KR101618693B1 - Method for controlling scanning profile in Charged Particle Microscope and apparatus using thereof - Google Patents
Method for controlling scanning profile in Charged Particle Microscope and apparatus using thereof Download PDFInfo
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- KR101618693B1 KR101618693B1 KR1020140071894A KR20140071894A KR101618693B1 KR 101618693 B1 KR101618693 B1 KR 101618693B1 KR 1020140071894 A KR1020140071894 A KR 1020140071894A KR 20140071894 A KR20140071894 A KR 20140071894A KR 101618693 B1 KR101618693 B1 KR 101618693B1
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Abstract
The present invention relates to a scanning signal control method for a charged particle beam microscope, and more particularly, to a method for controlling a scanning signal of a charged particle beam microscope, A generator for generating a scan profile for controlling the irradiation direction of the charged particle beam and providing the scan profile to the deflector; And a scan waveform control unit for controlling a current waveform actually output from the deflector, the method comprising the steps of: generating a scan signal of a charged particle beam microscope, And a device using the same.
Description
The present invention relates to a scanning signal control method for a charged particle microscope and an apparatus using the same, and more particularly, to a scanning signal generating method for moving a scanning position of a charged particle beam to acquire information on a surface of a sample, A scanning signal of a charged particle microscope capable of obtaining a high-speed image while preventing distortion of a surface of a sample to be measured by irradiating a charged particle beam at a desired position by correcting the dynamic characteristic distorted by the constituent elements of the magnetic lens Control method and apparatus using the same.
As a method for observing the surface morphology or structure of a material in a vacuum atmosphere at a nanoscale or atomic scale, a charged particle beam of electrons or ions can be used. Using such a charged particle beam, a high-resolution microscope capable of observing the surface of the material to be observed at the nano- or atomic level can be produced beyond the limit of the limited resolution in an optical microscope.
In such a charged particle microscope, a charged particle beam is irradiated to a target sample, and the particles emitted from the target sample or particles (same or different kinds of charged particles as the irradiated charged particles, or electromagnetic waves, photons) A scanning electron microscope can be used as a semiconductor manufacturing process for inspection of a semiconductor wafer, measurement of a pattern dimension, measurement of a pattern shape, and the like, A charged particle microscope such as a scanning ion microscope or a scanning transmission electron microscope has been used. In these applications, observation of semiconductor patterns and defects, detection of defects, analysis of cause of occurrence, dimensional measurement of patterns, and the like are carried out by using an image picked up.
The magnification of the charged particle microscope is determined by the magnitude of the voltage applied to the electrostatic lens or the intensity of the current flowing through the coil of the electromagnetic lens. The focus of the charged particle microscope is controlled by the current flowing through the coil of the objective lens in the form of an electrostatic lens or an electromagnetic lens do.
As an example, a scanning electron microscope is a widely used microscope for observing a microstructure and a shape of a small size in a solid state. Since it is easy to observe a three-dimensional image with a deep focal depth, a three- dimensional shape Is an analyzer that can observe at high magnification. It is composed of electron gun, electromagnetic lens, and detector.
The role of the electron gun is to make and accelerate electrons. The electron gun supplies a stable electron source used in the form of an electron beam. The primary electrons are made to be large enough to produce a sufficient amount of secondary cells, and are designed to effectively form a small beam by a magnetic lens.
The electromagnetic lens is a cylindrical electromagnet in which a coil is wound and serves to collect electrons in one place by utilizing the property of electrons being deflected by a magnetic field. The focusing lens serves to collect the electron beam that has exited the electron gun and is combined with the aperture to determine the intensity of the electron beam. If the size of the aperture is small, the size of the spot becomes small, the number of electrons passing through decreases, and spherical aberration is reduced.
The objective lens for determining the size of the beam irradiated on the sample is also referred to as an electron beam forming lens. In order to form a small electron beam, the focal distance is short and is positioned close to the surface of the sample.
