Electron probe positioning substrate, displacement measurement method, positioning control method

Abstract

The present invention discloses an electron probe positioning substrate, a displacement measurement method, and a positioning control method. The marking area of the substrate includes a first line group composed of multiple continuous first lines and a second line group composed of multiple discontinuous second lines. The first line group and the second line group are orthogonal, and the spacing of the first line group on the scanning line is not equal to the spacing of the second line group on the scanning line. By setting multiple mutually orthogonal first lines and second lines, and the spacing of the first line group on the scanning line is not equal to the spacing of the second line group on the scanning line, the periodic signals of the spacing of the first line group and the second line group on the scanning line can be separated from the video signal based on secondary electrons obtained by scanning, thereby facilitating the calculation of the displacements of the electron probe in two directions in the two-dimensional plane, so as to facilitate subsequent real-time control to eliminate the displacement of the electron probe.

Description

Technical Field

[0001] The present invention relates to the technical field of lithography equipment, and particularly to an electronic probe positioning substrate, a displacement measurement method, and a positioning control method. Background Art

[0002] An electron beam lithography equipment includes a beam device, a wafer stage, a substrate, and a control system, and the substrate is disposed on the wafer stage. Existing beam devices generally include an electron gun, a beam shutter, a condenser lens, an aperture, a scanning coil, a controller, etc. The electron beam lithography equipment has a high requirement for the positioning accuracy of the electron probe generated by the beam device. However, the structural vibration caused by floor vibration and the movement of the wafer stage will cause the electron probe to vibrate, reducing the positioning accuracy of the electron probe.

[0003] To solve this problem, many methods have been proposed, such as wafer stage positioning control and external vibration isolation technology. The vibration isolation technology includes setting rubber pads, coil springs, dampers or shock absorbers to achieve vibration reduction; for positioning control, the displacement of the electron probe is ultimately measured through a lithography test image, and this microscopic image can be directly used for vibration control. Currently, the special marker structure image used for measuring the displacement of the electron probe is a uniform linear pattern along one direction, which is only applicable to the probe displacement in one direction. As Figure 1 shown, where (a) is a conventional marker structure image, (b) is a microscopic image of the electron probe scanning the marker pattern without vibration, and (c) is a microscopic image of the electron probe scanning the marker pattern with vibration; reconfiguring the marker structure pattern is still required for measuring the probe displacement in a two-dimensional plane. When calculating the displacement of the electron probe through the microscopic image of vibration, it is necessary to fit the simulated microscopic image without vibration with the measured microscopic image, and the calculation load is high, far from meeting the requirements of real-time control applications. Summary of the Invention

[0004] The present invention provides an electronic probe positioning substrate, a displacement measurement method, and a positioning control method to solve the problems that the existing substrate marker image is only applicable to the measurement of the electron beam displacement in one direction, with a high calculation load and far from meeting the requirements of real-time control applications.

[0005] In a first aspect, an electronic probe positioning substrate is provided, and its marking area includes a first line group composed of multiple continuous first lines and a second line group composed of multiple discontinuous second lines. The first line group and the second line group are orthogonal, and the spacing of the first line group on the scanning line is not equal to the spacing of the second line group on the scanning line.

[0006] By setting a plurality of first lines and second lines that are orthogonal to each other, and the spacing of the first line group on the scanning line is not equal to the spacing of the second line group on the scanning line, a periodic signal of the spacing of the first line group and the second line group on the scanning line can be separated from the video signal based on secondary electrons obtained from the scanning pattern, thereby facilitating the calculation of the displacements of the electron probe in two directions in the two-dimensional plane.

[0007] According to the first aspect, in a possible implementation manner, the spacing of the first line group on the scanning line and the spacing of the second line group on the scanning line satisfy the following conditions:

[0008] P" = P / sinR, Q" = Q / cosR

[0009] P″ = αQ″

[0010] α > 3 / 2 or α < 2 / 3

[0011] In the formula, P" represents the spacing of the first line group on the scanning line; Q" represents the spacing of the second line group on the scanning line; P represents the spacing of the first line group, Q represents the spacing of the second line group; R represents the angle between the scanning line and the first line group.

[0012] According to the first aspect, in a possible implementation manner, the projected lengths of the line width of the first line, the line width of the second line, and the spacing between adjacent first and second lines on the scanning line are all greater than the horizontal pixel resolution.

