high. For example, if the image is uniformly shifted by about 10 mm on the detection surface, if the uniformity of the electric field used for deflection does not satisfy at least 10 ⁻³ , the image after the trajectory correction will be distorted due to distortion. Mixing of image charges occurs between matching pixels. Since the detection surface of the detection device using the TDI sensor has, for example, a width of about 30 mm, the spread of the secondary beam in the charged particle beam deflecting device is about 2 mm, and also considering the position through which the secondary beam passes. The electric field in a region of about 4 mm in diameter near the center of the charged particle beam deflector can contribute to the deflection of the secondary beam. However, as is clear from the equipotential lines in FIG.
The electric field in the charged particle beam deflecting device is fairly non-uniform, especially the more off-center the charged particle beam deflecting device is. It is actually difficult to obtain a uniform electric field of 10 ^-3 in a region of about 4 mm in diameter near the center for an inner diameter of about 20 mm of a typical charged particle beam deflector, and consequently, trajectory correction This has the problem that unacceptable distortions occur in subsequent images.

The present invention has been made in view of the above circumstances, and generates a uniform electric field, corrects the distortion of an image formed on a detection surface, and corrects the trajectory of a secondary beam. And a charged particle beam defect inspection apparatus and method using the same.

[0009]

In the following, in the examples shown in this section, for ease of understanding, specific items of the present invention will be described with reference numerals shown in the drawings of the embodiments. The configuration of the present invention or specific matters of the present invention are not limited to those restricted by these reference numerals. In order to solve the above problem, a charged particle beam deflecting device (A) according to a first aspect of the present invention includes a plurality of electrodes (71 to 78) arranged at equal intervals on a circumference, and the electrodes (71). To a voltage application device (5, 71a to 78a, 79) for applying a voltage to the electrodes (71 to 78). A predetermined voltage is applied to the electrodes (71 to 78) by the voltage application device (5, 71a to 78a, 79). A charged particle beam deflecting device (A) configured to generate an electric field in the circumference by applying the voltage and deflect a charged particle beam (B2) passing through the circumference; The relationship between an angle α that looks between two adjacent electrodes from the center of the circle and an angle β that looks at the electrode from the center of the circumference is 0.5 ≦ α / β ≦ 2. .

According to the present invention, the electric field for deflecting the charged particle beam formed inside the electrodes arranged on the circumference becomes uniform. In a conventional charged particle beam deflector, from the viewpoint of arranging electrodes with high accuracy and ease, for example, a treatment such as performing laser processing on an integral cylindrical metal is performed, so that a gap between the electrodes is generated. An angle α that is narrow and looks between two adjacent electrodes from the center of the circumference,
The relationship with the angle β at which the electrode is viewed from the center of the circumference is α≪β. For this reason, the equipotential lines concentrate between the electrodes as the distance from the center increases, so that the electric field distortion increases. The inventors have confirmed by numerical simulation that by increasing the spacing between the electrodes, the distortion of the equipotential lines is reduced, and thus the electric field generated within the circumference surrounded by the electrodes is uniform, If the relationship between the angle α that looks between two adjacent electrodes from the center of the circumference and the angle β that looks at the electrodes from the center of the circumference is 0.5 ≦ α / β ≦ 2, the charged particle beam We gained the insight that sufficient uniformity of the electric field can be obtained in the central region within the circumference used for deflection.
Thus, with such a configuration, a uniform electric field can be generated within the circumference where the electrodes are arranged, and the trajectory can be corrected by uniformly deflecting the charged particle beam.

The charged particle beam deflecting device (A) according to the second aspect of the present invention is the charged particle beam deflecting device (A) according to the first aspect, wherein the electrodes (71 to 78) are provided.
Is characterized in that an even number is provided.

The charged particle beam deflecting device (A) according to the third aspect of the present invention comprises an even number of electrodes (71 to 78) arranged at equal intervals on the circumference and the electrodes (71 to 7).
8) A voltage application device (5, 71a to 78) for applying a voltage to
a, 79), and by applying a predetermined voltage to the electrodes (71-78) by the voltage applying device (5, 71a-78a, 79), an electric field is generated within the circumference to generate the electric field. A charged particle beam deflector (A) configured to deflect a charged particle beam (B2) passing through the circumference, wherein the voltage applying device (5, 71a to 78a, 79)
Applies one voltage to two electrodes adjacent to each other among the even number of the electrodes (71 to 78), and applies adjacent voltages to these electrodes so as to face each other with the center of the circumference interposed therebetween. A deflection electric field generator (5, 71a to 78a, 79, 79a) for generating an electric field for deflecting the charged particle beam by applying a voltage having the same absolute value as that of the voltage to the two matched electrodes and applying voltages having different positive and negative values, respectively. And an electric field for deflecting the charged particle beam by applying a voltage obtained by reducing the voltage by a predetermined ratio to other remaining electrodes adjacent to the electrode to which the voltage is applied, substantially uniformly within the circumference. The first uniform electric field generator (5, 71a to 78a, 79, 79)
b) and a second uniform electric field generating unit (5, 71a to 78a, 5b) that re-adjusts the value of the voltage applied to the electrode to increase the uniformity of the electric field at the position where the charged particle beam passes.
79, 79c).

According to the present invention, the electric field generated in the circumference surrounded by the electrodes can be made uniform by adjusting the value of the voltage applied to the even number of electrodes. First, a deflection electric field generator generates a main electric field for deflecting a charged particle beam by applying a voltage to the four electrodes arranged opposite to each other, and then generates a positive electric field by a first uniform electric field generator. A voltage is applied to the remaining electrodes so that the voltage sequentially decreases at a predetermined ratio from the voltage to the negative voltage, thereby uniformly adjusting the electric field within the circumference. Further, the voltage applied to each electrode is adjusted by the second uniform electric field generating device to further uniformly adjust the electric field. In particular, when the charged particle beam does not pass through the center of the circumference, adjustment is performed to increase the uniformity of the electric field at the position where the charged particle beam passes. In general, in order to apply a voltage to a plurality of ideal point-like electrodes having no size arranged on the circumference and generate an electric field as uniform as possible in the circumference, it is necessary to set the center of the circumference from the center. It is sufficient to apply a voltage proportional to the cosine of the angle formed between the direction toward the electrode and the direction in which the charged particle beam is deflected.
The uniform electric field generating device and the second uniform electric field generating device adjust the voltage so as to approach this ideal voltage distribution and further increase the uniformity of the electric field at the position where the charged particle beam passes. . In this way, a uniform electric field can be generated within the circumference where the electrodes are arranged, and the trajectory can be corrected by uniformly deflecting the charged particle beam.

The charged particle beam deflector (A) according to a fourth aspect of the present invention is the charged particle beam deflector (A) according to the third aspect, wherein the two electrodes adjacent to each other from the center of the circumference are provided. Between α and the angle β when the electrode is viewed from the center of the circumference is 0.5 ≦ α /
β ≦ 2.

