WO2016024704A1

WO2016024704A1 - Particle beam control apparatus and method for charged particle microscope

Info

Publication number: WO2016024704A1
Application number: PCT/KR2015/005337
Authority: WO
Inventors: 한철수; 배문섭; 조복래; 박인용; 박창준; 김주황; 안상정
Original assignee: 한국표준과학연구원
Priority date: 2014-08-13
Filing date: 2015-05-28
Publication date: 2016-02-18
Also published as: KR20160020598A; KR101639581B1

Abstract

The present invention relates to a particle beam control apparatus and method for a charged particle microscope and, more particularly, to a charged particle beam control apparatus and a charged particle beam control method using the same, which controls a charged particle beam within a charged particle microscope, to correct dynamic characteristics distorted by a deflector (scanner) of an electrostatic scheme or a magnetic scheme and irradiate the charged particle beams to a desired location in order to acquire information on a specimen surface, thereby preventing a measured image of the specimen surface from being distorted, enabling rapid acquisition of the image, and enabling the specimen surface to be processed in a desired form.

Description

Apparatus and method for controlling particle beam of charged particle microscope

The present invention relates to an apparatus and a method for controlling a particle beam of a charged charge microscope, and more particularly, to control the charged particle beam in a charged particle microscope, so as to obtain information on the surface of a sample, by using an electrostatic or magnetic deflector (scanner). By correcting the dynamic characteristics distorted by), and irradiating the charged particle beam to a desired position, the image of the measured sample surface is prevented from being distorted, the image can be obtained at high speed, and the sample surface is processed to a desired shape. The present invention relates to a charged particle beam control apparatus and a method for controlling a charged particle beam using the same.

As a method for observing the surface form or structure of a material on a nano scale or atomic scale in a vacuum atmosphere, a charged particle beam of electrons or ions can be used. Using such a charged particle beam, it is possible to produce a high resolution microscope that can observe the surface of the material to be observed at the nano or atomic level beyond the limit of the limited resolution in the optical microscope.

In such a charged particle microscope, a charged particle beam is irradiated to a target sample, and a particle (e.g., charged particles of the same or different type as the irradiated charged particles or electromagnetic waves or photons) emitted from or passed through the target sample is detected by a detector. The enlarged image of the target sample can be acquired. In particular, in the semiconductor manufacturing process, a scanning electron microscope, a scanning ion microscope, a scanning transmission electron, etc. are used for the inspection of a semiconductor wafer, measurement of a pattern dimension, a crab side of a pattern shape, etc. Charged particle microscopes, such as a scanning transmission electron microscope, are used. In these applications, semiconductor images and defects are observed, defect detection and occurrence factor analysis, pattern measurement, etc. are performed using the image picked up.

The charged particle microscope is magnified by the magnitude of the applied voltage of the electrostatic lens or the intensity of the current through the coil of the electromagnetic lens, the focus of the image is adjusted by the current flowing through the coil of the objective lens of the electrostatic lens or electromagnetic lens type do.

An example of a charged particle microscope is a scanning electron microscope.

The scanning electron microscope is a microscope widely used for observing small-sized microstructures and shapes in a solid state, and has a high depth of focus and easy observation of three-dimensional images, and thus has a high magnification of three-dimensional shapes such as complex surface structures and crystal shapes. As an analytical device that can be observed with a scanning electron microscope, the scanning electron microscope is composed of an electron gun, an electromagnetic lens, and a detection device.

The role of the electron gun serves to create and accelerate electrons. The electron gun supplies a stable source of electrons used in the form of electron beams. It is designed to make a large amount of primary electrons enough to produce a sufficient amount of secondary batteries, but 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 using a property in which electrons are bent by a magnetic field. The focusing lens collects the electron beams that have exited the electron gun and is combined with the aperture to determine the intensity of the electron beams. Smaller apertures reduce spot size, reduce the number of electrons passing through, and reduce spherical aberration.

In addition, the objective lens, which determines the size of the beam irradiated onto the sample, is also called an electron beam forming lens. In order to produce a small electron beam, the focal length is short and is located close to the surface of the sample.

In addition, the irradiation direction of the charged particle beam may be controlled by a deflector provided between the focusing lens and the objective lens corresponding to the electromagnetic lens and controlling and changing the irradiation direction of the charged particle beam. The deflector may be provided in one or a plurality, and the position of the probe may be moved by adjusting the beam trajectory.

On the other hand the vacuum pump that the objective lens is located in the lower sample stage for moving the specimen, it is possible to attach the various detectors such as a secondary electron detector for detecting secondary electrons, the lower end of the equipment the vacuum chamber is maintained below 10 ^-5 torr, And a high voltage supply device for supplying a high voltage to an electron gun and a detector.

The brightness of a point in the scanning electron microscope image is proportional to the number of secondary electrons generated at the corresponding region of the specimen by the interaction of the electron beam and the specimen, and is determined by collecting a signal of the secondary electron at each point of the specimen of the electron beam. Record in pixels.

