Semiconductor manufacturing apparatus

Abstract

A semiconductor manufacturing apparatus includes: an electron beam source configured to emit an electron beam; a plurality of converging lenses disposed between the stage on which an object including a structure is placed and the electron beam source; an objective lens provided between the plurality of convergent lenses and the stage; an aperture provided between the plurality of converging lenses; and a controller configured to acquire a plurality of original images according to a working distance between the objective lens and the object, acquire a pattern image indicative of the structure from the plurality of original images, acquire a plurality of core images indicative of a distribution of the electron beam on the object, acquire a plurality of position vectors indicative of a relative position of the structure in the plurality of original images, and acquire a plurality of position vectors indicative of a relative position of the structure on the object. And adjusting a position of the aperture based on a motion vector indicating a motion according to a plurality of position vectors of the working distance.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0073966 filed on June 9, 2023 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to a semiconductor manufacturing device and control thereof. Background Art

[0004] In an apparatus utilizing an electron beam, such as a scanning electron microscope, it is necessary to accurately radiate the electron beam to an object to be analyzed or an object to be processed. The electron beam emitted from an electron beam source passes through an aperture, a converging lens formed by an electromagnetic field, etc., to be incident on the object. In order to accurately radiate the electron beam to the object, the position of the aperture should be controlled so that the electron beam and the aperture are accurately aligned. However, manually adjusting the position of the aperture takes a long time, thereby reducing the efficiency of the process. Summary of the invention

[0005] In general, in some aspects, the present disclosure relates to a semiconductor manufacturing apparatus and method that can improve process efficiency by automatically controlling the position of an aperture so that an electron beam and the aperture are precisely aligned.

[0006] According to some aspects of the present disclosure, a semiconductor manufacturing device includes: an electron beam source configured to emit an electron beam; a plurality of converging lenses disposed between a stage and the electron beam source, wherein the stage is configured to support an object including a structure; an objective lens disposed between the plurality of converging lenses and the stage; an aperture disposed between the plurality of converging lenses; and a controller configured to: acquire a plurality of original images according to a working distance between the objective lens and the object, acquire a pattern image indicating the structure from the plurality of original images, acquire a plurality of core images indicating a distribution of the electron beam on the object, acquire a plurality of position vectors indicating a relative position of the structure in the plurality of original images, and adjust a position of the aperture based on a motion vector indicating a motion of the plurality of position vectors according to the working distance.

[0007] According to some aspects of the present disclosure, a semiconductor manufacturing device includes: an electron beam source configured to emit an electron beam; a lens unit configured to transmit the electron beam generated by the electron beam source to an object; an aperture configured to limit the electron beam path of the lens unit; and a controller configured to: acquire multiple original images according to a working distance between the lens unit and the object, acquire multiple position vectors indicating the relative position of the structure of the object in the multiple original images using the multiple original images, calculate a motion vector indicating the movement of the multiple position vectors according to the working distance, and adjust the position of the aperture according to a compensation vector determined based on the motion vector.

[0008] According to some aspects of the present disclosure, a semiconductor manufacturing device includes: an electron beam source, which is configured to emit an electron beam; a plurality of converging lenses, which are arranged between a stage and the electron beam source, wherein the stage is configured to support an object; an objective lens, which is arranged between the plurality of converging lenses and the stage; an aperture, which is arranged between the plurality of converging lenses; and a controller, which is configured to: acquire a plurality of original images according to a working distance between the object and the objective lens configured to transmit the electron beam to the object, acquire a single pattern image indicating a structure included in the object, acquire a plurality of core images indicating a distribution of the electron beam on the object, acquire a plurality of position vectors indicating a relative position of the structure in the plurality of original images from the plurality of original images; acquire a motion vector indicating a direction of motion based on the plurality of position vectors according to the working distance; determine a compensation vector based on the motion vector; and move the position of the aperture that limits the electron beam path of the plurality of converging lenses based on the compensation vector.

[0009] According to some aspects of the present disclosure, a method for controlling a semiconductor manufacturing device includes: acquiring multiple original images according to a working distance between a lens unit that transmits an electron beam generated by an electron beam source to the object and an object; acquiring a single pattern image indicating a structure included in the object, multiple core images indicating the distribution of the electron beam on the object, and multiple position vectors indicating the relative positions of the structures in the multiple original images from the multiple original images; acquiring a motion vector indicating a movement direction based on the multiple position vectors according to the working distance; determining a compensation vector based on the motion vector; and moving the position of an aperture that limits the electron beam path of the lens unit based on the compensation vector. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Exemplary embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.

[0011] Figure 1 is a diagram illustrating a semiconductor manufacturing apparatus according to some embodiments.

[0012] Figure 2 is a diagram illustrating an electron beam path in a semiconductor manufacturing apparatus according to some embodiments.

[0013] Figure 3 is a diagram illustrating image motion according to aperture alignment of a semiconductor manufacturing apparatus according to some embodiments.

[0014] Figure 4A and Figure 4B is a diagram illustrating an image acquired by a semiconductor manufacturing apparatus according to some embodiments.

[0015] Figure 5 is a diagram illustrating a control method of a semiconductor manufacturing apparatus according to some embodiments.

[0016] FIG. 6A to FIG. 6C is a diagram illustrating a method of acquiring a plurality of original images according to some embodiments.

[0017] Figures 7 to 9 is a diagram illustrating a method of acquiring a plurality of position vectors from a plurality of original images according to some embodiments.

[0018] Fig.10 is a diagram illustrating a method of obtaining a motion vector from a plurality of position vectors according to some embodiments.

[0019] Fig.11 is a diagram showing a motion vector according to the position of the aperture on the XY plane.

[0020] Fig.12 is a diagram showing a compensation vector according to the position of the aperture on the XY plane.

[0021] FIG. 13A to FIG. 13C is a diagram showing an original image according to a working distance when a semiconductor manufacturing apparatus has astigmatism.

[0022] Fig.14 is a diagram showing a compensation vector according to the position of the aperture on the XY plane when the semiconductor manufacturing apparatus has astigmatism. DETAILED DESCRIPTION

[0023] Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings.

[0024] Figure 1 is a diagram illustrating an example of a semiconductor manufacturing apparatus.

