JP2005276881A - Pattern evaluation method and device manufacturing method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of creating a large two dimensional image by connecting small two dimensional images obtained for every beam in evaluating a pattern on a sample by scanning a plurality of beams; a pattern evaluation method having no problem of converging a primary beam finely and capable of effectively detecting also secondary electrons without any cross talk; a method of performing a CD measurement and measuring matching accuracy with high throughput; and a pattern evaluation method using an electronic optical system generating many multi-beams to the vicinity of one optical axis, effectively detecting a secondary electron signal from each beam when simultaneously scanning the beams, and having reduced stages of lenses. <P>SOLUTION: The method is to irradiate a sample with a plurality of beams for the evaluation of a pattern, and comprises (a) a step of irradiating an electron beam emitted from an electron gun to a plurality of openings, (b) a step of focusing a reduced image of the opening onto a sample surface, (c) a step of obtaining a two dimensional image for every beam by scanning the plurality of the focused beams, (d) a step of forming a large two dimensional image by connecting the two dimensional images for every beam, (e) a step of measuring an interval in one axis direction among the plurality of the beams, and (f) a step of adjusting the foregoing interval to integer times of a pixel size. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

Detailed Description of the Invention

TECHNICAL FIELD OF THE INVENTION

  The present invention relates to a method for evaluating a sample having a pattern with a minimum line width of 0.1 μm or less at a high throughput, and further to a method for manufacturing a device with high yield using the evaluation method.

Conventional technology and its problems

  Conventionally, when pattern evaluation such as defect inspection of semiconductor devices, CD (Critical Dimension) measurement, alignment accuracy measurement, etc. is performed using an electron beam, a multi-beam is formed in one optical system, and the multi-beam is scanned. Thus, a method for obtaining a two-dimensional image has been proposed.

  However, conventionally, there is no known technique for forming one large image by connecting small two-dimensional images obtained from a plurality of detectors corresponding to each beam. For this reason, the evaluation was performed for each beam, requiring a complicated procedure, and the efficiency was poor.

Conventionally, in order to form a multi-beam, a technique has been proposed in which a multi-beam is formed by irradiating an electron beam emitted from a plurality of emitters to an opening arranged at an equal distance from the optical axis.
However, this conventional technique is easy to detect the secondary electrons independently because the distance between the multi-beams is large. However, since the beam is relatively far from the optical axis, the primary electron beam has astigmatism. And coma aberration occurred, and there was a problem in converging the primary beam finely.

Further, CD measurement and alignment accuracy measurement have been conventionally performed by narrowing an electron beam to about 10 nm or less and measuring a line width and a line interval.
However, in the conventional technique, since the beam size is small, the beam current is small, and if it is attempted to improve the accuracy by obtaining a signal waveform with a good S / N ratio, it is necessary to reduce the scanning speed, resulting in a problem that the throughput is reduced. There was a point.

  Also, as a method of evaluating a sample by scanning the sample with a plurality of beams, a method using a multi-column or a method of arranging a plurality of beams on the circumference of a circle centering on the optical axis has been proposed. It was.

  However, in the method using multi-columns, even if the wafer size is 12 inches, only a few columns can be arranged on the wafer, so that the throughput cannot be improved so much and an expensive apparatus is required. was there. Also, in the method of arranging multiple beams on the circumference of a circle, it is necessary to increase the diameter of the circle in order to generate many beams, and various aberrations other than curvature of field, that is, astigmatism and coma aberration However, there was a problem that the beam could not be narrowed down.

  The present invention has been made in view of the above-described conventional problems, and a first object of the present invention is to provide a method for creating a large two-dimensional image by connecting a plurality of small two-dimensional images corresponding to a plurality of beams. The purpose is to do.

  A second object of the present invention is to provide a pattern evaluation method that can detect a secondary electron efficiently without causing any problem in converging the primary beam finely.

  It is a third object of the present invention to provide a method for measuring CD measurement and alignment accuracy with high throughput.

  The fourth object of the present invention is to generate many multi-beams in the vicinity of one optical axis and to efficiently detect secondary electron signals from each beam when these beams are scanned simultaneously. It is an object of the present invention to provide a pattern evaluation method using an electron optical system with a reduced number of lens stages.

In order to achieve the first object, the first pattern evaluation method according to the present invention includes:
It is a method of irradiating a sample with multiple beams and evaluating a pattern.
a. Irradiating a plurality of apertures with an electron beam emitted from an electron gun; b. Forming a reduced image of the aperture on the sample surface; c. Scanning the plurality of imaged beams to obtain a two-dimensional image for each beam; d. Connecting the two-dimensional images for each beam to form a large two-dimensional image e. Measuring a uniaxial spacing between the plurality of beams; f. The method has a step of adjusting the interval to an integral multiple of the pixel size.

    In the above method, a plurality of beams are used, and a two-dimensional image obtained for each beam is connected to form a large two-dimensional image, and the uniaxial spacing between the plurality of beams is set to an integral multiple of the pixel size. Since they are matched, a small two-dimensional image obtained by scanning one beam and a two-dimensional image obtained by scanning an adjacent beam can be accurately connected, and highly accurate pattern evaluation is possible. Is possible.

In order to achieve the first object, the second pattern evaluation method according to the present invention includes:
It is a method of irradiating a sample with multiple beams and evaluating a pattern.
a. Irradiating a plurality of apertures with an electron beam emitted from an electron gun; b. Forming a reduced image of the aperture on the sample surface; c. Scanning the plurality of imaged beams by the width of the stripe in one axis direction to obtain a two-dimensional image; d. When acquiring the two-dimensional image in step c, the sample stage continues to move in the other axis direction, and when it reaches the end of the evaluation area, the movement in the other axis direction is stopped, and the stage is moved by the width of the stripe. Stepwise moving in a uniaxial direction, and the stripe and the boundary between the stripes have irregularities corresponding to the uniaxial positions of the plurality of beams.

    According to this method, in order to evaluate a pattern with a plurality of beams, evaluation is performed with a plurality of beams for each stripe, and the boundary between the stripes has unevenness corresponding to the position in the uniaxial direction of the plurality of beams. Since it did in this way, it can evaluate efficiently with a some beam, without producing redundant scanning and insufficient scanning.

In order to achieve the first object, the third pattern evaluation method of the present invention includes:
It is a method of irradiating a sample with multiple beams and evaluating a pattern.
a. Irradiating a plurality of apertures with an electron beam emitted from an electron gun; b. Forming a reduced image of the aperture on the sample surface; c. Scanning the plurality of imaged beams in one axis direction to obtain a two-dimensional image with a signal from a detector corresponding to each beam; and d. A two-dimensional image of a wide area is formed by moving the position of the two-dimensional image by a predetermined distance in the x and y directions between the beams on the sample and connecting the two-dimensional images. And a step of performing.

    According to this method, when evaluating a pattern with a plurality of beams, the position of a small two-dimensional image obtained from each beam by a predetermined distance in the x and y directions between each beam on the sample. Since they are moved and connected, a large two-dimensional image in which all small two-dimensional images obtained from a plurality of beams are connected can be obtained.

In order to achieve the first object, the fourth pattern evaluation method of the present invention includes:
It is a method of irradiating a sample with multiple beams and evaluating a pattern.
a. Generating a plurality of beams b. Scanning a plurality of beams on a mark having an x-direction pattern or a y-direction pattern side, detecting electrons generated from each beam with a corresponding detector, and forming a two-dimensional image; c. Connecting the two-dimensional image from each detector based on a preset value of the inter-beam distance d. Changing the distance between the beams so that the shape of the mark image obtained by the above connection is normal, connecting the distance, and storing the distance between the beams where the mark image is most normal; e. Obtaining a two-dimensional image of a sample to be evaluated with each beam, and connecting the two-dimensional images obtained from each beam at the stored inter-beam distance to obtain a two-dimensional image of a wider sample. And

  According to this method, in order to connect a small two-dimensional image from each of the beams to form a large two-dimensional image, predetermined distances in the x and y directions between the beams on the sample are set. In addition to the connection by moving the position of the two-dimensional image only, the actual misalignment is corrected so that the shape of the mark image obtained by the connection becomes normal, and the distance between the beams is changed for connection. As a result, a large two-dimensional image with high accuracy can be obtained.

