A method, apparatus, device, medium and product for adjusting an electron beam current

Abstract

The application discloses a kind of electron beam current regulation method, device, equipment, medium and product, applied to integrated circuit technical field.The method first obtains the original excitation current value of condenser in scanning electron microscope;Then, based on the first corresponding relationship between excitation current value and electron beam current value, the original electron beam current value is determined.Further based on the original electron beam current value, scanning electron microscope is adjusted, so that the electron beam current value of scanning electron microscope is target electron beam current value.In the present implementation mode, when obtaining electron beam current value, it is no longer necessary to measure by Faraday cup each time, but by the corresponding relationship of excitation current value and electron beam current value of condenser to estimate directly, since the excitation current value of condenser is simple to obtain, and then the operation time of measurement using Faraday cup is saved, and the efficiency of obtaining electron beam current value is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of integrated circuits, and particularly relates to a method and device for adjusting an electron beam current, a medium and product. BACKGROUND

[0002] With the development of integrated circuit technology, the critical dimension of a chip is greatly reduced, even to the nanometer level. Therefore, a device with higher resolution is needed for detection or measurement. A scanning electron microscope uses an electron beam as a detection light source, has a smaller wavelength and a larger depth of field, and can meet the demand. When applied, the electron beam current and other parameters need to be adjusted according to the application requirements. In order to achieve accurate adjustment, the electron beam current value needs to be measured. The current measurement scheme is usually realized by a Faraday cup, that is, a beam of electrons passes through a small hole and enters the Faraday cup completely. The Faraday cup is connected to a picoammeter through a wire, and the size of the electron beam current can be directly read from the display of the picoammeter.

[0003] However, the Faraday cup is generally installed in a corner of a sample table. When testing, the Faraday cup needs to be moved to the center of the field of view of the scanning electron microscope, and then the field of view and focusing are adjusted. This process is time-consuming and affects the adjustment efficiency. SUMMARY

[0004] The embodiments of the application provide a method and device for adjusting an electron beam current, a medium and product, which can improve the efficiency of obtaining the electron beam current value.

[0005] In one aspect, the embodiments of the application provide a method for adjusting an electron beam current, comprising:

[0006] obtaining an original excitation current value of a condenser in a scanning electron microscope;

[0007] determining an original electron beam current value of the scanning electron microscope based on the original excitation current value and a first correspondence relationship; the first correspondence relationship is a correspondence relationship between the excitation current value of the condenser and the electron beam current value of the scanning electron microscope;

[0008] adjusting the scanning electron microscope based on the original electron beam current value, so that the electron beam current value of the scanning electron microscope is a target electron beam current value.

[0009] In another aspect, before the original electron beam current value of the scanning electron microscope is determined based on the original excitation current value and the first correspondence relationship, the method further comprises:

[0010] obtaining a set of excitation current values and a corresponding set of electron beam current values; the excitation current values in the set of excitation current values correspond one-to-one to the electron beam current values in the set of electron beam current values;

[0011] The first corresponding relationship is established based on the excitation current values ​​and electron beam current values ​​corresponding to each other in the excitation current value set and the electron beam current value set.

[0012] On the other hand, establishing the first corresponding relationship based on the excitation current values ​​and electron beam current values ​​corresponding to each other in the excitation current value set and the electron beam current value set includes:

[0013] Based on the focusing principle of the condenser, an initial correlation function is established between the excitation current value of the condenser and the electron beam current value of the scanning electron microscope;

[0014] Based on the excitation current values ​​and electron beam current values ​​corresponding to each other in the excitation current value set and the electron beam current value set, a constant value in the initial correlation function is determined to obtain a correlation function representing the first corresponding relationship.

[0015] On the other hand, the initial correlation function includes:

[0016] In the case of underfocus or overfocus of the condenser:

[0017] When the condenser is focused: I2 = B;

[0018] Among them, A is the first constant, B is the second constant, W is the third constant, P is the fourth constant, I1 is the excitation current value, and I2 is the electron beam current value.

[0019] On the other hand, establishing the first corresponding relationship based on the excitation current values ​​and electron beam current values ​​corresponding to each other in the excitation current value set and the electron beam current value set includes:

[0020] Curve fitting is performed based on the excitation current values ​​and electron beam current values ​​corresponding to each other in the excitation current value set and the electron beam current value set to obtain a fitting curve representing the first corresponding relationship.

[0021] On the other hand, a Faraday cup is provided in the lens barrel of the scanning electron microscope;

[0022] The step of obtaining the excitation current value set and the corresponding electron beam current value set includes:

[0023] When the scanning electron microscope emits an electron beam that enters the hole of the Faraday cup, the excitation current value of the condenser is obtained multiple times to obtain the excitation current value set, and the readings of the picoammeter connected to the Faraday cup are obtained multiple times to obtain the electron beam current value set.