[0025] Reference Figure 1 The semiconductor manufacturing apparatus 10 includes a scanning electron microscope (SEM) apparatus. The semiconductor manufacturing apparatus 10 includes an electron beam source 20, a lens unit 30, an aperture 40, a detector 50, a controller 60, and a stage 70.

[0026] The semiconductor manufacturing apparatus 10 may radiate an electron beam EB to an object 90 disposed on a stage 70, and may collect signals emitted from the object 90 to obtain an image of the object 90. For example, the object 90 may be a semiconductor device including a structure. In addition, the signal emitted from the object 90 by the electron beam EB radiated to the object 90 may include signals related to secondary electrons (SE), backscattered electrons (BSE), X-rays, visible light, cathode fluorescence, etc.

[0027] The electron beam source 20 may generate and emit an electron beam EB, and the electron beam emitted from the electron beam source 20 may be accelerated, converged by the lens unit 30, and radiated to the object 90. For example, the electron beam source 20 may include an electron gun that may heat a filament formed of tungsten or the like to generate electrons, and may accelerate the electrons by applying a voltage to generate the electron beam EB.

[0028] The lens unit 30 may include a plurality of converging lenses 31 and 32, an objective lens 33, and the like. The first converging lens 31 and the second converging lens 32 may converge the electron beam EB emitted from the electron beam source 20 so that the electron beam is effectively converged on a point of the object 90. For example, as the diameter of the electron beam EB radiated to the object 90 becomes smaller, the resolution of the image acquired by the controller 60 may be improved. To increase the resolution of the image, the lens unit 30 may include two or more converging lenses 31 and 32. The diameter of the electron beam EB emitted from the electron beam source 20 may gradually decrease while passing through the first converging lens 31 and the second converging lens 32.

[0029] The objective lens 33 may focus the electron beam EB converged by the first and second convergent lenses 31 and 32 onto the object 90. For example, the objective lens 33 may determine the diameter of the electron beam EB radiated onto the object 90. The distance between the objective lens 33 and the object 90 may be defined as a working distance, and the diameter of the electron beam EB radiated onto the object 90 may vary according to the working distance. Therefore, the resolution of the image corresponding to the object 90 may be adjusted by adjusting the position of the objective lens 33.

[0030] The objective lens 33 may include a plurality of scanning coils 81, an astigmatism adjuster 82, etc. The plurality of scanning coils 81 may steer the electron beam to a point of the objective lens 33. The astigmatism adjuster 82 may include a plurality of stigmatism devices, and may adjust the current flowing through the stigmatism devices to adjust the astigmatism of the electron beam EB passing through the objective lens 33. The objective lens 33 may adjust the astigmatism of the lens unit 30 by adjusting the current flowing through the plurality of scanning coils 81, etc., so that the electron beam EB may be radiated to the object 90 in a desired shape.

[0031] The aperture 40 may be disposed on the path of the electron beam EB, and may limit the path of the electron beam EB so that the electron beam EB is uniformly incident on the object 90, and may reduce spherical aberration. Figure 1In the example of FIG. 4 , the aperture 40 may be disposed between the first focusing lens 31 and the second focusing lens 32 .

[0032] The detector 50 may acquire a signal emitted from the object 90 due to the electron beam EB irradiating the object 90 , and may generate an image using the signal. The image generated by the detector 50 may be transferred to the controller 60 .

[0033] When the aperture 40 is not aligned with the axis of the electron beam EB, and the lens unit 30 adjusts the working distance between the objective lens 33 and the object 90 to have a desired focal length, a phenomenon occurs in which the imaging area of ​​the object 90 moves according to the working distance. When the imaging area moves while the lens unit 30 adjusts the focal length, it is difficult to fix the target imaging area, thereby making it difficult to repeatedly capture a specific imaging area during automatic imaging.

[0034] For example, when an imaging area according to a working distance is not fixed in a wide area top-down delay system (W-TDS) apparatus that repeatedly images a predetermined imaging area of ​​the object 90 while sequentially removing layers of the object 90 from an upper layer to a lower layer, the imaging area is corrected each time a layer is imaged. Correcting the imaging area takes time, resulting in an increase in imaging time.

[0035] The aperture 40 may be movable at least in the XY plane so that the aperture 40 can be aligned with the axis of the electron beam EB. When the operator manually adjusts the aperture 40, it may take a long time, and the alignment accuracy of the aperture 40 may depend on the skill level of the operator. In addition, when there is astigmatism in the lens unit 30, the shape of the imaged structure may change according to the working distance. Therefore, it may be difficult to manually align the aperture 40 accurately by visually checking the imaged structure.

[0036] According to some embodiments, the operation of optimizing the alignment of the aperture 40 in the semiconductor manufacturing apparatus 10 may be automated. Specifically, while adjusting the working distance between the objective lens 33 and the object 90, the controller 60 may acquire a plurality of original images of the object 90. The controller 60 may acquire a motion vector of an image pattern using the plurality of original images according to the working distance, and may acquire a compensation vector for compensating the position of the aperture 40 based on the motion vector. The controller 60 may automatically optimize the alignment of the aperture 40 based on the compensation vector.

[0037] The subject matter of the present disclosure is not limited to the case where the semiconductor manufacturing apparatus 10 is a scanning electron microscope apparatus, and the semiconductor manufacturing apparatus 10 may be applied to various apparatuses that have a lens unit and an aperture and transmit an electron beam to an object, such as a transmission electron microscope (TEM) apparatus.

[0038] Figure 2 is a diagram illustrating an example electron beam path in a semiconductor manufacturing apparatus according to some embodiments.

[0039] Figure 2 FIG. 1 exemplarily shows a path of an electron beam EB formed by an electron beam source 20, a lens unit 30 and an aperture 40 of a semiconductor manufacturing apparatus 10, as shown in FIG. Figure 1 described.

[0040] The electron beam EB output from the electron beam source 20 may be converged by the first condensing lens 31. The aperture 40 may transfer a portion of the electron beam EB focused by the first condensing lens 31 to the second condensing lens 32. The electron beam EB passing through the aperture 40 may be converged by the second condensing lens 32 and may be transferred to the objective lens 33. The objective lens 33 may focus the electron beam EB on one point.

