KR102088116B1 - Electron microscope based on heat transfer model prediction technique and control method thereof - Google Patents

Abstract

An electron microscope according to one embodiment may include: an electronic lens block; a cooling unit installed at the electronic lens block, and having a conduit through which a refrigerant flows and a cooler cooling the refrigerant; a temperature sensor which measures the temperature of the electronic lens block; and a control unit which derives a first heat exchange transfer function based on a time delay characteristic between a current applied to the electronic lens block and the temperature measured at the temperature sensor, and adjusting a cooling amount of the cooling unit based on the current applied to the electronic lens block and the first heat exchange transfer function.

Description

ELECTRON MICROSCOPE BASED ON HEAT TRANSFER MODEL PREDICTION TECHNIQUE AND CONTROL METHOD THEREOF

The following description relates to an electron microscope based on a heat transfer model prediction technique and a control method thereof.

An electron microscope is a device which observes the microstructure of a sample using an electron beam and an electron lens. In an electron microscope, a current value applied to a lens may change according to the magnification of an image observed during operation, and the change of the current may cause a change in temperature of the lens block.

The change in temperature of the electronic lens block can be propagated to adjacent electronic lens blocks, sample chambers or sample holders, and this change in temperature can cause expansion or contraction of the sample holder, which is why the observation point at high magnification due to thermal expansion It can cause drift, which can make high magnification and long time observation difficult.

Therefore, there is an increasing need for a device capable of cooling the heat of the electron lens quickly and effectively during operation of the electron microscope.

The background art described above is possessed or acquired by the inventors in the process of deriving the present invention, and is not necessarily a known technology disclosed to the public before the application of the present invention.

An object of an embodiment is to provide an electron microscope and a control method based on the heat transfer model prediction technique.

According to an embodiment, the electron microscope includes an electron lens block; A cooling unit for cooling the electronic lens block; A temperature sensor for measuring a temperature of the electronic lens block; And a control unit for deriving a first heat exchange transfer function based on a time delay characteristic between a test current applied to the electron lens block and a temperature measured by the temperature sensor, wherein the control unit receives an operation signal of an electron microscope. Detect and determine a current value to be applied to the electronic lens block, calculate the amount of heat to be generated in the electronic lens block by the determined current value through the first heat exchange transfer function, and do not change the temperature of the electronic lens block. It is possible to control the cooling amount of the cooling unit.

The first heat exchange transfer function may be calculated with a first order time delay system as shown in the following equation.

(Mathematical formula)

(Where G ₁ (s) is the first heat exchange transfer function, U ₁ (s) is the Laplace transform function of u ₁ (t), which is a function of the current input value applied to the electronic lens block in the time domain, Y ₁ ( s) is the Laplace transform function of y ₁ (t), which is a function of the output temperature value of the temperature sensor in the time domain, K is the amplitude ratio (gain) for the input signal of the output signal, T is the rate of change of the heat input, and L is Delay for heat transfer)

The cooling unit, a refrigerant supply device for cooling the refrigerant; A cooling end formed in the electronic lens block to cool the electronic lens block; And a refrigerant passage for circulating the refrigerant between the refrigerant supply device and the cooling end.

The cooling unit further includes a Peltier element installed at an inlet of the cooling end of the coolant flow path, and the controller is configured to supply the Peltier element based on a current applied to the electronic lens block and the first heat exchange transfer function. The current value applied can be adjusted.

The control unit derives a second heat exchange transfer function based on a time delay characteristic between a cooling amount supplied to the electronic lens block and a temperature measured by the temperature sensor, and the second heat exchange transfer function is represented by the following equation. It can be calculated with the first time delay system as

(Mathematical formula)

(Where G ₂ (s) is the second heat exchange transfer function, U ₂ (s) is the Laplace transform function of u ₂ (t), which is a function of the amount of cooling supplied to the electronic lens block in the time domain, Y ₂ (s ) Is the Laplace transform function of y ₂ (t), which is a function of the output temperature value of the temperature sensor in the time domain, K is the amplitude ratio (gain) for the input signal of the output signal, T is the rate of change of the heat input, and L is the heat Delay for delivery)

According to an embodiment of the present disclosure, a method of controlling an electron microscope including an electron lens block and a cooling unit for cooling the electron lens block may be based on a time delay characteristic between a test current value applied to the electron lens block and a temperature. A first cooling dynamics measurement step of deriving one heat exchange transfer function; And a cooling amount of the cooling unit based on the amount of heat to be generated in the electron lens block calculated by substituting the current value to be applied to the electron lens block according to the operation signal of the electron microscope into the first heat exchange transfer function. It may comprise the step of performing a first dynamic cooling to adjust the.