A charged particle beam defect inspection apparatus according to a first aspect of the present invention is a primary optical system for irradiating a charged particle beam from a charged particle source (10) as a primary beam (B1) onto an object (4). (5, 1, 11) and a secondary optical system (5, 5) that focuses electrons obtained from the object by irradiation of the primary beam on a detection surface as a secondary beam (B2).
(2, 20) and an imaging device (5, 30) arranged on the detection surface and detecting electrons of the secondary beam (B2) focused on the detection surface to image the object (4). A charged particle beam defect inspection apparatus provided, wherein the secondary optical system (5, 2, 20) deflects the primary beam (B1) or the secondary beam (B2). The charged particle beam deflector (A) includes a plurality of electrodes (71) on a circumference.
To 78) are arranged at equal intervals, and the relationship between the angle α that looks between two adjacent electrodes from the center of the circumference and the angle β that looks at the electrodes from the center of the circumference is:
0.5 ≦ α / β ≦ 2, and a voltage application device (5, 71a to 78a, 7) for applying a voltage to the electrodes (71 to 78).
9), an electric field is generated in the circumference by applying a predetermined voltage to the electrodes (71 to 78) by the voltage applying device (5, 71a to 78a, 79), and an electric field is generated in the circumference. It is characterized in that it is configured to deflect the passing charged particle beam.

The charged particle beam defect inspection apparatus according to a second aspect of the present invention is the charged particle beam defect inspection apparatus according to the first aspect, wherein the electrodes (71 to 78) are:
It is characterized in that an even number is provided.

A charged particle beam defect inspection apparatus according to a third aspect of the present invention provides a primary optical system for irradiating a charged particle beam from a charged particle source (10) as a primary beam (B1) onto an object (4). (5, 1, 11) and a secondary optical system (5, 2, 20) that focuses electrons obtained from the object (4) by irradiation of the primary beam (B1) as a secondary beam (B2) on a detection surface. ), And an imaging device (5, 3) that is arranged on the detection surface and detects electrons of the secondary beam (B2) focused on the detection surface to image the object (4).
0), wherein the secondary optical system (5, 2, 20) comprises a charged particle beam deflection device (A) for deflecting the charged particle beam, The charged particle beam deflecting device (A) includes an even number of electrodes (71 to 78) arranged at equal intervals on a circumference and a voltage applying device (5) for applying a voltage to the electrodes (71 to 78). , 71a to 78a, 79), and the electrodes (7
1 to 78) to the voltage applying devices (5, 71a to 78a,
79), by applying a predetermined voltage, an electric field is generated in the circumference to deflect a charged particle beam passing through the circumference, and the voltage application device (5,
71a to 78a, 79) apply one voltage to each of the two electrodes adjacent to each other, and two adjacent electrodes facing each other with the center of the circumference interposed therebetween. And a deflection electric field generation unit (5, 71) for generating an electric field for deflecting the charged particle beam by applying voltages having the same absolute value as the voltage and different positive and negative voltages, respectively.
a to 78a, 79, 79a) and an electric field for deflecting the charged particle beam by applying a voltage reduced by a predetermined ratio to the remaining electrodes adjacent to the electrode to which the voltage is applied, respectively. A first uniform electric field generating unit (5, 71a to 78a, 79, 79b) for making the charged particle beam substantially uniform in the circumference; Second uniform electric field generators (5, 71a to 78a, 79, 79) for improving the uniformity of the electric field at the position
c).

In the charged particle beam defect inspection apparatus according to a fourth aspect of the present invention, in the charged particle beam defect inspection apparatus according to the third aspect, a space between two adjacent electrodes is taken from the center of the circumference. The relationship between the angle α and the angle β at which the electrode is viewed from the center of the circumference is 0.5 ≦ α / β ≦
2 is characterized.

Further, the charged particle beam defect inspection apparatus according to the fifth aspect of the present invention is the charged particle beam defect inspection apparatus according to any one of the charged particle beam defect inspection apparatus according to the first aspect to the charged particle beam defect inspection apparatus according to the fourth aspect. The charged particle beam deflecting device (A) is provided at a position facing the imaging device (5, 30) downstream of the secondary optical system (5, 2, 20) in the traveling direction of the charged particle beam. It is characterized by.

Further, the charged particle beam defect inspection apparatus according to the sixth aspect of the present invention is the charged particle beam defect inspection apparatus according to any one of the charged particle beam defect inspection apparatus according to the fourth aspect to the charged particle beam defect inspection apparatus according to the fourth aspect. The charged particle beam deflecting device (A) is provided at a position facing the imaging device (5, 30) downstream of the secondary optical system (5, 2, 20) in the traveling direction of the charged particle beam, and The application device (5, 71a to 78a, 79) is configured to control at least one pair of the electrodes, which are opposed to each other across the center of the circumference, among the even number of the electrodes (71 to 78) to which the voltage is applied. Adding the additional voltage to the secondary optical system (5, 2, 20);
And a stigmator voltage application device (5, 7) for shaping the distortion of the cross-sectional shape of the secondary beam (B2) formed inside and for correcting the distortion of the image formed on the detection surface.
1a to 78a, 79, 79d).

The charged particle beam defect inspection method according to the first aspect of the present invention includes a charged particle beam irradiation step of irradiating a charged particle beam from a charged particle source as a primary beam onto an object, and irradiating the primary beam. A secondary beam focusing step of focusing electrons obtained from the object as a secondary beam on a detection surface, and an imaging step of imaging the object by detecting electrons of the secondary beam focused on the detection surface. In the charged particle beam defect inspection method having, the secondary beam focusing step comprises a charged particle beam deflection step of deflecting the secondary beam to adjust the position of the secondary beam on the detection surface, In the charged particle beam deflection step, an even number of electrodes are provided at equal intervals on the circumference at a position facing the detection surface, and one voltage is applied to two electrodes adjacent to each other. The voltage is applied to two electrodes adjacent to each other, which are arranged opposite to each other with the center of the circumference interposed therebetween, with the same absolute value as that of the voltage, and voltages of different positive and negative are applied to the two electrodes. A charged particle beam position adjusting step of generating an electric field for deflecting the beam and deflecting the secondary beam toward a predetermined position on the detection surface while passing the secondary beam within the circumference; and To the other electrode adjacent to the electrode to be applied, a voltage reduced by a predetermined ratio is applied to each of the other electrodes to make the electric field for deflecting the secondary beam uniform and to be generated by the charged particle beam position adjusting step. A first aberration correction step of correcting aberrations, and readjusting the value of the voltage applied to the electrode corresponding to the position of the aberration on the detection surface that is not corrected in the first aberration correction step, to adjust the secondary beam. side Characterized in that to increase the uniformity of the electric field and a second aberration correction step further corrects the aberration caused by the charged particle beam position adjusting step. In particular, in the charged particle beam defect inspection method according to the second aspect of the present invention, in the charged particle beam defect inspection method according to the first aspect, the charged particle beam deflection step includes the steps of: An additional voltage is applied to at least one pair of the electrodes disposed to face each other with the center of the circumference interposed therebetween, thereby shaping the distortion of the cross-sectional shape of the secondary beam formed inside the secondary optical system. And a step of applying a stigmator voltage for correcting distortion of an image formed on the detection surface.

