Proximity effect correction method, drawing method and drawing device

Abstract

Embodiments provide a proximity effect correction method, a drawing method, and a drawing apparatus that can appropriately correct proximity effect regardless of the substrate's surface shape. In the proximity effect correction method of the embodiment, the energy distribution of a backscattered beam resulting from backscattering of an electron beam within the substrate is calculated based on externally input drawing information and externally input surface shape information of the substrate. The required energy of the electron beam is then calculated based on the calculated energy distribution. The drawing information is information used to form a pattern in a resist film on the substrate by irradiating the electron beam, and the surface shape information is information regarding the height of the substrate, which varies relative to the irradiation direction of the electron beam.

Description

[0001] [Related Applications]

[0002] This application claims priority from Japanese Patent Application No. 2021-10415 (filing date: January 26, 2021), which is a basic application, and the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of the present invention relate to a drawing method and a drawing device. Background Art

[0004] Electron beam lithography equipment is sometimes used to produce a master for semiconductor manufacturing. In this case, depending on the surface shape of the master substrate, it may be difficult to appropriately correct the proximity effect caused by backscattering of the electron beam in the substrate. Summary of the Invention

[0005] The embodiment provides a proximity effect correction method, a drawing method, and a drawing apparatus capable of appropriately correcting the proximity effect regardless of the surface shape of a substrate.

[0006] In the proximity effect correction method of the embodiment, the energy distribution of the backscattered beam generated by the electron beam backscattering in the substrate is calculated based on externally inputted drawing information and externally inputted substrate surface shape information, and the required energy of the electron beam is calculated based on the calculated energy distribution. The drawing information is information used to form a pattern in the resist film on the substrate by irradiating the electron beam, and the surface shape information is information about the height of the substrate, which varies with respect to the irradiation direction of the electron beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A This is a diagram showing an example of a drawing device according to an embodiment.

[0008] Figure 1B This is a diagram showing another example of the drawing device according to the embodiment.

[0009] Figure 2A This is a cross-sectional view showing an example of a photomask blank to which the drawing apparatus according to the embodiment can be applied.

[0010] Figure 2B This is a cross-sectional view showing an example of a template base to which the drawing apparatus according to the embodiment can be applied.

[0011] Figure 2C This is a cross-sectional view showing another example of a mask blank to which the drawing apparatus according to the embodiment can be applied.

[0012] Figure 3 This is a flowchart showing an example of a proximity effect correction method according to an embodiment.

[0013] Figure 4 It is used to illustrate the proximity effect correction method of the embodiment. Figure 3 1 and 2. An explanatory diagram of an example of a process of acquiring drawing data shown in a flowchart of FIG.

[0014] Figure 5 It is used to illustrate the proximity effect correction method of the embodiment. Figure 3 1 is an explanatory diagram of an example of a process for acquiring surface shape data shown in the flowchart of FIG.

[0015] Figure 6 It is used to illustrate the proximity effect correction method of the embodiment. Figure 3 1 is an explanatory diagram of an example of a dividing step of dividing drawing data into meshes, as shown in the flowchart of FIG.

[0016] Figure 7 It is used to illustrate the proximity effect correction method of the embodiment. Figure 3 An explanatory diagram of an example of the tilt angle information and the tilt direction information shown in the flowchart.

[0017] Figure 8 It is used to illustrate the proximity effect correction method of the embodiment. Figure 3 1 is an explanatory diagram of an example of a calculation process of the energy distribution of the backscattered beam in the slope portion shown in the flowchart of FIG.

[0018] Figure 9 It is used to compare Figure 8 An explanatory diagram illustrating an example of a step of calculating the energy distribution of a backscattered beam in a slope portion in the proximity effect correction method according to the embodiment in more detail.

[0019] Figure 10 yes Figure 9 The following are explanatory diagrams for explaining an example of a step of calculating the energy distribution of a backscattered beam in a slope portion in the proximity effect correction method according to the embodiment.

[0020] Figure 11 It is used to illustrate the proximity effect correction method of the embodiment. Figure 3 1 is an explanatory diagram of an example of a calculation process of the cumulative energy distribution in the slope portion shown in the flowchart of .

[0021] Figure 12 It is used to illustrate the proximity effect correction method of the embodiment. Figure 3 1 is an explanatory diagram of an example of a calculation process of required energy shown in the flowchart of .

[0022] Figure 13 It is used to illustrate the proximity effect correction method of the embodiment. Figure 31 and 2. An explanatory diagram of an example of a calculation process of the inclination angle and inclination direction of the slope portion shown in the flowchart of FIG.

[0023] Figure 14 It is used to illustrate the proximity effect correction method of the embodiment. Figure 3 1 and 2 are explanatory diagrams of an example of a calculation process of the energy distribution of the backscattered beam in the boundary portion of the flat portion shown in the flowchart of FIG.

[0024] Figure 15 It is used to illustrate the proximity effect correction method of the embodiment. Figure 3 1 is an explanatory diagram of an example of a calculation process of the cumulative energy distribution in the flat portion shown in the flowchart of .

[0025] Figures 16A to 16E It is a cross-sectional view showing a method for manufacturing a photomask according to an embodiment.

[0026] Figures 17A to 17E It is a cross-sectional view showing a method for manufacturing a template according to an embodiment. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figures 1A to 17E In the drawings, the same or similar components are denoted by the same reference numerals and repeated descriptions are omitted.

[0028] (Drawing device)

[0029] Figure 1A This is a diagram showing an example of the drawing device 1 according to the embodiment. Figure 1B This is a diagram showing another example of the drawing device 1 according to the embodiment. Figure 1A and Figure 1B The drawing apparatus 1 shown can be used, for example, to draw a pattern on the substrate 6 (i.e., the resist film 9 on the substrate 6) by irradiating an electron beam EB when manufacturing a master plate for semiconductor manufacturing. The specific form of the substrate 6 is not particularly limited as long as it is suitable for manufacturing a master plate by irradiating an electron beam EB. For example, Figures 2A to 2C As described above, the substrate 6 may also be a mask substrate 6A, 6C or a template substrate 6B. More specifically, considering that the accumulated energy distribution of the backscattered beam in the resist film 9 (hereinafter referred to as the energy distribution of the backscattered beam) is different due to the difference in the surface shape of the substrate 6, the backscattered beam is used. Figure 1A and Figure 1B The depiction device 1 shown can appropriately correct the proximity effect caused by backscattering.