The first cooling dynamics measuring step may include: applying a first dynamic test current to a test lens having a predetermined pattern to the electronic lens block; A first output temperature measuring step of measuring a temperature of the electronic lens block; And a first heat exchange transfer function deriving step of deriving a first heat exchange transfer function in consideration of a time delay characteristic between a test current input to the electronic lens block and a temperature of the electronic lens block.

The test current may include a plurality of step currents in which at least one or more of the magnitude and the application time of the current are different from each other.

The first heat exchange transfer function may be calculated with a first order time delay system as shown in the following equation.

(Mathematical formula)

(Where G ₁ (s) is the first heat exchange transfer function, U ₁ (s) is the Laplace transform function of u ₁ (t), which is a function of the current input value applied to the electronic lens block in the time domain, Y ₁ ( s) is the Laplace transform function of y ₁ (t), which is a function of the output temperature value of the temperature sensor in the time domain, K is the amplitude ratio (gain) for the input signal of the output signal, T is the rate of change of the heat input, and L is Delay for heat transfer)

The cooling unit includes a Peltier element, and the performing of the first dynamic characteristic cooling may be performed on the Peltier element based on a temperature change prediction value calculated by substituting a current value to be applied to the electronic lens block into the first heat exchange transfer function. The current value applied can be determined.

The control method of the electron microscope includes: a second cooling dynamics measurement step of deriving a second heat exchange transfer function based on a time delay characteristic between a test current value applied to the Peltier element and a temperature of the electron lens block; And performing a second dynamic cooling operation by adjusting the cooling amount of the cooling unit based on the estimated cooling amount of the electronic lens block by substituting the cooling amount to be supplied to the electronic lens block into the second heat exchange transfer function. It may further include.

The second heat exchange transfer function may be calculated with a primary time delay system as shown in the following equation.

(Mathematical formula)

(Where G ₂ (s) is the second heat exchange transfer function, U ₂ (s) is the Laplace transform function of u ₂ (t), which is a function of the amount of cooling supplied to the electronic lens block in the time domain, Y ₂ (s ) Is the Laplace transform function of y ₂ (t), which is a function of the output temperature value of the temperature sensor in the time domain, K is the amplitude ratio (gain) for the input signal of the output signal, T is the rate of change of the heat input, and L is the heat Delay for delivery)

According to an electron microscope and a control method thereof according to an embodiment, instead of a method of post-cooling based on a temperature measured in the lens block, the electron microscope is applied to the lens block based on a dynamic model that inputs a current value to be applied to the lens block. Since the cooling amount corresponding to the amount of heat to be provided can be provided in advance, it is possible to prevent the temperature change of the lens block. Therefore, when long-term observation is required using an electron microscope, the drift problem of observing an object deviated from the field of the electron microscope can be prevented, thereby eliminating the trouble that the observer should not constantly check the field of the electron microscope. Can be.

According to an electron microscope and a control method thereof, an amount of cooling applied to an electronic lens block that is changed during operation may be adjusted based on a dynamic characteristic between a current value applied to the electronic lens block and a temperature change of the electronic lens block. Therefore, the temperature change of the electronic lens block can be reduced quickly and effectively as compared with the conventional cooling method.

According to an electron microscope and a control method thereof, cooling is performed before temperature propagation occurs between electronic lens blocks by additionally applying dynamic characteristics between a Peltier element having a fast cooling reaction rate and a temperature change of the electronic lens block. Can be.