As a conventional technique for improving the image of such a charged particle beam microscope, Korean Patent Laid-Open No. 10-2011-0061009 (2011.06.09.) Discloses a method for minimizing distortion at a point where a rise of a waveform starts after falling. A scanning waveform control apparatus of a runner electron microscope that minimizes distortion by delaying time by using a -spline curve generation method is described, and US Patent Publication No. US 7230240 (2007.06.12.) It describes a method of improving the SEM image by measuring the data consisting only of linear parts.

In addition, Korean Patent Registration No. 10-0858982 (2008.09.10.) Describes a technique related to an integrated controlled electron microscope that integrates and controls the components of the electron microscope using a single DSP and easily improves the UI. In Korean Patent Publication No. 10-2013-0135345 (Dec. 10, 2013), the gain of a detector of a charged particle microscope device is set to a first gain value and a second gain value, and the obtained value is calculated by weighting each of the first values. A method of synthesizing an image by combining an image and a second image is described.

However, in the prior art including the prior art, due to the physical characteristics of the deflector itself, the signal applied to the deflector does not linearly correspond to the signal actually output in the deflector, which is why it is not an actual image of the sample. There is a problem that the side shows a distorted shape.

Therefore, there is an urgent need for the development of a method and apparatus for controlling charged particle scanning signals that can more accurately obtain information on an actual image of a sample and also provide information of the sample quickly.

Therefore, in order to solve the above problem, the scanning signal control of a charged particle microscope capable of preventing the distortion of the control signal applied to the deflector by using a device capable of responding to the electric or magnetic force distortion due to the physical characteristics of the deflector It is an object of the invention to provide an apparatus and method.

In addition, the present invention provides a scan signal that minimizes the transient response distorted by the deflector, thereby minimizing the transient response, thereby providing information on the sample surface without distortion, thereby generating a distortion-free pattern of the sample surface information It is another object of the invention to provide a charged particle microscope.

In order to solve the above problems, the present invention provides 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 scan waveform generator for generating a scan profile r (t) for controlling the irradiation direction of the charged particle beam and providing it to the deflector; The response signal actually output from the deflector (

Response signal measuring instrument for measuring; And a scan profile r (t) in the scan waveform generator and a response signal from the response signal measuring device (

) Generates a corrected scan profile signal u (t), which is optionally input by a controller provided therein to a) the deflector and subsequently corrected scan profile signal u (t + 1) Is calculated from the previous corrected scan profile signal u (t) and the response signal xcoil (t + 1) actually output from the deflector and input to the deflector each time, or b) the corrected scan profile signal Provided is a charged particle beam microscope comprising a; scanning waveform control unit (u (t)) is stored in a memory that can be stored and repeatedly used as an input signal of the deflector to the deflector.

In another aspect, the present invention is one or more deflector for controlling and changing the irradiation direction of the charged particle beam; A scan waveform generator for generating a scan profile r (t) for controlling the irradiation direction of the charged particle beam and providing it to the deflector; The response signal actually output from the deflector (

Response signal measuring instrument for measuring; And a scan profile r (t) in the scan waveform generator and a scan profile signal u (t) corrected from the response signal measuring device, and generated by a controller provided therein. Claims [1] A method of controlling a scanning signal of a charged particle beam microscope, comprising: a scanning waveform controller for selectively inputting a signal u (t) into a memory in which a signal u (t) may be stored.

Generating and inputting a scan profile signal r (t) to the deflector so as to control the irradiation direction of the charged particle beam in the scan waveform generator according to a preset scan profile r (t); A response signal actually output from the deflector according to the scan profile signal (

Measuring); The scan profile controller r (t) and the response signal actually output from the deflector in the scan waveform controller

Obtaining a corrected scan profile signal u (t); And when the scan profile signal u (t) corrected by the controller is input to the deflector, the subsequent corrected scan profile signal u (t + 1) is the immediately corrected scan profile signal u (t). )) And from the response signal xcoil (t + 1) actually output from the deflector to be inputted to the deflector each time. The corrected scan profile signal u (t) is input to the memory. It provides a method of controlling the scanning signal of a charged particle beam microscope comprising a; processing the corrected scan profile signal (u (t)) to be used repeatedly as an input signal of the deflector.

The particle beam control apparatus of the charged particle microscope provided in the present invention can cope with the charged particle beam path distortion caused by electric or magnetic force distortion resulting from the physical characteristics of the deflector (scanner) operating in an electrostatic or electromagnetic manner. It is possible to prevent path distortion of the charged particle beam by preventing distortion of an applied scan signal.

In addition, the present invention can provide a charged particle microscope capable of minimizing a distorted transient response due to the presence of the deflector and thereby providing information on the sample surface without distortion.

In addition, according to the control method of the present invention, by using a method of controlling the scan signal to prevent distortion in real time, it is possible to measure more precisely than the existing technology, it is possible to implement more precise measurement, processing, and patterning.

In addition, according to the control method of the present invention, by using a method of repeatedly storing the corrected scan signal in a memory or the like, it can have a faster response time than the existing technology, thereby achieving high-speed scanning.