[0030] Figure 1AThe depicted imaging apparatus 1 includes a computer 2, a control device 3, an electron irradiation unit 4, and a stage 5. The computer 2 performs various calculations for proximity effect correction (for example, calculation of energy distribution of backscattered beams and calculation of required energy as described below). Figure 1A In the process, the computer 2 further performs calculations for rendering other than the proximity effect correction.

[0031] Figure 1B In the drawing apparatus 1 shown, the computer 2 is arranged outside the drawing apparatus 1 . Figure 1B In the drawing apparatus 1, the computer 2 outside the drawing apparatus 1 performs various calculation processes for proximity effect correction. In addition, the drawing apparatus 1 may also include a computer (not shown) that performs calculation processes for drawing other than proximity effect correction.

[0032] Unless otherwise specified, the following description of the device 1 is for Figure 1A and Figure 1B The electron irradiation unit 4 is configured to be universal for any imaging apparatus 1. The electron irradiation unit 4 is disposed within an electron optical lens barrel (not shown). A substrate 6 is placed on a stage 5 within a vacuum chamber connected to the electron optical lens barrel. The stage 5 can be moved, for example, in the horizontal (X and Y) and vertical (Z) directions by a drive device such as a motor. By moving the stage 5, the position at which the electron beam EB irradiates the substrate 6 on the stage 5 can be changed.

[0033] Here, before describing the components of the drawing apparatus 1 in more detail, an example of the substrate 6 to which the drawing apparatus 1 can be applied will be described. Figure 2A 1 is a cross-sectional view showing an example of a photomask blank 6A to which the drawing apparatus 1 according to the embodiment can be applied. Figure 2B 1 is a cross-sectional view showing an example of a template base 6B to which the drawing apparatus 1 according to the embodiment can be applied. Figure 2C This is a cross-sectional view showing another example of a photomask blank 6C to which the drawing apparatus 1 of the embodiment can be applied. The photomask blanks 6A and 6C are examples of substrates 6 used to manufacture a photomask serving as a master for photolithography. The template blank 6B is an example of substrate 6 used to manufacture a template serving as a master for nanoimprint etching.

[0034] like Figure 2A and Figure 2C As shown, the photomask base 6A, 6C as the substrate 6 has a light-transmitting substrate 61 and a light-shielding film 62 formed on the light-transmitting substrate 61. The light-transmitting substrate 61 may contain, for example, quartz as a main component. The light-shielding film 62 may contain, for example, a metal such as chromium (Cr) as a main component. Figure 2B As shown, the template base 6B serving as the substrate 6 contains, for example, quartz as a main component and therefore has light-transmitting properties as a whole.

[0035] In the case where there are steps or slopes on the surface of the film to be processed formed on the device substrate (wafer) for semiconductor devices, it is difficult to process the film to be processed with high precision if a mask or template with a flat surface is still used. Specifically, in the case of photolithography using a mask, it is difficult to focus the exposure light on the resist film on the film to be processed, and thus it is difficult to properly expose the resist film on the film to be processed. In the case of nanoimprint etching using a template, it is difficult to properly press the template against the resist on the device substrate as the film to be processed to transfer the pattern. As a result, it is difficult to form a circuit pattern on the film to be processed with the desired precision. Therefore, from the perspective of high-precision processing of the film to be processed with steps and slopes, the surface of the substrate 6A to 6C for the mask or template has a surface shape corresponding to the surface shape of the film to be processed. Specifically, Figure 2A The surface of the photomask base 6A shown has a flat portion 6a parallel to the in-plane direction d1, a flat portion 6c formed higher than the flat portion 6a by a step zd, and a slope portion 6b connecting the two flat portions 6a and 6c. Furthermore, when the photomask base 6A is placed on the stage 5, the in-plane direction d1 is aligned with the horizontal direction. Figure 2A The slope portion 6b shown is a straight inclined plane. Figure 2A As shown by reference numeral 6b', the slope portion 6b' may be an inclined curved surface. Figure 2B The template substrate 6B shown and Figure 2C The surface of the photomask base 6C shown has adjacent flat portions 6a and 6c formed to have different heights due to a step zd. Alternatively, the template base 6B may also have a sloped portion.

[0036] Here, when a pattern is drawn on the substrate 6 to manufacture a master plate (mask, template), a resist film 9 is formed on the substrate 6. Figure 16A In the embodiment, a resist film 9 is formed on a photomask blank 6A as an example of a substrate 6. Figure 17A In the embodiment, a resist film 9 is formed on a template base 6B as an example of a substrate 6. A pattern is drawn on the resist film 9 by irradiating the substrate 6 with the resist film 9 with an electron beam EB. The electron beam EB irradiated to the substrate 6 is backscattered in the substrate 6. The backscattered beam generated by the backscattering again exposes the resist film 9 on the substrate 6. The re-exposure of the resist film 9 causes a proximity effect in which the pattern size changes from the design value. Specifically, in a portion where the pattern density is high, the re-exposure amount of the resist film 9 due to backscattering from the periphery becomes large, so the pattern size is larger than the design value. On the other hand, in a portion where the pattern density is low, the re-exposure amount is small, so the pattern size is smaller than the design value. In order to ensure the dimensional accuracy of the pattern, it is necessary to correct the proximity effect. In the correction of the proximity effect, the irradiation amount of the electron beam EB is controlled according to the energy distribution of the backscattered beam. Gaussian distribution is often used as the energy distribution of the backscattered beam. However, as Figures 2A to 2C When drawing a pattern on substrates 6A-6C having surface steps or slopes, the backscattered beam energy distribution is non-uniform. Specifically, the backscattered beam energy distribution varies between flat portions, sloped portions, and the boundaries between adjacent flat portions. In this case, consistently using a Gaussian distribution for the backscattered beam energy distribution would fail to adequately correct for the proximity effect. To address this issue, the drawing apparatus 1 of the embodiment is configured to adequately correct for the proximity effect regardless of the surface shape of the substrate 6.