1 is a view showing the configuration of an electron microscope according to an embodiment.
2 is a diagram illustrating a configuration of a cooling unit of an electron microscope according to an embodiment.
3 is a flowchart illustrating a method of controlling an electron microscope according to an exemplary embodiment.
4 is a flowchart illustrating a first cooling dynamics measurement step according to an exemplary embodiment.
5 is a flowchart illustrating a second cooling dynamics measuring step according to an exemplary embodiment.
6 is a flowchart illustrating a cooling step according to an embodiment.
7 is a diagram schematically illustrating a process of deriving a heat exchange transfer function.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the embodiments, when it is determined that a detailed description of a related well-known configuration or function interferes with the understanding of the embodiment, the detailed description thereof will be omitted.

In addition, in describing the components of the embodiment, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. If a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected or connected to that other component, but there is another component between each component. It will be understood that may be "connected", "coupled" or "connected".

Components included in any one embodiment and components including common functions will be described using the same names in other embodiments. Unless stated to the contrary, the description in any one embodiment may be applied to other embodiments, and detailed descriptions thereof will be omitted in the overlapping range.

1 is a diagram illustrating a configuration of an electron microscope according to an embodiment, and FIG. 2 is a diagram illustrating a configuration of a cooling unit of an electron microscope according to an embodiment.

Referring to FIG. 1, an electron microscope 1 according to an exemplary embodiment of the present invention may include an electronic lens block 112 based on a dynamic characteristic between a current value applied to an electronic lens block and a temperature change of the electronic lens block. The amount of cooling supplied to the can be adjusted. For example, the type of electron microscope 1 may be a transmission electron microscope (TEM), a scanning electron microscope (SEM) or an electron microscope having an electron lens for focusing other electron beams. Can be. The electron microscope 1 may include a column part 11, a cooling part 13, and a control part 12.

The column part 11 may be formed as a vacuum chamber for irradiating an electron beam toward a sample contained therein. For example, the column part 11 may include an electron beam generator 111, a plurality of electron lens blocks 112, a sample holder 113, and a temperature sensor 114.

The electron beam generation unit 111 may be formed above the column part 11 to irradiate the electron beam toward the lower sample holder 113.

The plurality of electronic lens blocks 112 may be formed to be spaced apart from each other along the vertical direction of the column part 11. The plurality of electron lens blocks 112 may adjust the focus of the electron beam generated by the electron beam generator 111 according to the current value applied thereto. For example, when a user inputs an operation signal for enlarging or reducing an image of the electron microscope 1 or adjusting a focus, a current to be applied to each of the plurality of electron lens blocks 112 in response to the input operation signal. The value can be determined by the controller 12. As the current value applied to the electronic lens block 112 increases, the amount of heat generated by the electronic lens block 112 increases.

The sample holder 113 may be provided on a path of an electron beam focused along the plurality of electron lens blocks 112 to support a sample.

The temperature sensor 114 may be installed for each of the plurality of electronic lens blocks 112 to measure the temperature of each of the electronic lens blocks 112.

The cooling unit 13 may supply a refrigerant circulating inside the plurality of electronic lens blocks 112 to cool the plurality of electronic lens blocks 112. For example, the cooling unit 13 may independently cool the plurality of electronic lens blocks 112 through various methods such as a manifold flow path and a plurality of valves. The cooling unit 13 may include a refrigerant supply device 131, a refrigerant passage 133, and a cooling end 132.

The coolant supply device 131 may cool the coolant using, for example, a compressor, and may circulate the coolant through the coolant flow path 133. The refrigerant supply device 131 may include a refrigerant temperature sensor for measuring the temperature of the refrigerant and a temperature controller for adjusting the temperature of the refrigerant so that the refrigerant contained therein may always maintain a constant temperature. For example, the temperature control unit may comprise heating means and / or cooling means of various known means. According to such a temperature sensor and the temperature controller, the temperature of the refrigerant contained in the refrigerant supply device 131 is always kept constant, resulting in the electronic lens block 112 based on the heat exchange transfer function model to be described later. In cooling, control convenience can be improved.

The coolant flow path 133 may form a flow path for circulating the coolant between the coolant supply device 131 and the cooling end 132. For example, the refrigerant passage 133 is a supply passage 133a for guiding the refrigerant from the refrigerant supply device 131 to the cooling end 132, and the refrigerant discharged from the cooling end 132. It may include a discharge flow path (133b) to guide to.