[0024] On the other hand, an embodiment of the present application provides an electron beam current regulating device, comprising:

[0025] An acquisition module is used to obtain the original excitation current value of the condenser in the scanning electron microscope;

[0026] a determination module, configured to determine an original electron beam current value of the scanning electron microscope based on the original excitation current value and a first corresponding relationship; the first corresponding relationship being a corresponding relationship between the excitation current value of the condenser mirror and the electron beam current value of the scanning electron microscope;

[0027] The adjustment module is used to adjust the scanning electron microscope based on the original electron beam current value so that the electron beam current value of the scanning electron microscope reaches the target electron beam current value.

[0028] In another aspect, an embodiment of the present application provides an electron beam current regulating device, comprising: a processor and a memory storing computer program instructions;

[0029] When the processor executes the computer program instructions, the method for adjusting the electron beam current as described above is implemented.

[0030] On the other hand, an embodiment of the present application provides a computer-readable storage medium having computer program instructions stored thereon. When the computer program instructions are executed by a processor, the method for adjusting the electron beam current as described above is implemented.

[0031] On the other hand, an embodiment of the present application provides a computer program product. When instructions in the computer program product are executed by a processor of an electronic device, the electronic device executes the electron beam current adjustment method as described above.

[0032] An embodiment of the present application provides a method for adjusting an electron beam current. The method first obtains the original excitation current value of a condenser in a scanning electron microscope; then, based on a first correspondence between the excitation current value and the electron beam current value, the original electron beam current value is determined. The scanning electron microscope is then adjusted based on the original electron beam current value so that the electron beam current value of the scanning electron microscope is the target electron beam current value. In this implementation, when obtaining the electron beam current value, it is no longer necessary to measure it through a Faraday cup every time. Instead, it is directly estimated through the correspondence between the excitation current value of the condenser and the electron beam current value. Since the method for obtaining the excitation current value of the condenser is simple, the operation time for measuring using a Faraday cup is saved, thereby improving the efficiency of obtaining the electron beam current value. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0034] Figure 1A schematic flow chart of a method for adjusting an electron beam current provided by one embodiment of the present application is shown;

[0035] Figure 2 A schematic diagram of the lens barrel structure of a scanning electron microscope is shown;

[0036] Figure 3 A schematic diagram of a condenser adjusting beam current is shown;

[0037] Figure 4 A schematic diagram showing a condenser lens adjusting the illumination spot radius at the image plane is shown;

[0038] Figure 5 A graph showing the relationship between a measured excitation current value and an electron beam current value is shown;

[0039] Figure 6 A graph corresponding to an initial correlation function is shown;

[0040] Figure 7 A schematic structural diagram of an electron beam regulating device provided in an embodiment of the present application is shown;

[0041] Figure 8 A schematic diagram of the hardware structure of the electron beam regulating device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0042] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present application by illustrating the examples of the present application.

[0043] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises", or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "includes..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0044] With the development of integrated circuit technology, the critical dimension of the chip is greatly reduced, even to the nanometer level, which is far beyond the detection range of traditional optical equipment (about 0.2 um). In order to effectively control the yield of chip technology, higher resolution equipment must be used for detection or measurement.

[0045] The scanning electron microscope uses an electron beam as a detection light source, has a smaller wavelength and a larger depth of field, and a resolution generally below 5 nm, so it can meet the demand of high-resolution detection. In application, the scanning electron microscope needs to be adjusted according to application requirements, such as electron beam current, acceleration voltage, focusing current and field of view. Among them, the electron beam current has a particularly key influence on resolution and signal-to-noise ratio, and needs to be accurately adjusted in combination with application scenarios.

[0046] When adjusting the electron beam current, the original electron beam current value of the scanning electron microscope needs to be obtained, and then the scanning electron microscope is adjusted based on the original electron beam current value to the target electron beam current value actually required. Therefore, only accurate electron beam current value can be obtained, the electron beam current of the scanning electron microscope can be accurately adjusted to meet the demand.

[0047] The traditional method for measuring electron beam current is generally realized by a Faraday cup. The Faraday cup is a cylindrical metal structure, one end of which is provided with a hole (aperture can be 10 um-10 mm) for detection, and the other end is connected to a picoammeter (generally range can be 1 pA-1000 nA) through a wire. The electron beam emitted by the scanning electron microscope is completely punched into the hole on the Faraday cup, and the reading of the picoammeter is the measured electron beam current value.

[0048] However, the Faraday cup is generally installed in a corner of the sample table, and when measuring the electron beam current value, the Faraday cup needs to be moved to the center of the field of view of the scanning electron microscope first, and then the field of view and focusing are adjusted. These steps need to take at least 5 min. When the semiconductor detection and measurement equipment is applied, efficiency is particularly important, and the increase in debugging time will correspondingly reduce the detection and measurement efficiency of the scanning electron microscope.