[0013] In a second aspect, an electron probe displacement measurement method is provided, including:

[0014] Obtaining in real time a video signal W′(t) of the electron probe scanning the electron probe positioning substrate as described in any item of the first aspect;

[0015] Performing Fourier decomposition on the video signal W′(t) to obtain its fundamental waves F1′(t) and G1′(t), and the phases γ1′ and φ1′ of F1′(t) and G1′(t); F1′(t) and G1′(t) respectively represent the fundamental wave signals of the spacing of the first line group on the scanning line and the fundamental wave signals of the spacing of the second line group on the scanning line obtained in real time;

[0016] The displacement (u, v) of the electron probe in the current scanning round is expressed as follows:

[0017] u = P(γ1′ - γ1) / (2π), v = Q(φ1′ - φ1) / (2π)

[0018] In the formula, γ1 and φ1 respectively represent the phases of the fundamental wave signals of the spacings of the first line group and the second line group on the scanning line when the electron probe has no vibration, P represents the spacing of the first line group, and Q represents the spacing of the second line group.

[0019] According to a second aspect, in a possible implementation, the video signal W′(t) is decomposed into its fundamental waves F1′(t) and G1′(t) as follows:

[0020] W′(t) = F1′(t) + G1′(t)

[0021] F1′(t) = α1′sin(ω u t + γ1′), G1′(t) = β1′sin(ω v t + φ1′)

[0022] In the formula, γ1′ = tan -1 (A1′ / B1′), φ1′ = tan -1 (C1′ / D1′); F1′(t) represents the fundamental wave signal of the spacing of the first line group obtained in real time on the scanning line, and G1′(t) represents the fundamental wave signal of the spacing of the second line group obtained in real time on the scanning line; T s represents the period of each scan, t represents time; ω u = 2π / T u , ω v = 2π / T v , T u = P" / V, T v = Q" / V, where V represents the scanning speed of the electron probe, and P" and Q" respectively represent the spacing of the first line group and the spacing of the second line group on the scanning line.

[0023] In a third aspect, an electron probe displacement measurement method is provided, including:

[0024] Obtaining the fundamental wave amplitude θ N at the previous moment t N = [A1′(t N )B1′(t N )C1′(t N )D1′(t N )] T ; where the fundamental wave amplitude θ N = [A1′(t N )B1′(t N )C1′(t N )D1′(t N )]T Based on the time series of video signals {W1′, W2′, …, W N ′} of the electron probe scanning the electron probe positioning substrate as described in any one of the first aspects, where t = {t1, t2, …, t N ′}, and W N ′ represents the video signal value at time t N ;

[0025] Obtain the video signal value at the current time t N+1 , and use the least squares method to determine the base wave amplitude θ N+1 at the current time t N+1 = [A1′(t N+1 ) B1′(t N+1 ) C1′(t N+1 ) D1′(t N+1 )] T ;

[0026] The probe displacement (u(t N+1 ), v(t N+1 )) at the current time t N+1 can be expressed as follows:

[0027] u(t N+1 ) = P(γ1′(t N+1 ) - γ1) / (2π), v(t N+1 ) = Q(φ1′(t N+1 ) - φ1) / (2π)

[0028] In the formula, γ1′(t N+1 ) = tan -1 [A1′(t N+1 ) / B1′(t N+1 )], φ1′(t N+1 ) = tan -1 [C1′(t N+1 ) / D1′(t N+1 )], γ1 and φ1 respectively represent the phase of the fundamental wave signal of the spacing of the first line group on the scanning line and the phase of the fundamental wave signal of the spacing of the second line group on the scanning line when the electron probe has no vibration, P represents the spacing of the first line group, and Q represents the spacing of the second line group.

[0029] According to the third aspect, in a possible implementation, the time series of video signals {W1′, W2′, …, W N ′} is expressed as follows:

[0030]

[0031] In the formula, η N represents the error at time t N ; ωu = 2π / T u , ω v = 2π / T v , T u = P" / V, T v = Q" / V, V represents the scanning speed of the electron probe, P" and Q" respectively represent the pitch of the first line group on the scanning line and the pitch of the second line group on the scanning line; fundamental wave amplitude θ N = [A1′(t N )B1′(t N )C1′(t N )D1′(t N )] T is expressed as follows:

[0032]

[0033] In the formula,

[0034] Using the least squares method to determine the fundamental wave amplitude θ N+1 at the current moment t N+1 and P N+1 are expressed as follows:

[0035]

[0036] In the formula, W′ N+1 represents the video signal value at the current moment t N+1 .

[0037] Fourthly, an electron probe positioning control method is provided, including:

[0038] Obtaining the measurement values of multiple accelerometers arranged on the vacuum chamber, lens barrel, and wafer platform in real time, and inputting them into the feedforward controller to obtain the first input voltage of the scanning coil;

[0039] Using the electron probe displacement measurement method described in any one of the second or third aspects to obtain the real-time displacement of the electron probe, and inputting it into the feedback controller to obtain the second input voltage of the scanning coil;

[0040] According to the final input voltage obtained by fusing the first input voltage and the second input voltage of the scanning coil, the voltage of the scanning coil is controlled in real time.