[0041] The lens unit 30 can adjust the working distance WD of the objective lens 33 so that the focus of the objective lens 33 can be located in the imaging area of ​​the object 90. When the working distance and the focal length of the objective lens 33 are equal to each other, the electron beam distribution in the imaging area can have a circular shape. In addition, the image acquired in the imaging area can have a pattern in which the structure included in the imaging area can be accurately expressed without distortion.

[0042] Under an underfocusing condition where the working distance of the objective lens 33 is located closer than the focal length and an overfocusing condition where the working distance of the objective lens 33 is located farther than the focal length, the shape of the electron beam formed in the imaging area may be distorted.

[0043] The aperture 40 may limit the path of the electron beam EB to transmit a component of the electron beam EB perpendicular to the surface of the object 90 to the object 90. Figure 2 , showing a vertical axis AX indicating a path of the electron beam EB which is perpendicular to the path of the object 90. When the position of the aperture 40 is not aligned with the vertical axis AX of the electron beam EB, the axis of the electron beam delivered to the object 90 through the aperture 40 may not be perpendicular to the surface of the object 90 and may have an oblique angle. When the aperture 40 delivers the electron beam having an oblique angle to the object 90, the position of the electron beam formed on the object 90 may be different from the position under an underfocusing condition or under an overfocusing condition.

[0044] Figure 3 is a diagram illustrating image motion according to aperture alignment of a semiconductor manufacturing apparatus according to some embodiments.

[0045] Figure 3 The Monte Carlo simulation results for the electron beam path formed by the electron beam source 20, the lens unit 30 and the aperture 40 are shown. Figure 3 When the position of the aperture 40 is not aligned with the vertical axis, the electron beam EB having a tilt component relative to the surface of the object may be transmitted to the objective lens 33.

[0046] When the objective lens 33 radiates an electron beam having an oblique axis with respect to the surface of the object, an imaging region of the object may move according to a working distance of the objective lens 33 . Figure 3 A core image indicating the distribution of the electron beam in the object according to the working distance of the objective lens 33 is shown.

[0047] exist Figure 3 In the embodiment of the present invention, when the object is located at the focal length of the objective lens 33, the electron beam may be focused on the (0, 0) position of the XY plane. Under an over-focusing condition in which the object is located at a position farther than the focal length of the objective lens, the electron beam may have a wide distribution, and the distribution center of the electron beam may move in a first direction from the (0, 0) position of the XY plane. In addition, under an under-focusing condition in which the object is located at a position closer than the focal length of the objective lens, the distribution center of the electron beam may move in a second direction opposite to the first direction from the position (0, 0) of the XY plane.

[0048] When the position of the aperture 40 is not aligned with the vertical axis, the distribution of the electron beam may move according to the working distance of the objective lens 33, and the imaging position of the object may move according to the working distance of the objective lens 33. The movement of the imaging position of the object according to the working distance of the objective lens 33 can be represented by the movement of the relative position of the structure appearing in the original image captured at different working distances.

[0049] According to some embodiments, the semiconductor manufacturing apparatus 10 detects the relative position of the structure in a plurality of original images acquired by changing the working distance of the objective lens 33, and may acquire a motion vector of the structure to detect misalignment of the aperture 40. In addition, the semiconductor manufacturing apparatus 10 may adjust the position of the aperture 40 based on the motion vector to control the position of the aperture 40 to be aligned with the vertical axis.

[0050] Figure 4A and Figure 4B is an example of an image acquired by a semiconductor manufacturing apparatus as described herein.

[0051] Reference Figure 4A , the image acquired by the semiconductor manufacturing apparatus described herein includes a pattern having strong repeatability and weak directionality. Figure 4B , images acquired by the semiconductor manufacturing apparatus described herein include patterns having non-repeating and irregular shapes.

[0052] According to some embodiments, the position adjustment of the aperture may be automatically performed by detecting relative positions of structures included in an object irradiated by an electron beam in a plurality of original images, regardless of the orientation and shape of the structures in the object.

[0053] Figure 5 is a diagram illustrating a control method of a semiconductor manufacturing apparatus according to some embodiments.

[0054] In operation S11, the controller of the semiconductor manufacturing apparatus may be configured to change the working distance of the objective lens, and may acquire a plurality of raw images according to the working distance. The working distance may be the distance between the objective lens and the object. The plurality of raw images may include at least one overfocused image acquired under an overfocused condition where the working distance is farther than the focal length and at least one underfocused image acquired under an underfocused condition where the working distance is shorter than the focal length.

[0055] In operation S12, the controller may be configured to acquire a pattern image, a plurality of core images, and a plurality of position vectors from a plurality of raw images. The pattern image may be an image indicating a structure included in a target position where an electron beam is radiated on an object. The plurality of core images may be images showing the distribution of the electron beam radiated to the object according to the working distance of the objective lens. In addition, the plurality of position vectors may represent the relative position of the structure presented in each of the plurality of raw images according to the working distance of the objective lens.

[0056] In operation S13, the controller may be configured to acquire a motion vector based on the plurality of position vectors. The motion vector may represent a motion tendency of the plurality of position vectors according to a working distance of the objective lens.

[0057] In operation S14, the controller may be configured to determine whether the position of the aperture is aligned with the vertical axis. For example, when the position of the aperture is aligned with the vertical axis, changes in a plurality of position vectors according to the working distance of the objective lens are small, and the motion vector may be close to a zero vector.

[0058] When the magnitude of the motion vector is less than the threshold, the controller may be configured to determine that the position of the aperture is aligned with the vertical axis ("Yes" in operation S14), and the operation may be terminated. When the magnitude of the motion vector is equal to or greater than the threshold, the controller may determine that the position of the aperture is not aligned with the vertical axis ("No" in operation S14), and operation S15 may be performed.

[0059] In operation S15, the controller may be configured to determine a compensation vector based on the motion vector. The compensation vector may refer to a movement direction and a movement distance of the aperture for aligning the position of the aperture with the vertical axis.

[0060] In operation S16, the controller may be configured to move the aperture based on the compensation vector. In addition, the controller may be configured to determine whether the position of the aperture is aligned with the axis as a result of the movement of the aperture by repeatedly performing operations S11 to S14.

[0061] FIG. 6A to FIG. 6C is a diagram illustrating a method of acquiring a plurality of original images according to some embodiments.