[0049] In actual application, when adjusting the electron beam current of the scanning electron microscope, the excitation current of the condenser lens of the scanning electron microscope is generally adjusted to achieve it. Different excitation currents correspond to different focal lengths of the condenser lens, and the focal length of the condenser lens has a corresponding relationship with the on-axis field distribution of the condenser lens itself, and the on-axis field distribution of the condenser lens is proportional to the electron beam current of the scanning electron microscope. In summary, there is a corresponding relationship between the excitation current and the electron beam current, and the excitation current of the condenser lens is easier to obtain than the electron beam current of the scanning electron microscope. Based on this, the application proposes a scheme to obtain the excitation current of the condenser lens, and estimate the electron beam current of the scanning electron microscope through the corresponding relationship between the two.

[0050] In order to solve the problems of traditional solutions, the embodiments of the present application provide a method, device, equipment, medium and product for adjusting the electron beam current. The following first introduces the method for adjusting the electron beam current provided by the embodiments of the present application. Figure 1 FIG. 1 is a flow chart showing a method for adjusting the electron beam current provided by an embodiment of the present application. Figure 1 As shown, the method includes the following steps: S101 to S103.

[0051] S101: Obtain the original excitation current value of the condenser in the scanning electron microscope.

[0052] As mentioned above, the embodiments of this application specifically estimate the original excitation current value of the condenser through the correspondence between the excitation current value and the electron beam current value. Therefore, it is necessary to obtain the original excitation current value of the condenser in the scanning electron microscope. The condenser in the scanning electron microscope is driven by the excitation current. Different excitation currents can give the condenser different focal lengths, which in turn affects the electron beam current of the scanning electron microscope.

[0053] This application does not limit how to obtain the original excitation current value of the condenser. In actual applications, the power supply of the condenser usually directly displays the current excitation current size of the condenser. As a feasible implementation method, the excitation current value of the condenser can be directly obtained through software.

[0054] S102: Determine an original electron beam current value of the scanning electron microscope based on the original excitation current value and the first corresponding relationship.

[0055] In the embodiment of the present application, the first correspondence is specifically a correspondence between the excitation current value of the condenser and the electron beam current value of the scanning electron microscope. In practical applications, the data used to establish the first correspondence is not limited. As a feasible implementation method, a test can be performed before application to obtain the excitation current value of the condenser and the corresponding electron beam current value to form a measurement value set; then, based on the corresponding excitation current values ​​and electron beam current values ​​in the measurement value set, a correspondence between the two can be established.

[0056] Furthermore, in practical applications, the specific method for establishing the first correspondence is not limited. As an optional implementation, an inherent initial correlation function can be derived based on the light-gathering theory of a condenser. This initial correlation function is applicable to all scanning electron microscopes. The unknown constants in the initial correlation function are then solved using a set of measured values ​​to obtain a correlation function representing the first correspondence. As another optional implementation, a curve can be directly fitted based on a large number of measured values.

[0057] In the process of determining the original electron beam current value of the scanning electron microscope, the obtained original excitation current value is directly substituted into the correlation function or fitting curve representing the first corresponding relationship to directly obtain the corresponding original electron beam current value.

[0058] S103: adjusting the scanning electron microscope based on the original electron beam current value so that the electron beam current value of the scanning electron microscope reaches the target electron beam current value.

[0059] To set the actual required electron beam current size as the target electron beam current value, the scanning electron microscope needs to be adjusted, that is, the excitation current of the condenser mirror is adjusted, so that the electron beam current value of the scanning electron microscope is the target electron beam current value.

[0060] As a feasible implementation method, during the adjustment process, the original electron beam current value of the scanning electron microscope and the required target electron beam current value can be compared first, and then the corresponding adjustment method (adjustment direction and degree) can be adopted. If the adjustment is not in place or the adjustment is excessive, the above steps are repeated until the electron beam current value of the scanning electron microscope reaches the target electron beam current value.

[0061] This implementation only requires a single electron beam current test to determine the primary correspondence between the excitation current and the electron beam current. Subsequently, the current beam current can be determined simply by obtaining the input excitation from the condenser, eliminating the need for beam current evaluation using a Faraday cup. This significantly reduces beam current detection time. In summary, the embodiments of the present application directly map the electron beam current through the excitation of the condenser, saving time and improving the detection and measurement efficiency of the device.