In order to achieve the second object, the fifth pattern evaluation method of the present invention includes:
A method of scanning a pattern formed on a substrate with a multi-beam, detecting secondary electrons emitted from a scanning point, and evaluating the pattern,
a. Accelerating the electron beam emitted from the electron gun to AKV b. Irradiating the accelerated electron beam to an aperture plate having a plurality of apertures; c. Shrinking a plurality of beams at the aperture, forming an image on a sample to which a voltage of -BKV is applied, and scanning d. Expanding the distance between secondary electron groups emitted from the scan point to the detector; e. A step of independently detecting the secondary electron group by the detector and forming a two-dimensional image, wherein AB ≦ 0.6 KV, and the secondary electron group is a primary lens of a two-stage lens. It is characterized by a common passage with an electron beam.

  According to this method, in the electron optical system in which the primary electron beam and the secondary electron beam are shared by the two-stage lens, the ratio of the landing energy of the primary electron beam / the energy of the secondary electron is conventionally increased. Therefore, the focusing condition of the primary beam and the secondary beam can be easily adjusted, and therefore, a multi-beam can be formed in the vicinity of one optical axis.

In order to achieve the second object, the sixth pattern evaluation method of the present invention includes:
A method of scanning a pattern formed on a substrate with a multi-beam, detecting secondary electrons emitted from a scanning point, and evaluating the pattern,
a. Accelerating the electron beam emitted from the electron gun to AKV b. Making the electron beam into multiple beams at a plurality of apertures; c. Shrinking the multi-beam, imaging a sample with a voltage of -BKV, and scanning d. Directing the secondary electrons emitted from the scanning point to the detector at a larger distance from each other; e. And independently detecting the secondary electron group by the detector and forming a two-dimensional image, and AB−0.3 ≦ KV, and the secondary electron group has one stage. It is characterized in that the lens is a common path with the primary electron beam.

According to this method, in the electron optical system in which the primary electron beam and the secondary electron beam are used as a common path for the one-stage lens, it is possible to obtain the same operational effects as the sixth pattern evaluation method.
In order to achieve the second object, the seventh pattern evaluation method of the present invention includes:
A method of scanning a pattern formed on a substrate with a multi-beam, detecting secondary electrons emitted from a scanning point, and evaluating the pattern,
a. Accelerating the electron beam emitted from the electron gun to AKV b. Making the electron beam into multiple beams at a plurality of apertures; c. Reducing the multi-beam and imaging and scanning a sample to which a voltage of -BKV is applied; d. Detecting a secondary electron emitted from the scanning point and forming a two-dimensional image, wherein AB ≦ 0.5 (KV), closest to the sample, and the primary electron beam The lens through which the secondary electron beam passes includes an electromagnetic lens.

  According to this method, in the electron optical system in which the lens closest to the sample through which both the primary electron beam and the secondary electron beam pass includes the electromagnetic lens, the same effect as the sixth pattern evaluation method can be obtained. it can.

In order to achieve the second object, the eighth pattern evaluation method of the present invention includes:
The pattern formed on the substrate is scanned with a multi-beam, the secondary electrons emitted from the scanning point are detected, and the pattern is evaluated.
a. Accelerating the electron beam emitted from the electron gun to AKV b. Irradiating the accelerated electron beam to an aperture plate having a plurality of apertures; c. Shrinking a plurality of beams at the aperture, forming an image on a sample to which a voltage of -BKV is applied, and scanning d. Expanding the distance between secondary electron groups emitted from a plurality of scanning points to a detector; e. A step of independently detecting the secondary electron group by the detector and forming a two-dimensional image, wherein AB ≦ 0.5 KV, and the lens closest to the sample includes an electromagnetic lens. It is characterized by.

  According to this method, in the electron optical system in which the lens closest to the sample through which both the primary electron beam and the secondary electron beam pass includes the electromagnetic lens, the same effect as the sixth pattern evaluation method can be obtained. it can.

In order to achieve the second object, the ninth pattern evaluation method of the present invention includes:
In any one of the fifth to eighth pattern evaluation methods, the electron optical system has a plurality of optical axes, and the projection distances in the uniaxial direction of the plurality of optical axes are equal to each other. It is characterized by.

According to this method, since the electron optical system has a plurality of optical axes, in addition to the advantages of each method, the throughput can be improved according to the number of optical axes.
In order to achieve the third object, the tenth pattern evaluation method of the present invention includes:
A method for evaluating a pattern using a multi-beam,
a. Irradiating an aperture plate having a plurality of apertures with an electron beam emitted from a thermionic emission gun; b. Reducing the electron beam emitted from the aperture plate and focusing it on the sample c. Simultaneously scanning with multiple beams in a direction perpendicular to the pattern sides d. The secondary particle beam emitted from the scanning point is detected by a multi-detector corresponding to the multi-beam, and a signal waveform is acquired and stored. E. And calculating a CD value or pattern interval from a plurality of signal waveforms corresponding to the multi-beam.

In order to achieve the third object, the eleventh pattern evaluation method of the present invention includes:
In the tenth pattern evaluation method, the multi-beams are arranged along a straight line not parallel to the x-axis and the y-axis.

  According to these tenth and eleventh pattern evaluation methods, since the CD value or pattern interval is calculated from the number of signal waveforms corresponding to the multi-beams, the number of beams is measured in the evaluation of the CD value or pattern interval. Time can be shortened.

In order to achieve the third object, the twelfth pattern evaluation method of the present invention includes:
A method for evaluating a pattern using a multi-beam,
a. Irradiating an aperture plate having a plurality of apertures with an electron beam emitted from a thermionic emission gun; b. Reducing the electron beam that has passed through the aperture plate to focus on the sample c. Simultaneously scanning with multiple beams in a direction perpendicular to the pattern sides d. The secondary particle beam emitted from the scanning point is detected by a multi-detector corresponding to the multi-beam, and a signal waveform is acquired and stored. E. Moving the multi-beam by one pixel in a direction parallel to the pattern side and repeating steps c and d f. Forming a two-dimensional image of the pattern from a plurality of signal waveforms corresponding to the multi-beam; and g. and a step of calculating edge roughness from the pattern obtained in step f.

    According to this method, since the edge roughness is calculated from the number of signal waveforms corresponding to the multi-beams, the measurement time can be shortened by the number of beams in the evaluation of the edge roughness.

In order to achieve the third object, the thirteenth pattern evaluation method of the present invention includes:
In the tenth to twelfth pattern evaluation methods, the electron gun has a thermionic emission cathode, and the cathode is operated under a space charge limiting condition.

According to this method, shot noise can be reduced in each of the tenth to twelfth pattern evaluation methods.
In order to achieve the fourth object, the fourteenth pattern evaluation method of the present invention includes:
A method for evaluating a sample by scanning a sample with a plurality of beams, the following steps:
a. A process of adjusting the beam emission angle of an electron beam emitted from an electron gun with an anode having at least two electrodes b. A process of focusing the electron beam having the emission angle adjusted by a condenser lens to form a crossover at the NA aperture c. A process of forming a multi-beam with a multi-aperture provided in the vicinity of the condenser lens; d. Process of forming an image of NA aperture in the vicinity of the main surface of the objective lens by a reduction lens e. Process of focusing reduced image of multi-aperture on sample surface with reduction lens and objective lens f. Scanning the sample while applying dynamic focus with multiple beams g. Accelerating and passing secondary electrons emitted from the sample with an objective lens h. Process of deflecting secondary electrons with an EXB separator and directing it to the secondary optics i. A process of increasing the spacing of multiple secondary electrons and detecting them with multiple detectors; j. A process of independently detecting multiple secondary electrons, forming a two-dimensional image, and evaluating a sample.