[0062] Reference FIG. 6A to FIG. 6C, the semiconductor manufacturing apparatus 100 may include an objective lens 101, a stage 102, and an object 103. The objective lens 101, the stage 102, and the object 103 may correspond to the reference Figure 1 Objective lens 33, stage 70 and object 90 are described.

[0063] The object 103 may be arranged on the stage 102, and the controller of the semiconductor manufacturing apparatus 100 may be configured to change the working distance of the objective lens 101 to the first working distance WD1 to the third working distance WD3 to obtain a plurality of original images 111, 112, and 113. The electron beam collector 104 may be disposed on a side of the objective lens 101 close to the object 103. The working distance may be defined as the distance between the side of the objective lens 101 and the object 103.

[0064] Reference Fig. 6A , when the objective lens 101 is located at the first working distance WD1, the controller may be configured to acquire a first original image 111. The first working distance WD1 may be shorter than the focal length of the objective lens 101, and the first original image 111 may be an image captured under insufficient focusing conditions.

[0065] Next, refer to Figure 6B When the objective lens 101 is located at the second working distance WD2, the controller may be configured to acquire a second original image 112. The second working distance WD2 may be substantially consistent with the focal length of the objective lens 101, and thus, the structure included in the object may be displayed relatively clearly in the second original image 112.

[0066] Reference Figure 6C , when the objective lens 101 is located at the third working distance WD3, the controller may be configured to acquire a third original image 113. For example, the third working distance WD3 may be longer than the focal length of the objective lens 101, and the third original image 113 may be an image captured under an over-focusing condition.

[0067] As reference FIG. 6A to FIG. 6C As described above, the controller of the semiconductor manufacturing apparatus 100 may be configured to acquire multiple original images 111, 112, and 113 while changing the working distance of the objective lens. As described above, when the axis of the electron beam and the position of the aperture are not aligned, the imaging area may move according to the working distance of the objective lens. When the imaging area moves, the relative positions of the patterns included in the multiple original images 111, 112, and 113 may show movement.

[0068] For example, referring to the plurality of original images 111 , 112 , and 113 together, as the working distance of the objective lens increases from the first working distance WD1 to the third working distance WD3 , the inspected pattern may move in a lower left direction.

[0069] According to some embodiments, a position vector indicating a degree of movement of a relative position of a pattern in a plurality of original images may be acquired.

[0070] Figures 7 to 9 is a diagram illustrating a method of acquiring a plurality of position vectors from a plurality of original images according to some embodiments.

[0071] Reference Figure 7 , showing a plurality of original images 201 to 205 acquired at various working distances by irradiating an electron beam onto an imaging region of an object. A third original image 203 may be an image captured at a working distance close to the focal length of the objective lens, and a structure included in the imaging region of the object may be more clearly displayed in the third original image 203.

[0072] The first original image 201 and the second original image 202 may be images captured under an insufficiently focused condition, and the imaging area may be moved compared to the third original image 203. Compared to the pattern displayed in the third original image 203, the patterns of the first original image 201 and the second original image 202 may be displayed blurred, and the positions thereof may be moved.

[0073] The fourth original image 204 and the fifth original image 205 may be images captured under an overfocus condition, patterns thereof may appear blurred compared to the pattern shown in the third original image 203, and positions thereof may move in a direction opposite to that of the first original image 201 and the second original image 202.

[0074] The plurality of original images 201 to 205 may have different relative positions and pattern definitions, but the plurality of original images 201 to 205 may include patterns indicating the same structure. For example, each of the plurality of original images 201 to 205 may be obtained by applying a plurality of different position vectors 221 to 225 and a plurality of different core images 231 to 235 to the pattern image 210.

[0075] The pattern image may be an image of a display structure formed in a target area to be imaged of an object, the multiple position vectors may be vectors indicating the direction and amplitude of movement of the structure appearing in the pattern image in the original image, and the multiple core images may be images indicating the distribution of an electron beam radiated to an imaging area of ​​the object.

[0076] A shift operation using each of the plurality of position vectors 221 to 225 may be performed on the pattern image 210 , and a convolution operation using the plurality of core images 231 to 235 may be performed on the shifted images, respectively, to obtain the plurality of original images 201 to 205 .

[0077] In contrast, a deconvolution operation may be applied to each of the plurality of original images 201 to 205 to obtain a pattern image 210 , a plurality of position vectors 221 to 225 , and a plurality of core images 231 to 235 .

[0078] Since the pattern image 210, the plurality of position vectors 221 to 225, and the plurality of core images 231 to 235 may be unknown values, evaluation of the pattern image 210, evaluation of each of the plurality of position vectors 221 to 225, and evaluation of each of the plurality of core images 231 to 235 may be required.

[0079] According to some embodiments, the objective function F for optimizing the deconvolution for evaluating the pattern image 210, the plurality of position vectors 221 to 225, and the plurality of core images 231 to 235 may be represented by the following equation 1:

[0080] [Equation 1]

[0081]

[0082] In equation 1, f i may correspond to the i-th original image among the plurality of original images 201 to 205, u may correspond to the pattern image 210, and v i may correspond to the i-th position vector among the plurality of position vectors 221 to 225, and may correspond to the i-th core image among the plurality of core images 231 to 235. In addition, λ may be a balancing parameter.

[0083] The following assumptions can be applied to Equation 1. First, it can be assumed that the position vector v i In the original image f i is constant in all pixels of . For example, suppose the structure shown in the pattern image u is i Second, we can assume that the core image Defined as having a Gaussian distribution ∑ i Third, it can be assumed that the structure displayed on the pattern image u has clear features.

[0084] Equation 1 can be interpreted as follows. The objective function F can be a function for finding the pattern image 210, the plurality of position vectors 221 to 225, and the plurality of core images 231 to 235, which can make the mean of the difference between the calculated images calculated by using the pattern image 210, the plurality of position vectors 221 to 225, the plurality of core images 231 to 235 and the plurality of original images 201 to 205, and the gradient of the pattern image The sum is minimized.

[0085] In this case, the computed image can be referenced by utilizing Core Image By moving the pattern image u by the position vector v i The result of performing convolution operation on the acquired image In addition, the gradient of the pattern image u It can represent the clarity level of the pattern image. As the pattern image u is sharpened, the gradient Can be reduced.