According to the control method of the present invention, a method of updating and using a scan signal applied to a deflector in real time and a method of using a scan signal stored in a memory may be appropriately selected according to a user's environment or a user's choice. By providing a function that can be provided, the user can provide convenience according to the situation, and provides a function of automatically updating the correction scan signal stored in the memory.

1 is a diagram illustrating a general charged particle beam microscope.

FIG. 2 is a diagram for explaining a scanning search (raster scan) method for searching a surface of a sample in a charged particle beam microscope.

3 is a diagram showing analog signals (FIG. 3A) and digital deflection signals (FIG. 3B) applied in a fast direction and a slow direction among signals applied to a deflector in a control system when implementing a scanning search method in a charged particle beam microscope; to be.

FIG. 4 is a diagram illustrating a method of scanning a surface of a specimen (FIG. 4A) by implementing a scanning search method in a charged particle beam microscope, when a first distorted deflection signal shape (FIG. 4B) is applied to a deflector by physical properties. Is a picture showing a distorted image (FIG. 4C).

FIG. 5 is obtained by applying a second distorted deflection signal type (FIG. 5B) due to physical properties of the deflector when searching the surface of the specimen (FIG. 5A) by implementing a scanning search method in a charged particle beam microscope. It is a figure which shows the distorted image (FIG. 5C) which can be done.

6 is a diagram illustrating a scanning control system in a charged particle beam microscope of the present invention.

FIG. 7 illustrates a corrected signal output from the scanning waveform controller to the deflector in order to correct the detected signal of the deflector in the charged particle beam microscope according to an embodiment of the present invention (FIG. 7B). 7c) and a signal (FIG. 7d) detected by the deflector according to the corrected signal.

8 is a signal output from the deflector according to the corrected signal when searching the surface of the sample (FIG. 8A) by implementing the scanning search method in the charged particle beam microscope according to an embodiment of the present invention (FIG. 8B). ) And the image obtained (FIG. 8C).

* Description of the symbols for the main parts of the drawings *

11: optical axis 12: charged particle source

13: charged particle beam 14: charged particle beam deflected by an upper deflector

15: charged particle beam deflected by the lower deflector 16: charged particle beam collected by the objective lens

17: charged particle beam spot 21: intermediate focusing lens

22: objective 31: upper deflector

32: lower deflector 41: sample

42: sample stage 43: original image of the sample

44: Distorted image measured by distorted deflection signal form 1

45: Distorted image measured by distorted deflection signal form 2

46: Image obtained when the 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: charged particle beam control system 71: 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: charged particle moving path in the fast search direction

103: analog deflection signal applied in the fast search direction

104: Digital deflection signal that is humanized in the fast navigation direction

105: distortion signal type applied to the deflector 1 106: distortion signal applied to the deflector 2

107: Input signal to the deflector in the fast search direction controlled using the method according to the invention when a distortion signal applied by the deflector is generated

108: Control signal expected from the deflector

109: control signal actually applied to the deflector using the method according to the invention

200: slow search direction 201: movement path of the charged particle beam in the slow search direction

202: analog deflection signal applied in a slow search direction

203: Digital deflection signal applied in a slow search direction

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. In the drawings of the present invention, the size or dimensions of the structures are shown to be enlarged or reduced than actual for clarity of the present invention, and well-known configuration is omitted to show the characteristic configuration is not limited to the drawings. .

1 shows the structure of a charged particle beam microscope which is generally used. In more detail, the charged particle beam microscope is a charged particle source 12 in the vacuum chamber 62, an intermediate focusing lens 21 provided on the charged particle source side in the vacuum chamber, and a final focusing lens provided on the sample side. A focusing lens group including an objective lens 22, and provided between the intermediate focusing lens and the objective lens, and includes an upper deflector 31 and a lower deflector 32 for controlling and changing the irradiation direction of the charged particle beam. A deflector, a control system 70 generating a control signal to the deflector and applying a control signal through the high voltage amplifier 80, and a sample stage 42 capable of supporting and moving the sample 41 positioned at the lower end of the objective lens. ) May be included. For example, in the case of a scanning electron microscope, the charged particle beam spot 17 irradiated to the surface of the sample passing through the objective lens detects a reaction signal generated by reacting with the surface of the sample in the detector 50 and transmits the detection signal 51 to the control system. To pass. The transmitted detection signal is combined with coordinates in the control system to form measured image data, converted into a communication signal, and transmitted to the host computer 90 to provide the user with information on the sample surface.

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 a surface of a sample, wherein one or more By using a deflector to adjust the beam trajectory to move the position of the probe by scanning a beam on the surface of the sample to observe the shape of the sample or to emit secondary electrons from the sample to obtain the information of the sample. In this case, since the charged particle beam may collide with air molecules and be scattered, the charged particle beam should be exhausted to maintain a high vacuum environment by using a vacuum pump in a vacuum chamber including a beam scanning area between the charged particle source and the focusing lens group. .

In addition, the charged particle source may be made of an electron gun including a filament and the like, which may use tungsten and nickel, nickel alloy, titanium and the like.