[0037] Specifically, if Figure 1A 、 Figure 1B As shown, drawing data 7 is input to the computer 2. The drawing data 7 is data for drawing a pattern on the substrate 6 by irradiating the electron beam EB. The drawing data 7 is data produced by a computer different from the computer 2 based on, for example, the design data of the original. Figure 1A 、 Figure 1B As shown, surface shape data 8 is input into computer 2. Surface shape data 8 is data regarding the surface shape of substrate 6. Surface shape data 8 is generated by a computer separate from computer 2 based on, for example, master design data. The method for inputting drawing data 7 and surface shape data 8 into computer 2 is not particularly limited; for example, input via data communication or via a storage medium is acceptable. Further details regarding drawing data 7 and surface shape data 8 will be described below in connection with the embodiment of the proximity effect method.

[0038] The computer 2 calculates the energy distribution of the backscattered beam generated by the backscattering of the electron beam EB in the substrate 6 based on the drawing data 7 and surface shape data 8 obtained by input. Based on the calculated energy distribution, the computer 2 calculates the required energy of the electron beam EB irradiated on the substrate 6. The required energy is the energy of the electron beam EB required to appropriately correct the proximity effect regardless of the surface shape of the substrate 6. The computer 2 outputs data indicating the calculated required energy to the control device 3. An example of the calculation of the required energy by the computer 2 will be described in the embodiment of the proximity effect method described below.

[0039] The control device 3 controls the irradiation amount of the electron beam EB irradiated onto the substrate 6 based on the data indicating the required energy (i.e., the calculated required energy) input from the computer 2. That is, the control device 3 adjusts the irradiation amount of the electron beam EB so that the energy of the electron beam EB of the required energy is supplied to the resist film 9 on the substrate 6.

[0040] The electron irradiation unit 4 irradiates the substrate 6 with an electron beam EB having an irradiation amount controlled by the control device 3, thereby drawing a pattern on the resist film 9 on the substrate 6. The electron irradiation unit 4 includes, for example, an electron gun that emits the electron beam EB and an electron optical system (deflector, electromagnetic lens, etc.) that controls the trajectory of the emitted electron beam EB.

[0041] If the backscattered beam energy distribution and the required energy based on this energy distribution are calculated based solely on the drawing data 7, the proximity effect may not be appropriately corrected if there are steps or slopes on the surface of the substrate 6. This is because the drawing data 7 does not include information about the surface shape of the substrate 6, such as the steps or slopes. Therefore, the backscattered beam energy distribution based solely on the drawing data 7 cannot take the surface shape of the substrate 6 into account. In contrast, the drawing device 1 of the embodiment uses the backscattered beam energy distribution calculated based on both the drawing data 7 and the surface shape data 8, and the required energy based on this energy distribution, thereby appropriately correcting the proximity effect regardless of the surface shape of the substrate 6.

[0042] (Proximity Effect Correction Method)

[0043] Hereinafter, an embodiment of a proximity effect correction method using the rendering device 1 according to the embodiment will be described. Figure 3 This is a flowchart showing an example of a proximity effect correction method according to an embodiment.

[0044] like Figure 3 As shown, first, the computer 2 acquires the drawing data 7 (step S1). Figure 4 It is used to illustrate Figure 3 FIG. 7 is an explanatory diagram of an example of a process for obtaining drawing data 7 shown in the flowchart of FIG. Figure 4 As shown, the drawing data 7 represents a two-dimensional region corresponding to the surface of substrate 6 and has a pattern P defined within the region. The pattern P in the drawing data 7 is drawn at a corresponding position (i.e., coordinates) on the surface of substrate 6. Since the drawing data 7 is two-dimensional data, it does not contain information on the height direction, such as level differences or slopes on the surface of substrate 6.

[0045] In addition, if Figure 3 As shown, the computer 2 acquires the surface shape data 8 (step S2). The acquisition of the surface shape data 8 and the acquisition of the drawing data 7 may be performed in reverse order or simultaneously. Figure 5 It is used to illustrate Figure 3 FIG. 8 is an explanatory diagram of an example of a process for acquiring surface shape data 8 as shown in the flowchart of FIG. Figure 5As shown, the surface shape data 8 includes at least flat portion configuration information and height information. The flat portion configuration information is information indicating the configuration state (e.g., position) of a plurality of flat portions arranged on the surface of the substrate 6 in a manner having different heights due to step differences. More specifically, the flat portion configuration information indicates a two-dimensional area corresponding to the drawing data, having a flat portion defined within the area. The height information is information indicating the height of the flat portion relative to the irradiation direction of the electron beam. The height information is information indicating a relative height based on the height of one flat portion among the plurality of flat portions. As shown in FIG. Figure 5 As shown, the surface shape data 8 may further include the slope portion arrangement information described below. The surface shape data 8 may be in a table format.

[0046] After obtaining the drawing data 7 and the surface shape data 8, Figure 3 As shown, the computer 2 divides the drawing data 7 into a plurality of grids (step S3). The grids are data obtained by dividing the drawing data 7 so as to correspond to a plurality of areas on the surface of the substrate 6, respectively. Figure 6 It is used to illustrate the Figure 3 The flowchart of FIG is an explanatory diagram of an example of a segmentation process for segmenting the drawing data into grids. More specifically, Figure 6 As shown, the meshes M are data obtained by dividing the drawing data 7 into a mesh shape. Each mesh M is used for drawing a corresponding area on the surface of the substrate 6.