[0062] Here, the working principle of the scanning electron microscope is explained in combination with the lens barrel structure of the scanning electron microscope. Figure 2 Figure 2 shows a schematic diagram of the lens barrel structure of a scanning electron microscope. Figure 2 As shown, it includes: a cathode 201, an anode 202, an aperture 203, a condenser 204, a condenser coil 205, an objective aperture 206 (generally having multiple holes), a detector 207, an objective lens 208, a first deflector 209, a lower pole shoe 210 of the objective lens, a sample 211, an objective lens coil 212, a second deflector 213 and an electron beam 214.

[0063] The working principle of the scanning electron microscope is as follows: the electron beam 214 is emitted by the cathode 201, passes through the diaphragm 203 after acceleration, and the beam current size and half-angle of the electron beam 214 are adjusted by the condenser lens 204. After the electron beam 214 passes through the objective diaphragm 206, the grid scanning is realized by the first deflector 209 and the second deflector 213, and the electron beam 214 is focused into a nanoscale beam spot under the action of the objective lens 208, and is bombarded on the observed sample 211. The electron beam 214 interacts with the sample 211 to generate a large number of electrons, which are received by the detector 207. Finally, after processing, the image with a certain contrast is modulated.

[0064] The technology of the embodiment of the present application mainly relates to the structure between the condenser lens 204 and the objective diaphragm 206. Based on the excitation current of the condenser lens 204, the electron beam current value of the electron beam 214 bombarding the sample 211 can be estimated.

[0065] The method for adjusting the electron beam current provided by the embodiment of the present application comprises the following steps: obtaining the original excitation current value of the condenser lens in the scanning electron microscope; determining the original electron beam current value based on the first correspondence relationship between the excitation current value and the electron beam current value. Further, the scanning electron microscope is adjusted based on the original electron beam current value, so that the electron beam current value of the scanning electron microscope is the target electron beam current value. In the implementation mode, the measurement by the Faraday cup is no longer required when the electron beam current value is obtained, but the excitation current value of the condenser lens is directly estimated by the correspondence relationship between the excitation current value and the electron beam current value. Since the excitation current value of the condenser lens is obtained in a simple manner, the operation time for measuring by the Faraday cup is saved, and the efficiency of obtaining the electron beam current value is improved.

[0066] It is mentioned above that the data used to establish the first correspondence relationship is not limited. As an optional implementation mode, before the electron beam current value is determined based on the first correspondence relationship, a set of excitation current values and a set of corresponding electron beam current values are obtained; and the first correspondence relationship is established based on the excitation current values and the electron beam current values corresponding to each other in the set of excitation current values and the set of electron beam current values.

[0067] It should be noted that the data amount of the set of excitation current values and the set of electron beam current values is not limited in the embodiment of the present application. The excitation current value in the set of excitation current values corresponds to the electron beam current value in the set of electron beam current values, that is, the two have a correspondence relationship, and the purpose of the implementation mode is to extract the correspondence relationship. The embodiment proposes an implementation mode for determining the correspondence relationship in the two actually corresponding data sets, which can accurately establish the first correspondence relationship between the excitation current value and the electron beam current value.

[0068] After obtaining test data (i.e., a set of excitation current values ​​and a set of electron beam current values) based on a scanning electron microscope test, a first correspondence relationship needs to be established based on the two sets. In actual applications, the specific method of establishing the first correspondence relationship and the specific form of expression of the first correspondence relationship are not limited and can be selected based on actual conditions.

[0069] As a feasible implementation method, an initial correlation function between the excitation current value of the condenser and the electron beam current value of the scanning electron microscope can be established based on the focusing principle of the condenser. Then, based on the corresponding excitation current values ​​and electron beam current values ​​in the excitation current value set and the electron beam current value set, the constant value in the initial correlation function can be determined to obtain a correlation function that characterizes the first corresponding relationship.

[0070] In this implementation, the specific form of the function is first derived, and then the parameters are solved using test data. The obtained correlation function is consistent with the theory, and a more accurate result can be obtained based on less test data.

[0071] Here is a specific form of the initial correlation function:

[0072]

[0073] Where A is the first constant, B is the second constant, W is the third constant, P is the fourth constant, I1 is the excitation current value, and I2 is the electron beam current value. After obtaining the above initial correlation function, the first constant A, the second constant B, the third constant W, and the fourth constant P are solved based on the test data to obtain the specific values ​​of the two corresponding to the scanning electron microscope, and then the correlation function representing the first correspondence relationship is obtained.

[0074] The process of establishing the initial correlation function and the physical principles involved are described in detail below.

[0075] Figure 3 Figure 2 shows a schematic diagram of a condenser adjusting the beam. Figure 3 As shown, a first reference plane 301, a condenser plane 302, and a second reference plane 303 are taken. Condenser plane 302 is the plane where the center of the condenser is located. When the condenser is focusing, the first reference plane 301 is the object plane.

[0076] When the condenser mirror is not focused (no current passes through), the beam spot on the first reference plane 301 is projected onto the second reference plane 303 .