And the typically 10 ^-2 Pa or less, preferably 10 charged particles to maintain the pressure inside the vacuum chamber containing the source and the focusing lens group in the ^{high-vacuum-to} have a pressure of ³ Pa or less may be provided with a vacuum pump.

At this time, the charged particle beam emitted from the charged particle source is focused by a rotationally symmetric electric or magnetic field induced from the focusing lens group about the optical axis in FIG. 1. In the case of a charged particle beam, unlike an optical system, an electric field formed by an electrode or a magnetic field formed by an electric coil serves as a focusing lens group.

The size of the probe, which is a beam spot focused by the focusing lens group and formed on the surface of the sample, determines the resolution when the sample shape is observed. In general, the smaller the probe, the better the resolution and precision.

In addition, the focusing lens group controlling the charged particle beam has an aberration, and the size of the probe is determined by the aberration, and when the aberration of the lens is large, the size of the probe increases and the resolution of observation decreases.

In addition, when the trajectory of the charged particle beam is out of the center of the objective lens, the aberration rapidly increases to increase the spot size. To prevent this, a deflector may be provided on the objective lens. In general, the deflector may be configured in plural, and may have a two-stage structure divided into an upper deflector and a lower deflector.

In FIG. 1, a deflector composed of an upper deflector and a lower deflector is configured as the deflector to control the trajectory of the beam so that the trajectory of the beam passes through the center of the lens. More specifically, the first deflection of the charged particle beam incident on the upper deflector, the lower deflector deflects the charged particle beam deflected by the upper deflector to be incident on the center of the objective lens, thereby deviating from the center of the objective lens. Minimizes aberrations that occur.

The deflector adopts a magnetic lens shape for controlling a magnetic field in a charged particle microscope using an electron beam among charged particle beams, and an electrostatic lens type for controlling an electric field in a charged particle microscope using an ion beam.

FIG. 2 is a view illustrating a raster scan method for searching a surface of a sample in a general charged particle beam microscope, wherein the deflector searches a charged particle beam as shown in FIG. While scanning in the direction 100 and the slow search direction 200, the user obtains information of the sample or detects a signal generated by reacting with the sample to provide the surface information of the sample to the user.

That is, according to FIG. 2, the deflector moves the coordinates of the vertical axis in the slow search direction after performing a scan search for a predetermined time in the horizontal axis (x axis) direction, which is a fast direction, and then returns to the horizontal axis (x axis) direction. The scan search will be performed for a certain time.

FIG. 3 is a diagram illustrating an analog signal (FIG. 3A) or a digital deflection signal (FIG. 3B) applied in a fast direction and a slow direction among signals applied to a deflector when implementing a scan search method in a general charged particle beam microscope.

That is, the scan signal may use an analog signal applied in a fast search direction as shown in FIG. 3A and an analog signal applied in a slow search direction. Recently, as a digital system is developed, a digital signal applied in a fast search direction as shown in FIG. 3B is used. It also uses digital signals that are applied in the myth and slow search direction. The scan signal has a larger search area when the output size is larger, and the search area is reduced when the output size is smaller. In addition, the higher the scanning frequency of the scanning signal, the shorter the time for acquiring the sample surface information, and the lower the frequency.

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 corresponds linearly to the set scanning signal, so that the charged particle moving path in the fast search direction and the slow search direction are located on the surface of the sample. Must move along the charged particle migration path.

However, the path of movement of the charged particle beam is not always linear depending on the physical characteristics of the deflector. That is, in the lens of the deflector 30, the scan signal may be distorted according to the inherent impedance of the physical properties of the lens.

In other words, when a deflector for controlling an electron beam is used in a charged particle beam microscope, the applied current includes electrical characteristics such as delay time and counter electromotive current by resistance components and coil components in the deflector. It can distort the shape of the magnetic force that controls the path of the electron beam by distorting the linearly changing current signal, which causes distortion of the irradiated position and path on the sample surface of the charged particle beam, thereby collecting the wrong surface signal. It also interferes with trying to acquire surface information in a short time.

For example, the distortion of an inherent electrical or magnetic signal resulting from the deflector can be described in more detail in FIG. 4.

FIG. 4 illustrates a method of scanning a scanning particle in a charged particle beam microscope to search the surface of the sample (FIGS. 4A and 43) when the first distorted deflection signal shape (FIG. 4B) is applied to the deflector by physical properties. As a diagram illustrating a distorted image (FIGS. 4C and 44) that can be obtained, the information on the surface of the sample is distorted through this.

When scanning a charged particle beam on a standard sample in which a regular hexahedral structure having a constant horizontal, vertical and height as shown in FIG. 4A is arranged, distortion from a scanning signal in a fast search direction distorted by inherent impedance due to a deflector The measured image is displayed.

In more detail, FIG. 4B shows a distorted scan waveform according to the inherent physical characteristics of the deflector, and the scan waveform has a curved form, which shows a low initial increase and a high slope value over time. . The scan waveform having the curved slope has different coordinates from the linear slope directly input to the deflector. As a result, a distorted image is output as shown in FIG. 4C. It should have a coordinate x and y value, respectively, and the overlapping of coordinate y occurs, resulting in a distorted image.