[0041] According to the fourth aspect, in a possible implementation, the feedforward controller is expressed as follows:

[0042]

[0043] Among them, (V x , V y) represents the first input voltage of the scanning coil, δ J represents the measured value of the Jth accelerometer, G represents the transfer function from the measured values of multiple accelerometers to the displacement of the electron probe, and C represents the transfer matrix from the displacement of the electron probe to the first input voltage of the scanning coil;

[0044] The feedback controller is expressed as follows:

[0045]

[0046] wherein, (V x (t j ), V y (t j )) represents the second input voltage of the scanning coil at time t j , (u(t j ), v(t j )) represents the probe displacement at time t j , and k pu , k pv , k du , k du are all gain coefficients.

[0047] In a fifth aspect, an electron beam lithography apparatus is provided, the substrate of which adopts the electron probe positioning substrate according to any one of the first aspect, and includes a marking area and an exposure area thereon;

[0048] Its beam device adopts a multi-beam device, and one of the electron probes is used to scan the marking area, and the other electron probes are used to scan the exposure area.

[0049] The present invention provides an electron probe positioning substrate, a displacement measurement method, and a positioning control method, which have the following beneficial effects:

[0050] (1) A new type of marking structure pattern is proposed. By setting a plurality of mutually orthogonal first lines and second lines, and the spacing between the first line group and the second line group on the scanning line is not equal, the periodic signals of the spacing between the first line group and the second line group on the scanning line can be separated from the video signal based on secondary electrons obtained by scanning, and then it is convenient to calculate the displacements of the electron probe in two directions in the two-dimensional plane;

[0051] (2) Based on the new marking structure pattern, according to the video signal obtained by scanning, the displacements of the electron probe in two directions can be quickly calculated by Fourier decomposition or recursive least squares method. The calculation speed is fast, and real-time control can be realized;

[0052] (3) A feedforward controller and a feedback controller are provided. The feedforward controller controls the input voltage of the scanning coil based on the measurement data of the accelerometer, and the feedback controller controls the input voltage of the scanning coil based on the calculated real-time displacement of the electron probe. Through the synergistic effect of the feedforward controller and the feedback controller, real-time suppression of the displacement of the electron probe is achieved. Description of the Drawings

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0054] Figure 1 is a microscopic image of the traditional marking structure pattern provided by the present invention, where (a) is the traditional marking structure pattern, (b) is the microscopic image of the traditional marking structure pattern without vibration, and (c) is the microscopic image of the traditional marking structure pattern with vibration;

[0055] Figure 2 is a schematic diagram and a microscopic image of the marking area structure of the electron probe positioning substrate provided by an embodiment of the present invention; where (a) is the schematic diagram of the marking area structure of the electron probe positioning substrate, (b) is the microscopic image of the marking area of the electron probe positioning substrate without vibration, and (c) is the microscopic image of the marking area of the electron probe positioning substrate with vibration;

[0056] Figure 3 is a schematic diagram of the scanning process of the marking area of the electron probe positioning substrate provided by an embodiment of the present invention;

[0057] Figure 4 is the video signal and the response of each fundamental wave when the electron probe has no vibration provided by an embodiment of the present invention;

[0058] Figure 5 is the video signal and the response of each fundamental wave when the electron probe vibrates provided by an embodiment of the present invention;

[0059] Figure 6 is a schematic diagram of the mechanical dynamics analysis of the electron beam lithography equipment provided by an embodiment of the present invention;

[0060] Figure 7 is a multi-beam device provided by an embodiment of the present invention, where (a) is a multi-beam device with a single electron source, and (b) is a multi-beam device with multiple electron sources. Detailed Embodiments

[0061] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention. All other implementation manners obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0062] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "longitudinal", "transverse", "vertical", "horizontal", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. The terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or order. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0063] Embodiment 1

[0064] As Figure 2 、 Figure 3 shown, this embodiment provides an electron probe positioning substrate, the marked area of which includes a first line group 1 composed of a plurality of continuous first lines and a second line group 2 composed of a plurality of discontinuous second lines. The first line group 1 and the second line group 2 are orthogonal, and the spacing of the first line group 1 on the scan line is not equal to the spacing of the second line group 2 on the scan line.

[0065] Specifically, by scanning the marked area of the electron probe positioning substrate with an electron beam multiple times, its microscopic image can be obtained. Assuming that the spacing of the first line group 1 is P, the spacing of the second line group 2 is Q, and the angle between each scan line and the first line group 1 is R (R≠0, π / 2, π, 2π), then the spacing P" of the first line group 1 and the spacing Q" of the second line group 2 on the scan line are as follows:

[0066] P" = P / sinR, Q" = Q / cosR

[0067] Since the speed of each line scan is constant, the measured video signal based on secondary electrons contains signals with periods P" and Q".