[0047] After dividing the drawing data 7 into a grid M, as shown in FIG. Figure 3 As shown, the computer 2 determines whether there is slope portion configuration information corresponding to the mesh M as the surface shape data 8 for each mesh M (step S4). Figure 5 Information indicating the configuration state (eg, position) of the slope portion is shown.

[0048] When there is slope configuration information corresponding to the grid M (step S4: yes), Figure 3 As shown, the computer 2 determines whether or not there is inclination angle information and inclination direction information corresponding to the mesh M as the surface shape data 8 (step S5). Figure 7 It is used to illustrate Figure 3 An explanatory diagram of an example of tilt angle information and tilt direction information shown in the flowchart of FIG. Figure 7 As shown in FIG, the tilt angle information is information indicating the tilt angle θ of the slope portion. The tilt direction information is information indicating the direction of the slope portion. More specifically, Figure 7 In the example shown, the tilt direction information is information representing the two-dimensional direction in which the height of the slope portion decreases as an angle with respect to the two-dimensional reference direction d2. For example, since the two-dimensional direction in which the height of the slope portion a decreases coincides with the reference direction d2, Figure 7The slope a shown in FIG. 1 is inclined at 0 degrees. On the other hand, since the direction in which the height of the slope d decreases in two dimensions is opposite to the reference direction d2, Figure 7 The slope portion d shown has an inclination direction of 180 degrees.

[0049] If there is tilt angle information and tilt direction information corresponding to the grid M (step S5: Yes), the computer 2 obtains the tilt angle from the tilt angle information and obtains the tilt direction from the tilt direction information. Figure 3 As shown, the computer 2 calculates the energy distribution of the backscattered beam in the slope portion based on a function corresponding to the tilt angle and the tilt direction (step S6).

[0050] Figure 8 It is used to illustrate Figure 3 1 is an explanatory diagram of an example of a calculation process of the energy distribution of the backscattered beam in the slope portion shown in the flowchart of FIG. Figure 8 In FIG. 1 , a cross-sectional view and a top view are shown of a region B in the substrate 6 where the electron beam EB of one exposure irradiation irradiated to the slope portion is backscattered, and an energy distribution D of the backscattered beam generated by the backscattering. Figure 8 , for comparison with the slope portion, shows a region A where the electron beam EB irradiated on the flat portion in one exposure shot is backscattered in the substrate 6 and an energy distribution C of the backscattered beam resulting from the backscattering. Figure 8 In the example shown, the energy distribution C of the backscattered beam in the flat portion is a Gaussian distribution. Figure 8 As shown in FIG, the energy distribution D of the backscattered beam in the slope portion is calculated as a distribution different from the Gaussian distribution C. More specifically, Figure 8 In the example shown, the energy distribution D of the backscattered beam in the slope portion is calculated as a distribution in which the peak of the energy is shifted toward the inclination direction d3 of the slope portion relative to the Gaussian distribution C.

[0051] Figure 9 It is used to compare Figure 8 An explanatory diagram illustrating an example of a calculation process of the energy distribution of the backscattered beam in the slope portion in more detail. Figure 9 The depicted drawing data 7 is Figure 4 and Figure 6 In the energy distribution calculation process (step S6), the computer 2 first calculates the energy distribution of the part corresponding to the slope portion of the depicted data 7. Figure 9 As shown, the pattern area ratio in each mesh M corresponding to the slope portion is calculated (step S61). The pattern area ratio is a numerical value between 0 and 1 that represents the ratio of the area of ​​the pattern P to the area of ​​the mesh M for each mesh M. Figure 9 As shown, the larger the area occupied by the pattern P in the grid M, the larger the pattern area ratio.

[0052] Figure 10 yes Figure 9 The following is an explanatory diagram for explaining an example of the calculation process of the energy distribution of the backscattered beam in the slope portion. Figure 10 As shown, the computer 2 calculates the energy distribution of the backscattered beam in each mesh M corresponding to the slope portion (step S62). In other words, the computer 2 calculates the energy distribution of the backscattered beam generated when the area on the slope portion corresponding to each mesh M is irradiated with the electron beam EB corresponding to the pattern P contained in each mesh M. The energy distribution of the backscattered beam in each mesh M is calculated based on, for example, a function obtained by Monte Carlo simulation of the energy distribution of the backscattered beam with the slope portion as the target, or a function that approximates (i.e., simplifies) the function. The energy distribution of the backscattered beam in each mesh M can also be calculated based on a table indicating the energy of each mesh M obtained based on experimental results.

[0053] Figure 10 The energy distribution of the backscattered beam generated by the electron beam EB irradiated onto the region on the slope portion corresponding to each of the meshes M1 to M3 according to the pattern P included in each of the meshes M1 to M3 of interest is shown. Figure 10 In FIG, the numerical values ​​described in each grid M1 to M3 and M represent the energy of the backscattered beam corresponding to each grid M1 to M3 and M. More specifically, Figure 10 The energy described in each grid M1 to M3 and M is a value converted with the maximum value being 1. Figure 10 The energy of the meshes M1 to M3 and the pattern area ratio corresponding to each mesh M1 to M3 (see Figure 9 ) are consistent. Figure 10 In the figure, each grid M1 to M3 and M is filled with black dots with a density roughly corresponding to the energy of the backscattered beam. Figure 10 In FIG. 1 , the slope portion is schematically shown to indicate the height of the area on the slope portion corresponding to each grid M1 to M3 and M. Figure 10As shown, in the grid M1 that does not contain the pattern P, that is, the pattern area ratio is 0, and is far away from the grids M2 and M3 that contain the pattern P, the energy is 0. This is because the grid M1 not only does not generate backscattering due to the electron beam EB irradiated according to its own pattern P, but is also not affected by the backscattering caused by the electron beam EB irradiated according to the pattern P in other grids. On the other hand, in the grid M2 with a pattern area ratio of 0.3, the energy distribution across the grid M2 and the grids M around it is calculated based on the backscattered beam generated by the electron beam EB irradiated according to the pattern P contained in the grid M2. This is because the backscattering of the electron beam EB generated according to the pattern P of the grid M2 affects not only the grid M2, but also the surrounding grids M. In the grid M3 with a pattern area ratio of the maximum value of 1, the energy distribution across the grids M3 and M in a wider range is calculated based on the backscattered beam generated by the electron beam EB irradiated according to the pattern P contained in the grid M3. As shown Figure 10 As shown, the energy distribution of the backscattered beam in the slope portion is not an isotropic distribution centered on the meshes M2 and M3 of interest, but an anisotropic distribution biased toward the inclination direction d3 of the slope portion.