  According to this method, since the emission angle and crossover dimension of the beam from the electron gun can be adjusted with a lens having a plurality of anodes, a single stage of the necessary lens and its alignment device are not required, and simple A multi-beam can be formed by an optical system.

In order to achieve the fourth object, the fifteenth pattern evaluation method of the present invention is
A method for evaluating a sample by scanning a sample with a plurality of beams, comprising: a. Focusing the electron beam emitted from the electron gun on the NA aperture with a condenser lens b. Focusing the image of the NA aperture in the vicinity of the main surface of the objective lens with a reduction lens; c. Forming a multi-beam with a multi-aperture provided in front of or behind the condenser lens; d. Focusing the multi-beam on the sample with a reduction lens and an objective lens e. Scanning the sample while applying dynamic focus with multiple beams f. Accelerating and passing secondary electrons emitted from the scanning point with an objective lens g. A process in which secondary electrons are deflected by an EXB separator and directed to a secondary optical system h. Expanding the spacing of the secondary secondary electrons and detecting with multiple detectors; and i. A step of independently detecting multi-secondary electrons, forming a two-dimensional image, and evaluating the sample. The electric field strength in the vicinity of the sample is 1.5 KV / mm to 5.5 KV / It is characterized by being adjustable in the mm range.

  According to this method, in order to evaluate the pattern of a sample by focusing and scanning a multi-beam on the sample surface to form a two-dimensional image, the electric field strength in the vicinity of the sample is reduced. Since it can be adjusted in the range of 15 KV / mm to 5.5 KV / mm, the magnitude of the secondary electron blur at the detector is small by adjusting the electric field strength as appropriate according to the properties of the sample surface. It is possible to provide a pattern evaluation method that does not cause a discharge between the lens and the sample.

In order to achieve the fourth object, the sixteenth pattern evaluation method of the present invention includes:
A method for evaluating a sample by scanning a sample with a plurality of beams, and the following steps:
a. Irradiating the multi-aperture with an electron beam emitted from an electron gun having a thermionic emission cathode b. Focusing the electron beam that has passed through the multi-aperture to the NA aperture c. A step of reducing the electron beam separated by the multi-aperture with a reduction lens and an objective lens and scanning the sample; d. Accelerate and pass secondary electrons emitted from the scanning point of the sample with an objective lens e. Directing the secondary electrons to the secondary optics with an EXB separator f. Enlarging the interval between the multiple secondary electron images and detecting with a plurality of detectors; g. Multi-secondary electrons are independently detected, a two-dimensional image is formed, and a sample is evaluated. The arrangement of the multi-beams is m rows and n columns, i rows and j columns, and i + 1 rows and j columns. The interval between columns is characterized by being approximately equal to the interval between i rows and j columns and i rows and j + 1 columns.

  According to this method, it is possible to arrange as many beams as possible in a circle as small as possible under the condition that the beam of the primary optical system is larger than the resolution of the secondary optical system and all the uniaxial spacings of the beams are equal. As a result, the beam can be narrowed down without increasing astigmatism or coma.

In order to achieve the fourth object, the seventeenth pattern evaluation method of the present invention includes:
In the fourteenth to sixteenth pattern evaluation methods, a plurality of the electron gun, primary optical system, secondary optical system, and detection system are arranged on one wafer, and the lens of the primary optical system is one. A plurality of electrodes having holes for optical axes corresponding to the number of optical systems are stacked on a single ceramic substrate.

  According to this method, the throughput of pattern evaluation can be improved according to the number of optical systems, and the structure is simple, and manufacturing and assembly are easy, so that an electron optical system for pattern evaluation can be produced at low cost. Can do.

In addition, the present invention is characterized in that in the manufacture of a device, a wafer during or after the process is evaluated using any one of the pattern evaluation methods described above.
According to this method, a device manufacturing method having the advantages of each pattern evaluation method can be obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is an explanatory diagram of an electron optical system used in the pattern evaluation method according to the first embodiment of the present invention. The electron beam emitted from the electron gun 1 is aligned with the condenser lens 2 and the multi-aperture 3 by the alignment deflector 27. The beam that has passed through the multi-aperture is aligned with the NA aperture 4 and the reduction lens 5 by the alignment deflector 28. The multi-aperture creates a reduced image at 26 and further forms 6 to 20 multi-beams on the sample 12 with the objective lens 11. In the multi-beam, the sample 12 is scanned by the two-stage deflectors 29 and 10 along the width of the stripe in one axis direction, and a two-dimensional image is obtained by scanning with the deflector and continuously moving the sample table in the other axis direction. . Secondary electrons emitted from the sample 12 are accelerated and focused by the objective lens 11, separated from the primary optical system by the EXB separator 9 and incident on the secondary optical system, and the electron images are magnified by the magnifying lenses 13 and 14. Is multiplied by the MCP detector 15, absorbed by the multi-anode 16, converted into an electric signal by the resistor 17, and a two-dimensional image is created by the amplifier / A / D converter and the image forming circuit 18, and stored in the memory of the CPU 7. Stored. Here, the stripe is an area that can be evaluated by a single stage (sample support) continuous movement, and has a scanning width by the deflector × an area in the dimension of the other axis of the sample, and the inside and the boundary thereof. There are patterns to be evaluated.

  Before starting the evaluation of the sample, an L-shaped marker 19 (shown in the lower right of FIG. 1) which is always on the stage is scanned with a multi-beam 20-25, and secondary electrons generated from the respective beams are respectively scanned. Detect with a detector and make a small two-dimensional image of each. Based on the design values at each position of the multi-beam, the results are joined together.

  Assuming that a pattern as shown in FIG. 8 (shown on the left side of FIG. 1) is obtained as a result of the stitching, stitching is seen between the small two-dimensional images as shown at 30. From this gap, it can be seen whether the actual design value is further shifted from the first design value in the x direction. If the actual deviation from the design value of the x coordinate of each position of the multi-beam is corrected, the deviation of 30 can be eliminated. For example, if the pattern created by the lower beam in the figure is shifted to the right with respect to the upper pattern as shown in FIG. 30, the x coordinate of the lower beam may be shifted to the left from the design value. This actual misalignment can be corrected while viewing the image.

  Next, the y-direction interval between multiple beams will be described. Assuming that the pixel size in this system is 100 nm, the beam interval is 1 μm, and 10 beams, as shown in FIG. 2, the signal waveform when scanning the pattern P having a size in the y direction of 9 μm is shown below. . As shown in the figure, the signal from the upper end beam 31 finely adjusts the position of the entire multi-beam 31-40 in the y direction so that the amplitude is 50% of the waveform from the intermediate beams 32-39. That is, if the signal waveform is smaller than 50%, the 31 beams correspond to scanning above (outside) the pattern, and therefore the entire beam may be moved downward. In this way, the beam position is adjusted so that the amplitude is 50% (that is, the upper end beam 31 is halfway on the end of the pattern), and then the waveform from the lower end beam 40 is observed. At that time, as indicated by the solid line, if the amplitude of the waveform from the beam 40 exceeds 50% of the amplitude of the waveform from the intermediate beam 32-39, the interval between the beams in the y direction is too small. If it is less than 50%, the interval is too large. That is, the distance in the y-axis direction between the plurality of beams is accurately measured. If the interval is narrow, the excitation voltage of the reduction lens is increased, the focal length of this lens is shortened, and the reduction rate should be close to 0. If the interval is large, the reduction rate should be close to 1. That's fine. Since this measurement method is a measurement method enlarged ten times so as to evaluate the distance between adjacent beams, adjustment with very high accuracy is possible. In this way, the beam interval of 1 μm could be accurately matched 10 times (integer multiple) of the pixel size of 100 nm.

  In this way, by adjusting the distance between the beams, storing the distance between the beams, acquiring a small two-dimensional image by a plurality of beams, and connecting them based on the stored distance between the beams, A large two-dimensional image with high accuracy can be formed.