That is, as shown in FIG. 4B, when the distorted deflection signal resulting from the deflector has a low value compared to the linear signal (y = kx slope value) during the initial time, Since the value of the y-axis is lower than the actual value, the image of the finally output image is bound to obtain an image of the form as shown in FIG.

Therefore, when a standard sample having a constant size as shown in FIG. 4A is used, but the signal applied to the deflector is output as a distorted scanning waveform as shown in FIG. 4B, an image of the output image finally obtained by the distorted deflection signal is obtained. It can be seen that the distorted shape as shown in Figure 4c.

FIG. 5 is a diagram illustrating a case where it may be generated according to a distorted scanning waveform having a shape different from that of FIG. 4. More specifically, when searching the surface of the sample (FIGS. 5A and 43) by implementing a scanning search method in a charged particle beam microscope, the deflector may be applied in the form of a second distorted deflection signal (FIG. 5B) due to physical properties. When the distorted image (Figs. 5C, 45) can be obtained, the scanning waveform output from the deflector is curved in the form of a curve according to the inherent properties of the deflector. While the shape of the scan waveform has a high slope value as it passes by, the scan waveform shows a shape in which the initial increase is large in the form of a curve and has a low slope value as time passes. It can be seen that the image is distorted as shown in FIG. 5C.

Accordingly, the present invention is to provide a novel particle beam control device of the charged particle microscope and a control method using the same to prevent the image obtained in the distorted form as shown in Figure 4 and / or 5 as described above.

In the present invention for this purpose it can provide a particle beam control device of the charged particle microscope according to FIG.

Looking at this in more detail, the particle beam control apparatus of the charged particle microscope includes 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 scan waveform generator for generating a scan profile r (t) for controlling the irradiation direction of the charged particle beam and providing it to the deflector; The response signal actually output from the deflector (

) Generates a corrected scan profile signal u (t), which is optionally input by a controller provided therein into a) the deflector and subsequently corrected scan profile signal u (t + 1) ) Is calculated from the previous corrected scan profile signal u (t) and the response signal xcoil (t + 1) actually output from the deflector and input to the deflector each time, or b) the corrected scan profile And a scan waveform control unit storing the file signal u (t) in a memory in which it can be stored and repeatedly using the file signal u (t) as an input signal of the deflector.

In the present invention, the charged particle source and the deflector are the same as described above, for example, the charged particle beam used in the charged particle beam microscope may be any one selected from electron beam, hydrogen ion beam, helium ion beam, The deflector may include two upper deflection coils and a lower deflection coil.

In addition, the scan waveform generator receives a preset value from a user and generates a scan profile (r (t)) to provide it to the deflector, which has a predetermined period in a triangle, sawtooth, and trapezoidal shape. It is possible to generate a set scan profile signal, which is a periodic signal value before being changed by the deflector as the original scan profile signal, which can be first generated in the scan waveform generator and input to the deflector.

In addition, in the present invention, the response signal measuring device is a current waveform actually output from the deflector according to the scan profile signal (

And a current waveform of the distorted output by the deflector.

In one embodiment, the current waveform measuring device indirectly detects the strength of the magnetic field flowing in the scanner lead wire and measures the current intensity, and measures the voltage drop of the sensing resistor installed at the end of the lead wire of the scanner to indirectly convert the current waveform flowing in the lead wire. It can have a form such as a current detecting device for detecting by using, it is possible to detect the strength of the magnetic field flowing through the scanner lead through this to measure the strength of the current flowing through the lead, the voltage drop of the sensing resistor installed at the end of the lead It may have a function of indirectly detecting a current waveform flowing through the conductive line by measuring.

Here, since the current waveform (x coil (t)) actually output from the deflector is a signal after passing through the deflector, the current waveform has a different value from the scan profile signal originally input by the influence of the coil in the deflector. The difference between the two (e (t) = r (t) -xcoil (t)) represents the degree of distortion by the deflector, and can be used to create a corrected scan profile signal.

On the other hand, the scan waveform control unit is a portion for controlling the current waveform actually output from the deflector, and is corrected from the scan profile (r (t)) signal preset by the user and the current waveform signal actually output from the deflector Corresponding to an apparatus in which the deflector controls the scan signal of the charged particle beam by obtaining the scan profile signal u (t) and inputting it to the deflector.

To this end, the charged particle beam microscope of the present invention is a response signal actually output from the deflector in the response signal measuring device (

), The scan profile (r (t)) in the scan waveform generator and the response signal (

From the corrected scan profile signal u (t).

Here, the corrected scan profile signal u (t) is a scan profile r (t) in the scan waveform generator and a response signal actually output from the deflector (

) Can be obtained using the difference (e (t) = r (t)-xcoil (t)).

Meanwhile, in the present invention, the corrected scan profile signal u (t) may be selectively controlled by a controller provided in the scan waveform controller in one of two cases.

The first control method (a) inputs the corrected scan profile signal u (t) to the deflector and the subsequent corrected scan profile signal u (t + 1) is the immediately corrected scan profile signal u (t)) and from this, the response signal xcoil (t + 1) actually output from the deflector is newly calculated each time and input to the deflector.