The cooling end 132 may absorb heat generated in the electronic lens block 112 by circulating a refrigerant inside the electronic lens block 112. For example, the cooling end 132 may include a circulation passage 1321 and a Peltier element 1322.

The circulation flow path 1321 may be a flow path circulating inside the electronic lens block 112. For example, the circulation flow path 1321 may be installed at a position inside or adjacent to the electromagnet coil 1121 of the electron lens block 112. As a result, the refrigerant flowing through the circulation flow path 1321 absorbs heat generated by applying current to the electromagnet coil 1121, thereby cooling the electron lens block 112.

The Peltier element 1322 may be installed at an inlet portion at which the supply flow path 133a is connected to the circulation flow path 1321 to provide additional cooling to the refrigerant supplied to the circulation flow path 1321. For example, through the endothermic reaction generated by applying a current to the Peltier element 1322, a cool refrigerant may be made and supplied immediately at the inlet end of the circulation flow path 1321.

The control unit 12 can control the operation of the electron microscope 1. For example, the control unit 12 may form an electron beam irradiated toward the sample holder 113 through the electron beam generating unit 111, and by applying a current to the plurality of electron lens blocks 112, The beam can be focused towards the sample.

The controller 12 may perform cooling of the plurality of electron lens blocks 112 by driving the cooling unit 13 during the operation of the electron microscope 1. For example, the controller 12 may drive the coolant supply device 131 to circulate the coolant to the electronic lens block 112, and simultaneously control the temperature of the coolant.

For example, the controller 12 may measure the temperature of the electronic lens block 112 through the temperature sensor 114. For example, the controller 12 may apply a current to the Peltier element 1322 to cool the refrigerant flowing into the circulation flow path 1321.

For example, the controller 12 derives the first heat exchange transfer function based on the time delay characteristic between the current applied to the electronic lens block 112 and the temperature measured by the temperature sensor 114, and the electronic lens. The amount of cooling to be supplied to the electronic lens block 112 through the cooling unit 13 may be adjusted based on the current applied to the block 112 and the first heat exchange transfer function.

For example, the controller 12 may control the driving of the refrigerant supply device 131 based on the amount of cooling calculated through the first heat exchange transfer function.

For example, the controller 12 may adjust the current value applied to the Peltier element 1322 based on the current applied to the electronic lens block 112 and the first heat exchange transfer function.

For example, the controller 12 derives the second heat exchange transfer function based on the time delay characteristic between the current applied to the Peltier element 1322 and the temperature measured by the temperature sensor 114, and the first heat exchange. The driving of the Peltier element 1322 may be controlled based on the amount of cooling calculated through the transfer function and the second heat exchange transfer function.

Deriving the first heat exchange transfer function and the second heat exchange transfer function will be described later with reference to FIGS. 3 to 7.

According to the electron microscope 1 according to an exemplary embodiment, the electronic lens block 112 is in operation based on a dynamic characteristic between a current value applied to the electron lens block 112 and a temperature change of the electron lens block 112. Since the driving of the cooling unit 13 is adjusted according to the current value applied thereto, cooling can be performed faster and more efficiently than a general cooling method.

In addition, by installing the Peltier element 1322 capable of performing cooling at a high response speed at the inlet of the circulation flow path 1321 circulating the electronic lens block 112, the cooling reaction speed can be further improved.

Further, by additionally applying dynamic characteristics between the current applied to the Peltier element 1322 and the temperature measured by the temperature sensor, the refrigerant supply device 131 and the Peltier element based on the current value applied to the electronic lens block 112. Since the cooling provision of 1322 can be actively controlled, faster cooling reaction rates can be expected.

3 is a flowchart illustrating a method for controlling an electron microscope according to an embodiment, FIG. 4 is a flowchart illustrating a first cooling dynamics measurement step according to an embodiment, and FIG. 5 is a second cooling dynamics measurement according to an embodiment. 6 is a flowchart illustrating a step of performing cooling according to an embodiment, and FIG. 7 is a diagram schematically illustrating a process of deriving a heat exchange transfer function.