[0054] After calculating the energy distribution of the backscattered beam in the slope, as shown in Figure 3 As shown, the computer 2 calculates the cumulative energy distribution (step S7). The cumulative energy distribution is a distribution obtained by integrating the calculated energy distribution for each grid. Figure 11 It is used to illustrate Figure 3 An explanatory diagram of an example of a calculation process of the cumulative energy distribution in the slope portion shown in the flowchart of Figure 9 and Figure 10 The depicted data 7 is calculated Figure 11 The cumulative energy distribution is shown in Figure 2. Figure 11 The accumulated energy recorded in each grid is a value converted with the maximum value being 1.

[0055] After calculating the cumulative energy distribution, if Figure 3 As shown, the computer 2 calculates the required energy based on the calculated cumulative energy distribution (step S8). Figure 12 It is used to illustrate Figure 3 1 is an explanatory diagram of an example of a calculation process of required energy shown in the flowchart of . Figure 12 , the required energy (μC) in the slope portion is calculated for each exposure. Figure 12For ease of explanation, the pattern P1 corresponding to the required energy for each exposure is shown. The resist film 9 on the substrate 6 depicted with the pattern P1 is exposed not only by the electron beam EB but also by the backscattered beam. That is, the resist film 9 is not only given the irradiation energy of the electron beam EB but also the energy of the backscattered beam. Therefore, it is necessary to calculate the required energy taking into account the energy of the backscattered beam. Thus, as Figure 12 As shown, the computer 2 first defines the irradiation energy of the electron beam EB for each exposure shot, which is obtained by adding the cumulative energy according to the cumulative energy distribution. The defined irradiation energy is the irradiation energy before adjustment for proximity effect correction.

[0056] Next, the computer 2 sets the energy of a specific ratio (e.g., 50%) to the maximum value of the irradiation energy before adjustment as a threshold value. Furthermore, the computer 2 sets the distribution width of the irradiation energy of each exposure irradiation in the threshold value ( Figure 12 The irradiation energy of each exposure is adjusted in a manner consistent with the horizontal width in the image. The adjusted irradiation energy is calculated as the required energy. The calculated required energy is used in the control device 3 to adjust the irradiation amount of the electron beam EB. In this way, the proximity effect is corrected. In the case where the proximity effect is not corrected, as shown in FIG. Figure 12 The pattern P2 shown by the dotted line portion is drawn as a plurality of adjacent patterns P2 with equal widths in the design data. On the other hand, when the proximity effect is corrected according to the embodiment, as shown in FIG. Figure 12 The pattern P1 shown by the solid line portion of can be appropriately drawn so that a plurality of adjacent patterns P1 having the same width on the design data are converted into patterns P1 having the same width.

[0057] Alternatively, the computer 2 may recalculate the energy distribution of the backscattered beam using the irradiation dose of the electron beam EB adjusted based on the required energy. In this case, the computer 2 may recalculate the cumulative energy distribution based on the recalculated energy distribution of the backscattered beam, and recalculate the required energy for each exposure based on the recalculated cumulative energy distribution. This recalculation of the required energy may be repeated as needed.

[0058] In the case where there is no tilt angle information and tilt direction information corresponding to the grid M (step S5: No), Figure 3 As shown, the computer 2 calculates the inclination angle and inclination direction of the slope portion (step S9). Figure 13 It is used to illustrate Figure 3 The inclination angle and inclination direction of the slope portion can be calculated using a linear function or polynomial based on the slope portion configuration information and height information. Figure 13As shown, the inclination angle θ and the inclination direction d3 are calculated based on the X coordinate (x1) and Z coordinate (z1) of the lower end of the slope portion and the X coordinate (x2) and Z coordinate (z2) of the upper end of the slope portion shown in the slope portion configuration information and the height information. Figure 13 In the example shown, the inclination angle θ is the arctangent (tan) of the slope (z2-z1) / (x2-x1) of the linear function connecting the coordinates of the lower end (x1, z1) and the upper end (x2, z2) of the slope. -1 ).also, Figure 13 In the example shown, the tilt direction d3 is the direction in which the Z value of the linear function decreases, that is, the direction from x2 to x1. After step S9, the process proceeds to step S6.

[0059] In the case where there is no slope configuration information corresponding to the grid M (step S4: No), Figure 3 As shown, the computer 2 determines whether the grid corresponds to a boundary between adjacent flat portions without intervening a sloped portion (step S10). If the grid corresponds to a boundary between the flat portions (step S10: Yes), the computer 2 calculates the energy distribution of the backscattered beam at the boundary between the flat portions based on a function corresponding to the size of the level difference at the boundary and the distance from the boundary (step S11).

[0060] Figure 14 It is used to illustrate Figure 3 1 and 2 are explanatory diagrams of an example of a calculation process of the energy distribution of the backscattered beam at the boundary portion of the flat portion shown in the flowchart of FIG. Figure 14 In FIG. 1 , a cross-sectional view and a top view are shown of a region B in the substrate 6 where the electron beam EB of one exposure irradiation irradiated to the boundary between the flat portions 6L and 6H is backscattered, and an energy distribution D of the backscattered beam generated during the backscattering. Figure 14 , as a comparison with the boundary between the flat portions 6L and 6H, shows the area A in which the electron beam EB of one exposure irradiation on a completely flat portion without step difference is backscattered in the substrate 6, and the energy distribution C of the backscattered beam generated in the backscattering. Figure 14 In the example shown, the energy distribution C of the backscattered beam in the completely flat portion is a Gaussian distribution. Figure 14 As shown in FIG. 1 , the energy distribution D of the backscattered beam at the boundary between the flat portions 6L and 6H is calculated as a distribution different from the Gaussian distribution C. More specifically, Figure 14 In the example shown, the energy distribution D of the backscattered beam at the boundary between the flat portions 6L and 6H is calculated as a distribution in which the energy is concentrated on the side of the higher flat portion 6H, compared to the Gaussian distribution C. Figure 14This is an example of a case where the electron beam EB is irradiated in such a manner that the beam center is located on the high flat portion 6H. Figure 14 The energy distribution is calculated in which the energy is concentrated on the side of the flat portion 6L with a relatively low height.