As an example, when the corrected scan profile signal u (t) is input to the deflector, the subsequent corrected scan profile signal u (t + 1) is the last corrected scan profile signal u. (t)) and the difference between the response signal (xcoil (t + 1)) actually output from the deflector (e (t) = u (t)-xcoil (t + 1)) Can be input to the deflector.

In this case, the scan waveform controller receives the response signal output in real time from the deflector and reflects it to the scan profile signal to be output in the next step, and inputs it back to the deflector by an internal controller, thereby distorting the distortion resulting from the deflector. Even if the deflection signal occurs unexpectedly, it can be reflected to provide a distortion-free image suitable for the actual situation.

That is, by using the corrected signal immediately before the value input to the deflector, the scan profile signal output to the deflector can be reduced by correcting the distortion resulting from the deflector in real time.

As an example, the corrected scan profile signal U (t) may be obtained from Equation 1 below.

[Equation 1]

Where Kp is proportional gain, which is control gain, Ki is integral gain, and Kd is differential gain, each of which is a real number.

Here, an optimal corrected scan profile signal can be presented when k1 and k2 are appropriately selected as arbitrary values.

On the other hand, the second control method (b) in the present invention is the scan profile (r (t)) in the scanning waveform generator and the response signal from the response signal measuring device (

Generate the corrected scan profile signal u (t) in the memory in which the corrected scan profile signal u (t) can be stored by the controller in the scan waveform controller and store it in the deflector. It is a method of inputting to a deflector by using it repeatedly as an input signal.

In this case, the scanning waveform control unit stores the optimized profile signal in the memory such as a deflection signal having little distortion signal from the deflector by an internal controller and repeatedly uses the same, so that the charged particle beam microscope responds more quickly. It may have a speed, there is an advantage that can implement a high-speed scanning.

The control method of the scan waveform controller of the present invention can be more easily understood through FIG. 6. 6 is a diagram illustrating a scanning control system in a charged particle beam microscope of the present invention, in which a scan profile (r (t)) signal from the scanning waveform generator is input to a deflector and is actually output from the deflector signal(

) Can be obtained from the response signal measuring device and the scan profile signal u (t) corrected from both. It can be stored in memory by the controller and repeatedly inputted to the deflector (b method), or with the corrected scan profile signal u (t) immediately before to correct the distortion signal from the deflector in real time. From this, the scan profile signal corrected in real time using the difference (e (t) = u (t)-xcoil (t + 1)) of the response signal xcoil (t + 1) actually output from the deflector ( u (t + 1)) and input it to the deflector (a method).

That is, in the present invention, the scanning waveform control unit can selectively control the first control method (a) and the second control method (b) by an internal controller, so that specific experimental conditions or deflectors of the charged particle beam microscope The user can select a more convenient condition according to the electric and magnetic conditions of the surroundings.

For example, in the case of a charged particle beam microscope, it may take several hours to several days to set an optimum vacuum condition, and a great deal of human, physical and temporal resources may be administered to optimize other electromagnetic conditions. Therefore, in the case of the experiment using the charged particle beam microscope, in order to remove the distorted signal from the deflector to obtain a more accurate image, a response signal output in real time from the deflector is provided and the scan to be output in the next step is performed. It may be necessary to reflect in the profile signal, or alternatively, it may be necessary to require a faster response speed, and there may be a case in which they need to be converted and used within a specific period so that they may be parallel to each other within a predetermined time period. In this case, the present invention can provide a charged particle beam microscope that satisfies all of the previously described needs.

FIG. 7 illustrates a corrected signal output from the scanning waveform controller to the deflector in order to correct the detected signal in the deflector in FIG. 7B in the charged particle beam microscope according to the exemplary embodiment of the present invention. 7C) and a signal (FIG. 7D) detected by the deflector according to the corrected signal.

In detail, FIG. 7A illustrates a control signal 108 expected when the control signal according to the present invention is applied to the deflector, and in FIG. 7B, a high initial increment is used as the actual detection signal 106 in the deflector. 7C, the corrected scan profile signal 107 of the scanning waveform control unit is obtained in a form corresponding to the actual detection signal 106 as shown in FIG. A detection signal 109 in which distortion is prevented can be obtained.

8 is a signal actually output from the deflector according to the corrected signal when searching the surface of the sample (FIG. 8A) by implementing a scanning search method in a charged particle beam microscope according to an embodiment of the present invention (FIG. 8B ) And the obtained image (FIG. 8C), which show that the actual surface state is seen without distortion. According to FIG. 8, unlike FIG. 4 and FIG. 5, the distorted image information resulting from the deflector does not appear, thereby outputting the same image as the original image.