Further, the semiconductor device according to the first aspect of the present invention is characterized by being inspected by using the charged particle beam defect inspection apparatus according to the sixth aspect to the charged particle beam inspection apparatus according to the first aspect. I do. And the second of the present invention
The semiconductor device according to the aspect is inspected by using the charged particle beam defect inspection method according to the second aspect from the charged particle beam defect inspection method according to the first aspect.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a charged particle beam deflecting device according to an embodiment of the present invention and a charged particle beam defect inspection device using the same will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a charged particle beam defect inspection apparatus according to one embodiment of the present invention. In the following description, the XYZ orthogonal coordinate system shown in FIG. 1 is set, and the positional relationship between the members will be described with reference to the XYZ coordinate system. In the XYZ rectangular coordinate system shown in FIG.
An XY plane is set in the object plane of the sample, and the normal direction of the object plane of the sample is set in the Z-axis direction. In the XYZ coordinate system in FIG. 1, the XY plane is actually set to a plane parallel to the horizontal plane, and the Z axis is set vertically downward.

The charged particle beam defect inspection apparatus according to the present embodiment mainly includes a primary column 1 for guiding an electron beam to a sample as a primary beam B1, and a secondary column obtained by irradiating the sample with the electron beam. It is composed of a secondary column 2 for focusing as a beam B2 on a detection surface of a detection device 30, and a chamber 3 containing a sample 4 to be observed. The optical axis of the primary column 1 is set oblique to the Z axis, and the optical axis of the secondary column 2 is set substantially parallel to the Z axis. Therefore, the primary beam B1 enters the secondary column 2 from the primary column 1 from an oblique direction. A vacuum exhaust system (not shown) is connected to the primary column 1, the secondary column 2, and the chamber 3, and the primary column 1, the secondary column 2, and the chamber 3 are evacuated by a vacuum pump such as a turbo pump provided in the vacuum exhaust system. It is to be maintained in a state.

A thermionic emission type electron gun 10 is provided inside the primary column 1, and a primary optical system 11 is arranged on the optical axis of an electron beam emitted from the electron gun 10. Here, as the cathode of the electron gun 10, it is preferable to use, for example, lanthanum hexaborite (LaB ₆ ) which can extract a large current with a rectangular cathode. The primary optical system 11 includes a field stop FS1, illumination lenses 12, 13, 1
4, an aligner 15, 16, an aperture 17 and the like. Here, the irradiation lenses 12, 13, and 14 are electronic lenses, and for example, a circular lens, a quadrupole lens, an octupole lens, or the like is used. The convergence characteristics of the irradiation lenses 12, 13, and 14 included in the primary optical system 11 with respect to the primary beam B1 change depending on the applied voltage value. The irradiation lenses 12, 13, and 14 may be rotation axis symmetric lenses called unipotential lenses or Einzel lenses.

In the secondary column 2, a secondary optical system 20 is arranged. The secondary optical system 20 focuses secondary electrons generated when the sample 4 is irradiated with the primary beam B1 as a secondary beam B2 and focuses the secondary electrons on the detection surface of the detection device 30. The cathode lens 21, the aligner 22, the aperture stop AS, the Wien filter 23, the stigmator 24, the imaging lens front group 25, the second aligner 26, the stigmeter 27, the field stop FS2,
An imaging lens rear group 28 is arranged and configured. Further, a beam deflecting device A for deflecting the secondary beam B2 is provided on a side facing the detection device 30 at the most downstream side of the secondary beam B2. In the present embodiment, the distance from the exit pupil of the secondary optical system 20 to the beam deflecting device A is approximately 30 mm, and the distance from the beam deflecting device A to the detection surface of the detection device 30 is approximately 500 mm. ing. Here, the field stop F provided in the secondary optical system 20
S2 is set in a positional relationship conjugate with the object plane of the sample 4 with respect to the cathode lens 21 and the front group 25 of the imaging lens. The front lens group 25 and rear lens group 28 of the secondary optical system 20 are electronic lenses, for example, circular lenses, quadrupole lenses, octupole lenses, and the like.
Note that the cathode lens 21, the front group 25 of the imaging lens, and the rear group 28 of the imaging lens may be a rotation axis symmetric lens called a unipotential lens or an Einzel lens.

As shown in FIGS. 2 and 3, the beam deflector A comprises eight electrodes 71 to 78 arranged at equal intervals on a circumference centered on the optical axis, and these electrodes 71 to 78. And power supplies 71a to 78a for applying a voltage to the electrodes 71 to 78. In the electrodes 71 to 78, the relationship between the angle α that looks between two adjacent electrodes from the center O of the circumference on the optical axis and the angle β that looks at the electrode from the center O of the circumference is α = β. ing. In addition, power supplies 71a to 78a
Are controlled by the beam deflecting device control unit 79, and the voltages applied to the electrodes 71 to 78 are provided so as to be independently adjustable. That is, the beam deflecting device control unit 79 controls the power supplies 71a to 78a to
1 to 78, one voltage is respectively applied to two electrodes adjacent to each other, and the voltage and the two electrodes adjacent to each other which are opposed to each other with a center O of the circumference interposed therebetween are applied to these electrodes. A deflection electric field generation control system 79a for generating an electric field for deflecting the secondary beam B2 by applying voltages having the same absolute value and different positive / negative values, and four other electrodes adjacent to the four electrodes to which the voltages are applied. A first uniform electric field generation control system 79b for applying a voltage obtained by reducing the voltage by a predetermined ratio to the electrodes to make the electric field for deflecting the secondary beam B2 substantially uniform in the circumference; And a second uniform electric field generation control system 79c that re-adjusts the value of the voltage applied to the second electric field and increases the uniformity of the electric field at the position where the secondary beam B2 passes. In addition, the beam deflecting device controller 79
The electrode 7 of the beam deflecting device A is used so as to use the beam deflecting device A as a stigmeter for correcting deformation of the beam cross-sectional shape that is asymmetric with respect to the optical axis generated in the secondary optical system 20
A stigmator voltage control system 79d for applying an additional voltage to at least a pair of electrodes opposed to each other across the center O among 1 to 78 is provided.

The primary optical system 11 and the beam deflecting device A
The values of the voltage, current value, and the like supplied to each section of the secondary optical system 20 provided with are controlled by the main control system 5. That is, the main control system 5 includes the primary optical system control unit 5
1, secondary optical system control unit 52, and secondary optical system control unit 52
Control signal is output to each of the beam deflecting device control units 79 through the optical system to control the optical characteristics of the primary optical system 11 and the secondary optical system 20, control of the deflection of the secondary beam B2 by the beam deflecting device A, Wien filter 23 and the like.