3 to 7, a method of controlling an electron microscope according to an exemplary embodiment will be described. The control method of the electron microscope may be, for example, a method of controlling the cooling unit 13 for cooling the electron lens block 112 of the electron microscope 1 shown in FIGS. 1 and 2. The control method of the electron microscope may include a first cooling dynamics measuring step 31, a second cooling dynamics measuring step 32, a cooling performing step 33, and a cooling stop confirmation step 34.

The first cooling dynamics measuring step 31 may be a step of deriving a first heat exchange transfer function based on a time delay characteristic between a current applied to the electronic lens block 112 and a temperature measured by the temperature sensor.

For example, the first cooling dynamics measurement step 31 may include a first dynamic test current application step 311, a first output temperature measurement step 312, and a first heat exchange transfer function derivation step 313. have.

The first dynamic test current applying step 311 may be a step in which the controller 12 applies a test current having a preset pattern to the electronic lens block 112. For example, in the first dynamic test current applying step 311, the controller 12 may include a plurality of step currents in which at least one or more of the magnitude and the application time of the current are different from each other as shown in the lower graph of FIG. 7. Can be applied to the electromagnetic coil 1121.

The first output temperature measuring step 312 may be a step of measuring in real time the temperature of the electronic lens block 112 measured through the temperature sensor 114 after applying a test current to the electronic lens block 112. have.

The first heat exchange transfer function deriving step 313 may include a first heat exchange transfer function “G ₁ (s) for a correlation of the temperature value of the electromagnetic lens block 112 to the current value input to the electromagnet coil 1121. ", Using a Transfer function model of heat exchanger approximated by a First Order Time Delay System. For example, the first heat exchange transfer function G ₁ (s) may be calculated for each of the plurality of electronic lens blocks 112. As another example, the first heat exchange transfer function G ₁ (s) may be calculated only for the electronic lens block 112 closest to the sample holder 113 of the plurality of electronic lens blocks 112.

For example, when a test current as shown in the lower side of FIG. 7 is applied, the controller 12 may exchange heat as shown in Equation 1 based on values obtained through Equations 2 to 5 below. A transfer function model can be obtained.

(Where G ₁ (s) is the first heat exchange transfer function, U ₁ (s) is the Laplace transform function of u ₁ (t), which is a function of the current input value applied to the electronic lens block in the time domain, Y ₁ ( s) is the Laplace transform function of y ₁ (t), which is a function of the output temperature value of the temperature sensor in the time domain, K is the amplitude ratio (gain) for the input signal of the output signal, T is the rate of change of the heat input, and L is Delay for heat transfer)

For example, the control unit 12 has the magnitudes of the currents "A", "0", "μA", and "0" as u ₁ (t) as a function of the current input value in the time domain shown in the lower part of FIG. And a test current having a pattern divided into “0”, “D”, “D + Δ”, and “2D + Δ” may be applied to the electronic lens block 112. The test current having the above pattern can be formed in various ways. For example, the sizes of "A", "-A", "μA" and "-μA" at the time points of "0", "D", "D + Δ" and "2D + Δ" in four power sources, respectively. By applying a step current having a test current having such a pattern can be formed.

When a test current having such a pattern is applied, it can be seen that the output temperature value in the time domain for the electronic lens block 112 is measured in the same pattern as the graph y ₁ (t) in FIG. 7.

In the measured graph y ₁ (t), three points of discontinuous slope (t = t _a , t _b and t _c ) and the measured values of the output temperature at each point "y _1a ", "y _1b " And "y _1c ", an equation such as Equation 2 below can be obtained.

From the relation derived from Equation 2, the temperature change rate (T) for the input of heat, the amplitude ratio (K) for the input signal of the output signal, and the delay (L) for heat transfer, respectively, Can be calculated as:

By substituting the T, K, and L values calculated through Equations 3, 4, and 5 again on the right side of Equation 1, as a result, the current applied to the electronic lens block 112 and the temperature measured by the temperature sensor It is possible to derive the first heat exchange transfer function due to the dynamic characteristics. Using the first heat exchange transfer function derived above, the amount of heat to be generated in the electronic lens block 112 may be calculated in advance according to the current value applied to the electronic lens block 112. Accordingly, the control unit 12 applies a current to the electronic lens block 112 based on a user's operation signal, and controls the cooling amount of the cooling unit 13 so that the temperature of the electronic lens block 112 does not change. By controlling over time, the electronic lens block 112 may be predictively cooled.