The present invention also provides a charged particle 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 to control and change the irradiation direction of the charged particle beam emitted from the charged particle source; A scan waveform generator for generating a scan profile r (t) for controlling the irradiation direction of the charged particle beam and providing it to the deflector; The response signal actually output from the deflector (

Response signal measuring instrument for measuring; A scan profile r (t) in the scan waveform generator and a response signal from the response signal measuring device

) Generates a corrected scan profile signal u (t), which is optionally input by a controller provided therein to a) the deflector and subsequently corrected scan profile signal u (t + 1) ) Is newly calculated each time from the previous corrected scan profile signal u (t) and the response signal xcoil (t + 1) actually output from the deflector, or input to the deflector, or b) the corrected scan profile A scanning waveform control unit storing the signal u (t) in a memory in which it can be stored and repeatedly using the signal u (t) as an input signal of the deflector; And a sample stage positioned at the lower end of the objective lens and capable of supporting and moving the sample to which the charged particle beam is irradiated.

It is an additional component of the charged particle beam microscope, and includes a focusing lens group including an intermediate focusing lens provided on the charged particle source side and an objective lens which is the final focusing lens provided on the sample side, and a charged particle beam located at the lower end of the objective lens. Corresponds to the additional provision of a sample stage capable of supporting and moving the sample to be irradiated.

In addition, 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 changing the path of the particle beam.

The invention also provides 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 which is a final focusing lens provided on a sample side; At least one deflector provided between the intermediate focusing lens and the objective lens to control and change an irradiation direction of an electron beam emitted from an electron beam source; A scan waveform generator for generating a scan profile r (t) for controlling an irradiation direction of an electron beam and providing the scan profile to the deflector; The response signal actually output from the deflector (

) Generates a corrected scan profile signal u (t), which is optionally input by a controller provided therein into a) the deflector and subsequently corrected scan profile signal u (t + 1) ) Is calculated from the previous corrected scan profile signal u (t) and the response signal xcoil (t + 1) actually output from the deflector and input to the deflector each time, or b) the corrected scan profile A scan waveform control unit storing the file signal u (t) in a memory in which it can be stored and repeatedly using the file signal u (t) as an input signal of the deflector; A sample stage positioned at a lower end of an objective lens and capable of supporting and moving a sample to which the electron beam is irradiated; And a secondary electron detector for detecting secondary electrons emitted from the sample.

This corresponds to the use of the charged particle beam microscope as a scanning electron microscope, and thus corresponds to one embodiment of including a secondary electron detector for detecting secondary electrons emitted from a sample.

The present invention also provides a method for controlling the scanning signal of the charged particle beam microscope. More specifically, the method includes one or more deflectors for controlling and changing the irradiation direction of the charged particle beam; A scan waveform generator for generating a scan profile r (t) for controlling the irradiation direction of the charged particle beam and providing it to the deflector; The response signal actually output from the deflector (

Response signal measuring instrument for measuring; And a scan profile signal r (t) in the scan waveform generator and a scan profile signal u (t) corrected from the response signal measuring device, and generated by a controller provided therein. A scanning waveform control unit for selectively inputting a scan profile signal (u (t)) to a memory that can be stored, comprising: a method for controlling a scanning signal of a charged particle beam microscope comprising:

Obtaining a corrected scan profile signal u (t); And when the corrected scan profile signal u (t) is input to the deflector, the subsequent corrected scan profile signal u (t + 1) is the last corrected scan profile signal u ( t)) and from the response signal xcoil (t + 1) actually outputted from the deflector, are newly calculated each time and input to the deflector, and the corrected scan profile signal u (t) is input to the memory. And processing the corrected scan profile signal u (t) so that it can be used repeatedly as an input signal of the deflector.

In this case, the current waveform of the preset scan profile r (t) may be any one selected from sawtooth, triangle, and trapezoid or a combination thereof.

The method of controlling the scanning signal of the charged particle beam microscope relates to a scanning signal control method of the charged particle beam microscope including the scanning waveform generator, the response signal measuring device and the scanning waveform control unit in the present invention. As described, the implementation thereof corresponds to those skilled in the art.

Although the above has been described with reference to the embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be appreciated.

The present invention relates to an apparatus and method for controlling a particle beam of a charged particle microscope, wherein the image of a sample surface measured by correcting a dynamic characteristic distorted by a deflector (scanner) and irradiating the charged particle beam to a desired position is distorted. It is possible to provide a charged particle beam control device that can prevent and obtain an image at high speed, there is industrial applicability.

Claims

A charged particle source 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 scan waveform generator for generating a scan profile r (t) for controlling the irradiation direction of the charged particle beam and providing it to the deflector;

The response signal actually output from the deflector (
Response signal measuring instrument for measuring; And

The scan profile r (t) in the scanning waveform generator and the response signal from the response signal measuring device (
) Generates a corrected scan profile signal u (t), which is optionally input by a controller provided therein to a) the deflector and subsequently corrected scan profile signal u (t + 1) Is calculated from the previous corrected scan profile signal u (t) and the response signal x coil ( t + 1 ) actually output from the deflector and input to the deflector each time, or b) the corrected scan And a scanning waveform control unit for storing the profile signal u (t) in a memory in which it can be stored and repeatedly using it as an input signal of the deflector to the deflector.
The method of claim 1,

Charged particle beam microscope, characterized in that the deflector consists of two upper and lower deflection coils.
The method of claim 1,