Also, the irradiation direction of the charged particle beam can be controlled by a deflector provided between the focusing lens corresponding to the electromagnetic lens and the objective lens and controlling the irradiation direction of the charged particle beam. The deflector may include one or a plurality of deflectors, and the position of the probe may be moved by adjusting a beam locus therefrom.
On the other hand, a general scanning electron microscope can produce an image of a sample by detecting secondary electrons or reflection electrons generated in the sample when the electron beam scans the surface of the sample surface in a plane.
As a conventional technique for improving the image of such a charged particle beam microscope, in order to minimize distortion at the point where the rising of the waveform starts after the descent, in the prior art publication No. 10-2011-0061009 (June, In the US Patent No. 7230240 (Jun. 12, 2007), there is disclosed a passive type control device of a passive electron microscope which minimizes distortion by a method of delaying time using a spline curve generation method. Discloses a method for improving the SEM image by measuring the portion of the charged particle beam microscope apparatus as data only. In Patent Document 10-2013-0135345 (Oct. 10, 2013) A gain value and a second gain value, and calculating a weight value of each of the obtained values, thereby synthesizing the first image and the second image, and capturing an image.
However, in the prior art including the prior art, the signal applied to the deflector is not linearly correlated with the signal actually output in the deflector due to the physical characteristics of the deflector itself, and therefore, And the like.
Therefore, there is an urgent need to develop a control method of a charged particle scan signal which can obtain information of the sample realistically more accurately and also obtain the information of the sample quickly.
SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a charged particle microscope capable of preventing distortion of a control signal applied to a deflector, It is an object of the present invention to provide a method and an apparatus for controlling a scanning signal.
It is another object of the present invention to provide a charged particle microscope capable of minimizing a transient response and thereby rapidly providing information on a surface of a sample without distortion by providing a scan profile that minimizes a distorted transient response due to the deflector. .
According to an aspect of the present invention, there is provided a lithographic apparatus comprising: at least one deflector for controlling and changing a direction of irradiation of a charged particle beam; A generator for generating a scan profile for controlling the irradiation direction of the charged particle beam and providing the scan profile to the deflector; And a scan waveform control unit for controlling a current waveform actually output from the deflector, the method comprising the steps of: (a) generating a scan waveform in accordance with a preset scan profile r (t) Generating a scan profile signal r (t) so as to control the irradiation direction of the charged particle beam and inputting the scan profile signal r (t) to the deflector; A current waveform actually output from the deflector in accordance with the scan profile signal
Where k1 is a positive real number greater than zero, and k2 is a real number.
In one embodiment, the charged particle beam used in the charged particle beam microscope may be any one selected from an electron beam, a hydrogen ion beam, and a helium ion beam.
In one embodiment, the corrected scan profile signal u (t) may be stored in the memory of the spheric control unit and used repeatedly as an input signal to the deflector.
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In one embodiment, the current waveform of the predetermined scan profile r (t) may be any one selected from the serpentine, triangular, and trapezoidal shapes or a combination thereof.
In one embodiment, the corrected scan profile signal u (t) is a difference between the corrected scan profile signal u (t-1) immediately before in the sine wave control unit and the current waveform signal actually output from the deflector e (t) = r (t-1) - x coil (t)).
The present invention also provides a charged particle beam exposure apparatus, comprising: a charged particle source for emitting a charged particle beam; At least one deflector for controlling and changing the irradiation direction of the charged particle beam emitted from the charged particle source; A generator for generating a scan profile (r (t)) for controlling the irradiation direction of the charged particle beam and providing the generated scan profile to the deflector; The current waveform actually output from the deflector (
Where k1 is a positive real number greater than zero, and k2 is a real number.
In this case, the deflector may be positioned at the upper end and the lower end, respectively, and the sine wave type control unit may output the corrected scan profile signal by controlling the upper deflection coil and the lower deflection coil, respectively.