In the second cooling dynamics measuring step 32, the amount of cooling supplied to the electronic lens block 112 by the refrigerant and / or the Peltier element 1322, and the temperature value of the electronic lens block 112 are determined as a primary time delay system. By substituting the approximated heat exchange transfer function model into the second heat exchange transfer function " G ₂ (s) ".

For example, the second cooling dynamics measurement step 32 may include a second dynamic test cooling amount supply step 321, a second output temperature measurement step 322 of measuring the temperature of the electronic lens block 112, A second heat exchange transfer function derivation step 323 may be included.

The second dynamic test cooling amount supplying step 321 may be a step of supplying the test cooling amount by controlling the refrigerant and / or Peltier element 1322 to the electronic lens block 112. On the other hand, in consideration of the fast response of the Peltier element 1322, the second dynamic test cooling amount supplying step 321 can be simplified by adjusting the test current input to the Peltier element 1322. In this case, u ₂ (t) described in Equation 6 can be understood as a function of the current input value supplied to the Peltier element 1322 in the time domain.

The second heat exchange transfer function deriving step 323 may include a second heat exchange transfer function “G ₂ for a correlation between the amount of cooling supplied to the electronic lens block 112 and the temperature value measured at the electronic lens block 112. (s) ". For example, the second heat exchange transfer function G ₂ (s) may be calculated for each of the plurality of electronic lens blocks 112. As another example, the second heat exchange transfer function G ₂ (s) may be calculated only for the electronic lens block 112 closest to the sample holder 113 of the plurality of electronic lens blocks 112.

(Where G ₂ (s) is the second heat exchange transfer function, U ₂ (s) is the Laplace transform function of u ₂ (t), which is a function of the amount of cooling supplied to the electronic lens block in the time domain, Y ₂ (s ) Is the Laplace transform function of y ₂ (t), which is a function of the output temperature value of the temperature sensor in the time domain, K is the amplitude ratio (gain) for the input signal of the output signal, T is the rate of change of the heat input, and L is the heat Delay for delivery)

Since the process of deriving the second heat exchange transfer function is the same as the process of deriving the first heat exchange transfer function through Equations 1 to 5, a detailed description thereof will be omitted.

Meanwhile, the process of deriving the heat exchange transfer functions through the first cooling dynamics measuring step 31 and the second cooling dynamics measuring step 32 may be performed in advance before proceeding with the observation through the actual electron microscope 1. Can be. In addition, in consideration of the possibility of changing the heat exchange transfer function according to the change of the external environment, the electron microscope 1 may be performed at idle or may be automatically performed at a predetermined cycle. It may also be performed in the initial value setting process before the operation of the position of the electron microscope 1 or the initial operation after the reinstallation.

The performing cooling step 33 is based on the first heat exchange transfer function and the second heat exchange transfer function derived from the first cooling dynamics measuring step 31 and the second cooling dynamics measuring step 32, respectively. 131 and the driving of the Peltier device 1322 may be controlled. The cooling step 33 may include a first dynamic cooling step 331 and a second dynamic cooling step 332.

In the performing of the first dynamic cooling operation 331, the control unit 12 substitutes a current value applied to the electronic lens block 112 into a first heat exchange transfer function to derive a temperature change prediction value of the electronic lens block 112. The cooling amount of the cooling unit 13 may be adjusted according to the corresponding temperature change prediction value. The controller 12 may adjust the cooling amount of the coolant supply device 131 and / or the Peltier element 1322 based on the predicted temperature change of the electronic lens block 112. For example, the amount of cooling supplied to the plurality of electronic lens blocks 112 may be controlled based on the heat exchange transfer function obtained for each of the plurality of electronic lens blocks 112.