The detection device 30 for detecting the secondary beam B2 formed on the detection surface by the secondary optical system 20 includes an MCP 30a for amplifying electrons and a fluorescent plate 30b for converting electrons to light. Further, a FOP 31 made of an optical fiber for transmitting a light signal converted by the fluorescent screen 30b is provided, and the light signal is incident on a camera 32 equipped with a TDI sensor via the FOP 31. I have. Also, the camera 32 has
A control unit 33 controlled by the main control system 5 is connected. The control unit 33 supplies a clock signal for accumulating image charges to the TDI sensor, reads out the image signals serially from the camera 32, sequentially outputs the image signals to the main control system 5, and accumulates them as image data in the storage device 53. It is configured as follows. When the image signal output from the control unit 33 to the main control system 5 is displayed on a display device such as a CRT (Cathod Ray Tube), the image of the sample 4 is displayed on the display device. The main control system 5 thus controls the control unit 33
The image signal output from the CPU 4 is subjected to image processing such as template matching, for example, to determine whether or not the sample 4 has a defect.

Next, the configuration inside the chamber 3 will be described. An XY stage 38 configured to be movable in an XY plane while the sample 4 is placed inside the chamber 3.
Is arranged. One end on the XY stage 38 has L
A letter-shaped movable mirror 39 is attached, and a laser interferometer 40 is arranged at a position facing the mirror surface of the movable mirror 39. Although shown in a simplified manner in FIG. 1, the movable mirror 39 is composed of a plane mirror having a reflection surface perpendicular to the X axis and a plane mirror having a reflection surface perpendicular to the Y axis. The laser interferometer 40 has an X-axis laser interferometer that irradiates the movable mirror 39 with a laser beam along the X-axis, and two Y-axis lasers that irradiates the movable mirror 39 with a laser beam along the Y-axis. X-axis of the XY stage 38 by one laser interferometer for the X axis and one laser interferometer for the Y axis.
The coordinates and the Y coordinate are measured, and the rotation angle of the XY stage 38 in the XY plane is measured based on the difference between the measured values of the two laser interferometers for the Y axis. The measurement result of the laser interferometer 40 is output to the main control system 5,
The main control system 5 outputs a control signal to the driving device 41 based on the measurement result, and controls the position of the XY stage 38 in the XY plane while moving the sample 4 for the inspection of the surface state in the Y axis. Move in the forward direction. The main control system 5 further outputs a control signal to a Z sensor including a light transmitting system 37a and a light receiving system 37b, and measures the position coordinates of the sample 4 in the Z-axis direction. Although not shown, a Z stage that changes the position of the sample 4 in the Z-axis direction other than the XY stage 38 based on the measurement of the position coordinates in the Z-axis direction, or the sample 4
It is preferable to provide a tilt stage for controlling the inclination of the object plane with respect to the XY plane.

In the figure, reference numeral 42 denotes a variable power supply for setting a negative voltage to the sample 4, and the set voltage of the sample 4 is controlled by the main control system 34. Here, sample 4
Is set to a negative voltage in order to accelerate secondary electrons emitted when the primary beam B1 is irradiated on the sample 4 as the secondary beam B2 in the direction of the cathode lens 21, that is, in the −Z direction. .

The charged particle beam defect inspection apparatus provided with the beam deflecting device A according to the present embodiment has the above-described configuration, and then the charged particle beam defect inspection apparatus 4
Will be described in detail with reference to the trajectory of the primary beam B1 and the secondary beam B2 and the correction of the trajectory of the secondary beam B2 by the beam deflector A.

A beam irradiation step (a charged particle beam irradiation step) of irradiating an electron beam from the electron gun 10 as a charged particle source onto the object as a primary beam B1 will be described below.
First, FIG. 4 is a diagram showing the trajectory of the primary beam B1 of the charged particle beam defect inspection device according to one embodiment of the present invention. Here, in the drawings, illustration of some of the members included in the primary optical system 11 is omitted for easy understanding. The primary beam B1 emitted from the electron gun 10 is converged or diverged under the influence of the electric field formed by the irradiation lenses 12, 13, and 14, as shown in the figure. Here, when the long axis direction of the rectangular cathode of the electron gun 10 is set in the x-axis direction and the short axis direction is set in the y-axis direction, the trajectory of the electrons emitted in the x-axis cross section of the rectangular cathode becomes The trajectory indicated by the symbol Px in the figure is the trajectory indicated by the symbol Py in the figure, and the trajectory of the electrons emitted in the y-axis direction cross section of the rectangular cathode
The trajectory is shown as follows. Irradiation lens 12, 13, 1
After being affected by the electric field due to 4, the primary beam B1 enters the Wien filter 23 from an oblique direction. When the primary beam B1 enters the Wien filter 23, its optical path is deflected in a direction substantially parallel to the Z axis. The primary beam B1 deflected by the Wien filter 23 reaches the aperture stop AS, and forms an image of the electron gun 10 at this position. After passing through the first aligner 22, the primary beam B1 that has passed through the aperture stop AS irradiates the sample 4 under the lens action of the cathode lens 21.

Here, the Wien filter 23 is a device for deflecting charged particles at different angles depending on the traveling direction of the charged particles. FIG. 5 is a diagram for explaining the configuration and operation principle of the Wien filter 23, and FIG.
FIG. 2 is a schematic perspective view showing the configuration of a Wien filter 23. As shown in the figure, the primary beam B1 incident from the primary optical system 11 is deflected by the Wien filter 23. This is due to the electric field acting in the + Y direction when the electrons of the charge q of the primary beam B1 travel at the velocity v in the + Z-axis direction in the electric field E and the magnetic field B orthogonal to each other as shown in FIG. Force FE (= qE) and force FB (= qv
This is for receiving the resultant force with B). On the other hand, the secondary beam B2 generated from the sample 4 travels straight through the Wien filter 23. This is because, as shown in FIG. 5C, when the electrons of the charge q of the secondary beam B2 advance at the velocity v in the −Z axis direction,
In this embodiment, the electric field and the magnetic field are adjusted so as to satisfy the condition of E = vB by receiving the combined force of the force FE (= qE) due to the electric field acting in the + Y direction and the force FB (= −qvB) due to the magnetic field acting in the −Y direction. Is generated, so that the resultant force FE + FB becomes zero. Thus, the Wien filter 23
Has a function as a so-called electromagnetic prism that selects an optical path of an electron beam passing through the inside.