FIG. 3 shows a second example of the present embodiment.
When scanning with a single beam as in the prior art, as shown in FIG. 3A, the first scan (start point 41, scan 44, scan end point 47) and the second and third scans are performed. Since the x coordinates of the start points 41, 42 and 43 and the x coordinates of the scanning end points 47, 48 and 49 are the same, the stripe boundaries 50 and 51 may be straight lines parallel to the y axis. However, when using multiple beams, the x-coordinates of the scanning start points 31-40 are different because the x-direction coordinates are not the same as shown in 20-25 of FIG. Of course, since the scanning is performed for the same time, the x coordinate of the end point of the scanning is also different. Therefore, when evaluating with multi-beams, as shown in FIG. 3B, the boundary between the left stripe (white background) and the right stripe (with scanning lines) corresponds to the beam position in the x direction. What is necessary is just to make it a shape. As a result, duplicate scanning does not occur and extra irradiation is not given to the sample, and non-evaluation areas are not created by insufficient scanning. In order to obtain a two-dimensional image by the scanning method of FIG. 3, assuming that the position of the image obtained from the signal from 31 beams is (0, 0), the small two-dimensional image obtained from the signal from 32 beams is used. The position of the image is (x ₁ , ₂ , y ₁ , ₂ ) and the position of the small two-dimensional image obtained from the signals from the 33 beams is (x _1,3 , y _1,3 ), generally ( The positions may be shifted and connected by x _{1, i} , y _{1, i} ).

FIG. 4 shows a third example of the present embodiment.
This embodiment shows a method of forming a large two-dimensional image from a small two-dimensional image when the pattern 57 is evaluated with a plurality of beams 51-56.
Here, the distance in the y direction between adjacent beams 51-56 is equal (Δy _51-52 = Δy _52-53 = Δy _53-54 = Δy _54-55 = Δy _55-56 ), for example, 1 μm. And the distance in the x direction between adjacent beams is also equal (Δx _51-52 = Δx _52-53 = Δx _54-55 = Δx _55-56 ), for example, 0.3 μm, and the beam 21 and the beam 24 Are equal in x coordinate (x ₅₁ = x ₅₄ ).

  As shown in FIG. 5A, each beam 51-56 is scanned by the stripe width in the x direction and the pixel is moved by the inter-beam distance in the y direction to scan from the signal corresponding to each beam. Two-dimensional images 51a-56a are obtained. Since the beam 56 is outside the pattern, there is no corresponding image. By correcting the position between the beams of these small two-dimensional images, a wide-area two-dimensional image can be obtained. For example, in the example of the beam position described above, the image 52 a obtained from the beam 52 is moved by 1 μm in the y direction and −0.3 μm in the x direction on the basis of the image obtained from the beam 51. The obtained image 53a is moved 2 μm in the y direction and −0.6 μm in the x direction, the image 54a obtained from the beam 54 is moved 3 μm in the y direction and 0 μm in the x direction, and the image 55a obtained from the beam 55 is obtained. Is moved by 4 μm in the y direction and −0.3 μm in the x direction, and the position between the beams is corrected, whereby a two-dimensional image 58 of a continuous pattern can be obtained. Of course, also in this embodiment, as described above, it is desirable to adjust the distance in the y direction between the beams 51 to 56 so as to be an integral multiple of the pixel size.

  In this embodiment, since the interval of the multi-beams in the direction of continuous movement of the sample stage is an integer multiple of the pixel size, a small image obtained by scanning one beam and a small image obtained by scanning the next beam are scanned. Large two-dimensional images can be created by accurately connecting images.

(Second embodiment)
FIG. 5 shows an electron optical system used in the second embodiment of the present invention. The electron gun 101 has a single crystal L _a B ₆ cathode having _a radius of curvature of 30 μm at its tip, and an electron beam emitted from the electron gun 101 is irradiated to a multi-aperture plate 102 provided in the vicinity of the optical axis to form a multi-beam. The The beam exiting from the multi-aperture is converged by the condenser lens 103 to form a crossover at the NA aperture 105, converged by the reduction lens 104, further reduced by the first objective lens 106 and the second objective lens 108, and reduced to the sample surface 109. The beam is imaged and the sample surface is scanned by electrostatic deflectors 142 and 143. Since the EXB separator 107 is disposed at a position other than the image point of the primary beam, deflection chromatic aberration is generated in the primary beam. In order to avoid this, the deflection amount by the electromagnetic deflector of the EB separator 107 is set to be twice the deflection amount of the electrostatic deflector so that the chromatic aberration of the primary beam is not generated. In this state, pre-deflection is performed by the deflector 144 in order to pass the center of the first objective lens 106. Further, assuming that the axial path of the chief ray of the primary electron beam is 110, the light passes through the center of the second objective lens 108 but is incident on the sample 109 at a position slightly away from the optical axis. Secondary electrons generated from this take the axis of the dotted line 111, further deflected by the EXB separator 107, and input to the secondary optical system 112. The distance between each other is enlarged by the magnifying lens 113, multiplied by each multi-beam by the MCP 115, absorbed by the multi-anode 116, converted to a voltage signal by the resistor 118, multiplied by 119, A / D converted, and 2 A dimension signal is created and stored in the memory 120. In the figure, 114 is a deflector, 117 is a lead wire, and 141 is. A plan view of the detector is shown in the lower right of FIG.

  Here, in order to create an enlarged image on the incident surface of the MCP 115 with the magnifying lens 113, an enlarged image is formed with the lens 108 and the lens 106 at a position where the secondary electrons emitted from the sample 109 are close to the main surface of the magnifying lens 113. In addition, it is necessary to create an image of secondary electrons at a position close to the main surface of the magnifying lens 113 as described above under the lens conditions in which the primary beam is focused on the surface of the sample 109 by the lens 106 and the lens 108. is there. This condition will be referred to as a “primary beam and secondary beam simultaneous focusing condition”.

Next, the simultaneous focusing condition of the primary beam and the secondary beam is obtained using FIG.
FIG. 6 shows three types of optical systems through which the primary beam and the secondary beam pass in common. FIG. 6A shows a one-stage objective lens, and FIG. 6B shows the same as FIG. In (C), the objective lens includes an electromagnetic lens. (B) corresponds to FIG. 1, and (A) and (C) are modifications of FIG.

  (A) shows a case where the primary beam and the secondary beam pass through only one stage of the lens in common. If the primary beam often used in the past is 0.3 KV or more, the secondary electrons are in focus condition just above the objective lens 108 and in front of the EB separator 107, and the object point distance of the magnifying lens 113 is too long. If the lens is a magnifying lens, the secondary optical system has a long dimension. As a result of a simple simulation, it is clear that the landing energy of the primary beam needs to be 300 V or less in order to make the image point position of the secondary beam close to 124 under the lens conditions satisfying the focusing condition of the primary beam. It was. In the figure, 121 is a primary beam image, 122 is a secondary beam image, and 123 is a first multi-beam reduced image.

  Next, as shown in (B), when the primary beam and the secondary beam pass through the lens 106 and the lens 108 in common, the landing energy condition that satisfies the simultaneous primary and secondary focusing conditions is considerably relaxed. When the landing energy of the primary electron beam was 600 V or less, the secondary electron image point could be imaged at a position 124 in front of the magnifying lens 113. When this landing energy was set to 600 V or more, the trajectory 121 of the primary beam opened upward in the figure, the beam diameter increased at the position of the lens 106, and the aberration of the primary beam increased.

  Further, the case of (C) will be described. Here, the objective lens 108 is a synthetic lens of an electromagnetic lens and an electrostatic lens. In the magnetic circuit, there is no ferromagnetic material, that is, the lens gap 125 is on the sample side, and the Z position where the on-axis magnetic field of the lens is maximum is on the sample side from the gap. The beam is most strongly focused at the Z position where the on-axis magnetic field is maximized. An electrode 126 for applying a positive high voltage is provided in the vicinity, and the axial chromatic aberration is reduced by reducing the (energy width / beam energy at the lens position) ratio. That is, the ratio was reduced by increasing the denominator. Since the lens action of the electromagnetic lens is inversely proportional to the 1/2 power of the beam energy, and the electrostatic lens is inversely proportional to the first power of the beam energy, the landing voltage of the primary beam in this case is inherently ( Compared with 300V in the case of A), it should be significantly larger. As a result of the simulation, when the landing voltage is 500 V or less, the object point 123 of the primary beam and the image point 124 of the secondary beam are in realistic positions.