[0086] In short, the pattern image 210, the plurality of position vectors 221 to 225, and the plurality of core images 231 to 235 may be generated while sharpening the pattern image 210 to a certain extent by using the objective function F. The pattern image 210, the plurality of position vectors 221 to 225, and the plurality of core images 231 to 235 may be optimized so that the calculated image may be similar to the plurality of original images 201 to 205.

[0087] From Equation 1, Equation 2 for extracting the pattern image u can be derived as follows: i Equation 3, and is used to extract the position vector v i Equation 4:

[0088] [Equation 2]

[0089]

[0090] Equation 2 represents an equation for updating a pattern image u by applying gradient descent to a previous pattern image u. In Equation 2, ⊙ may represent an effective convolution, can represent a fully padded convolution, and Represents Core Image The (x, y) values ​​of the image are reversed:

[0091] [Equation 3]

[0092]

[0093] Equation 3 expresses the gradient descent applied to the previous Gaussian distribution ∑ i To update the Gaussian distribution∑ i In Equation 3, K can represent the size of the core image:

[0094] [Equation 4]

[0095]

[0096] Equation 4 represents the equation for updating the motion vector v i The x-axis component v i1 and the y-axis component v i Specifically, Equation 4 represents the equation for the core image based update and pattern image u to obtain v i1 Value and v i2 The mathematical expression of the value, where v i1 The value obtained by differentiating the objective function F is '0'. i2 The value obtained by differentiating the objective function F is '0'.

[0097] Will refer to Figure 8 Describes the optimization of the pattern image u and the Gaussian distribution ∑ by applying Equation 2, Equation 3, and Equation 4 i and position vector v i method.

[0098] Reference Figure 8 , in operation S21, the controller of the semiconductor manufacturing apparatus may initialize the pattern image 210, the plurality of position vectors 221 to 225, and the plurality of core images 231 to 235. In order to optimize the pattern image u and the Gaussian distribution ∑ by applying gradient descent to Equation 2 and Equation 3 i , it is necessary to select an initial value for the pattern image 210 , an initial value for each of the plurality of position vectors 221 to 225 , and an initial value for each of the plurality of core images 231 to 235 .

[0099] According to some embodiments, the initial value of the pattern image 210 may be set to a random noise image, the initial value of each of the plurality of position vectors 221 to 225 may be set to a zero vector, and the initial value of each of the plurality of core images 231 to 235 may be set to a non-directional Gaussian distribution function.

[0100] In operation S22, the controller may update the pattern image 210 by applying Equation 2. In operation S23, the controller may update the Gaussian distribution ∑ i To update the plurality of core images 231 to 235. In operation S24, the controller may update the plurality of position vectors 221 to 225 by applying Equation 4.

[0101] In operation S25, the controller may determine whether the pattern image 210, the plurality of core images 231 to 235, and the plurality of position vectors 221 to 225 are optimized. For example, as a result of performing operations S22 to S24, the controller determines whether the difference between the previous value and the updated value of the pattern image 210, the plurality of core images 231 to 235, and the plurality of position vectors 221 to 225 is less than a threshold value.

[0102] When each of the difference values ​​is less than the threshold value, it may be determined that the values ​​of the pattern image 210, the plurality of core images 231 to 235, and the plurality of position vectors 221 to 225 have converged to the optimized values ​​according to the gradient descent. Therefore, the controller may determine that the pattern image 210, the plurality of core images 231 to 235, and the plurality of position vectors 221 to 225 have been optimized ("Yes" in operation S25), and may end the operation.

[0103] When each of the difference values ​​is greater than or equal to the threshold, the controller may determine that the pattern image 210, multiple core images 231 to 235, and multiple position vectors 221 to 225 are not optimized ("No" in operation S25), and may repeatedly perform operations S22 to S24 until the pattern image 210, multiple core images 231 to 235, and multiple position vectors 221 to 225 are optimized.

[0104] Reference Fig. 9 , the pattern image 310 may be initialized as a random noise image, and a specific structure may not appear in the initialized pattern image 310. The plurality of position vectors 321 to 325 may be initialized as zero vectors, and a motion of the pattern may not appear in the plurality of position vectors 321 to 325. In addition, the plurality of core images 331 to 335 may be initialized as a non-directional Gaussian distribution function, and the electron beam distribution in each of the plurality of core images 331 to 335 may appear in the form of the same point spread function.

[0105] The pattern image 310 may be updated by repeatedly performing optimization based on the original images 201 to 205, such as Figure 7 As shown, finally, a pattern image 410 showing a structure included in a target area of ​​the object can be acquired. Similarly, a plurality of position vectors 421 to 425 with different directivities can be acquired by updating a plurality of position vectors 321 to 325 with a zero vector. In addition, a plurality of core images 331 to 335 in the form of a point spread function can be updated to acquire a plurality of core images 431 to 435 represented by a two-dimensional Gaussian distribution function with different distributions.

[0106] According to some embodiments, the pattern image, the plurality of core images, and the plurality of position vectors may be accurately separated from the plurality of original images. For example, in an objective lens of a semiconductor manufacturing device having astigmatism, when the working distance and the focal length precisely coincide, the distribution of the electron beam may have a circular shape, but under insufficient focusing conditions, the distribution of the electron beam may have a shape extending in a first direction, and under excessive focusing conditions, the distribution of the electron beam may have a shape extending in a second direction perpendicular to the first direction. Therefore, the structures in the plurality of original images may have different shapes, and it is difficult for the naked eye to accurately determine their direction of movement and size.

[0107] According to some embodiments, the pattern image extracted from the plurality of original images may have a pattern of a sharpened shape. In addition, in the core image extracted from the plurality of original images, the distribution of the electron beam extends perpendicularly to each other in the image under insufficient focus and the image under excessive focus. For example, the pattern image and the plurality of core images may be accurately extracted from the plurality of original images. In addition, by removing the influence of the shape of the pattern and the shape of the electron beam caused by astigmatism, a plurality of position vectors may be extracted from the plurality of original images.

[0108] Therefore, the position vector of the pattern for each working distance can be acquired using a plurality of original images regardless of the pattern of the structure included in the target area of ​​the object or the astigmatism of the objective lens of the semiconductor manufacturing apparatus.