Also, the corrected scan profile signal u (t) is stored in a memory included in the scan waveform controller and is used repeatedly as an input signal of the deflector.
Also, the charged particle beam microscope includes a focusing lens group including an intermediate focusing lens provided on the charged particle source side and an objective lens serving as a final focusing lens provided on the sample side; And a sample stage located at the lower end of the objective lens and capable of supporting and moving the sample to which the charged particle beam is irradiated.
The scanning signal control method of the charged particle microscope provided in the present invention can cope with the electric force or the magnetic force distortion caused by the physical characteristics of the deflector without adding a separate device and can prevent the distortion of the control signal applied to the deflector .
Also, the present invention can provide a charged particle microscope capable of minimizing distorted transient response due to the presence of a deflector, thereby promptly providing information on a sample surface without distortion.
Also, according to the control method of the present invention, by storing a distortion-prevented scan signal in a memory or the like, the response time can be faster than that of the conventional technique, thereby realizing high-speed scanning.
1 is a view showing the structure of a general charged particle beam microscope.
2 is a view for explaining a raster scan method for searching a surface of a sample in a charged particle beam microscope.
FIG. 3 is a graph showing an analog signal (FIG. 3A) and a digital deflection signal (FIG. 3B) applied in the fast and slow directions of signals applied to the deflector in the control system when the scanning search method is implemented in a charged particle beam microscope to be.
FIG. 4 is a schematic view showing an electric equivalent circuit when a deflector for controlling an electron beam is used in a charged particle beam microscope. FIG.
FIG. 5 is a schematic diagram of an embodiment of a scanning electron microscope according to the present invention, which is implemented when scanning the surface of a sample (FIG. 4A) by implementing a scan search scheme and acquiring a first distorted deflection signal form (FIG. 5B) (Fig. 5C), which is a view of a distorted image.
FIG. 6 is a schematic diagram of a scanning electron microscope (SEM), when applied to the deflector in a second distorted deflection signal form (FIG. 6B) by physical characteristics, when searching the surface of the sample (FIG. 5A) (Fig. 6C) that can be used to reconstruct a distorted image.
7 is a flowchart showing the method proposed by the present invention.
FIG. 8 is a diagram illustrating a charged particle beam microscope according to an embodiment of the present invention. In the case where a detected signal in the deflector is distorted (FIG. 8A), a corrected signal 8B) and a signal detected in the deflector according to the corrected signal.
FIG. 9 is a graph showing the relationship between the signal (FIG. 9B) outputted from the deflector and the obtained image (FIG. 9C) when the scanning search method is implemented in the charged particle beam microscope according to the embodiment of the present invention, ).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings of the present invention, the sizes and dimensions of the structures are enlarged or reduced from the actual size in order to clarify the present invention, and the known structures are omitted so as to reveal the characteristic features, and the present invention is not limited to the drawings . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention.
1 shows a structure of a charged particle beam microscope which is generally used. More specifically, the charged particle beam microscope includes a charged
Here, the charged particle beam microscope apparatus of FIG. 1 focuses a charged particle beam emitted from a charged particle source in a vacuum chamber into a plurality of focusing lens groups to form a beam spot, that is, a probe focused on the surface of the sample, And the position of the probe is adjusted by adjusting the beam locus using a deflector of the sample to observe the shape of the sample or to emit secondary electrons from the sample to obtain information of the sample. At this time, since the charged particle beam can collide with air molecules and be scattered, the vacuum chamber including the beam scanning region between the charged particle source and the focusing lens group must be evacuated to maintain a high vacuum environment by using a vacuum pump .
A vacuum pump may be provided so as to have a pressure of 10 -2 Pa or less, preferably 10 -3 Pa or less, in order to maintain the pressure inside the vacuum chamber including the charge-receiving source and the focusing lens group at a high vacuum.