[0068] Therefore, in order to obtain P" = αQ" (α≠1), by appropriately selecting each spacing (P and Q) and the direction R of the pattern, the video signals generated by the first line group 1 and the second line group 2 can be separated into W u and W v. In practical applications, when α > 3 / 2 or α < 2 / 3, the reliability of video signal separation can be improved. The projected lengths of the line width A of the first line, the line width B of the second line, and the spacing S between the adjacent first and second lines on the scanning line only need to be greater than the horizontal pixel resolution (W / M). W is the horizontal length of the measured microscopic image, and M is the number of pixels in the horizontal direction.

[0069] In addition, the lower detection limit of the vibration amplitude of the electron probe is determined by the horizontal pixel resolution, and its upper limit is less than W due to observability. Therefore, the geometric parameters of the pattern and the observation magnification should be selected according to the actual vibration amplitude.

[0070] By setting multiple mutually orthogonal first lines and second lines, and the spacings between the first line group 1 and the second line group 2 on the scanning line are not equal, a periodic signal of the spacings between the first line group and the second line group on the scanning line can be separated from the video signal based on secondary electrons obtained by scanning, and then it is convenient to calculate the displacements of the electron probe in two directions in the two-dimensional plane.

[0071] Embodiment 2

[0072] Based on the electron probe positioning substrate provided in the above Embodiment 1, this embodiment provides an electron probe displacement measurement method, including:

[0073] S1: Real-time obtain the video signal W′(t) of the electron probe scanning the electron probe positioning substrate as described in Embodiment 1;

[0074] S2: Perform Fourier decomposition on the video signal W′(t) to obtain its fundamental waves F1′(t) and G1′(t), and the phases γ1′ and φ1′ of F1′(t) and G1′(t); F1′(t) and G1′(t) respectively represent the fundamental wave signals of the spacings between the first line group on the scanning line and the second line group on the scanning line obtained in real time;

[0075] S3: The displacement (u, v) of the current scanning round of the electron probe is expressed as follows:

[0076] u = P(γ1′ - γ1) / (2π), v = Q(φ1′ - φ1) / (2π)

[0077] In the formula, γ1 and φ1 respectively represent the phases of the fundamental wave signals of the spacings between the first line group on the scanning line and the second line group on the scanning line when the electron probe has no vibration, P represents the spacing of the first line group, and Q represents the spacing of the second line group.

[0078] Specifically, when scanning the pattern of the marked area on the substrate with an electron probe, the secondary electrons generated at this time, i.e., the video signal W(t), are measured. The displacement of the electron probe needs to be calculated based on the measurement data during each scan period T s As described above, the video signal measured during the observation process of the electron probe scanning the pattern of the marked area on the substrate is a periodic signal of P" and Q". Represented by Fourier series as follows:

[0079]

[0080] F(t) = ∑ m α m sin(mω u t + γ m ), G(t) = ∑ n β n sin(nω v t + φ n )

[0081] In the formula, γ m = tan -1 (A m / B m ) and φ n = tan -1 (C n / D n ); In addition, assuming that the scanning speed of the electron probe is V, then ω u = 2π / T u and ω v = 2π / T v , T u = P" / V, T v = Q" / V; The number of sine waves of the periodic signals of P" and Q" is m and n, and their angular frequencies are integer multiples of ω u or ω v . F(t) and G(t) represent the periodic signals of P" and Q" respectively. Assuming that due to filtering processing and other reasons, the interference noise η(t) is small enough, the Fourier coefficients (A m , B m , C n , D n ) are determined as follows.

[0082]

[0083] In implementation, only the fundamental wave of the video signal is needed. Therefore, for simplicity, it is assumed here that the video signal only contains the fundamental wave, that is, only m = 1 and n = 1. At this time, the video signal W(t) can be abbreviated as follows:

[0084] W(t) = F1(t) + G1(t)

[0085] F1(t) = α1sin(ω u t + γ1), G1(t) = β1sin(ω v t + φ1)

[0086] Wherein, F1(t) and G1(t) are respectively the fundamental wave signals of the spacing of the first line group on the scanning line and the fundamental wave signal of the spacing of the second line group on the scanning line.

[0087] The responses of the video signal and each fundamental wave when the electron probe has no vibration are as Figure 4 shown. When the electron probe vibrates, the waveform of the video signal and the responses of each fundamental wave are as Figure 5 shown. Since the oscillation period of the electron probe is usually larger than the line scanning period, it can be considered that the probe displacement is constant in each line scan.