  FIG. 7 shows an electron optical system according to a second example of the present embodiment. A plurality of optical systems shown in FIG. 5 are arranged in a straight line. This is because the ceramic substrate 170 is provided with a plurality of holes 172 and 174 corresponding to the optical axis, and a necessary number of plates having a metal coating 173 around the holes are formed. The primary optical from the anode of the electron gun 101 to the lower pole of the objective lens 108 with the knock pin 171. It is assembled about the system. In FIG. 8, reference numbers corresponding to the optical components are shown on the right side. In the figure, 101 is an electron gun, 102 is a multi-aperture plate, 103 is a condenser lens, 104 is a condenser lens, 106 is a reduction lens, 107 is an EB separator, 108 is an objective lens, 109 is a sample, and 113 is two The magnifying lens of the next optical system, 115 is an MCP, 116 is a multi-anode, and 142, 143 and 144 are electrostatic deflectors. In addition, for the secondary optical system, the optical axis is inclined in the opposite direction to each other with respect to the primary optical axis aligned in a straight line, so the secondary optical system is connected to the adjacent optical axis. Since the interval is doubled, there is no problem even if each axis is made. That is, in FIG. 8, the secondary optical system is provided so that the optical axes 111 and 113 are in the front direction of the paper surface, and the optical axes 112 and 114 are in the back direction of the paper surface. And 113, or 112 and 114, which is twice the distance between 111 and 112. Therefore, an optical system for each optical axis may be made as usual.

  According to the present embodiment, the ratio of (landing energy of primary electron beam / energy of secondary electron) is (600 eV / 2 eV) = 300 or less (in the case of A in FIG. 6), (300 eV / 2 eV) = 150. Below (in the case of B), (500 eV / 2 eV) = 250 or less (in the case of C), which is smaller than the conventional (1000 eV / 2 eV) = 500, so the simultaneous focusing conditions of the primary beam and the secondary beam are easy. Therefore, a secondary beam can be formed in the vicinity of one optical axis in the primary optical system, and secondary electrons can be detected independently without crosstalk.

(Third embodiment)
FIG. 9 shows an outline of an electron optical system used in the third embodiment of the present invention. Electron gun _L a _{B 6} single crystal cathode 201, the Wehnelt 202 consists anode 203, cathode 201 can be less than 1/4 of the case of the Schottky cathode shot noise by operating in a space charge limited condition A sufficient S / N ratio can be obtained when the number of electrons per pixel is about 250. Therefore, even a resist whose resist shape is easily changed by electron beam irradiation such as an ArF resist can be evaluated without deforming the resist.

  The electron beam emitted from the electron gun is focused by the condenser lens 204 and irradiates the multi-aperture 205, and at the same time forms a crossover at the NA aperture 224. A plurality of beams formed by the multi-aperture 205 is reduced by the reduction lens 206 and the objective lens 208 to form a multi-beam narrowed on the target, that is, the sample 209. These beams are scanned on the sample 209 by the electrostatic deflector 223 and the electrostatic deflector of the EB separator 207. The secondary electrons emitted from the scanning point of the sample are accelerated and focused in the direction of the objective lens 208 because, for example, −4 KV is applied to the sample 209 to form a thin beam bundle. A secondary electron image is created in the vicinity of the vessel 207. The secondary beam is deflected from the primary beam by about 20 ° by the EB separator 207, the magnification is adjusted by the magnifying lenses 210 and 211 of the secondary optical system 212, and the pitch of the multi-anode 214 on the back surface is input to the MCP 213. An image corresponding to is formed. The electrons from each beam are multiplied by the MCP 213, each beam is independently absorbed by the multi-anode 214, converted to a voltage signal by the resistor 215, and converted to a digital signal by the preamplifier / A / D converter group 216. Various processes are performed by the two-dimensional image forming circuit 217 and stored in the memory 218.

  The multi-beams are arranged in a line in the direction of about 45 ° as indicated by 222 in the lower right of the figure. The signal waveform when the y line 219 is scanned in the x direction is shown in FIG. 10A, and the signal waveform when the two x line patterns 20 and 21 are scanned in the y direction is shown in FIG. Is shown in The edge roughness measurement method is shown for the y line in (C).

  At the time of CD measurement shown in FIG. 10A, processing is performed with a signal waveform before a two-dimensional image is formed. That is, for each of the seven signal waveforms 232, a threshold value 231 is given, a time interval 233 at which the waveform intersects the threshold value is obtained, converted from scanning speed to dimensions, and a CD value is obtained for each beam and averaged. Alternatively, the time interval 233 may be obtained by improving the S / N ratio by adjusting the position of the signal waveform of 232 for the time corresponding to the interval difference in the x direction of the beam and performing averaging. .

  Further, instead of the threshold method, tangent lines 234 and 235 are formed at the rising and falling edges of the signal waveform, the intersection between the tangent line and the signal base line 236 is obtained, and the time difference 237 between them is obtained and converted into dimensions. . Whether the threshold method or the tangent is used may be determined by the pattern material or the longitudinal structure.

  Next, the alignment accuracy measuring method shown in FIG. When measuring the alignment accuracy in the y direction, the multi-beam 222 is moved near the pattern 221 formed in the next layer in the vicinity of the pattern 220 formed in the previous layer, and simultaneously scanned in the y direction. At that time, the signal waveform from the detector corresponding to each beam is represented by (B). It is only necessary to select a steep waveform at the rising portion and falling portion of these waveforms, and obtain the time interval or distance 238 between the intersection points of these waveforms and the threshold value 231 ′. In this case, the threshold value is determined by using either the rising or falling edge of the signal waveform, unlike the case of using both the rising and falling edges of the signal waveform. The steepest value of the rise or fall of the waveform, usually a value of 50% of the amplitude may be selected. Of course, the tangent line 234 is approximated to the rising part or the falling part, the time 239 is obtained from the intersection of the tangent line and the base line, converted into a distance, and the matching accuracy can be calculated by comparing with the design value.

  Next, a third example of the present embodiment will be described with respect to a method for measuring edge roughness. The multi-beam is moved near the y pattern 240 to scan the multi-beam in the x direction. When there are several pixels in the y direction, the multi-beam is scanned simultaneously while shifting the position of the beam in the y direction by one pixel as shown by 241-245 until all the inter-beam distances are filled. Scanning is repeated to acquire a two-dimensional image. The edge roughness can be measured by measuring the uneven PP value or effective value from the acquired images as shown in 246 and 247. Here, it is necessary to slow down the pixel frequency so that the signal waveform in each scan sufficiently improves the S / N ratio.

  According to the present embodiment, since the time for scanning the pattern may be less in accordance with the number of beams in order to evaluate the pattern, the measurement time can be shortened.

(Fourth embodiment)
FIG. 11 is an explanatory diagram of an electron optical system used in the pattern evaluation method according to the fourth embodiment of the present invention.