[0061] and Figure 9 and Figure 10 Similar to the example shown, the energy distribution of the backscattered beam at the boundary between the flat portions 6L and 6H is calculated for each mesh M. For example, the energy distribution of the backscattered beam in each mesh M is calculated based on a function corresponding to the magnitude of the level difference zd at the boundary between the flat portions 6L and 6H and the two-dimensional distance from the boundary. More specifically, the energy distribution of the backscattered beam in each mesh M can be calculated based on a function obtained through a Monte Carlo simulation of the boundary between the flat portions 6L and 6H, or a function that approximates (i.e., simplifies) the function. Alternatively, the energy distribution of the backscattered beam in each mesh M can be calculated based on a table indicating the energy of each mesh M obtained based on experimental results. After step S11, the process proceeds to step S6.

[0062] If the grid does not correspond to a boundary between flat portions (step S10: No), the computer 2 determines that the grid corresponds to a completely flat portion with no step difference. In this case, the computer 2 calculates the energy distribution of the backscattered beam in the flat portion based on a Gaussian distribution (step S12). The energy distribution obtained based on the Gaussian distribution is expressed, for example, by the following equation.

[0063] g(x)=η×D(x')×(1 / πσ 2 )×exp{-(x-x') 2 / σ 2}

[0064] Where g(x) is the energy of the backscattered beam at coordinate x, i.e., the energy distribution. η is the backscatter coefficient. D(x') is the irradiance of the electron beam EB at coordinate x'. σ is the backscatter radius of the backscattered beam.

[0065] and Figure 9 and Figure 10 As in the example shown, the energy distribution of the backscattered beam in the flat portion is calculated based on the Gaussian distribution for each mesh M. After step S12 , the process proceeds to step S6 . Figure 15 It is used to illustrate Figure 3 1 is an explanatory diagram of an example of a calculation process of the cumulative energy distribution in the flat portion shown in the flowchart of . Figure 15 An example of the integrated energy distribution calculated in step S6 based on the energy distribution of the backscattered beam obtained by the Gaussian distribution is shown.

[0066] In addition, the calculation of the energy distribution of the backscattered beam is not limited to Figure 3 For example, the energy distribution at the boundary between the flat portion and the slope portion may be calculated based on the function or experimental results based on the Monte Carlo simulation described above.

[0067] According to the proximity effect correction method of the embodiment, the energy distribution of the backscattered beam can be calculated based on the drawing data 7 and the surface shape data 8, and the required energy of the electron beam can be calculated based on the calculated energy distribution. As a result, the proximity effect can be appropriately corrected regardless of the surface shape of the substrate 6.

[0068] In addition, according to the proximity effect correction method of the embodiment, the energy distribution of the backscattered beam in the slope portion can be appropriately calculated based on the depiction data 7 and the flat portion configuration information, height information and slope portion configuration information, the inclination angle of the slope portion, and the inclination direction of the slope portion as the surface shape data 8.

[0069] Furthermore, according to the proximity effect correction method of the embodiment, the required energy can be appropriately calculated based on the cumulative energy distribution obtained by integrating the energy distribution of the backscattered beam for each grid.

[0070] In addition, according to the proximity effect correction method of the embodiment, the energy distribution of the backscattered beam is calculated using appropriate calculation methods corresponding to the slope portion, the boundary portion of the flat portion, and the completely flat portion, respectively, so that the proximity effect can be appropriately corrected corresponding to the surface shape of the substrate 6.

[0071] (Original manufacturing method)

[0072] Figures 3 to 15 The proximity effect correction method of the embodiment described in the embodiment can be used to manufacture a master plate. Hereinafter, as a master plate manufacturing method to which the proximity effect correction method of the embodiment is applied, an embodiment of a mask manufacturing method and an embodiment of a template manufacturing method are described in order.

[0073] Figure 16A 1 is a cross-sectional view showing a method for manufacturing a photomask according to an embodiment of the present invention. Figure 16A As shown, in Figure 2A The resist film 9 is formed on the photomask base 6A. The formation of the resist film 9 includes coating of the resist film 9 and pre-baking after coating. Figure 16A In the example shown, the resist film 9 is a positive resist film, but the resist film 9 may be a negative resist film.

[0074] Figure 16B yes Figure 16A The following is a cross-sectional view showing a method for manufacturing a photomask according to an embodiment of the present invention. Figure 16BAs shown, the electron beam EB having an irradiation dose adjusted by the proximity effect correction method of the embodiment is irradiated by the drawing apparatus 1. As a result, the resist film 9 at the portion irradiated with the electron beam EB is exposed.

[0075] Figure 16C yes Figure 16B The following is a cross-sectional view showing a method for manufacturing a photomask according to an embodiment of the present invention. The resist film 9 is exposed and the exposed resist film 9 is post-baked. Figure 16C As shown, the resist film 9 is developed. The development of the resist film 9 is performed in a wet process using a chemical solution. The exposed portion of the resist film 9 is removed by the development, and the light shielding film 62 is partially exposed at the portion where the resist film 9 has been removed.

[0076] Figure 16D yes Figure 16C The following is a cross-sectional view showing a method for manufacturing a photomask according to an embodiment. After developing the resist film 9, the light shielding film 62 is etched (ie, processed) using the developed resist film 9 as a mask. The etching is performed in a dry process.