At this time, the charged particle beam emitted from the charged particle source is focused by a rotationally symmetrical electric field or a magnetic field induced from the focusing lens group around the optical axis indicated by the one-dot chain line in Fig. Unlike the optical system, in the case of a charged particle beam, a magnetic field formed by an electric field or an electric coil formed by an electrode functions as a focusing lens group.
The size of the probe, which is a beam spot focused on the surface of the sample by the focusing lens group, determines the resolution when observing the shape of the sample. Generally, the smaller the probe size, the better the resolution and precision.
Further, the focusing lens group for controlling the charged particle beam has an aberration, the size of the probe is determined by the aberration, and as the aberration of the lens is increased, the size of the probe is increased and the observation resolution is degraded.
Also, if the trajectory of the charged particle beam deviates from the center of the objective lens, the aberration rapidly increases and the spot size becomes large. In order to prevent this, a deflector may be provided on the objective lens. Generally, the deflector may be composed of a plurality of deflectors, and may have a two-stage structure, which is exemplarily divided into a top flat plate and a bottom deflector.
In Fig. 1, as the deflector, a deflector composed of a top deflector and a bottom deflector is configured to control the beam trajectory so that the trajectory of the beam passes through the center of the lens. More specifically, the lower deflector deflects the charged particle beam incident on the upper deflector, and the lower deflector deflects the charged particle beam deflected by the upper deflector so as to be incident on the center of the objective lens, And serves to minimize the aberration generated.
The deflector uses a magnetic lens type which controls a magnetic field in a charged particle microscope using an electron beam in a charged particle beam, and uses an electrostatic lens type that controls an electric field in a charged particle microscope using an ion beam.
FIG. 2 is a view for explaining a Raster scan method for searching a surface of a sample in a general charged particle beam microscope, wherein the deflector includes a charged particle beam as shown in FIG. 2,
That is, according to FIG. 2, the deflector moves the coordinates of the vertical axis in the slow search direction after scanning the charged particle beam in the fast scan direction for a predetermined time in the direction of the horizontal axis (x axis) The scan is performed for a predetermined time.
FIG. 3 is a diagram showing an analog signal (FIG. 3A) or a digital deflection signal (FIG. 3B) applied in the fast and slow directions of signals applied to the deflector when the scanning search method is implemented in a general charged particle beam microscope.
That is, the scan signal can use an analog signal applied in a fast search direction and an analog signal applied in a slow search direction as shown in FIG. 3A. Recently, a digital system has been developed, They also use digital signals that are applied in myth and slow seek direction. Such a scanning signal has a wider search area when the output size is larger and a smaller search area when the output size is smaller. Also, the higher the scanning frequency of the scanning signal, the shorter the time to acquire the sample surface information and the slower the frequency becomes.
On the other hand, in order to acquire the sample surface information without distortion in the charged particle beam microscope, the spot of the charged particle beam linearly corresponds to the set scanning signal, so that the surface of the sample is moved in the direction of the charged particle in the fast searching direction and in the slow searching direction It must move along the charge particle movement path.
However, the path of the charged particle beam is not always linear depending on the physical characteristics of the deflector. That is, the scanning signal may be distorted in accordance with the inherent impedance of the lens constituting the deflector 30 in the lens constituting the deflector 30.
This will be described in detail with reference to FIG. FIG. 4 is a schematic view showing an electric equivalent circuit when a deflector for controlling an electron beam is used in a charged particle beam microscope. FIG.
The applied current has electric characteristics such as delay time and counter electromotive force due to the resistance component and the coil component. This electrical characteristic can distort the shape of the magnetic force that controls the path of the electron beam by distorting the linearly varying current signal, which causes the position and path of the charged particle beam to be irradiated on the surface of the sample to be distorted, There is a problem to be collected, and it is also hindered to acquire information of the surface in a short time.
The distortion of the inherent electrical or magnetic signal due to the deflector can be more specifically seen in FIGS. 5 and 6. FIG.