The electron gun consists of L _a B ₆ cathode 301, a Wehnelt electrode 302 and the three-electrode an anode 303, forming a small convex lens with spherical aberration by providing a positive voltage to the center electrode of a three electrode anode 303. The irradiation area of the multi-aperture 307 can be adjusted by adjusting the focusing action of the convex lens. Alternatively, the NA value (focusing half angle) of the primary beam on the sample 317 may be adjusted by changing the size of the crossover image formed in the NA aperture 309 by changing the focal length of the lens. Anyway, the primary beams emitted from the electron guns 301, 302, and 303 are aligned with the condenser lens 305 and the multi-aperture 307 by the alignment deflectors 331 and 332. The excitation voltage of the condenser lens 305 is determined so that the crossover is focused on the NA aperture 309. The electron beam separated into multiple beams by the multi-aperture 307 is aligned with both the NA aperture 309 and the reduction lens 310 by the two-stage alignment deflectors 333 and 334, and reduced by the reduction lens 310 and the objective lens 315. The surface of the sample 317 is focused, and the sample 317 is simultaneously raster-scanned by the deflectors 311 and 314. When the sample is scanned with a multi-beam, in order to correct aberration due to curvature of field, the focusing power of the lens is changed in synchronization with the scan, and scanning is performed with dynamic focus so that the sample surface is always focused. Secondary electrons emitted from multiple scanning points on the sample are accelerated and focused by an accelerating electric field for the secondary electrons in the vicinity of the sample formed by the objective lens 315 and the sample 317, and after passing through the objective lens 315, the EXB separator 313. The light is deflected and incident on the secondary optical system, and the distance between the secondary electrons is expanded by the two-stage magnifying lenses 319 and 321, and the distance between the secondary electron images coincides with the distance between the secondary electron detectors 323. Zooming is performed. Here, it has been revealed by simulation that the larger the electric field strength in the vicinity of the surface of the sample 317 is, the smaller the blur of the secondary electron image at the detector 323 is. However, if the electric field strength is too high, a discharge occurs between the lens 315 and the sample 317, which may cause destruction of the sample. Therefore, the voltage applied to the lower electrode of the lens 315 is determined so that a bare electric field that does not cause discharge between the sample 317 and the lens 315 is generated on the wafer surface. The electric field strength at which the sample causes discharge is determined and not constant depending on the state of the surface of the sample. For example, when there are protrusions such as vias on the wafer surface, a locally large electric field even if the average electric field strength is as small as 1.6 KV / mm. Is formed and discharged. In the case of a flat wafer having an S _i O ₂ film formed on the surface, the electric field strength causing discharge is as high as 6 KV / mm.

  Therefore, the voltage applied to the lower electrode is made variable in the range of at least 1.5 KV / mm to 5.5 KV / mm in the average electric field strength formed between the sample 317 and this electrode, and the sample with via is evaluated. In this case, the voltage is determined to be 1.5 KV / mm, which is slightly smaller than 1.6 KV / mm, and in the case of the sample on which the SiO 2 film is formed, the electrode is set to 5.5 KV / mm, which is slightly smaller than 6 KV / mm. What is necessary is just to decide the voltage given to. Accordingly, it is possible to obtain the characteristics of the secondary optical system that minimizes the blur of the secondary electron image without causing discharge.

  Next, with regard to the arrangement of the primary electron beams, the distance between adjacent beams of the primary electron beams needs to be larger than the resolution of the secondary optical system, and the beam interval d where all the beams are projected on the y-axis. All need to be equal. An example in which the above two conditions are satisfied and a certain number of beams are arranged in a circle as small as possible is indicated by a circle on the left side of FIG. Here, a total of 16 beams in 4 rows and 4 columns could be arranged inside the circle 335. In the case of 14 beams, it is inside the circle 336. In order to fit a predetermined number of beams in a circle as small as possible in this way, each beam is numbered i in the x direction and j in the y direction as shown in the figure, and adjacent beams (i, j) The distance 328 between the i th and (i, j + 1) th and the distance 329 between the (i, j + 1) th and (i + 1, j) th may be made substantially equal.

  In FIG. 11, 316 is a positive high voltage power source, 318 is a negative power source, 320 and 322 are deflectors for alignment, 323 is a scintillator, 324 is a light guide, 325 is a PMT, 326 is an A / D converter, 327 Is an image forming apparatus.

FIG. 12 shows an electron optical system used in the pattern evaluation method according to the second example of the present embodiment. The electron beam emitted from the electron gun 361 creates a cross-over 379 once by the focusing action of the three-electrode anode 374, and irradiates the multi-aperture 362 with a beam diverging from the cross-over 379, thereby creating a multi-beam. These beams are reduced by the condenser lens 363 and the objective lens 365 and focused on the sample 366. The sample 366 is scanned by the electrostatic deflector 375 and the electrostatic deflector 376 of the EXB separator 364, and secondary electrons emitted from the scanning point are positively applied to the electrode 365 ′ provided at the lowermost pole of the objective lens 365. Is applied to the secondary optical system by the EXB separator 364, and the magnifying lens 367 increases the distance between the secondary electron groups. The light is converted into light by the scintillator 368, converted into an electrical signal by the light guide 369, and a two-dimensional image is formed by a plurality of subsequent A / D converters, image forming circuits, and the like. Further, a negative high voltage 378 is applied to the sample 366, and the primary beam is irradiated with a landing energy as low as about 200V.
FIG. 12 shows a configuration in which a plurality of optical systems are arranged in a straight line as in the embodiment of FIG.

  Similarly to the embodiment of FIG. 8, the EXB separator, electrostatic deflector, lens, and the like are provided with holes 372 and 374 corresponding to the optical axis in one ceramic substrate 370, and the periphery thereof is indicated by 373. A metal-coated plate was assembled by using a knock pin 371 at the required Z position so that all optical axes coincided with each other, and a primary optical system from the electron gun 361 to the lowermost pole of the objective lens 365 was produced. As for the secondary optical system, the optical axes adjacent to the optical axis of the primary optical system arranged in a straight line are drawn in the opposite directions (in the direction of the front and back of the paper) in an oblique direction, so the pitch is doubled. Since the distance can be maintained, it can be manufactured with a normal lens structure.

  According to the present embodiment, since the beam emission angle and crossover dimension of the electron gun are adjusted by a lens having a plurality of anodes, one stage of the necessary lens and its axis alignment device are not necessary. Since the optical axis length can be shortened, a multi-beam can be configured with a simple optical system.

FIG. 13 shows an application of the pattern evaluation method shown in the above embodiment to wafer evaluation in a semiconductor device manufacturing process.
An example of the device manufacturing process will be described with reference to the flowchart of FIG.

This manufacturing process example includes the following main processes.
(1) Wafer manufacturing process for manufacturing a wafer (or preparation process for preparing a wafer) (Step 10)
(2) Mask manufacturing process for manufacturing a mask used for exposure (or mask preparation process for preparing a mask) (step 11)
(3) Wafer processing process for performing necessary processing on the wafer (Step 12)
(4) Chip assembly process for cutting out chips formed on the wafer one by one and making them operable (step 13)
(5) Chip inspection process for inspecting assembled chips (step 14)
Each process is further composed of several sub-processes.

Among these main processes, the main process that has a decisive influence on the performance of the semiconductor device is a wafer processing process. In this process, designed circuit patterns are sequentially stacked on a wafer to form a large number of chips that operate as memories and MPUs. This wafer processing step includes the following steps.
(1) A thin film forming process for forming a dielectric thin film to be an insulating layer, a wiring part, or a metal thin film for forming an electrode part (using CVD, sputtering, etc.)
(2) Oxidation process for oxidizing the formed thin film layer and wafer substrate (3) Lithography process for forming a resist pattern using a mask (reticle) to selectively process the thin film layer and wafer substrate (4) ) Etching process (for example, using dry etching technology) that processes thin film layers and substrates according to resist patterns
(5) Ion / impurity implantation / diffusion process (6) Resist stripping process (7) Inspection process for inspecting the processed wafer The wafer processing process is repeated for the required number of layers to produce a semiconductor device that operates as designed. .

The lithography process that forms the core of the wafer processing process is shown in the flowchart of FIG. This lithography process includes the following steps.
(1) Resist coating process for coating a resist on the wafer on which the circuit pattern is formed in the preceding process (step 20)
(2) Exposure process for exposing resist (step 21)
(3) Development step of developing the exposed resist to obtain a resist pattern (step 22)
(4) Annealing process for stabilizing the developed pattern (step 23)
Known processes are applied to the semiconductor device manufacturing process, the wafer processing process, and the lithography process.