In order to achieve a faster and more accurate cooling response speed of the electronic lens block 112, the second dynamic cooling operation step 332 may be performed by performing the first dynamic cooling function using the second heat exchange transfer function considering the cooling delay of the cooling amount. By further reflecting at 331, cooling of the electronic lens block 112 may be performed. According to the second dynamic cooling performing step 332, the transmission delay time of the cooling amount can be taken into consideration, so that the temperature of the electronic lens block 112 can be controlled more quickly and accurately.

For example, the controller 12 may preset the ratio of the cooling amount of the refrigerant supply device 131 and the Peltier element 1322, and the electronic lens block 112 calculated in the first dynamic cooling step 331. The amount of cooling may be adjusted according to a cooling ratio of each of the refrigerant supply device 131 and / or the Peltier element 1322 based on the predicted temperature change.

For example, the controller 12 may apply the temperature change prediction value of the electronic lens block 112 corresponding to the cooling amount allocated to the Peltier element 1322 to the Peltier element 1322 by substituting the second heat exchange transfer function. The value of the current may be calculated in advance, and the Peltier element 1322 may be driven through the calculated current value.

According to the second dynamic cooling step 332, since the cooling reaction speed of the Peltier device 1322 having the fast cooling response characteristic can be maximized, the cooling of the electronic lens block 112 can be performed very quickly.

For example, the second dynamic cooling performance step 332 may be performed alone except for the second dynamic cooling performance step 332.

As described above, the first and second dynamic cooling performing steps 331 and 332 are intended to cool by open loop control using a previously obtained heat exchange transfer function, whereby the temperature of the electronic lens block 112 is increased. Cooling may be carried out in consideration of the propagation delay time of the calorie and / or cooling amount before being raised. Meanwhile, the performing of the cooling step 33 may further include correcting the amount of cooling based on the setting deviation when the temperature sensed by the temperature sensor 114 is out of the setting deviation. In other words, the performing cooling step 33 may further include a closed loop control step.

The cooling stop confirmation step 34 may be a step of determining whether to stop cooling of the electronic lens block 112 through the cooling unit 13. For example, the controller 12 may continuously perform the aforementioned cooling performing step 33 until the user instructs the cooling of the electronic lens block 112 to stop.

Although embodiments have been described with reference to the accompanying drawings as described above, various modifications and variations are possible to those skilled in the art from the above description. For example, the described techniques may be performed in a different order than the described method, and / or components of the described structure, apparatus, etc. may be combined or combined in a different form than the described method, or may be combined with other components or equivalents. Appropriate results can be achieved even if they are replaced or substituted.

Claims (12)

Electronic lens blocks;
A cooling unit for cooling the electronic lens block;
A temperature sensor for measuring a temperature of the electronic lens block; And
A control unit for deriving a first heat exchange transfer function based on a time delay characteristic between a test current applied to the electronic lens block and a temperature measured by the temperature sensor,
The controller detects an operation signal of an electron microscope to determine a current value to be applied to the electron lens block, and calculates an amount of heat to be generated in the electron lens block through the first heat exchange transfer function based on the determined current value. The amount of cooling of the cooling unit is controlled so that the temperature of the electronic lens block does not change.
Wherein said first heat exchange transfer function is calculated with a first order time delay system as in the following equation.
(Mathematical formula)

(Where G ₁ (s) is the first heat exchange transfer function, U ₁ (s) is the Laplace transform function of u ₁ (t), which is a function of the current input value applied to the electronic lens block in the time domain, Y ₁ ( s) is the Laplace transform function of y ₁ (t), which is a function of the output temperature value of the temperature sensor in the time domain, K is the amplitude ratio (gain) of the output signal to the input signal, T is the rate of change of the heat input, and L is Delay for heat transfer)
delete The method of claim 1,
The cooling unit,
A refrigerant supply device for cooling the refrigerant;
A cooling end formed in the electronic lens block to cool the electronic lens block; And
And a coolant flow path for circulating a coolant between the coolant supply device and the cooling end.
The method of claim 3, wherein
The cooling unit further includes a Peltier element installed in the inlet portion of the cooling end of the refrigerant passage,
And the control unit adjusts a current value applied to the Peltier element based on the current applied to the electron lens block and the first heat exchange transfer function.
The method of claim 4, wherein
The controller derives a second heat exchange transfer function based on a time delay characteristic between a cooling amount supplied to the electronic lens block and a temperature measured by the temperature sensor,
And said second heat exchange transfer function is calculated with a first order time delay system as in the following equation.
(Mathematical formula)