The charged particle beam microscope used for the charged particle beam microscope is any one selected from an electron beam, a hydrogen ion beam, and a helium ion beam.
The method of claim 1,

The corrected scan profile signal u (t) is a response signal actually output from the scan profile r (t) and the deflector in the scan waveform generator.
Charged particle beam microscope characterized in that it is obtained by using the difference (e (t) = r (t) -x coil ( t )).
The method of claim 1,

When the scan profile signal u (t) corrected by the controller inside the scanning waveform control unit is input to the deflector, the subsequent corrected scan profile signal u (t + 1) is the immediately corrected scan profile. Using the difference between the signal u (t) and the response signal actually output from the deflector (e (t) = u (t) -x coil ( t + 1 )), it is newly calculated each time and input into the fragrance. Charged particle beam microscope, characterized in that.
The method of claim 4, wherein

The corrected scan profile signal U (t) is

Charged particle beam microscope, characterized in that obtained from the formula.

Here, Kp is proportional gain which is control gain, Ki is integral gain and Kd is differential gain, each of which is a real number.
A charged particle source 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 provided on the sample side;

At least one deflector provided between the intermediate focusing lens and the objective lens to control and change the irradiation direction of the charged particle beam emitted from the charged particle source;

A scan waveform generator for generating a scan profile r (t) for controlling the irradiation direction of the charged particle beam and providing it to the deflector;

The response signal actually output from the deflector (
Response signal measuring instrument for measuring;

The scan profile r (t) in the scanning waveform generator and the response signal from the response signal measuring device (
) Generates a corrected scan profile signal u (t), which is optionally input by a controller provided therein to a) the deflector and subsequently corrected scan profile signal u (t + 1) Is calculated from the previous corrected scan profile signal u (t) and the response signal x coil ( t + 1 ) actually output from the deflector and input to the deflector each time, or b) the corrected scan A scanning waveform control unit storing the profile signal u (t) in a memory in which it can be stored and repeatedly using the profile signal u (t) as an input signal of the deflector; And

A charged particle beam microscope comprising: a sample stage positioned at the lower end of the objective lens and capable of supporting and moving a sample to which the charged particle beam is irradiated.
An electron beam source for emitting an electron beam;

A focusing lens group including an intermediate focusing lens provided at the electron beam source side and an objective lens serving as a final focusing lens provided at the sample side;

At least one deflector provided between the intermediate focusing lens and the objective lens to control and change an irradiation direction of an electron beam emitted from an electron beam source;

A scan waveform generator for generating a scan profile r (t) for controlling an irradiation direction of an electron beam and providing the scan profile to the deflector;

The response signal actually output from the deflector (
Response signal measuring instrument for measuring;

The scan profile r (t) in the scan waveform generator and the response signal

Response signal from
) Generates a corrected scan profile signal u (t), which is optionally input by a controller provided therein to a) the deflector and subsequently corrected scan profile signal u (t + 1) Is calculated from the previous corrected scan profile signal u (t) and the response signal x coil ( t + 1 ) actually output from the deflector and input to the deflector each time, or b) the corrected scan profile A scanning waveform control unit storing the signal u (t) in a memory in which it can be stored and repeatedly using the signal u (t) as an input signal of the deflector;

A sample stage positioned at a lower end of an objective lens and capable of supporting and moving a sample to which the electron beam is irradiated; And

Scanning electron microscope comprising a; secondary electron detector for detecting secondary electrons emitted from the sample.
At least one deflector for controlling and changing the irradiation direction of the charged particle beam;

A scan waveform generator for generating a scan profile r (t) for controlling the irradiation direction of the charged particle beam and providing it to the deflector;

The response signal actually output from the deflector (
Response signal measuring instrument for measuring; And

The scan profile r (t) in the scan waveform generator and the corrected scan profile signal u (t) are generated from the response signal measuring device, and the deflector or the corrected scan profile is provided by a controller provided therein. Claims [1] A method of controlling a scanning signal of a charged particle beam microscope, comprising: a scanning waveform control unit for selectively inputting a memory (u (t)) into a memory in which a signal can be stored.

Generating and inputting a scan profile signal r (t) to the deflector so as to control the irradiation direction of the charged particle beam in the scan waveform generator according to a preset scan profile r (t);

A response signal actually output from the deflector according to the scan profile signal (
Measuring); The scan profile signal r (t) and a deflector in the scan waveform controller

Actually output response signal (
Obtaining a corrected scan profile signal u (t); And

When the scan profile signal u (t) corrected by the controller is input to the deflector, the subsequent corrected scan profile signal u (t + 1) is the immediately corrected scan profile signal u ( t)) and from the response signal x coil ( t + 1 ) actually outputted from the deflector to be newly calculated each time and input to the deflector, and the corrected scan profile signal u (t) is input to the memory. And processing the corrected scan profile signal u (t) so that it can be used repeatedly as an input signal of the deflector.
The method of claim 9,

And a current waveform of the preset scan profile (r (t)) is one selected from a sawtooth, a triangle, and a trapezoid, or a combination thereof.