  In the wafer inspection process of (7) above, when the pattern evaluation method according to each of the above embodiments of the present invention is used, even with a semiconductor device having a fine pattern, it is highly accurate in a state where there is no image defect of the secondary electron image. Since defects can be inspected, product yield can be improved and shipment of defective products can be prevented.

    The pattern evaluation according to the present invention can be widely applied to the pattern evaluation of samples such as defect inspection, line width measurement, alignment accuracy, potential contrast measurement of samples such as photomasks, reticles, and wafers.

It is the schematic which shows the electron optical lens barrel used with the pattern evaluation method in the 1st Embodiment of this invention. It is the schematic which shows the adjustment method between beams in the pattern evaluation method by the 1st Example of 1st Embodiment. It is the schematic which shows the shape of the stripe boundary in the pattern evaluation method by the 2nd Example of 1st Embodiment. It is the schematic which shows the connection point of the small image in the pattern evaluation method by the 3rd Example of 1st Embodiment. It is the schematic which shows the electron optical system used in the 2nd Embodiment of this invention. It is explanatory drawing in three cases for calculating | requiring the simultaneous focusing conditions of the primary beam and secondary beam in 2nd Embodiment. It is a figure which shows 2nd Example of 2nd Embodiment, and is the schematic of the apparatus which arranged in parallel the optical system which formed the multi-beam around one optical axis. It is sectional drawing which shows the apparatus of 2nd Example of 2nd Embodiment, and is a figure which shows the example in the case of making with the ceramic plate which arranged the some optical element on the Z-axis direction. It is the schematic which shows the electron optical system used with the pattern evaluation method by 3rd Embodiment of this invention. It is explanatory drawing of the pattern evaluation method by 3rd Embodiment, (A) shows CD measurement, (B) shows the alignment precision measurement, (C) shows the point of edge Fuchness measurement. It is the schematic which shows the electron optical system used for the pattern evaluation method by the 4th Embodiment of this invention. It is the schematic which shows the 2nd electron optical system used for 4th Embodiment. It is a flowchart which shows a semiconductor device manufacturing process. 14 is a flowchart showing a lithography process in the semiconductor device manufacturing process of FIG. 13.

Explanation of symbols

1: electron gun, 2: condenser lens, 3: multi-aperture plate, 4: NA aperture, 5: reduction lens, 8: formed two-dimensional pattern, 9: EXB separator, 10: scanning deflector, 11: Objective lens, 12: sample, 13: magnifying lens, 14: magnifying lens, 15: MCP, 16: multi-anode, 17: resistor, 18: preamplifier + DAC, 19: pattern, 20-25: beam, 27: axis Alignment deflector, 28: Axis alignment deflector, 29: Scanning deflector, 31-40: Multi-beam 101: Electron gun, 102: Multi-aperture plate, 103: Condenser lens, 104: Reduction lens, 105: NA aperture, 106: First objective lens, 107: EXB separator, 108: Second objective lens, 109: Sample, 110: Primary beam chief ray trajectory, 111: Secondary beam chief ray trajectory, 112: Two Beam optical axis, 113: magnifying lens, 114: deflector, 115: MCP, 119: amplifier and A / D converter, 120: image forming circuit and memory, 121: primary beam imaging diagram, 122: secondary beam connection Image diagram, 123: first multi-beam reduced image, 124: secondary electron imaging surface, 125: lens gap, 126: photovoltage electrode, 170: ceramic substrate, 171: knock hole, 172: hole for optical axis, 173 : Metal coat, 174: Anode hole 201: Cathode, 202: Wehnelt, 203: Anode, 204: Condenser lens, 205: Multi-aperture, 206: Reduction lens, 207: EXB separator, 208: Objective lens, 209: Sample, 210: magnifying lens, 211: second magnifying lens, 213: MCP, 216: amplifier and A / D converter, 17: signal processing circuit and two-dimensional image forming circuit, 218: memory, 219: y pattern, 220: first layer x pattern, 221: second layer x pattern, 222: multi-beam, 223: electrostatic deflector, 224 : NA aperture, 231: Threshold, 232: Secondary electron signal waveform, 233: CD value, 234: Tangent, 235: Tangent to falling waveform, 236: Base line, 237: CD value, 238: Line spacing, 239: line interval, 240: y line, 246, 247: edge ease (PP value)
_301: L a _{B 6} cathode, 302: Wehnelt, 303: triple anode, 305: condenser lens, 307: multi-aperture, 309: NA aperture, 310: reduction lens, 311: deflector, 312 and 313: EXB separator, 314: Scanning deflector, 315: Objective lens, 316: Positive high voltage power supply, 317: Sample, 318: Negative power supply, 319: Magnifying lens, 320: Axis alignment, 321: Magnifying lens, 322: Deflector, 323: Scintillator, 324: Light guide, 325: PMT, 326: A / D converter, 327: Image forming circuit, 328: Beam distance in y direction, 329: Beam distance in x direction, 330: Beam distance projected on y axis, 331, 332: Axis alignment, 333, 334: Axis alignment, 335: Circle with a certain aberration or less, 336: Aberration smaller Round circle, 361: electron gun, 362: multi-aperture, 363: condenser lens, 364: EXB separator, 365: objective lens, 366: sample, 367: magnification lens, 368: scintillator, 369: PMT, 370: ceramic substrate , 371: knock hole, 372: lens electrode hole, 373: metal coating portion, 374: anode hole, 375: crossover, 376: lower pole of objective lens, 377: positive voltage power supply, 378: negative voltage power supply, 379: Light guide

Claims (21)