FIG. 5 is a schematic diagram of an embodiment of a scanning electron microscope according to the present invention, which is implemented when a scanning search method is implemented to search a surface of a sample (FIG. 5A) and obtains a first distorted deflection signal form (FIG. 5B) (Fig. 5C), which is a view of a distorted image.
That is, when a charged particle beam is scanned on a standard sample having a hexahedron structure having a predetermined length, length, and height, as shown in FIG. 5A, a scan with a fast search direction distorted by the inherent impedance caused by the deflector The distorted measurement image is shown from the signal.
More specifically, FIG. 5B shows a distorted line wave type according to the inherent physical characteristics of the deflector, and the above-mentioned line wave type shows a shape having a high initial value in a curve form and a high slope value with time . The above-described sinusoidal waveform having a curved slope has a coordinate different from that of the linear slope directly inputted to the deflector. As a result, a distorted image is output as shown in FIG. 5C. It should have the x and y values of each coordinate but the overlapping of the coordinate y occurs and the distorted image is output.
That is, as shown in FIG. 5B, when the distorted deflection signal originating from the deflector has a low value in comparison with the linear signal (the slope value of y = kx) during the initial time, the value of the y-axis becomes lower than the actual value, so that the image of the final output image can not be obtained as the image of the form shown in Fig. 5C.
5A, when a signal applied to the deflector is output in a distorted shape as shown in FIG. 5B, an image of an output image finally obtained due to the distorted deflection signal Is distorted as shown in FIG. 5C.
FIG. 6 is a diagram illustrating a case where the distortion can be generated according to a distorted line wave type having a shape different from that of FIG. 6a) by implementing a scanning search scheme in a charged particle beam microscope, and when applied to a second deflected deflection signal form (Fig. 6b) by a physical property on a deflector, FIG. 5B is a graph showing a distorted image (FIG. 6C) that can be obtained. In FIG. 5B, the initial waveform of the output waveform from the deflector is curved in accordance with the inherent properties of the deflector, 6B shows a shape in which the initial waveform is increased in the form of a curve and has a lower slope value as time elapses. Thus, the image of the finally obtained output image is also shown in FIG. 6C It can be confirmed that the shape is distorted.
Therefore, the present invention is to provide a novel scanning electron microscope (SEM) scanning signal control method for preventing the distorted image as shown in FIG. 5 and / or FIG. 6 from being obtained.
The present invention provides a scanning signal control method of the charged particle beam microscope described with reference to FIG.
In more detail, the control method includes at least one deflector for controlling and changing the irradiation direction of the charged particle beam. A generator for generating a scan profile for controlling the irradiation direction of the charged particle beam and providing the scan profile to the deflector; And a scan waveform control unit for controlling a current waveform actually output from the deflector, the method comprising the steps of: (a) generating a scan waveform in accordance with a preset scan profile r (t) Generating a scan profile signal r (t) so as to control the irradiation direction of the charged particle beam and inputting the scan profile signal r (t) to the deflector; A current waveform actually output from the deflector in accordance with the scan profile signal
In the present invention, the deflector is the same as that described above, and the repetitive wave generator generates a scan profile of a predetermined value from a user and provides the scan profile to the deflector.
The scan waveform control unit controls the current waveform actually output from the deflector. The scan waveform control unit controls the scan waveform signal u (t) from the preset scan profile signal and the current waveform signal actually output from the deflector, And inputting it to the deflector, thereby allowing the deflector to control the scanning signal of the charged particle beam.
The control method of the present invention will be described in more detail with reference to FIGS. 8 and 9 below.
(R (t)) so that the irradiation direction of the charged particle beam can be controlled in accordance with the preset scan profile signal r (t), which is the first step in the control method of the present invention, And inputting the scan profile signal to the deflector includes inputting a scan profile signal having a predetermined period in a triangular shape, a saw shape, or a trapezoid shape into the deflector, And a step of generating a signal value corresponding to the input signal in the deflector.