[0088] When calculating the displacement of the electron probe, the video signal W′(t) is acquired and Fourier decomposed to obtain its fundamental waves F1′(t) and G1′(t), which are expressed as follows:

[0089] W′(t) = F1′(t) + G1′(t)

[0090] F1′(t) = α1′sin(ω u t + γ1′), G1′(t) = β1′sin(ω v t + φ1′)

[0091] Wherein, γ1′ = tan -1 (A1′ / B1′), φ1′ = tan -1 (C1′ / D1′); F1′(t) represents the fundamental wave signal of the spacing of the first line group on the scanning line obtained in real time, and G1′(t) represents the fundamental wave signal of the spacing of the second line group on the scanning line obtained in real time; T s represents the period of each scan, and t represents time.

[0092] In this case, since the oscillation period of the electron probe is usually large enough compared with the line scanning period, it can be considered that the probe displacement is constant in each line scan. Thus, the displacement (u k , v k ) of the electron probe at the kth line scan can be expressed by the changes of the phases γ1′ and φ1′ of the fundamental waves starting from rest as follows:

[0093] u k = P(γ1′ - γ1) / (2π), v k= Q(φ1′ - φ1) / (2π)

[0094] In the formula, γ1 and φ1 respectively represent the phase of the fundamental wave signal of the spacing of the first line group on the scanning line and the phase of the fundamental wave signal of the spacing of the second line group on the scanning line when the electron probe has no vibration. P represents the spacing of the first line group, and Q represents the spacing of the second line group.

[0095] Based on the new marked structure pattern, according to the video signal obtained by scanning it, the displacements of the electron probe in two directions are quickly calculated through Fourier decomposition. The calculation speed is fast, and real-time control can be achieved.

[0096] Embodiment 3

[0097] Based on the electron probe positioning substrate provided in the above Embodiment 1, this embodiment provides a method for measuring the displacement of an electron probe, including:

[0098] Step 1: Obtain the previous moment t of the current moment N of the fundamental wave amplitude θ N = [A1′(t N )B1′(t N )C1′(t N )D1′(t N )] T ; Among them, the fundamental wave amplitude θ N = [A1′(t N )B1′(t N )C1′(t N )D1′(t N )] T Based on t = {t1 t2…t N}, the video signal time series {W1′ W2′…W N ′} of the electron probe scanning the electron probe positioning substrate as described in Embodiment 1 is obtained, and W N ′ represents the video signal value at the moment of t N ;

[0099] Step 2: Obtain the video signal value at the current moment t N+1 , and use the least squares method to determine the fundamental wave amplitude θ N+1 at the current moment t N+1 = [A1′(t N+1 )B1′(t N+1 )C1′(t N+1 )D1′(t N+1 )] T ;

[0100] Step 3: The probe displacement at the current moment t N+1 (u(t N+1 ), v(tN+1 ) can be expressed as follows:

[0101] u(t N+1 ) = P(γ1′(t N+1 ) - γ1) / (2π), v(t N+1 ) = Q(φ1′(t N+1 ) - φ1) / (2π)

[0102] Where γ1′(t N+1 ) = tan -1 [A1′(t N+1 ) / B1′(t N+1 )], φ1′(t N+1 ) = tan -1 [C1′(t N+1 ) / D1′(t N+1 )]. γ1 and φ1 respectively represent the phase of the fundamental wave signal of the spacing of the first line group on the scanning line and the phase of the fundamental wave signal of the spacing of the second line group on the scanning line when the electron probe has no vibration. P represents the spacing of the first line group, and Q represents the spacing of the second line group.

[0103] As described in Embodiment 2, when using the Fourier decomposition method to calculate the probe displacement, it is calculated by measuring the video signal for a period of time (such as the time used for one line scan). What is shown in this embodiment is how to calculate the probe displacement in real time using the recursive least squares method.

[0104] The previous moment t of the current moment N The corresponding video signal time series {W1′W2′…W N ′} is expressed as follows:

[0105]

[0106] Where η N represents the error at the moment of t N ; ω u = 2π / T u , ω v = 2π / T v , T u = P" / V, T v = Q" / V, V represents the scanning speed of the electron probe, P" and Q" respectively represent the spacing of the first line group on the scanning line and the spacing of the second line group on the scanning line; the fundamental wave amplitude θ N = [A1′(t N )B1′(t N )C1′(t N )D1′(t N )] T is expressed as follows:

[0107]

[0108] In the formula,

[0109] The fundamental wave amplitude θ at the next moment can be gradually calculated by using the recursive least squares method N+1 and P N+1 . At the current moment t N+1 The fundamental wave amplitude θ corresponding to the video signal time series {W′1 W′2 … W′ N+1} N+1 and P N+1 can be determined by the least squares method as follows:

[0110]

[0111] In the formula, W′ N+1 represents the video signal value at the current moment t N+1 .