[0077] Figure 16E yes Figure 16D The following is a cross-sectional view showing a method for manufacturing a photomask according to an embodiment of the present invention. Figure 16E As shown in FIG. 1 , the resist film 9 is removed. Thus, a photomask 60A is obtained.

[0078] Figures 17A to 17E : is a cross-sectional view showing a method for manufacturing the template 60B according to the embodiment. Figures 17A to 17E As shown, the method for manufacturing the template 60B is basically the same as the method for manufacturing the photomask 60A. The method for manufacturing the template 60B differs from the method for manufacturing the photomask 60A in that the etching target is not the light shielding film 62 but the template base 6B.

[0079] According to the method for manufacturing the photomask 60A and template 60B of the embodiment, the photomask base 6A and template base 6B are exposed using an electron beam EB whose irradiation dose has been adjusted using the proximity effect correction method of the embodiment. This allows the production of photomask 60A and template 60B with a pattern having high dimensional accuracy, in which proximity effects are appropriately corrected regardless of the surface shape. By applying these photomasks 60A and template 60B to semiconductor manufacturing processes, a dimensionally accurate pattern can be formed on device substrates with surface steps or slopes, thereby enabling the appropriate manufacture of semiconductor devices.

[0080] Figure 1A and Figure 1BAt least a part of the computer 2 shown can be composed of hardware or software. In the case of being composed of software, the program that realizes at least a part of the functions of the computer 2 can also be stored in a recording medium such as a floppy disk or a CD-ROM (compact disc read only memory), and read and executed by the computer. The recording medium is not limited to a removable recording medium such as a magnetic disk or an optical disk, but can also be a fixed recording medium such as a hard disk device or a memory. In addition, the program that realizes at least a part of the functions of the computer 2 can also be distributed via a communication line such as the Internet (including wireless communication). Furthermore, the program can also be distributed in an encrypted, modulated or compressed state via a wired line or wireless line such as the Internet, or stored in a recording medium.

[0081] While several embodiments have been described above, these embodiments are provided as examples only and are not intended to limit the scope of the invention. The novel devices and methods described in this specification may be implemented in various other ways. Furthermore, various omissions, substitutions, and modifications may be made to the devices and methods described in this specification without departing from the spirit of the invention. The scope of the appended claims and their equivalents are intended to encompass any such embodiments or variations within the scope or spirit of the invention.

[0082] (Note)

[0083] (1) A proximity effect correction method comprising:

[0084] acquiring drawing information for drawing a pattern on a substrate by irradiating an electron beam;

[0085] acquiring surface shape information about the surface shape of the substrate;

[0086] Calculating the energy distribution of a backscattered beam generated by backscattering of the electron beam in the substrate based on the acquired depiction information and the acquired surface shape information; and

[0087] The required energy of the electron beam is calculated based on the calculated energy distribution.

[0088] (2) A proximity effect correction method according to (1), wherein the surface shape information includes: first configuration information indicating a configuration state of a plurality of flat portions configured on the surface of the substrate in a manner having different heights due to a step difference; and height information indicating the heights of the plurality of flat portions.

[0089] (3) The proximity effect correction method according to (2), wherein the energy distribution is calculated based on the drawing information, the first configuration information, the height information, the inclination angle of the slope portion configured on the surface of the substrate, and the inclination direction of the slope portion.

[0090] (4) The proximity effect correction method according to (3), wherein the surface shape information further includes second arrangement information indicating an arrangement state of the slope portion.

[0091] The calculation of the energy distribution further includes calculating the tilt angle and the tilt direction based on the second arrangement information and the height information.

[0092] (5) The proximity effect correction method according to (3), wherein the surface shape information further includes tilt angle information indicating the tilt angle and tilt direction information indicating the tilt direction.

[0093] (6) The proximity effect correction method according to any one of (3) to (5), wherein the slope portion has an inclined plane.

[0094] (7) The proximity effect correction method according to any one of (3) to (5), wherein the slope portion has an inclined curved surface.

[0095] (8) The proximity effect correction method according to any one of (1) to (7), further comprising dividing the drawing information into a plurality of divided information corresponding to a plurality of regions of the surface of the substrate,

[0096] Calculating the energy distribution for each segmentation information,

[0097] The required energy is calculated based on the accumulated energy distribution obtained by accumulating the calculated energy distribution for each of the divided information.

[0098] (9) The proximity effect correction method according to (8), wherein the energy distribution is calculated based on Gaussian distribution in the segmentation information corresponding to the flat portion on the surface of the substrate.

[0099] (10) The proximity effect correction method according to (8) or (9), wherein, in the segmentation information corresponding to the slope portion on the surface of the substrate, the energy distribution is calculated based on a function corresponding to the inclination angle of the slope portion.

[0100] (11) A proximity effect correction method according to any one of (8) to (10), wherein, in segmentation information corresponding to the boundaries between multiple flat portions on the surface of the substrate that are adjacent to each other without a slope portion interposed therebetween, the energy distribution is calculated based on a function corresponding to the size of the step difference at the boundary and the distance from the boundary.

[0101] (12) A method for manufacturing an original plate, comprising:

[0102] controlling the irradiation amount of the electron beam based on the required energy calculated using the proximity effect correction method described in any one of (1) to (11); and

[0103] The electron beam having the controlled irradiation amount is irradiated onto a substrate to draw a pattern on the substrate.

[0104] (13) The original plate manufacturing method according to (12), further comprising forming a resist film on the substrate,

[0105] The pattern is drawn on the resist film.

[0106] (14) The original plate manufacturing method according to (13), further comprising: developing the resist film on which the pattern is drawn;

[0107] processing the substrate using the developed resist film as a mask; and

[0108] The resist film is removed from the processed substrate.

[0109] (15) The method for producing an original plate according to any one of (12) to (14), wherein the original plate is a photomask.

[0110] (16) The method for manufacturing an original plate according to any one of (12) to (14), wherein the original plate is a template for nanoimprint etching.