The beam mapping step (secondary beam focusing step) for focusing secondary electrons obtained from the sample 4 by irradiation with the primary beam B1 on the detection surface of the detector 30 as the secondary beam B2 will be described below. First, when the primary beam B1 is irradiated on the sample 4, secondary electrons having a distribution according to the surface shape, the material distribution, the change in potential, and the like of the sample 4 are obtained from the sample 4.
The surface state of the sample 4 is inspected using the secondary electrons as a secondary beam B2. FIG. 6 is a diagram showing the trajectory of the secondary beam B2 of the charged particle beam defect inspection device according to one embodiment of the present invention. Here, in the drawings, illustration of some of the members included in the secondary optical system 20 is omitted for easy understanding. The energy of secondary electrons generated from sample 4 is low,
It is about 0.5 to 2 eV. The secondary electrons are accelerated by the cathode lens 21 as a secondary beam B2. The secondary beam B2 subsequently passes through the first aligner 22, the aperture stop AS, and the Wien filter 23 in this order. Vienna filter 2
The secondary beam B2 that has passed through 3 is converged by the imaging lens front group 25, and an image of the sample 4 is formed at the position of the field stop FS2. Secondary beam B2 that has passed through field stop FS2
Are converged again by the imaging lens rear group 28, and an enlarged image nearly 100 times as large as the object plane of the sample 4 is formed on the detection surface of the detection device 30.

The imaging step of detecting electrons of the secondary beam B2 and capturing an enlarged image of the sample 4 formed on the detection surface is performed as follows. First, the position of the sample 4 is grasped by the main control system 5 by the laser interferometer 40 as needed.
It is moved in the positive Y-axis direction by a driving device 41 controlled by the main control system 5. Image data of the sample 4 is collected from the detection device 30 controlled by the main control system 5 based on information on the position of the sample 4. For example, as shown in FIG.
Assuming that secondary electrons are emitted from a predetermined point on the sample 4 at a position indicated by 1 and are imaged as a secondary beam B2 at a position indicated by P1 on a detection surface of the detection device 30.
When this point moves on the detection surface along with the movement of the sample 4 and the position where secondary electrons are emitted on the sample 4 reaches the position indicated by Q2 in the figure, it reaches the position indicated by P2 on the detection surface. Moving. During this time, the TDI sensor mounted on the camera 32 accumulates image charges as shown in FIGS. The image data thus stored is read out to the main control system 5 and stored in the storage device 53.

In the beam mapping step, the secondary beam B2 is emitted off the optical axis due to the processing accuracy of the secondary optical system 20, the assembly error, and the like. And a beam deflection step (charged particle beam deflection step) for adjusting the position of the secondary beam B2 on the detection surface.

In this embodiment, the beam deflecting device A is provided at a position downstream of the secondary optical system 20 in the traveling direction of the secondary beam B2 and facing the detection device 30. The beam deflecting device A provided closest to the detecting device 30 is required because the distance to the detecting device 30 is short and the deflection angle and electric field strength required for correcting the trajectory of the secondary beam B2 are the largest. The uniformity of the electric field is high. By providing the beam deflecting device A according to the present embodiment at a position downstream of the secondary optical system 20 in the traveling direction of the secondary beam B2 and facing the detection device 30, the required uniformity of the deflection electric field can be obtained. The trajectory of the secondary beam B2 can be finally corrected while keeping the image distortion on the detection surface small.

FIG. 2 shows, as an example, the electrode 7 so that the secondary beam B2 is deflected in the direction (f) and the trajectory is corrected.
1 to 78 show a state in which a voltage is applied, respectively.
The deflected secondary beam B2 passes through a position slightly off the center O of the circumference. The beam cross-sectional shape S of such a secondary beam B2 is shown by a chain line in FIG. The beam deflecting device control section 79 performs a beam position adjusting step (a charged particle beam position adjusting step) by using a deflection electric field generation control system 79 a controlled by the main control system 5 in the direction of (f) of the electrodes 71 to 78. Two adjacent electrodes 7 located
Power supply 7 so as to apply a positive voltage Va to
1a, 72a, and these electrodes 71,
The power supplies 75a and 76a are controlled to apply a negative voltage -Va to two electrodes 75 and 76 adjacent to each other with the center O of the circumference interposed therebetween at 72, and the secondary beam B2 is changed to (f). ) To generate an electric field that is deflected in the direction of. Then, the trajectory of the secondary beam B2 is corrected so that the secondary beam B2 emitted from the position Q1 near the optical axis of the sample 4 is converged to a position on the optical axis of the detection surface of the detection device 30. At this time, due to the non-uniform deflection electric field in the beam deflector A, more specifically, near the position indicated by the chain line in FIG. An image distortion or the like due to aberration occurs in the image of the sample 4. For this reason, the beam deflecting device control unit 79 performs the first aberration correcting step of correcting the aberration caused by the beam position adjusting step.
By the uniform electric field generation control system 79b, the voltage Va is applied to the electrodes 73, 78 adjacent to the electrodes 71, 72 to which the voltage Va is applied at a predetermined ratio t (in the present embodiment, approximately 0.
4) The power supplies 73a and 78a are controlled to apply the voltage t × Va reduced by only 4), and the electrodes 74 and 77 adjacent to the electrodes 75 and 76 to which the voltage −Va is applied.
Then, the power supplies 74a and 77a are controlled so as to apply -t * Va in which the voltage -Va is reduced by the predetermined ratio t, and the electric field for deflecting the secondary beam B2 is made substantially uniform in the circumference.
Further, the detection device 30 that is not corrected in the first aberration correction step
As a second aberration correction step of readjusting the value of the applied voltage of the electrode corresponding to the position of the aberration on the detection surface of the above to reduce the distortion of the image of the sample 4, the power supply 71a is controlled by the second uniform electric field generation control system 79c. To 78a, and the values of the voltages applied to the electrodes 71 to 78 are adjusted as follows. That is, the voltage applied to the electrodes 71 and 72 is Va + Δ
Va1, Va + ΔVa2, and voltages applied to the electrodes 76, 75 are −Va + ΔVa3, −Va + ΔVa4, respectively.
And the voltages applied to the electrodes 78 and 73 are t ×
Va + ΔVb1, t × Va + ΔVb2, and electrodes 77,
The voltage to be applied to 74 is −t × Va + ΔVb3,
−t × Va + ΔVb4. FIG. 3 shows equipotential lines when such a voltage is applied to the electrodes 71 to 78. By this operation, the uniformity of the electric field at the position where the secondary beam B2 surrounded by the chain line in the figure passes is secured, and the distortion of the enlarged image of the sample 4 formed on the detection surface of the detection device 30 is reduced. Is done. Since the arrangement of the electrodes 71 to 78 has a rotational symmetry of eight times, if the voltage distribution as shown in FIG. 2 is rotated clockwise by 45 °, the direction of (f) will be clockwise. An electric field is obtained which deflects in a direction rotated around by 45 °, for example, in a direction like (g). However, since the electrode arrangement varies due to an assembly error or the like, even if the rotation operation is performed while maintaining the same voltage distribution ratio, the electric field distribution is not converted in the same manner. Therefore, ΔVa1 to ΔVa are controlled by the second uniform electric field generation control system 79c so as to enhance the uniformity of the electric field.
4. The values of ΔVb1 to ΔVb4 are appropriately adjusted. When the cross-sectional shape of the secondary beam B2 is symmetric with respect to the deflection direction, such as to deflect the secondary beam B2 in the direction (f),
For example, ΔVa1 to ΔVa2, such as ΔVa1 = ΔVa2
While a4 and ΔVb1 to ΔVb4 are distributed substantially symmetrically, when the secondary beam B2 is deflected, for example, in the direction of (g), the cross-sectional shape of the secondary beam B2 is not symmetrical with respect to the deflection direction. Therefore, naturally, ΔVa1 to ΔVa4,
The voltage distribution of ΔVb1 to ΔVb4 is also asymmetric. As described above, in the second aberration correction step, the optimum voltage value for reducing the distortion of the enlarged image of the sample 4 is set in accordance with the relationship between the direction of deflection of the secondary beam B2 and the cross-sectional shape of the secondary beam B2. be able to. Further, the first uniform electric field generation control system 79 is also provided for a direction that cannot be obtained by symmetrically operating the direction (f).
b, the value of the voltage reduction ratio t, ΔVa1 to ΔVa4, ΔVb1 to ΔVb4 by the second uniform electric field generation control system 79c.
By adjusting the value of, uniform electric fields suitable for the respective directions of deflection can be obtained. In general, in order to apply a voltage to a plurality of ideal point-like electrodes having no size arranged on the circumference and generate an electric field as uniform as possible in the circumference, it is necessary to set the center of the circumference from the center. Since a voltage proportional to the cosine of the angle formed between the direction toward the electrode and the direction in which the secondary beam B2 is deflected may be applied, the voltage applied to the electrodes 71 to 78 by the beam deflection device control unit 79 is The optimal value is appropriately set according to the direction in which the beam B2 is deflected.