[0112] Therefore, the probe displacement (u(t j ), v(t j )) at any moment t j can be calculated according to as follows:

[0113] u(t j ) = P(γ1′(t j ) - γ1) / (2π), v(t j ) = Q(φ1′(t j ) - φ1) / (2π)

[0114] In the formula, γ1′(t j ) = tan -1 [A1′(t j ) / B1′(t j )], φ1′(t j ) = tan -1 [C1′(t j ) / D1′(t j )], γ1 and φ1 respectively represent the phase of the fundamental wave signal of the spacing of the first line group on the scanning line and the phase of the fundamental wave signal of the spacing of the second line group on the scanning line when the electron probe has no vibration, P represents the spacing of the first line group, and Q represents the spacing of the second line group.

[0115] Based on the new marked structure pattern, according to the video signal obtained by its scanning, the displacements of the electron probe in two directions are quickly calculated by the recursive least squares algorithm, with fast calculation speed and real-time control can be achieved.

[0116] Embodiment 4

[0117] Based on the foregoing Embodiment 2 or Embodiment 3, this embodiment provides an electron probe positioning control method, including:

[0118] Obtain the measurement values of multiple accelerometers disposed on the vacuum chamber, the lens barrel, and the wafer stage in real time, and input them to a feedforward controller to obtain the first input voltage of the scanning coil;

[0119] Use the electron probe displacement measurement method described in Embodiment 2 or Embodiment 3 to obtain the real-time displacement of the electron probe, and input it to a feedback controller to obtain the second input voltage of the scanning coil;

[0120] Perform real-time control of the scanning coil voltage according to the final input voltage obtained by fusing the first input voltage and the second input voltage of the scanning coil. Wherein the fusion process is the addition of the first input voltage and the second input voltage.

[0121] Wherein, the design method of the feedforward controller is as follows:

[0122] As Figure 6 shown, it is a schematic diagram of the mechanical dynamics analysis of an electron beam lithography apparatus. The vibration of the lithography apparatus comes from the vibration of the floor or the vibration of the lower part of the wafer stage caused by the reaction force of the accelerated movement of the wafer stage. By installing J accelerometers on the vacuum chamber, the lens barrel, and the wafer stage, at this time, the relationship between the displacement (u, v) of the electron probe and the outputs δ1, δ2,..., δ J of the accelerometers is expressed as follows in the frequency domain:

[0123]

[0124] Wherein, G represents the transfer function from the measurement values of multiple accelerometers to the displacement of the electron probe, which is measured through a vibration test. The vibration test is to perform overall vibration on the apparatus by using a vibrator or perform local vibration on the apparatus through the wafer stage. As described above, the probe displacement is measured using the marker structure pattern of a new substrate; and the calibration of the scanning coil is also performed using the same method as the vibration test. First, the following relationship is formed between the input voltage (V x , V y ) of the scanning coil and the displacement (u, v) of the electron probe:

[0125]

[0126] Among them, C represents the transfer matrix of the first input voltage of the electron probe displacement to the scanning coil. When a random signal or a sine signal is input to the scanning coil, the electron probe displacement can be measured through the marking structure pattern of the new substrate to determine the matrix transfer C. And, different from the transfer function G, the transfer matrix C is independent of frequency. As described above, if the input voltages (V x , V y ) are selected as follows, the electron probe displacements (u, v) caused by floor vibration and wafer stage movement can be eliminated.

[0127]

[0128] The above formula is the final expression of the feedforward controller.

[0129] The design method of the feedback controller is as follows:

[0130] The feedback controller uses a classical feedback control algorithm to suppress the probe displacement. Therefore, the feedback controller is expressed as follows:

[0131]

[0132] In the formula, (V x (t j ), V y (t j )) represents the second input voltage of the scanning coil at time t j , (u(t j ), v(t j )) represents the probe displacement at time t j , and k pu , k pv , k du , k du are all gain coefficients; and The "·" in represents taking the derivative.

[0133] Example 5

[0134] This example provides an electron beam lithography apparatus, whose substrate adopts the electron probe positioning substrate described in Example 1, and includes a marking area 3 and an exposure area 4 thereon;

[0135] Its beam device adopts a multi-beam device, and one of the electron probes is used to scan the marking area, and the other electron probes are used to scan the exposure area.

[0136] The electron beam lithography equipment provided in this embodiment has a plurality of accelerometers installed on its vacuum chamber, lens barrel, and wafer stage. The plurality of accelerometers are connected to a control system, and the control system also acquires a video signal obtained by an electron probe scanning a marked area on a substrate. The control system is further configured to execute the electron probe positioning control method described in Embodiment 4. The control system generates an input voltage for a scanning coil based on the acquired accelerometer measurement values and the video signal to control the scanning coil.