As a second step, the current waveform actually output from the deflector in accordance with the scan profile signal
In the third step, the corrected scan profile signal u (t) is obtained from the scan profile signal and the current waveform signal actually output from the deflector in the scan wave control unit, r (t)) and the current waveform actually output from the deflector
Here, since the current waveform (x coil (t)) to be actually output undergoes an deflected because I is after the signal originally under the influence of the bias-flight coil (coil) input scan profile signal and is to have a different value in the deflector, The difference e (t) = r (t) - x coil (t) can correct the degree of distortion by the deflector.
On the other hand, the present invention can input a correction value obtained according to the following equation as the optimal corrected scan profile signal from the difference e (t) = r (t) - x coil (t) .
Where r (t) and x coil (t) are as previously defined, k1 is a positive real number greater than zero, and k2 is a real number.
Here, an optimal corrected scan profile signal can be presented when k1 and k2 are appropriately selected as arbitrary values.
The step of controlling the irradiating direction of the charged particle beam by allowing the corrected scan profile signal u (t) to be input to the deflector by the fourth step of the sine wave type control unit includes: u (t)) into the deflector, thereby correcting the distorted scan waveform resulting from the deflector.
8A and 8B are diagrams for explaining a case where the detection signal in the deflector is distorted (FIG. 8A) in a charged particle beam microscope according to an embodiment of the present invention, 8b and a signal detected by the deflector in accordance with the corrected scanning signal.
More specifically, when the detection signal in the deflector has a curve having a shape with a high initial value and a low slope value as time passes, as shown in FIG. 8A, 8b) is input to the deflector, the signal finally detected by the deflector according to the corrected scanning signal has a shape as shown in FIG. 8c, thereby preventing distortion.
FIG. 9 is a graph showing the relationship between the signal (FIG. 9B) outputted from the deflector and the obtained image (FIG. 9C) when the scanning search method is implemented in the charged particle beam microscope according to the embodiment of the present invention, ).
According to FIG. 9, unlike FIGS. 5 and 6, distorted image information caused by a deflector is not displayed, so that an image identical to an original image can be output.
Illustratively, the scan waveform generator and the scan waveform controller in the present invention may be provided in a
In the present invention, the charged particle beam used in the charged particle beam microscope may be any one selected from an electron beam, a hydrogen ion beam, a helium ion beam, and a gallium ion beam.
Also, the current waveform of the preset scan profile r (t) in the present invention may be any one selected from the serpentine, triangular, and trapezoidal shapes or a combination thereof.
Also, in the present invention, the corrected scan profile signal u (t) may be stored in the memory of the spheric control unit and used repeatedly as an input signal of the deflector. In this case, it is possible to have a response time faster than that of the conventional technology, thereby realizing high-speed scanning.
In other words, the corrected scan profile signal according to the present invention can be stored in the memory to repeatedly use the u (t) value of the scan profile signal stored in the memory, and the repeated use of the signal stored in the memory Therefore, high-speed scanning can be realized.
In the present invention, the corrected scan profile signal u (t) is a difference between the corrected scan profile signal u (t-1) immediately before in the sine wave control unit and the current waveform signal actually output from the deflector e (t) = u (t-1) - x coil (t)). Where u (t-1) is the immediately preceding scan profile, which is the difference between the previous corrected scan profile u (t-2) or the preset scan profile r (t) Can be obtained by using the difference of the current waveform (x coil (t-1)).
That is, by using the corrected signal immediately before the value input to the deflector, the distortion of the scan profile signal output to the deflector from the deflector can be further reduced.
Further, the present invention can provide a charged particle beam microscope capable of implementing a method of controlling a scanning signal of the charged particle beam microscope. More specifically, it comprises: a charged particle source for emitting a charged particle beam; At least one deflector for controlling and changing the irradiation direction of the charged particle beam emitted from the charged particle source; A generator for generating a scan profile (r (t)) for controlling the irradiation direction of the charged particle beam and providing the generated scan profile to the deflector; The current waveform actually output from the deflector (
In one embodiment, the current waveform meter measures a voltage drop of a sensing resistor provided at an end of a wire of a hall sensor, which detects the intensity of a magnetic field flowing through a scanner wire and measures the intensity of the current, And it is possible to measure the intensity of the current flowing through the conductor by detecting the intensity of the magnetic field flowing through the scanner conductor and to measure the voltage drop of the sensing resistor provided at the end of the lead of the scanner And indirectly detecting the current waveform flowing through the conductor.