[0109] The controller of the semiconductor manufacturing device can acquire a motion vector of a pattern according to a working distance based on the acquired position vector, and can acquire a compensation vector for determining a compensation direction of an aperture position based on the acquired motion vector. Hereinafter, a method of acquiring a motion vector and a compensation vector will be described in more detail.

[0110] Fig.10 is a diagram illustrating a method of obtaining a motion vector from a plurality of position vectors according to some embodiments.

[0111] exist Fig.10 In the graph of FIG. 1 , a plurality of position vectors according to the working distance of the objective lens are shown as points. Specifically, each point represents the end point of the position vector starting from the origin (0, 0).

[0112] A plurality of position vectors may have a specific trend depending on the working distance of the objective lens. Fig.10 In the example of , when the working distance of the objective lens changes from an underfocused condition to an overfocused condition as the working distance gradually increases from a state closer than the focal length, the end point of the position vector may often move from the upper left to the lower right. For example, referring to the plurality of original images 201 to 205 according to the working distance of the objective lens, the pattern may move from the upper left to the lower right as the working distance gradually increases.

[0113] The controller of the semiconductor manufacturing device may obtain a motion vector indicating the motion direction of a plurality of position vectors using a principal component analysis (PCA) technique. Specifically, the controller may generate one-dimensional data indicating the motion of the plurality of position vectors based on the plurality of position vectors distributed in a two-dimensional graph. In addition, the controller may determine the direction of the one-dimensional data as the direction of the motion vector.

[0114] The controller may determine the magnitude of the motion vector based on the standard deviation of the plurality of position vectors. For example, when the position of the end point of the position vector greatly changes according to the working distance of the objective lens, the standard deviation of the plurality of position vectors may increase. Therefore, the controller may determine that the magnitude of the motion vector is proportional to the standard deviation of the plurality of position vectors.

[0115] Hereinafter, a method of acquiring a compensation vector for compensating the position of the aperture based on the motion vector will be described.

[0116] Fig.11 is a diagram showing a motion vector according to the position of the aperture on the XY plane.

[0117] exist Fig.11 In FIG. 1 , the horizontal axis may represent the position of the aperture in the X direction, and the vertical axis may represent the position of the aperture in the Y direction. Fig.11 The plurality of graphs may be arranged in a matrix along the horizontal axis and the vertical axis. Each of the plurality of graphs shows a motion vector according to a working distance of the objective lens at a different aperture position.

[0118] In the position of the aperture, the aperture may be substantially aligned with the axis at a position where the motion vector approaches a zero vector. Fig.11 An aligned position 511 is shown, which may be a position where the aperture is precisely aligned with the axis. As the position of the aperture moves away from the aligned position 511, the magnitude of the motion vector at that position may tend to increase.

[0119] Referring together to the directions of the motion vectors shown in the plurality of graphs, the motion vectors may have a tendency to converge to the alignment position 511 along a spiral path. For example, in the aperture located at the first position 501 at the coordinates (6, -6), when the position of the aperture moves by the magnitude and direction of the motion vector located at the first position 501, the aperture may be placed at the second position 502. In addition, in the aperture located at the second position 502, when the position of the aperture moves by the magnitude and direction of the motion vector located at the second position 502, the aperture may be placed at the third position 503. When the operation of moving the aperture by the magnitude and direction of the motion vector located at the current position is repeatedly performed until the magnitude of the motion vector is less than a threshold magnitude, the position of the aperture may converge to the alignment position 511 through the fourth position 504 to the tenth position 510.

[0120] Even in the aperture located at a position other than the first position 501 , when an operation of moving the position of the aperture by the magnitude and direction of the motion vector located at a position corresponding thereto is repeatedly performed, the aperture may be located at the aligned position 511 .

[0121] According to some embodiments, the controller may capture a plurality of raw images according to the working distance of the objective lens at the current position of the aperture to obtain a motion vector, and may determine the movement direction and size of the aperture based on the motion vector. The aperture may be controlled to reach the alignment position by obtaining a compensation vector and repeatedly performing an operation of moving the aperture based on the compensation vector at the current position of the aperture until the motion vector is less than a threshold magnitude.

[0122] exist Fig.11 In the example of , the direction of the compensation vector of the aperture may be equal to the direction of the motion vector of the aperture at the current position. However, the subject matter of the present disclosure is not limited thereto. According to some embodiments, the direction of the compensation vector of the aperture may be obtained by rotating the direction of the motion vector by a predetermined angle, and the predetermined angle may be selected from an angle range such that the direction of the compensation vector according to the position of the aperture may converge to one position of the aperture. For example, the controller may determine a predetermined angle at which the position of the aperture reaches the alignment position with fewer repetitions.

[0123] Fig.12 is a diagram showing a compensation vector according to the position of the aperture on the XY plane.

[0124] exist Fig.12 In FIG. 1 , the horizontal axis may represent the position of the aperture in the X direction, and the vertical axis may represent the position of the aperture in the Y direction. Fig.12 The plurality of graphs may be arranged in a matrix along the horizontal axis and the vertical axis. Each of the plurality of graphs shows a compensation vector at a different position of the aperture.

[0125] According to some embodiments, a compensation vector according to the position of the aperture may be obtained by rotating the motion vector according to the position of the aperture by a predetermined angle. Fig.11 and Fig.12 , which can be achieved by Fig.11 The motion vectors shown are rotated 45 degrees counterclockwise to obtain Fig.12 The individual compensation vectors are shown.

[0126] In the aperture located at the first position 601, when the position of the aperture moves by the magnitude and direction of the compensation vector located at the first position 601, the aperture can be placed at the second position 602. When the operation of moving the aperture by the magnitude and direction of the compensation vector located at the current position is repeatedly performed until the magnitude of the motion vector is less than the threshold magnitude, the position of the aperture can converge to the alignment position 604 through the third position 603. Fig.11 In comparison, Fig.12 In the example, the position of the aperture can converge to the aligned position with a smaller number of repetitions.

[0127] Fig.11 The motion vectors in can converge to the aligned position along the spiral path, and Fig.12 The compensation vector in can converge to the alignment position along a straight line path. The rotation angle used to obtain the compensation vector can be obtained through experiments. For example, the rotation angle can be selected so that the motion vector with a spiral path has a path close to a straight line.

[0128] According to some embodiments, even if the semiconductor manufacturing apparatus has astigmatism, the controller may control the position of the aperture to reach an aligned position.