[0077] When the condenser is focusing, the lens is focused on the first reference plane 301, and the beam spot is imaged on the second reference plane 303 (the first reference plane 301 is the object plane and the second reference plane 303 is the image plane).

[0078] When the condenser is underfocused, the lens is focused on a plane (ie, the object plane) above the first reference plane 301 .

[0079] When the condenser lens is overfocused, the lens is focused on a plane (ie, the object plane) below the first reference plane 301 .

[0080] Figure 3 In, r c is the beam spot radius of the first reference plane 301, α c is the half angle of the beam spot on the first reference plane 301, R is the radius of the condenser aperture. L is the distance between the first reference plane 301 and the second reference plane 303, KL is the distance between the condenser plane 302 and the first reference plane 301, (1-K)L is the distance between the condenser plane 302 and the second reference plane 303, and K is a constant (0 <K<1)。

[0081] Among them, the focal length of the condenser F=CL, C represents the relative length value of the focal length measured by L, and C changes with the change of the excitation current of the condenser.

[0082] When the condenser is not focused, the electron beam aperture half angle When the condenser is underfocused or overfocused, if the image is formed on the second reference plane 303, the image distance q = (1-K)L, and the corresponding object plane will be at the conjugate plane Z0. Then the object distance p should satisfy the following formula:

[0083]

[0084] but:

[0085]

[0086] So the lateral magnification m, the angular magnification m r They are:

[0087]

[0088] r c The opening angle at the conjugate plane Z0 is:

[0089]

[0090] h=±(KL-p). Regardless of whether the condenser is underfocused or overfocused, the value of h represents the distance between the conjugate planes of the first reference plane 301 and the second reference plane 303 (overfocusing takes a positive sign, underfocusing takes a negative sign).

[0091]

[0092] Among them, α ais the half-angle of the electron beam aperture in the underfocus and overfocus states. Omitting the plus and minus signs, we have:

[0093]

[0094] Introduce a mapping function:

[0095]

[0096] The aperture half angle of the electron beam in the underfocus and overfocus states is:

[0097]

[0098] In the case of positive focus, the image distance q = (1-K) L, and the object distance p = K L. At the same time, it also satisfies:

[0099]

[0100] Since C = K(1-K), the mapping function is expressed as:

[0101]

[0102] It can be seen that the aperture half angle α a tends to infinity, but in fact, at this time α a The maximum value of α is limited by the objective lens aperture, a The maximum value α m The actual value of and The smaller of the two.

[0103] Assume that the current density on the second reference plane 303 is j a Based on the principle of brightness invariance, the brightness β will remain unchanged regardless of whether there is a condenser or not. So the following formula is obtained:

[0104] When the condenser is not focused:

[0105] When the condenser is underfocused or overfocused:

[0106] When the condenser is focusing: At this time a is a constant.

[0107] Figure 4 Figure 2 shows a schematic diagram of a condenser adjusting the illumination spot radius at the image plane. Figure 4 As shown, when the condenser is not focused: the radius of the beam spot on the second reference plane 303 is r0=α cL. When the condenser is underfocused or overfocused, the position of the image plane will be above or below the second reference plane 303, so the object distance p = KL, and the image distance q should satisfy:

[0108]

[0109] but:

[0110]

[0111] So the lateral magnification m, the angular magnification m r They are:

[0112]

[0113] r c The opening angle at the image plane is: α c ·m r =α c / m, the illumination radius r projected onto the second reference plane 303 a for:

[0114]

[0115] H=±[(1-K)Lq] (19)

[0116] Where H is the distance from the image plane to the second reference plane 303 (overfocusing takes a positive sign, underfocusing takes a negative sign). Then:

[0117]

[0118] Research:

[0119] Because the focal length F = CL, for the condenser, there is the following corresponding relationship:

[0120]

[0121] B(z)∝(n·I1)

[0122] Where n is the number of coil turns, I1 is the excitation current value, and B(z) is the on-axis field distribution of the condenser.

[0123] therefore,

[0124] Will Rewrite as (W, P are constants and have fixed values ​​for a specific scanning electron microscope).

[0125] During use, assuming that the aperture of the objective lens is not changed, and the beam spot diameter on the objective lens aperture is larger than the aperture diameter, the area of ​​the electron beam passing through the aperture is a constant value, which is πd 2 光 / 4, then the electron beam current value that finally reaches the sample surface is I2=(πd 2 光 / 4)*J a It can be seen that the electron beam current value I2 and the current density J a One-to-one correspondence, based on the above current density J a The corresponding formulas in different situations show that when the condenser is under-focused or over-focused, the electron beam current value I2 is Relatedly, when the condenser is focusing, the electron beam current value I2 is a constant, namely the second constant B.