[0137] The substrate includes two regions, a marked region 3 and an exposure region 4 (a photoresist layer for exposure). By using a multi-beam device, the marked region and the exposure region can be irradiated by light beams simultaneously. In this embodiment, two types of multi-beam devices are provided, as Figure 7 shown in (a) below, is a multi-beam device with a single electron source, including an electron gun 11, a collimator 12, an aperture array 13, a beam shutter array 14, a condenser lens 15, an aperture 16, a scanning coil 17, and an objective lens 18. It is realized by making the electron beam switch rapidly between the two regions through the beam shutter array 14. The function of the beam shutter array 14 itself is to deflect the light beam using an electrostatic lens or a similar device and block the light beam at the non-opening of the aperture; as Figure 7 shown in (b) below, is a multi-beam device with multiple electron sources, including a light source controller 21, a multi-light power source 22, a condenser lens array 23, a condenser lens 24, a scanning coil 25, and an objective lens 26. It does not require a beam shutter array, and multiple electron probes scan the marked region and the exposure region simultaneously. The video signal of the marked region scan is used as a reference for real-time calculation and control of the probe displacement.

[0138] It should be noted that the other specific structures of the electron beam lithography equipment are not the improvement points of the present invention and will not be elaborated here.

[0139] In other embodiments of the present invention, a computer-readable storage medium is further provided, on which a computer program is stored. The computer program is used to implement the method described in Embodiment 2 or Embodiment 3 or Embodiment 4.

[0140] It can be understood that the same or similar parts in the above embodiments can be referred to each other, and the content not detailed in some embodiments can be referred to the same or similar content in other embodiments.

[0141] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0142] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices produce means for implementing the functions specified in one or more flows and / or blocks. Figure 1 one or more flows and / or blocks Figure 1 or means for implementing the functions specified in one or more blocks.

[0143] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means that implement the functions specified in one or more flows and / or blocks. Figure 1 one or more flows and / or blocks Figure 1 or means for implementing the functions specified in one or more blocks.

[0144] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more flows and / or blocks. Figure 1 one or more flows and / or blocks Figure 1 or steps for implementing the functions specified in one or more blocks.

[0145] Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. An electronic probe positioning substrate, characterized in that, For the positioning of the electron probe during vibration, its marked area includes a first line group composed of multiple continuous first lines and a second line group composed of multiple discontinuous second lines. The first line group and the second line group are orthogonal and arranged at an alternating interval, and the spacing between adjacent first lines on the scanning line and the spacing between adjacent second lines on the scanning line are not equal; the scanning line is neither parallel nor perpendicular to the first line group.

2. The electron probe positioning substrate according to claim 1, wherein The spacing between the first line group on the scanning line and the spacing between the second line group on the scanning line satisfy the following conditions: P" = P / sinR, Q" = Q / cosR P″ = αQ″ α > 3 / 2 or α < 2 / 3 Wherein, P" represents the spacing between adjacent first lines on the scanning line; Q" represents the spacing between adjacent second lines on the scanning line; P represents the spacing between adjacent first lines, Q represents the spacing between adjacent second lines; R represents the angle between the scanning line and the first line group.

3. The electronic probe positioning substrate according to claim 1, wherein The projected lengths of the line width of the first line, the line width of the second line, and the spacing between adjacent first and second lines on the scanning line are all greater than the horizontal pixel resolution.

4. An electronic probe displacement measurement method, characterized in that, It includes: Real-time acquisition of the video signal W′(t) of the electron probe scanning the electron probe positioning substrate as described in any one of claims 1 to 3; Performing Fourier decomposition on the video signal W′(t) to obtain its fundamental waves F1′(t) and G1′(t), and the phases γ1′ and φ1′ of F1′(t) and G1′(t); F1′(t) and G1′(t) respectively represent the fundamental wave signals of the spacing between adjacent first lines on the scanning line and the fundamental wave signals of the spacing between adjacent second lines on the scanning line obtained in real time. The displacement (u, v) of the current scanning cycle of the electron probe is expressed as follows: u = P(γ1′ - γ1) / (2π), v = Q(φ1′ - φ1) / (2π) Wherein, γ1 and φ1 respectively represent the phases of the fundamental wave signals of the spacing between adjacent first lines on the scanning line and the fundamental wave signals of the spacing between adjacent second lines on the scanning line when the electron probe has no vibration, P represents the spacing between adjacent first lines, and Q represents the spacing between adjacent second lines.