[0129] FIG. 13A to FIG. 13C is a diagram showing an original image according to a working distance when a semiconductor manufacturing apparatus has astigmatism.

[0130] Fig.13A The original image 201 may be an image under insufficient focus. Fig. 13B The original image 203 may be an image at a focal length, and Fig. 13C The original image 205 may be an image under an over-focus condition. FIG. 13A to FIG. 13C , the pattern having a substantially circular shape at a focal length may have a shape extending in a first direction D1 under an underfocusing condition, and may have a shape extending in a second direction D2 perpendicular to the first direction under an overfocusing condition.

[0131] When the semiconductor manufacturing apparatus has astigmatism, due to the shapes of the patterns in the plurality of raw images, the plurality of raw images may appear as if the patterns are rotated and moved according to the working distance. For example, comparing the raw image 201 and the raw image 205, the same pattern may appear to move in a rightward and downward direction while being rotated 90 degrees. The position vectors acquired from the raw images may also have a curved distribution.

[0132] According to some embodiments, the position of the aperture may be corrected to an aligned position regardless of the shape of the distribution of position vectors caused by astigmatism.

[0133] Fig.14 is a diagram showing a compensation vector according to the position of the aperture on the XY plane when the semiconductor manufacturing apparatus has astigmatism.

[0134] exist Fig.14 In FIG. 1 , the horizontal axis may represent the position of the aperture in the X direction, and the vertical axis may represent the position of the aperture in the Y direction. Fig.14 , the plurality of graphs may be arranged in a matrix along the horizontal axis and the vertical axis. Each of the plurality of graphs shows the distribution of the position vector and the compensation vector according to the working distance of the objective lens at different aperture positions. Fig.14 In FIG. 1 , the compensation vector is shown as an arrow. In addition, the position vector is shown as a point and is graphically shown rotated by the same angle as the rotation angle of the compensation vector.

[0135] Reference Fig.14 , the position vectors at different aperture positions may have a curved distribution rather than a straight line distribution. For example, referring to the curve at the first position 701, the position vector may have a curved distribution.

[0136] According to some embodiments, the controller may acquire a motion vector from a position vector using a PCA technique, and may thereby acquire a linear motion vector regardless of the distribution of the position vector. In addition, the controller may acquire a linear compensation vector by rotating the motion vector at a predetermined rotation angle.

[0137] Reference Fig.14 Although the distribution of the position vector is bent due to astigmatism of the semiconductor manufacturing apparatus, the compensation vector may converge to the alignment position 704 .

[0138] For example, when a compensation vector is acquired based on a position vector in the aperture located at the first position 701 and the position of the aperture moves the magnitude and direction of the compensation vector, the aperture may be placed at the second position 702. In addition, when the aperture position moves the magnitude and direction of the compensation vector in the aperture located at the second position 702, the aperture may converge to a third position 703 close to the alignment position 704.

[0139] According to some embodiments, regardless of whether the semiconductor manufacturing apparatus has astigmatism, the controller of the semiconductor manufacturing apparatus may align the aperture on the vertical axis based on a motion vector acquired using a plurality of original images according to the working distance of the objective lens. When the working distance of the objective lens is adjusted by aligning the aperture, the controller may fix the imaging area. Therefore, the semiconductor manufacturing apparatus can quickly acquire an image of the target area to be imaged.

[0140] The controller may acquire multiple core images and multiple position vectors based on the multiple original images, calculate motion vectors based on the multiple position vectors to align the aperture, and adjust the stigmator based on the multiple core images to improve the astigmatism.

[0141] Furthermore, according to some embodiments, since the operation of aligning the aperture may be automated, the aperture may be aligned quickly and accurately compared to manually adjusting the position of the aperture, and variations in the arrangement of the aperture between semiconductor manufacturing apparatuses may also be reduced.

[0142] According to some embodiments, the controller may include at least one of a central processing unit (CPU) and a graphics processing unit (GPU), wherein the graphics processing unit may perform operations of acquiring a pattern image, a plurality of core images, and a plurality of position vectors from a plurality of original images. Compared to the central processing unit (CPU), since the graphics processing unit (GPU) can be specialized in parallel operations, operations on the image can be parallelized and processed quickly. Therefore, the operation of aligning the aperture can be performed faster.

[0143] According to some embodiments, an apparatus using an electron beam can change the working distance between a lens and an object, can detect misalignment between the electron beam and an aperture using a plurality of acquired raw images, and can adjust the position of the aperture to compensate for the misalignment. Since the position control of the aperture can be automated, the efficiency of a semiconductor process using an electron beam can be improved.

[0144] Problems to be solved by the subject matter of the present disclosure are not limited to the above-mentioned problems, and other unmentioned problems will be clearly understood by those skilled in the art through the following description.

[0145] While example embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations may be made without departing from the scope of the present disclosure as defined by the appended claims.

[0146] Although the present disclosure includes many specific implementation details, these should not be interpreted as limiting the scope of the claimed protection. Certain features described in the context of separate embodiments in the present disclosure may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented individually in multiple embodiments or in any suitable sub-combination. In addition, although features may be described above as working in certain combinations, and even initially required in this way, in some cases, one or more features from a combination may be removed from the combination, and the combination may point to a variant of a sub-combination or a sub-combination.

Claims

1. A semiconductor manufacturing device, include: an electron beam source configured to emit an electron beam; a plurality of converging lenses disposed between a stage and the electron beam source, wherein the stage is configured to support an object; an objective lens disposed between the plurality of converging lenses and the stage; an aperture disposed between the plurality of converging lenses; and A controller configured to: acquiring a plurality of original images according to the working distance between the objective lens and the object, acquiring a pattern image from the plurality of original images, wherein the pattern image exhibits object features corresponding to structures from the object, acquiring a plurality of core images indicating the distribution of the electron beam on the object, acquiring a plurality of position vectors indicating the relative positions of features of the object in the plurality of original images, and The position of the aperture is adjusted based on a motion vector indicating motion of the plurality of position vectors according to the working distance.

2. The semiconductor manufacturing apparatus according to claim 1, in, The multiple original images include: at least one overfocused image captured under an overfocused condition in which the working distance is longer than a focal length of the objective lens, and At least one out-of-focus image is captured under an out-of-focus condition, wherein the working distance is shorter than a focal length of the objective lens.