[0126] Therefore, we only need to study If this is applied to a real-world situation, the values ​​of two constants, W and P, need to be determined. To determine these two parameters, an experiment is designed, using a Faraday cup to measure the corresponding electron beam current at different excitation currents. Finally, the least squares method is used to fit the two parameters, W and P, in the formula. For higher accuracy, additional test data will be needed (generally, an accuracy of 1% is sufficient).

[0127] After the two parameters W and P are calculated, we can get J a , the electron beam current on the current sample surface can be indirectly estimated based on the condenser excitation current. This relationship is written into the host computer, and when the condenser excitation current is adjusted, the electron beam current on the current sample surface can be obtained.

[0128] Figure 5 A curve diagram showing the relationship between the measured excitation current value and the electron beam current value is shown. Figure 5 As shown, the horizontal axis is the excitation current value of the condenser, and the vertical axis is the electron beam current value of the scanning electron microscope. Based on the corresponding relationship between the two, the measured values ​​are plotted into a relationship curve. Figure 6 A graph corresponding to an initial correlation function is shown. Figure 6 As shown, the formula The fitted curve after arbitrarily assigning values ​​to the parameters W and P is similar to the curve obtained from the actual test. It can be seen that the derived formula is consistent with the actual situation.

[0129] In this implementation, a correlation function is first established based on practical theory, and then the parameters of the correlation function are solved using measured values. This allows for a more accurate correspondence to be obtained with less measured data. This implementation also provides a specific form of the correlation function, based on which the accurate original electron beam current value can be solved.

[0130] As mentioned above, the specific form of the function representing the first correspondence can be derived first, and then the parameters can be solved to obtain the final function. This approach, based on theoretical derivation, results in smaller errors. However, in practical applications, other alternatives can also be adopted. As a feasible implementation, a curve fitting can be performed based on the corresponding excitation current values ​​and electron beam current values ​​in the set of excitation current values ​​and the set of electron beam current values ​​to obtain a fitting curve representing the first correspondence.

[0131] Specifically, the values ​​in the excitation current and beam current value sets can be chosen to be closer to actual applications, ensuring the practicality of the fitted curve. Because this approach eliminates the process of deriving the specific form of the function based on actual physical theory, the resulting fitted curve may contain significant errors. To improve the fitting accuracy, extensive experiments are required to obtain more test data to ensure the accuracy of the curve.

[0132] In addition, as an optional implementation, a polynomial function can be determined based on the fitting curve. During application, an excitation current value is input into the polynomial function to obtain a corresponding electron beam current value.

[0133] This implementation method eliminates the complex process of establishing a correlation function and directly performs curve fitting through test data. Although a large amount of test data is required for fitting, the results obtained are more consistent with the actual situation of the scanning electron microscope and can avoid errors in theoretical deduction.

[0134] In practical applications, if a Faraday cup is placed in a corner of the sample stage, acquiring test data takes a long time. Therefore, as an alternative embodiment, the Faraday cup can be placed inside the barrel of a scanning electron microscope. To obtain the set of excitation current values ​​and the corresponding set of electron beam current values, the excitation current values ​​of the condenser lens can be repeatedly acquired while the electron beam emitted by the scanning electron microscope enters the aperture of the Faraday cup. Furthermore, the readings of a picoammeter connected to the Faraday cup can be repeatedly acquired to obtain the set of electron beam current values.

[0135] Because in this implementation, the Faraday cup is installed in the barrel of the scanning electron microscope instead of on the sample stage, the electron beam on the main axis can be deflected onto the Faraday cup through electric field deflection or magnetic field deflection. Although the newly added module will bring some constraints to the overall design and the complexity of the design will increase accordingly, the current electron beam current size can be tested more conveniently and quickly.

[0136] In order to solve the above technical problems, the present invention also provides an electron beam current regulating device. Figure 7 FIG. 1 shows a schematic diagram of the structure of the electron beam regulating device provided in an embodiment of the present application. Figure 7As shown, the apparatus includes the following modules:

[0137] The acquisition module 701 is configured to acquire an original excitation current value of the condenser in the scanning electron microscope.

[0138] The determination module 702 is configured to determine an original electron beam current value of the scanning electron microscope based on the original excitation current value and a first correspondence relationship, the first correspondence relationship being a correspondence relationship between the excitation current value of the condenser and the electron beam current value of the scanning electron microscope.

[0139] The adjustment module 703 is configured to adjust the scanning electron microscope based on the original electron beam current value, so that the electron beam current value of the scanning electron microscope is a target electron beam current value.

[0140] In some embodiments, the acquisition module 701 is further configured to, before determining the original electron beam current value of the scanning electron microscope based on the original excitation current value and the first correspondence relationship, acquire a set of excitation current values and a corresponding set of electron beam current values, the excitation current values in the set of excitation current values corresponding to the electron beam current values in the set of electron beam current values one by one.