(Where G ₂ (s) is the second heat exchange transfer function, U ₂ (s) is the Laplace transform function of u ₂ (t), which is a function of the amount of cooling supplied to the electronic lens block in the time domain, Y ₂ (s ) Is the Laplace transform function of y ₂ (t), which is a function of the output temperature value of the temperature sensor in the time domain, K is the amplitude ratio (gain) for the input signal of the output signal, T is the rate of change of the heat input, and L is the heat Delay for delivery)
An electron microscope control method comprising an electron lens block and a cooling unit for cooling the electron lens block,
A first cooling dynamics measurement step of deriving a first heat exchange transfer function based on a time delay characteristic between temperature and a test current value applied to the electronic lens block; And
Based on the amount of heat to be generated in the electron lens block calculated by substituting the current value to be applied to the electron lens block according to the operation signal of the electron microscope into the first heat exchange transfer function, the cooling amount of the cooling unit is determined. A first dynamic cooling step of adjusting;
The first cooling dynamics measurement step,
A first dynamic test current applying step of applying a test current having a preset pattern to the electronic lens block;
A first output temperature measuring step of measuring a temperature of the electronic lens block; And
And a first heat exchange transfer function deriving step for deriving a first heat exchange transfer function in consideration of a time delay characteristic between a test current input to the electron lens block and a temperature of the electron lens block.
delete The method of claim 6,
The test current control method of an electron microscope, characterized in that the at least one or more of the magnitude and the application time of the current includes a plurality of step currents different from each other.
The method of claim 6,
And the first heat exchange transfer function is calculated with a first order time delay system as in the following equation.
(Mathematical formula)

(Where G ₁ (s) is the first heat exchange transfer function, U ₁ (s) is the Laplace transform function of u ₁ (t), which is a function of the current input value applied to the electronic lens block in the time domain, Y ₁ ( s) is the Laplace transform function of y ₁ (t), which is a function of the output temperature value of the temperature sensor in the time domain, K is the amplitude ratio (gain) of the output signal to the input signal, T is the rate of change of the heat input, and L is Delay for heat transfer)
An electron microscope control method comprising an electron lens block and a cooling unit including a Peltier element for cooling the electron lens block.
A first cooling dynamics measurement step of deriving a first heat exchange transfer function based on a time delay characteristic between temperature and a test current value applied to the electronic lens block; And
Based on the amount of heat to be generated in the electron lens block calculated by substituting the current value to be applied to the electron lens block according to the operation signal of the electron microscope into the first heat exchange transfer function, the cooling amount of the cooling unit is determined. A first dynamic cooling step of adjusting;
In the performing of the first dynamic cooling, the current value applied to the Peltier element is determined based on a temperature change predicted value calculated by substituting the current value to be applied to the electronic lens block into the first heat exchange transfer function. The control method of an electron microscope.
The method of claim 10,
A second cooling dynamics measurement step of deriving a second heat exchange transfer function based on a time delay characteristic between a test current value applied to the Peltier element and a temperature of the electronic lens block; And
Performing a second dynamic cooling step of adjusting the cooling amount of the cooling unit based on the estimated cooling amount of the electronic lens block by substituting the cooling amount to be supplied to the electronic lens block into the second heat exchange transfer function. Control method of the electron microscope further comprising.
The method of claim 11,
And the second heat exchange transfer function is calculated with a first order time delay system as in the following equation.
(Mathematical formula)

(Where G ₂ (s) is the second heat exchange transfer function, U ₂ (s) is the Laplace transform function of u ₂ (t), which is a function of the amount of cooling supplied to the electronic lens block in the time domain, Y ₂ (s ) Is the Laplace transform function of y ₂ (t), which is a function of the output temperature value of the temperature sensor in the time domain, K is the amplitude ratio (gain) for the input signal of the output signal, T is the rate of change of the heat input, and L is the heat Delay for delivery)

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