With the configuration of the present embodiment, when correcting the deviation of the trajectory of the secondary beam B2 caused by an assembling error of the primary optical system 11 or the secondary optical system 20, it is caused by the non-uniformity of the deflection electric field. The distortion of the cross-sectional shape of the beam and the image formed on the detection surface can be reduced. That is, according to the configuration of the beam deflecting device A according to the present embodiment, the electric field for deflecting the secondary beam B2 becomes uniform. First, as described above, the beam deflecting device control unit 79 applies the positive voltage Va to two of the electrodes 71 to 78 adjacent to each other by the deflection electric field generation control system 79a controlled by the main control system 5. Power supplies 71a to 78 are applied respectively.
a so as to apply a negative voltage −Va to two electrodes that are adjacent to each other and that are opposed to each other with the center O of the circumference interposed therebetween.
To generate a primary electric field that deflects the secondary beam B2 in one direction. Next, the beam deflecting device control unit 79 applies the voltage Va to the electrode adjacent to the electrode to which the voltage Va is applied by a predetermined ratio t by the first uniform electric field generation control system 79b.
The power supplies 71a to 78a apply the voltages t × Va reduced by (approximately 0.4 in the present embodiment), respectively.
And the voltage -Va is reduced by a predetermined ratio t to an electrode adjacent to the electrode to which the voltage -Va is applied.
The power supplies 71a to 78a are controlled so as to apply t × Va, respectively, so that the electric field for deflecting the secondary beam B2 is made substantially uniform within the circumference. In this way, the electric field is uniformly arranged within the circumference. Further, the beam deflecting device control unit 79 controls the power supplies 71a to 78a by the second uniform electric field generation control system 79c, adjusts the voltage applied to each electrode, and further regulates the electric field uniformly. In particular, when the secondary beam B2 does not pass through the center of the circumference, adjustment is performed to increase the uniformity of the electric field at the position where the secondary beam B2 passes. In general, in order to apply a voltage to an ideal point-like electrode having no size and arranged on a circumference to generate an electric field as uniform as possible in the circumference, it is necessary to set the center of the circumference from the center. It is sufficient to apply a voltage proportional to the cosine of the angle formed between the direction toward the electrode and the direction to deflect the beam.
The uniform electric field generation control system 79b and the second uniform electric field generation control system 79c make such an ideal voltage distribution as possible, and furthermore, the uniformity of the electric field at the position where the secondary beam B2 passes. Fine-tune the voltage again to increase. In this manner, the trajectory of the secondary beam B2 can be corrected while suppressing the shape of the beam and the distortion of the image on the detection surface.

Further, the cross-sectional shape of the secondary beam B2 asymmetric with respect to the optical axis generated in the secondary optical system 20 in the step of applying the stigmator voltage is shaped, and the image formed on the detection surface of the detection device 30 is distorted. Is corrected. This is because the electrode 71 of the beam deflector A is controlled by
This is performed by adding an additional voltage to .about.78.

According to the present embodiment, it is possible to correct an asymmetric image distortion on the detection surface caused by an assembly error of the secondary optical system 20 or the like. That is, among the eight electrodes 71 to 78 of the beam deflector A, an additional voltage is further applied to at least a pair of electrodes arranged to face each other with the center therebetween, and the shape of the secondary beam B2 is finally corrected. At the same time, it can be used as a stigmeter for correcting image distortion on the detection surface. Since the beam deflector A according to the present embodiment has eight electrodes, it can be used as four stigmeters. Thus, the cross-sectional shape of the secondary beam B2 can be finally corrected so that the distortion of the image on the detection surface is reduced.

As described above, according to the present embodiment, a uniform electric field is generated within the circumference of the beam deflector A, and distortion of the enlarged image of the sample 4 formed on the detection surface is suppressed to a small value. Therefore, even when the image charge is accumulated by the TDI sensor with the movement of the sample 4, the mixture of the image charge with the adjacent pixel does not occur, and the resolution does not decrease. Further, even when the cross-sectional shape of the secondary beam B2 is asymmetrically deformed in the secondary optical system 20 and the image of the sample 4 is distorted, the voltage applied to the electrodes 71 to 78 of the beam deflector A is adjusted. Thus, the distortion can be corrected.

In the above embodiment, the angle α between the two adjacent electrodes from the center O of the circumference on the optical axis is:
The relationship between the angle β at which the electrode is viewed from the center O of the circumference is α = β
0.5 ≦ α / β <1 or 1 <
α / β ≦ 2 may be adopted.

In the above embodiment, the eight electrodes 7
1 to 78 are provided so as to obtain the required uniformity of the electric field, but in general, it is possible to obtain a more uniform electric field by increasing the number of electrodes. Alternatively, a plurality may be used. In particular, by providing an even number of electrodes and arranging the electrodes in an isotropic manner, the non-uniformity of the electric field required at any time in any direction of the beam deflection can be effectively reduced by the symmetry of the arrangement of the electrodes. Can be reduced.
If at least eight electrodes are arranged, a sufficiently uniform electric field can be generated.

Further, since the beam deflecting device A can deflect the beam with a uniform electric field, the primary optical system 1
1. Any location may be provided as long as it is necessary within the secondary optical system 20, or a plurality of locations may be provided. Furthermore, the beam deflecting device A may be used not only by being incorporated into a charged particle beam defect inspection apparatus but also by being incorporated into an apparatus that deflects a charged particle beam. Here, the charged particle beam is not limited to an electron beam, but refers to a proton beam, an ion beam, or the like. Of course, the beam deflector A may be used for an electrode such as an electrostatic lens.