In one embodiment, the deflector may be positioned at the upper end and the lower end, respectively, and the above-mentioned sine wave type control unit controls the upper deflection coil and the lower deflection coil, respectively, or simultaneously, have.
The present invention also relates to a charged particle beam source for emitting a charged particle beam; A focusing lens group including an intermediate focusing lens provided on the charged particle source side and an objective lens serving as a final focusing lens provided on the sample side; At least one deflector provided between the intermediate focusing lens and the objective lens for controlling and changing the irradiation direction of the charged particle beam emitted from the charged particle source; A generator for generating a scan profile (r (t)) for controlling the irradiation direction of the charged particle beam and providing the generated scan profile to the deflector; The current waveform actually output from the deflector (
This is an additional component of the charged particle beam microscope, which includes a focusing lens group including an intermediate focusing lens provided on the charged particle source side and an objective lens serving as a final focusing lens provided on the sample side, and a focusing lens group disposed on the lower end of the objective lens, This is equivalent to additionally providing a sample stage capable of supporting and moving the sample to be irradiated.
Also, in the present invention, the charged particle beam microscope may further include a beam column through which the particle beam emitted from the focusing lens passes, and which changes the path of the particle beam.
The present invention also relates to an electron beam source for emitting an electron beam; A focusing lens group including an intermediate focusing lens provided on the electron beam source side and an objective lens serving as a final focusing lens provided on the sample side; At least one deflector provided between the intermediate focusing lens and the objective lens for controlling and changing the irradiation direction of the charged particle beam emitted from the charged particle source; A generator for generating a scan profile (r (t)) for controlling the irradiation direction of the charged particle beam and providing the generated scan profile to the deflector; The current waveform actually output from the deflector (
This corresponds to an embodiment in which the charged particle beam microscope corresponds to that used as a scanning electron microscope and thus includes a secondary electron detector for detecting secondary electrons emitted from the sample.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims. It can be understood that it is possible.
11: optical axis 12: charged particle source
13: a charged particle beam 14: a charged particle beam deflected by an upper deflector
15: charged particle beam deflected by the lower deflector
16: a charged particle beam collected by the objective lens
17: charged particle beam spot 21: intermediate focus lens
22: objective lens 31: top deflector
32: lower deflector 41: sample
42: Sample stage 43: Original image of the sample
44: Distorted image measured by deflection signal type 1
45: distortion image measured by distorted deflection signal type 2
46: The image obtained when a control signal is applied to the deflector by the method proposed in the present invention
50: detector 51: detection signal
61: Vacuum chamber 62: Vacuum chamber interior
70: a charged particle beam control system 71: an upper deflector deflection control signal
72: lower deflector deflection control signal
80: high voltage amplifier 81: amplified upper deflector deflection control signal
82: amplified lower deflector deflection control signal
90: Host computer
91: Communication signal between host and charged particle beam control system
100: Fast search direction 101: Charge moving path in fast search direction
103: analog deflection signal applied in fast seek direction
104: Digital deflection signal being human in fast seek direction
105: Distortion signal applied to deflector type 1
106: Distortion signal applied by the deflector 2
107: input signal to deflector of fast seek direction controlled using the method according to the invention when a distorted signal applied by the deflector is generated
108: a control signal actually applied to the deflector expected when the deflector control signal obtained using the method according to the present invention is applied to the deflector
200: Slow search direction 201: Travel path of the charged particle beam in the slow search direction
202: analog deflection signal applied in the slow seek direction
203: Digital deflection signal applied in the slow seek direction
Claims (13)
A generator for generating a scan profile for controlling the irradiation direction of the charged particle beam and providing the scan profile to the deflector; And
And a scan waveform controller for controlling a current waveform actually output from the deflector, the method comprising the steps of:
Generating a scan profile signal r (t) so as to control the irradiating direction of the charged particle beam in the re-shaping generator according to a preset scan profile r (t) and inputting the scan profile signal r (t) to the deflector;
A current waveform actually output from the deflector in accordance with the scan profile signal
Obtaining a corrected scan profile signal u (t) from the scan profile signal and the current waveform signal actually output from the deflector; And
And controlling the irradiating direction of the charged particle beam so that the corrected scan profile signal u (t) is input to the deflector by the sine wave type controller,
The corrected scan profile signal may be generated by a predetermined scan profile r (t) and a current waveform actually output from the deflector
Or the corrected scan profile signal U (t)
Where k1 is a positive real number greater than zero, and k2 is a real number.