[0141] The adjustment apparatus of the electron beam current further includes an establishment module configured to establish the first correspondence relationship based on the excitation current values and the electron beam current values corresponding to each other in the set of excitation current values and the set of electron beam current values.

[0142] In some embodiments, the establishment module is specifically configured to:

[0143] establish an initial correlation function between the excitation current value of the condenser and the electron beam current value of the scanning electron microscope based on a focusing principle of the condenser;

[0144] determine a constant value in the initial correlation function based on the excitation current values and the electron beam current values corresponding to each other in the set of excitation current values and the set of electron beam current values, to obtain a correlation function representing the first correspondence relationship.

[0145] In some embodiments, the establishment module is specifically configured to:

[0146] perform curve fitting based on the excitation current values and the electron beam current values corresponding to each other in the set of excitation current values and the set of electron beam current values, to obtain a fitting curve representing the first correspondence relationship.

[0147] In some embodiments, a Faraday cup is arranged in a lens barrel of the scanning electron microscope.

[0148] The acquisition module 701 is specifically configured to:

[0149] When the electron beam emitted by the scanning electron microscope enters the hole of the Faraday cup, the excitation current value of the condenser is obtained multiple times to obtain an excitation current value set, and the readings of the picoammeter connected to the Faraday cup are obtained multiple times to obtain an electron beam current value set.

[0150] The device provided in the embodiment of the present application is the same as the method in the above embodiment, so the two have the same embodiments and beneficial effects, which will not be repeated here.

[0151] Figure 8 FIG. 1 shows a schematic diagram of the hardware structure of the electron beam regulating device provided in an embodiment of the present application. Figure 8 As shown, the electron beam current regulating device may include a processor 801 and a memory 802 storing computer program instructions.

[0152] Specifically, the processor 801 may include a central processing unit (CPU) or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

[0153] The memory 802 may include a large capacity memory for data or instructions. By way of example and not limitation, the memory 802 may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive, or a combination of two or more of these. Where appropriate, the memory 802 may include removable or non-removable (or fixed) media. Where appropriate, the memory 802 may be inside or outside the integrated gateway disaster recovery device. In a specific embodiment, the memory 802 is a non-volatile solid-state memory.

[0154] The memory 802 may include a read-only memory (ROM), a random access memory (RAM), a magnetic disk storage medium device, an optical storage medium device, a flash memory device, an electrical, optical, or other physical / tangible memory storage device. Thus, generally, the memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., a memory device) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to an aspect of the present disclosure.

[0155] The processor 801 reads and executes computer program instructions stored in the memory 802 to implement any one of the electron beam current adjustment methods in the above embodiments.

[0156] In one example, the electron beam current regulating device may further include a communication interface 803 and a bus 804. The processor 801, the memory 802, and the communication interface 803 are connected via the bus 804 and communicate with each other.

[0157] The communication interface 803 is mainly used to implement communication between various modules, devices, units and / or equipment in the embodiments of the present application.

[0158] The bus 804 includes hardware, software, or both that couples the components of the electron beam current regulating device to each other. By way of example and not limitation, the bus may include an Accelerated Graphical Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hyper Transport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an InfiniBand interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VLB) bus, or other suitable buses or a combination of two or more of these. Where appropriate, the bus 804 may include one or more buses. Although embodiments herein describe and illustrate a particular bus, this application contemplates any suitable bus or interconnect.

[0159] In addition, in conjunction with the electron beam current adjustment method in the above embodiments, embodiments of the present application may provide a computer storage medium for implementation. The computer storage medium stores computer program instructions; when the computer program instructions are executed by a processor, any of the electron beam current adjustment methods in the above embodiments is implemented.

[0160] An embodiment of the present application further provides a computer program product, including a computer program, which implements any one of the electron beam current adjustment methods in the above embodiments when the computer program is processed and executed.

[0161] It should be understood that the present application is not limited to the specific configurations and processes described above and illustrated in the figures. For the sake of brevity, a detailed description of known methods is omitted here. In the above embodiments, several specific steps are described and illustrated as examples. However, the method process of the present application is not limited to the specific steps described and illustrated. Those skilled in the art can make various changes, modifications, and additions, or change the order of the steps after understanding the spirit of the present application.