[0047]

The present invention has the following effects. According to the charged particle beam deflecting device according to the first aspect of the present invention, a plurality of electrodes are arranged on the circumference at equal intervals, and an angle α between the center of the circumference and a distance between two adjacent electrodes, The relationship with the angle β at which the electrode is seen from the center of the circumference is 0.
Since 5 ≦ α / β ≦ 2, a uniform electric field can be generated within the circumference where the electrodes are arranged, and the trajectory can be corrected by uniformly deflecting the charged particle beam.

Further, according to the charged particle beam deflecting device according to the third aspect of the present invention, a voltage applying device which has an even number of electrodes arranged at equal intervals on the circumference and applies a voltage to these electrodes A deflection electric field generator for generating an electric field for deflecting the charged particle beam, a first uniform electric field generator for making the electric field for deflecting the charged particle beam substantially uniform in the circumference, and the charged particle beam passing therethrough. Second to improve the uniformity of the electric field at the position
Since it has a uniform electric field generator, it adjusts the voltage value of each electrode to generate a uniform electric field within the circumference where the electrodes are arranged, and deflects the charged particle beam uniformly to orbit Can be modified.

Further, according to the charged particle beam defect inspection apparatus according to the first aspect of the present invention, a charged particle beam deflection apparatus is provided, and the charged particle beam deflection apparatus has a plurality of electrodes arranged at equal intervals on a circumference. Since the relationship between the angle α that is disposed and sees between two adjacent electrodes from the center of the circumference and the angle β that sees the electrode from the center of the circumference is 0.5 ≦ α / β ≦ 2, A uniform electric field can be generated within the circumference of the array of electrodes, and the primary and secondary beams can be uniformly deflected to correct their trajectories, resulting from non-uniform electric field deflection. Distortion of the beam shape of the primary beam and the secondary beam can be suppressed to a small value.

Further, according to the charged particle beam defect inspection apparatus according to the third aspect of the present invention, a charged particle beam deflection apparatus is provided, and the charged particle beam deflection apparatus comprises an even number of evenly arranged circular circles. A plurality of electrodes, a voltage application device for applying a voltage to these electrodes, the voltage application device generates a deflection electric field for deflecting the charged particle beam,
A first uniform electric field generator for making the electric field for deflecting the charged particle beam substantially uniform in the circumference and a second uniform electric field generator for improving the uniformity of the electric field at the position where the charged particle beam passes. Adjust the voltage value of each electrode to generate a uniform electric field within the circumference of the array of electrodes, and deflect the primary and secondary beams uniformly to correct their trajectories And the distortion of the beam shape of the primary beam and the secondary beam caused by the deflection due to the non-uniform electric field can be suppressed.

Further, according to the charged particle beam defect inspection method according to the first aspect of the present invention, the same effects as those of the charged particle beam defect inspection apparatus of the present invention can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a charged particle beam defect inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a charged particle beam deflecting device according to one embodiment of the present invention.

FIG. 3 is a diagram showing equipotential lines generated by a charged particle beam deflecting device according to an embodiment of the present invention.

FIG. 4 is a diagram showing a trajectory of a primary beam of a charged particle beam defect inspection apparatus according to an embodiment of the present invention.

FIG. 5 is a diagram for explaining the configuration and operating principle of a Wien filter included in the charged particle beam defect inspection device according to one embodiment of the present invention.

FIG. 6 is a diagram showing a trajectory of a secondary beam of the charged particle beam defect inspection apparatus according to one embodiment of the present invention.

FIG. 7 is a diagram for explaining a schematic configuration and an operation principle of the charged particle beam defect inspection apparatus.

FIG. 8 is a diagram showing a configuration of an electrode of a conventional charged particle beam deflector viewed from a direction along an optical axis.

FIG. 9 is a diagram illustrating a detection device including a TDI sensor.

FIG. 10 is a diagram for explaining a schematic configuration and an operation principle of the TDI sensor.

FIG. 11 is a diagram showing a state in which a predetermined portion of a sample image formed on a detection surface of the detection device moves on the detection surface as the sample moves.

[Explanation of symbols]

A: Beam deflecting device (charged particle beam deflecting device) B1: Primary beam B2: Secondary beam (charged particle beam) 1: Primary column 2: Secondary column 3: Chamber 4 Sample (object) 5 Main control system (primary optical system, secondary optical system, imaging device, voltage application device, deflection electric field generator, first uniform electric field generator, second uniform electric field Generation unit, stigmeter voltage application device) 11 primary optical system 20 secondary optical system 30 detection device (imaging device) 71 to 78 electrodes 71 a to 78 a power supply (voltage application) Device, deflection electric field generation unit, first uniform electric field generation unit, second uniform electric field generation unit, stigmator voltage applying device) 79 ... beam deflecting device control unit (voltage applying device, deflection electric field generating unit, first to eleventh) Electric field generator, second uniform electric field generator, stigmator voltage Application device) 79a ... deflection electric field generation control system (deflection electric field generation unit) 79b ... First uniform electric field generation control system (first uniform electric field generation unit) 79c ... Second uniform electric field generation control System (second uniform electric field generator) 79d ... Stigmeter voltage control system (Stigmeter voltage application device)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G21K 5/04 H01J 37/28 B H01J 37/28 37/29 37/29 G01R 31/28 L F-term (Reference) 2G001 AA03 BA07 CA03 DA01 DA09 EA05 GA06 GA09 HA12 HA13 JA03 KA03 PA07 PA11 PA14 2G014 AA01 AB21 AB59 AC11 2G132 AA00 AD15 AF12 5C033 FF03 FF08 UU01 UU04

Claims (14)