3. The semiconductor manufacturing apparatus according to claim 1, in, Each of the plurality of original images corresponds to a convolution between an image moved by applying each of the plurality of position vectors to the pattern image and each of the plurality of core images, and The controller is configured to apply a deconvolution operation to each of the plurality of original images.

4. The semiconductor manufacturing apparatus according to claim 1, in, The controller is configured to obtain the pattern image, the plurality of core images, and the plurality of position vectors using an objective function capable of minimizing the sum of (i) a gradient of the pattern image and (ii) a mean of differences between the plurality of original images and the calculated image, wherein the calculated image is calculated by performing a convolution operation on an image moved by applying each of the plurality of position vectors to the pattern image using each of the plurality of core images.

5. The semiconductor manufacturing apparatus according to claim 4, in, The controller is configured to: defining the plurality of core images as point spread functions having a Gaussian distribution, and The components of the plurality of position vectors are respectively defined as constants having the same value in any pixel of the pattern image.

6. The semiconductor manufacturing apparatus according to claim 4, in, The controller is configured to: Applying gradient descent to an objective function for the pattern image to update the pattern image, applying gradient descent to an objective function for each of the multiple core images to update each of the multiple core images, differentiating the objective function with each of the components of the multiple position vectors, and obtaining components of the multiple position vectors whose differential values ​​are 0 to update the multiple position vectors.

7. The semiconductor manufacturing apparatus according to claim 6, in, The controller is configured to repeatedly perform the following operations until a difference between before and after performing the operation is less than a threshold: an operation of updating the pattern image, an operation to update each of the plurality of core images, and An operation of updating the plurality of position vectors.

8. The semiconductor manufacturing apparatus according to claim 6, in, The controller is configured to: Initializing the pattern image to a random noise image; Initializing each of the plurality of core images as a point spread function having a non-directional Gaussian distribution; as well as Each of the plurality of position vectors is initialized to a zero vector.

9. The semiconductor manufacturing apparatus according to claim 1, in, The controller includes a central processing unit and a graphics processing unit, The graphics processing unit is configured to perform an operation of acquiring the pattern image, the multiple core images and the multiple position vectors from the multiple original images.

10. The semiconductor manufacturing apparatus according to claim 1, in, The objective lens further comprises an stigmator configured to adjust astigmatism, The controller is configured to adjust the stigmator based on the multiple core images.

11. A semiconductor manufacturing device, include: an electron beam source configured to emit an electron beam; a lens unit configured to deliver the electron beam to an object; an aperture configured to limit an electron beam path of the lens unit; as well as A controller configured to: acquiring a plurality of original images according to a working distance between the lens unit and the object, acquiring a plurality of position vectors indicating relative positions of the structures of the object in the plurality of original images, calculating a motion vector indicating motion of the plurality of position vectors according to the working distance, and The position of the aperture is adjusted according to a compensation vector determined based on the motion vector.

12. The semiconductor manufacturing apparatus according to claim 11, in, The controller is configured to: A principal component analysis technique is applied to the plurality of position vectors, and the direction of the motion vector is determined.

13. The semiconductor manufacturing apparatus according to claim 12, in, The controller is configured to: The magnitude of the motion vector is determined based on a standard deviation of a distribution of the plurality of position vectors.

14. The semiconductor manufacturing apparatus according to claim 11, in, The controller is configured to: The compensation vector is determined such that a direction of the compensation vector is equal to a direction of the motion vector and a magnitude of the compensation vector is proportional to a magnitude of the motion vector.

15. The semiconductor manufacturing apparatus according to claim 11, in, The controller is configured to: The compensation vector is determined such that the compensation vector has a direction determined by rotating the direction of the motion vector by a predetermined angle and has a magnitude proportional to the magnitude of the motion vector.

16. The semiconductor manufacturing apparatus according to claim 15, in, The predetermined angle is an angle at which the direction of the compensation vector converges to one position according to the position of the aperture.

17. The semiconductor manufacturing apparatus according to claim 11, in, The controller is configured to repeatedly perform the following operations until the magnitude of the motion vector is less than a threshold magnitude: an operation of adjusting the position of the aperture using the motion vector, an operation of acquiring the plurality of original images, and An operation of obtaining the plurality of position vectors.

18. A semiconductor manufacturing device, include: an electron beam source configured to emit an electron beam; a plurality of converging lenses disposed between a stage and the electron beam source, wherein the stage is configured to support an object; an objective lens disposed between the plurality of converging lenses and the stage; an aperture disposed between the plurality of converging lenses; and A controller configured to: acquiring a plurality of raw images according to a working distance between the object and the objective lens configured to deliver the electron beam to the object, acquiring a single pattern image indicative of structures included in the object, acquiring a plurality of core images indicating distribution of the electron beam on the object, and acquiring a plurality of position vectors indicating relative positions of the structure in the plurality of original images from the plurality of original images; acquiring a motion vector indicating a motion direction based on the plurality of position vectors according to the working distance; determining a compensation vector based on the motion vector; and The position of the aperture that limits electron beam paths of the plurality of condensing lenses is moved based on the compensation vector.

19. The semiconductor manufacturing apparatus according to claim 18, in, The controller acquires the single pattern image, the multiple core images, and the multiple position vectors from the multiple original images by the following steps: Initializing the single pattern image to a random noise image; Initializing each core image of the plurality of core images as a point spread function having a non-directional Gaussian distribution; Initializing each position vector of the plurality of position vectors to a zero vector; updating the single pattern image by applying gradient descent to an objective function for optimizing a convolution between each image shifted by applying each of the plurality of position vectors to the single pattern image and each of the plurality of core images and for optimizing a difference between each of the plurality of original images; updating each core image of the plurality of core images by applying gradient descent to the objective function; as well as The plurality of position vectors are updated so that a value of a function obtained by differentiating the target function is zero.

20. The semiconductor manufacturing apparatus according to claim 19, in, The controller acquires the single pattern image, the multiple core images and the multiple position vectors from the multiple original images by the following steps: Repeat the following steps until the difference between the value before and after the operation is less than a threshold: including an operation of updating the single pattern image; updating the plurality of core images; and The plurality of position vectors are updated.

Images