Wherein the charged particle beam used in the charged particle beam microscope is any one selected from an electron beam, a hydrogen ion beam, and a helium ion beam.
Wherein the corrected scan profile signal u (t) is stored in a memory of a sine wave control unit and is used repeatedly as an input signal of a deflector.
Wherein the current waveform of the preset scan profile r (t) is any one selected from a saw-tooth, triangle, and trapezoidal shape or a combination thereof.
The corrected scan profile signal u (t) is obtained by subtracting a difference (e (t) = 1) between the corrected scan profile signal u (t-1) immediately before and the current waveform signal actually output from the deflector, u (t-1) -xcoil (t)), respectively. The method for controlling the scanning signal of the charged particle beam microscope according to claim 1,
At least one deflector for controlling and changing the irradiation direction of the charged particle beam emitted from the charged particle source;
A generator for generating a scan profile (r (t)) for controlling the irradiation direction of the charged particle beam and providing the generated scan profile to the deflector;
The current waveform actually output from the deflector (
(R (t)) of the scan waveform generator is compared with a signal from the current waveform meter,
The scan profile (r (t)) and the current waveform actually output from the deflector (
Where k1 is a positive real number greater than zero, and k2 is a real number.
Wherein the deflector is located at an upper end and a lower end, respectively.
Wherein the sine wave type control unit outputs the corrected scan profile signal by controlling the upper deflection coil and the lower deflection coil respectively or simultaneously.
Wherein the corrected scan profile signal u (t) is stored in a memory provided in the scan waveform controller and is used repeatedly as an input signal of the deflector.
Wherein the charged particle beam microscope comprises a focusing lens group including an intermediate focusing lens provided on a charged particle source side and an objective lens serving as a final focusing lens provided on a sample side; And
And a sample stage located at the lower end of the objective lens and capable of supporting and moving the sample to which the charged particle beam is irradiated.
A focusing lens group including an intermediate focusing lens provided on the electron beam source side and an objective lens serving as a final focusing lens provided on the sample side;
At least one deflector provided between the intermediate focusing lens and the objective lens for controlling and changing the irradiation direction of the charged particle beam emitted from the charged particle source;
A generator for generating a scan profile (r (t)) for controlling the irradiation direction of the charged particle beam and providing the generated scan profile to the deflector;
The current waveform actually output from the deflector (
(R (t)) of the scan waveform generator is compared with a signal from the current waveform meter,
The scan profile (r (t)) and the current waveform actually output from the deflector (
A sample stage located at the lower end of the objective lens and capable of supporting and moving the sample irradiated with the electron beam; And
And a secondary electron detector for detecting secondary electrons emitted from the sample.
Where k1 is a positive real number greater than zero, and k2 is a real number.
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| PCT/KR2015/005287 WO2015190723A1 (en) | 2014-06-13 | 2015-05-27 | Method for controlling scanning signal of charged particle microscope, and apparatus using same |
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