It is a method of irradiating a sample with multiple beams and evaluating a pattern.
a. Irradiating a plurality of apertures with an electron beam emitted from an electron gun; b. Forming a reduced image of the aperture on the sample surface; c. Scanning the plurality of imaged beams to obtain a two-dimensional image for each beam; d. Connecting the two-dimensional images for each beam to form a large two-dimensional image e. Measuring a uniaxial spacing between the plurality of beams; f. A pattern evaluation method comprising a step of adjusting the interval to an integer multiple of a pixel size. It is a method of irradiating a sample with multiple beams and evaluating a pattern.
a. Irradiating a plurality of apertures with an electron beam emitted from an electron gun; b. Forming a reduced image of the aperture on the sample surface; c. Scanning the plurality of imaged beams by the width of the stripe in one axis direction to obtain a two-dimensional image; d. When acquiring the two-dimensional image in step c, the sample stage continues to move in the other axis direction, and when it reaches the end of the evaluation area, the movement in the other axis direction is stopped, and the stage is moved by the width of the stripe. And a step of moving the step in a uniaxial direction, and the boundary between the stripes has irregularities corresponding to the uniaxial positions of the plurality of beams. It is a method of irradiating a sample with multiple beams and evaluating a pattern.
a. Irradiating a plurality of apertures with an electron beam emitted from an electron gun; b. Forming a reduced image of the aperture on the sample surface; c. Scanning the plurality of imaged beams in one axis direction to obtain a two-dimensional image with a signal from a detector corresponding to each beam; and d. A two-dimensional image of a wide area is formed by moving the position of the two-dimensional image by a predetermined distance in the x and y directions between the beams on the sample and connecting the two-dimensional images. A pattern evaluation method characterized by comprising the steps of: It is a method of irradiating a sample with multiple beams and evaluating a pattern.
a. Generating a plurality of beams b. Scanning a plurality of beams on a mark having an x-direction pattern or a y-direction pattern side, detecting electrons generated from each beam with a corresponding detector, and forming a two-dimensional image; c. Connecting the two-dimensional image from each detector based on a preset value of the inter-beam distance d. Changing the distance between the beams so that the shape of the mark image obtained by the above connection is normal, connecting the distance, and storing the distance between the beams where the mark image is most normal; e. Obtaining a two-dimensional image of a sample to be evaluated with each beam, and connecting the two-dimensional images obtained from each beam at the stored inter-beam distance to obtain a two-dimensional image of a wider sample. Pattern evaluation method.   A device manufacturing method, wherein a wafer during or after the process is evaluated using the method according to claim 1. A method of scanning a pattern formed on a substrate with a multi-beam, detecting secondary electrons emitted from a scanning point, and evaluating the pattern,
a. Accelerating the electron beam emitted from the electron gun to AKV b. Irradiating the accelerated electron beam to an aperture plate having a plurality of apertures; c. Shrinking a plurality of beams at the aperture, forming an image on a sample to which a voltage of -BKV is applied, and scanning d. Expanding the distance between secondary electron groups emitted from the scan point to the detector; e. A step of independently detecting the secondary electron group by the detector and forming a two-dimensional image, wherein AB ≦ 0.6 KV, and the secondary electron group is a primary lens of a two-stage lens. A pattern evaluation method characterized by a common passage with an electron beam. A method of scanning a pattern formed on a substrate with a multi-beam, detecting secondary electrons emitted from a scanning point, and evaluating the pattern,
a. Accelerating the electron beam emitted from the electron gun to AKV b. Making the electron beam into multiple beams at a plurality of apertures; c. Shrinking the multi-beam, imaging a sample with a voltage of -BKV, and scanning d. Directing the secondary electrons emitted from the scanning point to the detector at a larger distance from each other; e. And independently detecting the secondary electron group by the detector and forming a two-dimensional image, and AB−0.3 ≦ KV, and the secondary electron group has one stage. A pattern evaluation method characterized by using a lens as a common path with a primary electron beam. A method of scanning a pattern formed on a substrate with a multi-beam, detecting secondary electrons emitted from a scanning point, and evaluating the pattern,
a. Accelerating the electron beam emitted from the electron gun to AKV b. Making the electron beam into multiple beams at a plurality of apertures; c. Reducing the multi-beam and imaging and scanning a sample to which a voltage of -BKV is applied; d. Detecting a secondary electron emitted from the scanning point and forming a two-dimensional image, wherein AB ≦ 0.5 (KV), closest to the sample, and the primary electron beam A pattern evaluation method, wherein a lens through which a secondary electron beam passes includes an electromagnetic lens. The pattern formed on the substrate is scanned with a multi-beam, the secondary electrons emitted from the scanning point are detected, and the pattern is evaluated.
a. Accelerating the electron beam emitted from the electron gun to AKV b. Irradiating the accelerated electron beam to an aperture plate having a plurality of apertures; c. Shrinking a plurality of beams at the aperture, forming an image on a sample to which a voltage of -BKV is applied, and scanning d. Expanding the distance between secondary electron groups emitted from a plurality of scanning points to a detector; e. A step of independently detecting the secondary electron group by the detector and forming a two-dimensional image, wherein AB ≦ 0.5 KV, and the lens closest to the sample includes an electromagnetic lens. A pattern evaluation method characterized by the above.   10. The pattern evaluation method according to claim 6, wherein the electron optical system has a plurality of optical axes, and the projection distances in the uniaxial direction of the plurality of optical axes are equal to each other. Pattern evaluation method characterized by things.   A device manufacturing method comprising performing pattern evaluation during or after a process using the pattern evaluation method according to claim 6. A method for evaluating a pattern using a multi-beam,
a. Irradiating an aperture plate having a plurality of apertures with an electron beam emitted from a thermionic emission gun; b. Reducing the electron beam emitted from the aperture plate and focusing it on the sample c. Simultaneously scanning with multiple beams in a direction perpendicular to the pattern sides d. The secondary particle beam emitted from the scanning point is detected by a multi-detector corresponding to the multi-beam, and a signal waveform is acquired and stored. E. And a step of calculating a CD value or a pattern interval from a plurality of signal waveforms corresponding to the multi-beam.   13. The pattern evaluation method according to claim 12, wherein the multi-beams are arranged along a straight line not parallel to the x-axis and the y-axis. A method for evaluating a pattern using a multi-beam,
a. Irradiating an aperture plate having a plurality of apertures with an electron beam emitted from a thermionic emission gun; b. Reducing the electron beam that has passed through the aperture plate to focus on the sample c. Simultaneously scanning with multiple beams in a direction perpendicular to the pattern sides d. The secondary particle beam emitted from the scanning point is detected by a multi-detector corresponding to the multi-beam, and a signal waveform is acquired and stored. E. Moving the multi-beam by one pixel in a direction parallel to the pattern side and repeating steps c and d f. Forming a two-dimensional image of the pattern from a plurality of signal waveforms corresponding to the multi-beam; and g. and a step of calculating edge roughness from the pattern obtained in step f.   15. The pattern evaluation method according to claim 12, wherein the electron gun has a thermionic emission cathode, and the cathode is operated under a space charge limiting condition.   A device manufacturing method, comprising: evaluating a wafer during or after a process using the method according to claim 12. A method for evaluating a sample by scanning a sample with a plurality of beams, the following steps:
a. A process of adjusting the beam emission angle of an electron beam emitted from an electron gun with an anode having at least two electrodes b. A process of focusing the electron beam having the emission angle adjusted by a condenser lens to form a crossover at the NA aperture c. A process of forming a multi-beam with a multi-aperture provided in the vicinity of the condenser lens; d. Process of forming an image of NA aperture in the vicinity of the main surface of the objective lens by a reduction lens e. Process of focusing reduced image of multi-aperture on sample surface with reduction lens and objective lens f. Scanning the sample while applying dynamic focus with multiple beams g. Accelerating and passing secondary electrons emitted from the sample with an objective lens h. Process of deflecting secondary electrons with an EXB separator and directing it to the secondary optics i. A process of increasing the spacing of multiple secondary electrons and detecting them with multiple detectors; j. A pattern evaluation method comprising: detecting a plurality of secondary electrons independently, forming a two-dimensional image, and evaluating a sample. A method for evaluating a sample by scanning a sample with a plurality of beams, comprising: a. Focusing the electron beam emitted from the electron gun on the NA aperture with a condenser lens b. Focusing the image of the NA aperture in the vicinity of the main surface of the objective lens with a reduction lens; c. Forming a multi-beam with a multi-aperture provided in front of or behind the condenser lens; d. Focusing the multi-beam on the sample with a reduction lens and an objective lens e. Scanning the sample while applying dynamic focus with multiple beams f. Accelerating and passing secondary electrons emitted from the scanning point with an objective lens g. A process in which secondary electrons are deflected by an EXB separator and directed to a secondary optical system h. Expanding the spacing of the secondary secondary electrons and detecting with multiple detectors; and i. A step of independently detecting multi-secondary electrons, forming a two-dimensional image, and evaluating the sample. The electric field strength in the vicinity of the sample is 1.5 KV / mm to 5.5 KV / A pattern evaluation method characterized by being adjustable within a range of mm. A method for evaluating a sample by scanning a sample with a plurality of beams, and the following steps:
a. Irradiating the multi-aperture with an electron beam emitted from an electron gun having a thermionic emission cathode b. Focusing the electron beam that has passed through the multi-aperture to the NA aperture c. A step of reducing the electron beam separated by the multi-aperture with a reduction lens and an objective lens and scanning the sample; d. Accelerate and pass secondary electrons emitted from the scanning point of the sample with an objective lens e. Directing the secondary electrons to the secondary optics with an EXB separator f. Enlarging the interval between the multiple secondary electron images and detecting with a plurality of detectors; g. Multi-secondary electrons are independently detected, a two-dimensional image is formed, and a sample is evaluated. The arrangement of the multi-beams is m rows and n columns, i rows and j columns, and i + 1 rows and j columns. A pattern evaluation method characterized in that an interval between columns is substantially equal to an interval between i rows and j columns and i rows and j + 1 columns.   20. The pattern evaluation method according to claim 17, wherein a plurality of the electron gun, the primary optical system, the secondary optical system, and the detection system are arranged on a single wafer, and the lens of the primary optical system. Is a pattern evaluation method characterized in that a plurality of electrodes having optical axis holes corresponding to the number of optical systems are stacked on a single ceramic substrate.   21. A device manufacturing method, wherein a wafer during or after the process is evaluated using the pattern evaluation method shown in any one of claims 17 to 20.

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