[0162] The functional blocks shown in the block diagram above can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, ASICs, appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of the present application are programs or code segments that are used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or communication link via a data signal carried in a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROMs, flash memories, erasable ROMs (Erasable ROM, EROMs), floppy disks, compact disc read-only memory (Compact Disc Read-Only Memory, CD-ROMs), optical discs, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0163] It should also be noted that the exemplary embodiments mentioned in this application describe some methods or systems based on a series of steps or devices. However, this application is not limited to the order of the above steps. In other words, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0164] The above describes various aspects of the present disclosure with reference to the flowcharts and / or block diagrams of a method, device, equipment, medium and product for regulating an electron beam current according to an embodiment of the present disclosure. It should be understood that each box in the flowchart and / or block diagram and the combination of boxes in the flowchart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine so that these instructions executed by the processor of the computer or other programmable data processing device enable the implementation of the functions / actions specified in one or more boxes in the flowchart and / or block diagram. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor or a field programmable logic circuit. It can also be understood that each box in the block diagram and / or flowchart and the combination of boxes in the block diagram and / or flowchart can also be implemented by special-purpose hardware that performs the specified function or action, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0165] The above content is only a specific implementation method of the present application. Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the scope of protection of the present application is not limited to this. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed in this application, and these modifications or replacements should be included in the scope of protection of the present application.

Claims

1. A method for adjusting electron beam current, characterized in that: include: Obtain the original excitation current value of the condenser in the scanning electron microscope; Determining an original electron beam current value of the scanning electron microscope based on the original excitation current value and a first corresponding relationship; wherein the first corresponding relationship is a corresponding relationship between the excitation current value of the condenser and the electron beam current value of the scanning electron microscope; The scanning electron microscope is adjusted based on the original electron beam current value, so that the electron beam current value of the scanning electron microscope is equal to the target electron beam current value.

2. The electron beam current adjustment method according to claim 1, characterized in that: Before determining the original electron beam current value of the scanning electron microscope based on the original excitation current value and the first corresponding relationship, the method further includes: Acquire an excitation current value set and a corresponding electron beam current value set; wherein the excitation current values ​​in the excitation current value set correspond one-to-one to the electron beam current values ​​in the electron beam current value set; The first corresponding relationship is established based on the excitation current values ​​and electron beam current values ​​corresponding to each other in the excitation current value set and the electron beam current value set.

3. The electron beam current adjustment method according to claim 2, characterized in that: The establishing the first corresponding relationship based on the excitation current values ​​and electron beam current values ​​corresponding to each other in the excitation current value set and the electron beam current value set includes: Based on the focusing principle of the condenser, an initial correlation function is established between the excitation current value of the condenser and the electron beam current value of the scanning electron microscope; Based on the excitation current values ​​and electron beam current values ​​corresponding to each other in the excitation current value set and the electron beam current value set, a constant value in the initial correlation function is determined to obtain a correlation function representing the first corresponding relationship.

4. The electron beam current adjustment method according to claim 3, characterized in that: The initial correlation function includes: In the case of underfocus or overfocus of the condenser: When the condenser is focused: I2 = B; Among them, A is the first constant, B is the second constant, W is the third constant, P is the fourth constant, I1 is the excitation current value, and I2 is the electron beam current value.

5. The electron beam current adjustment method according to claim 2, characterized in that: The establishing the first corresponding relationship based on the excitation current values ​​and electron beam current values ​​corresponding to each other in the excitation current value set and the electron beam current value set includes: Curve fitting is performed based on the excitation current values ​​and electron beam current values ​​corresponding to each other in the excitation current value set and the electron beam current value set to obtain a fitting curve representing the first corresponding relationship.

6. The electron beam current adjustment method according to any one of claims 2 to 5, characterized in that: A Faraday cup is provided in the lens barrel of the scanning electron microscope; The step of obtaining the excitation current value set and the corresponding electron beam current value set includes: When the scanning electron microscope emits an electron beam that enters the hole of the Faraday cup, the excitation current value of the condenser is obtained multiple times to obtain the excitation current value set, and the readings of the picoammeter connected to the Faraday cup are obtained multiple times to obtain the electron beam current value set.

7. An electron beam current regulating device, characterized in that: include: An acquisition module is used to obtain the original excitation current value of the condenser in the scanning electron microscope; a determination module, configured to determine an original electron beam current value of the scanning electron microscope based on the original excitation current value and a first corresponding relationship; the first corresponding relationship being a corresponding relationship between the excitation current value of the condenser mirror and the electron beam current value of the scanning electron microscope; The adjustment module is used to adjust the scanning electron microscope based on the original electron beam current value so that the electron beam current value of the scanning electron microscope reaches the target electron beam current value.

8. An electron beam current regulating device, characterized in that: include: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, the electron beam current adjustment method according to any one of claims 1 to 6 is implemented.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer program instructions, and when the computer program instructions are executed by a processor, the method for adjusting the electron beam current according to any one of claims 1 to 6 is implemented.

10. A computer program product, characterized in that When the instructions in the computer program product are executed by a processor of an electronic device, the electronic device is enabled to perform the electron beam current adjustment method according to any one of claims 1 to 6.

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