[0111] (17) A drawing apparatus comprising a control unit that controls the irradiation amount of an electron beam for drawing a pattern on a substrate based on the calculated required energy of the electron beam.

[0112] The required energy is energy according to energy distribution of a backscattered beam generated by backscattering of the electron beam in the substrate.

[0113] The energy distribution of the backscattered beam is an energy distribution according to drawing information for drawing the pattern and surface shape information regarding the surface shape of the substrate.

[0114] (18) The drawing device according to (17), further comprising:

[0115] a first calculation unit that calculates the energy distribution based on the drawing information and the surface shape information; and

[0116] The second calculation unit calculates the required energy based on the calculated energy distribution.

[0117] (19) The drawing device according to (17), wherein the control unit acquires information indicating the calculated required energy from a computer outside the drawing device that calculates the required energy.

[0118] [Explanation of Symbols]

[0119] 1: Drawing device

[0120] 2: Computer

[0121] 3: Control device

[0122] 6: substrate

[0123] 7: Depicting Data

[0124] 8: Surface shape data.

Claims

1. A proximity effect correction method, characterized in that include: Input drawing information from the outside, input substrate surface shape information from the outside, Dividing the depiction information into a plurality of grids, For each of the meshes, determining whether there is a slope or a step difference based on information included in the surface shape information corresponding thereto, For the grid having the slope or the step, the energy distribution of the backscattered beam generated by the electron beam backscattering in the substrate is calculated based on the drawing information and the surface shape information. Calculating the required energy of the electron beam based on the calculated energy distribution, The drawing information is information for forming a pattern on the resist film on the substrate by irradiation with the electron beam, The surface shape information is information on the height of the substrate having a surface that varies in height with respect to an irradiation direction of the electron beam.

2. The proximity effect correction method according to claim 1, wherein: The substrate has a first flat portion and a second flat portion, The surface shape information includes: first arrangement information indicating respective arrangement states of the first flat portion having a first height and the second flat portion having a second height; and The height information indicates the height of each of the first flat portion and the second flat portion.

3. The proximity effect correction method according to claim 2, wherein: The energy distribution is calculated based on the drawing information, the first arrangement information, the height information, an inclination angle of a slope portion arranged on the surface of the substrate, and an inclination direction of the slope portion.

4. The proximity effect correction method according to claim 1, wherein Also includes: dividing the drawing information into a plurality of divided information corresponding to a plurality of regions of the surface of the substrate; Calculating the energy distribution for at least two or more pieces of segmentation information, The required energy is calculated based on the cumulative energy distribution obtained by accumulating the calculated energy distribution for each piece of divided information.

5. The proximity effect correction method according to claim 3, characterized in that Also includes: dividing the drawing information into a plurality of divided information corresponding to a plurality of regions of the surface of the substrate; The energy distribution is calculated for each of at least two or more pieces of segmentation information. The energy distribution is calculated using a function corresponding to the inclination angle of the slope portion in the segmentation information corresponding to the area including the slope portion on the surface of the substrate, and the calculation of the required energy is performed based on the cumulative energy distribution obtained by accumulating the energy distribution of each calculated segmentation information.

6. The proximity effect correction method according to claim 1, wherein Also includes: dividing the drawing information into a plurality of divided information corresponding to a plurality of regions of the surface of the substrate; The energy distribution is calculated for each of at least two or more pieces of segmentation information. In calculating the energy distribution of at least one region among the plurality of regions, a function corresponding to the size and distance of the step difference is used, The required energy is calculated based on the cumulative energy distribution obtained by accumulating the calculated energy distribution for each segment information. The magnitude of the level difference is the magnitude of the level difference at the boundary between a plurality of flat portions located on the surfaces of the adjacent substrates. The distance is the distance from the boundary to the one region.

7. The proximity effect correction method according to claim 1, wherein: The drawing information includes pattern information.

8. The proximity effect correction method according to claim 2, wherein: The first height is different from the second height.

9. The proximity effect correction method according to claim 1, wherein: The calculated energy distribution is an anisotropic distribution.

10. A drawing method, characterized in that include: acquiring drawing information for drawing a pattern on a substrate by irradiating an electron beam; acquiring surface shape information about the heights of a plurality of surfaces of the substrate having different heights relative to an irradiation direction of the electron beam; dividing the depiction information into a plurality of grids; For each of the meshes, determining whether there is a slope or a step difference based on information included in the surface shape information corresponding thereto; For the grid having the slope or the level difference, calculating, based on the acquired depiction information and the acquired surface shape information, an energy distribution of a backscattered beam generated by backscattering of the electron beam in the substrate; calculating the required energy of the electron beam based on the calculated energy distribution; as well as The electron beam is irradiated onto a substrate according to the calculated required energy to form a pattern on a resist on the substrate.

11. The drawing method according to claim 10, wherein: The substrate is a photomask.

12. The drawing method according to claim 10, wherein: The substrate is a template for imprint etching.

13. The drawing method according to claim 10, wherein: The calculated energy distribution is an anisotropic distribution.

14. A drawing device, characterized in that have: a stage for mounting a substrate; a drawing unit for drawing a pattern on the substrate; a control unit for controlling an irradiation amount of the electron beam irradiated to the substrate; as well as a computer for calculating a required energy of the electron beam for controlling an irradiation amount of the electron beam; The computer calculates the required energy based on the energy distribution of the backscattered beam generated by the electron beam backscattering in the substrate. The energy distribution of the backscattered beam is used to obtain drawing information for drawing the pattern and surface shape information of the substrate at different heights relative to the irradiation direction of the electron beam. The drawing information is divided into a plurality of meshes, and for each of the meshes, whether a slope or a step is present is determined based on information included in the surface shape information corresponding thereto; For the grid having the slope or the level difference, calculating, based on the depiction information and surface shape information, an energy distribution of a backscattered beam generated by backscattering of the electron beam in the substrate; The required energy of the electron beam is calculated based on the calculated energy distribution.

15. The drawing device according to claim 14, wherein: The calculated energy distribution is an anisotropic distribution.

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