5. The electron probe displacement measurement method according to claim 4, wherein The decomposition of the video signal W′(t) to obtain its fundamental waves F1′(t) and G1′(t) is expressed as follows: W′(t) = F1′(t) + G1′(t) F1′(t) = α1′sin(ω u t + γ1′), G1′(t) = β1′sin(ω v t + φ1′) In the formula, γ1′ = tan -1 (A1′ / B1′), φ1′ = tan -1 (C1′ / D1′); F1′(t) represents the fundamental wave signal of the spacing of adjacent first lines obtained in real time on the scanning line, and G1′(t) represents the fundamental wave signal of the spacing of adjacent second lines obtained in real time on the scanning line; T s represents the period of each scan, and t represents time; ω u = 2π / T u , ω v = 2π / T v , T u = P" / V, T v = Q" / V, where V represents the scanning speed of the electron probe, and P" and Q" respectively represent the spacing of adjacent first lines on the scanning line and the spacing of adjacent second lines on the scanning line.

6. An electronic probe displacement measurement method, characterized in that, It includes: Obtain the previous moment t of the current moment N The fundamental wave amplitude θ N = [A1'(t N ) B1'(t N ) C1'(t N ) D1'(t N )] T , A'1(t N )、B1'(t N )、C1'(t N ) and D1'(t N ) are the Fourier coefficients at moment t N ; among them, the fundamental wave amplitude θ N = [A1'(t N ) B1'(t N ) C1'(t N ) D1'(t N )] T Based on t = {t1 t2…t N}, the video signal time series {W1' W2'…W N '} of the electron probe positioning substrate described in any one of claims 1 to 3 is obtained by electron probe scanning, and W N ' represents the video signal value at moment t N ; Obtain the video signal value at the current moment t N+1 , and use the least squares method to determine the amplitude θ of the time base wave at the current moment t N+1 as follows N+1 θ = [A1′(t N+1 ) B1′(t N+1 ) C1′(t N+1 ) D1′(t N+1 )] T ; The current moment t N+1 of the probe displacement (u(t N+1 ), v(t N+1 )) can be expressed as follows: u(t N+1 ) = P(γ1′(t N+1 ) - γ1) / (2π), v(t N+1 ) = Q(φ1′(t N+1 ) - φ1) / (2π) where γ1′(t N+1 ) = tan -1 [A1′(t N+1 ) / B1′(t N+1 )], φ1′(t N+1 ) = tan -1 [C1′(t N+1 ) / D1′(t N+1 )], γ1 and φ1 respectively represent the phases of the fundamental wave signals of the spacings between adjacent first lines and adjacent second lines on the scanning line when the electron probe has no vibration, P represents the spacing between adjacent first lines, and Q represents the spacing between adjacent second lines.

7. The method for measuring the displacement of an electron probe according to claim 6, wherein The video signal time series {W1′W2′…W N ′} is represented as follows: where η N represents the error at time t N ; ω u = 2π / T u , ω v = 2π / T v , T u = P" / V, T v = Q" / V, where V represents the scanning speed of the electron probe, and P" and Q" respectively represent the spacing between adjacent first lines on the scanning line and the spacing between adjacent second lines on the scanning line; the fundamental wave amplitude θ N = [A1′(t N )B1′(t N )C1′(t N )D1′(t N )] T is expressed as follows: In the formula, N is the length of the time series of the video signal; Determine the current time t using the least squares method N+1 The amplitude θ of the fundamental wave of the time base N+1 and P N+1 are expressed as follows: Where, W' N+1 represents the video signal value at the current moment t N+1 .

8. An electronic probe positioning control method, characterized in that, It includes: Real-time acquisition of the measurement values of multiple accelerometers arranged on the vacuum chamber, the lens barrel, and the wafer platform, and inputting them into the feedforward controller to obtain the first input voltage of the scanning coil; Using the electron probe displacement measurement method as described in any one of claims 4 to 7 to obtain the real-time displacement of the electron probe, and inputting it into the feedback controller to obtain the second input voltage of the scanning coil; Performing real-time control of the scanning coil voltage according to the final input voltage obtained by fusing the first input voltage and the second input voltage of the scanning coil.

9. The electronic probe positioning control method according to claim 8, wherein The feedforward controller is expressed as follows: where (V x , V y ) represents the first input voltage of the scanning coil, δ J represents the measured value of the Jth accelerometer, G represents the transfer function from the measured values of multiple accelerometers to the displacement of the electron probe, and C represents the transfer matrix from the displacement of the electron probe to the first input voltage of the scanning coil; The feedback controller is expressed as follows: where, (V x (t j ), V y (t j )) represents the second input voltage of the scanning coil at time t j , (u(t j ), v(t j )) represents the probe displacement at time t j , and k pu , k pv , k du , k du are all gain coefficients.

10. An electron beam lithography apparatus, characterized in that, Its substrate adopts the electron probe positioning substrate as described in any one of claims 1 to 3, and includes a marked area and an exposure area thereon; Its beam device adopts a multi-beam device, where one electron probe is used to scan the marking area and the other electron probes are used to scan the exposure area.

Images