[Claims] 1. A system comprising: a plurality of electrodes arranged at equal intervals on a circumference; and a voltage application device for applying a voltage to the electrodes.
A charged particle beam deflecting device configured to apply a predetermined voltage to the electrode by the voltage applying device to generate an electric field in the circumference and deflect a charged particle beam passing through the circumference. And a relationship between an angle α that looks between two adjacent electrodes from the center of the circumference and an angle β that looks at the electrodes from the center of the circumference is 0.5 ≦ α / β ≦ 2. A charged particle beam deflecting device, characterized in that: 2. The charged particle beam deflecting device according to claim 1, wherein an even number of the electrodes are provided. 3. An apparatus comprising: an even number of electrodes arranged at equal intervals on a circumference; and a voltage application device for applying a voltage to the electrodes, wherein a predetermined voltage is applied to the electrodes by the voltage application device. A charged particle beam deflector configured to generate an electric field in the circumference to deflect a charged particle beam passing through the circumference, wherein the voltage application device includes an even number of the electrodes. Among them, one voltage is applied to two electrodes adjacent to each other, and the absolute value of the voltage is made equal to the voltage of two electrodes adjacent to each other which are arranged opposite to each other with the center of the circumference interposed therebetween. A deflection electric field generating unit for generating an electric field for deflecting the charged particle beam by applying voltages having different positive and negative voltages; and a predetermined ratio of the voltage to the other remaining electrodes adjacent to the electrode to which the voltage is applied. Reduced electricity And a first uniform electric field generator for making the electric field for deflecting the charged particle beam substantially uniform within the circumference, and readjusting the value of the voltage applied to the electrode to charge the charged particle beam. A charged particle beam deflecting device, comprising: a second uniform electric field generator for increasing the uniformity of the electric field at a position where the particle beam passes. 4. The charged particle beam deflecting device according to claim 3, wherein an angle α between two adjacent electrodes from the center of the circumference and an angle β from the center of the circumference to the electrodes. The charged particle beam deflecting device satisfies 0.5 ≦ α / β ≦ 2. 5. A primary optical system for irradiating a charged particle beam from a charged particle source as a primary beam onto an object, and a secondary beam for focusing electrons obtained from the object by irradiation of the primary beam on a detection surface as a secondary beam. A charged particle beam defect inspection apparatus, comprising: a secondary optical system, and an imaging device arranged on the detection surface and detecting an electron of the secondary beam focused on the detection surface to image the object. The secondary optical system includes at least one charged particle beam deflecting device that deflects the primary beam or the secondary beam, wherein the charged particle beam deflecting device includes a plurality of electrodes arranged at equal intervals on a circumference. And the angle β between the two adjacent electrodes from the center of the circumference and the angle β from the center of the circumference to the electrode are 0.5 ≦ α /
β ≦ 2, a voltage application device that applies a voltage to the electrode, and a predetermined voltage is applied to the electrode by the voltage application device to generate an electric field in the circumference to generate an electric field in the circumference. A charged particle beam defect inspection apparatus configured to deflect a passing charged particle beam. 6. The charged particle beam defect inspection apparatus according to claim 5, wherein an even number of the electrodes are provided. 7. A primary optical system for irradiating a charged particle beam from a charged particle source as a primary beam onto an object, and a secondary beam for focusing electrons obtained from the object by irradiation of the primary beam on a detection surface as a secondary beam. A charged particle beam defect inspection apparatus, comprising: a secondary optical system, and an imaging device arranged on the detection surface and detecting an electron of the secondary beam focused on the detection surface to image the object. The secondary optical system includes a charged particle beam deflecting device that deflects the charged particle beam, wherein the charged particle beam deflecting device has an even number of electrodes arranged at equal intervals on a circumference, and A voltage application device for applying a voltage to the electrode, a charged particle beam passing through the circumference by generating an electric field in the circumference by applying a predetermined voltage to the electrode by the voltage application device deflection The voltage applying device applies one voltage to each of the two electrodes adjacent to each other, and the two voltage applying devices oppose each other with the center of the circumference interposed therebetween. A deflection electric field generating unit that generates an electric field for deflecting the charged particle beam by applying voltages having the same absolute value to the voltage and different positive and negative voltages to the electrodes, and adjacent to the electrode to which the voltage is applied A first uniform electric field generating unit that applies a voltage obtained by reducing the voltage by a predetermined ratio to the other remaining electrodes to make an electric field for deflecting the charged particle beam substantially uniform within the circumference; A second uniform electric field generating unit for re-adjusting the value of the voltage applied to each of the first and second electric fields to improve the uniformity of the electric field at the position where the charged particle beam passes. Inspection device 8. The charged particle beam defect inspection apparatus according to claim 7, wherein an angle α between two adjacent electrodes from the center of the circumference and an angle from the center of the circumference to the electrodes. A charged particle beam defect inspection device, wherein the relationship with β is 0.5 ≦ α / β ≦ 2. 9. The charged particle beam defect inspection apparatus according to claim 5, wherein the charged particle beam deflecting device is located downstream of the secondary optical system in the traveling direction of the charged particle beam. A charged particle beam defect inspection device is provided at a position facing the imaging device. 10. The charged particle beam defect inspection apparatus according to claim 6, wherein the charged particle beam deflecting device is located downstream of the secondary optical system in the traveling direction of the charged particle beam. The voltage application device is provided at a position facing the imaging device, and among the even-numbered electrodes to which a voltage is applied, an additional voltage is applied to at least one pair of the electrodes that are arranged to face each other across the center of the circumference. A stigmator voltage applying device that corrects the distortion of the image formed on the detection surface while shaping the distortion of the cross-sectional shape of the secondary beam formed inside the secondary optical system by adding A charged particle beam defect inspection apparatus. 11. A charged particle beam irradiation step of irradiating a charged particle beam from a charged particle source as a primary beam onto an object, and focusing electrons obtained from the object by irradiation of the primary beam as a secondary beam on a detection surface. A charged particle beam defect inspection method, comprising: a secondary beam focusing step of causing the secondary beam focusing step; and an imaging step of imaging the object by detecting electrons of the secondary beam focused on the detection surface. The step of deflecting the secondary beam to adjust the position of the secondary beam on the detection surface, the charged particle beam deflecting step, the charged particle beam deflecting step, an even number at a position facing the detection surface The electrodes are provided at equal intervals on the circumference, and a voltage is applied to two electrodes adjacent to each other,
The voltage is applied to two electrodes adjacent to each other, which are arranged opposite to each other with the center of the circumference interposed therebetween, with the same absolute value as that of the voltage, and voltages of different positive and negative are applied to the two electrodes. A charged particle beam position adjusting step of generating an electric field for deflecting the beam, deflecting the secondary beam toward a predetermined position on the detection surface while passing the secondary beam within the circumference, To the other electrode adjacent to the electrode to be applied, a voltage reduced by a predetermined ratio is applied to each of the other electrodes to make the electric field for deflecting the secondary beam uniform and to be generated by the charged particle beam position adjusting step. A first aberration correcting step of correcting the aberration, and readjusting the value of the voltage applied to the electrode corresponding to the position of the aberration on the detection surface which is not corrected in the first aberration correcting step, to thereby adjust the secondary beam. side The charged particle beam defect inspection method characterized by and a second aberration correction step of further modifying the aberration caused by the charged particle beam position adjustment process to increase the uniformity of the electric field. 12. The charged particle beam defect inspection method according to claim 11, wherein, in the charged particle beam deflecting step, among the even-numbered electrodes to which a voltage is applied, the electrodes face each other across the center of the circumference. An additional voltage is applied to at least one pair of the arranged electrodes to shape the cross-sectional shape of the secondary beam formed inside the secondary optical system, and to form an image formed on the detection surface. A charged particle beam defect inspection method, comprising a step of applying a stigmator voltage for correcting distortion of the charged particle beam. 13. A semiconductor device inspected by using the charged particle beam defect inspection apparatus according to claim 5. Description: 14. A semiconductor device inspected using the charged particle beam defect inspection method according to claim 11. Description: