Method for adjusting a multibeam lithography system and method for multibeam lithography

Abstract

Improve drawing accuracy. [Solution] This embodiment provides a method for adjusting the beam array shape in a multibeam lithography apparatus that performs multiple drawing on a substrate area using multiple beams while continuously moving a stage on which a substrate is placed. In this method, a first position error, which is the distortion of the beam array, is measured. Based on the first position error, a second position error is calculated, which is the drawing position error when a first multiple drawing is applied, in which the beam array is drawn overlappingly while shifting it in a first direction perpendicular to the direction of continuous movement, and a second multiple drawing is applied, in which the beam array is drawn overlappingly while shifting it in a second direction orthogonal to the first direction. Based on the first distortion component, which is the distortion component of the beam array that can be adjusted by adjusting the optical elements, a second distortion component is calculated, which is the adjustable distortion component of the beam array when the first multiple drawing and the second multiple drawing are applied. Based on the result of comparing the second position error and the second distortion component, the optical elements are adjusted to adjust the beam array shape.

Description

Technical Field

[0001] The present invention relates to a method for adjusting a multi-beam drawing apparatus and a multi-beam drawing method.

Background Art

[0002] With the increasing integration of LSIs, the circuit linewidth required for semiconductor devices has been continuously miniaturized year by year. In order to form a desired circuit pattern on a semiconductor device, a method of reducing and transferring a high-precision original pattern formed on quartz onto a wafer using a reduction projection exposure apparatus is adopted. The high-precision original pattern is drawn by an electron beam drawing apparatus, and so-called electron beam lithography technology is used.

[0003] For example, there is a drawing apparatus using multi-beams. Compared with the case of drawing with a single electron beam, by using multi-beams, many beams can be irradiated at once, so the throughput can be significantly improved. In a multi-beam type drawing apparatus, for example, an electron beam emitted from an electron source is passed through a shaping aperture array substrate having a plurality of apertures to form multi-beams, and each beam is blanking-controlled, and each unshielded beam is reduced by an optical system and deflected by a deflector and irradiated to a desired position on a sample.

[0004] In a multi-beam drawing apparatus, there are beams whose irradiation positions are shifted due to various factors, and distortion has occurred in the beam array shape of the multi-beams. In order to improve the position accuracy and resolution of the drawing pattern, it is necessary to reduce the distortion of the beam array shape on the drawing surface (sample surface). Conventionally, the optical system has been adjusted so that the beam array shape becomes an ideal shape such as a square. However, there are distortion components that cannot be reduced by adjusting the optical system and distortion components that result in a trade-off, and it has been difficult to suppress the distortion and improve the drawing accuracy.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2013-55145 [Patent Document 2] Japanese Patent Publication No. 2017-107959 [Patent Document 3] Japanese Patent Publication No. 2018-26516 [Overview of the project] [Problems that the invention aims to solve]

[0006] This invention has been made in view of the above-mentioned conventional circumstances, and aims to provide a multibeam lithography apparatus adjustment method and a multibeam lithography method that improves drawing accuracy. [Means for solving the problem]

[0007] A multibeam lithography apparatus adjustment method according to one aspect of the present invention is a method for adjusting the beam array shape in a multibeam lithography apparatus that performs multiple drawing of a drawing area on a substrate using multiple beams while continuously moving a stage on which a substrate is placed, the method comprising: measuring a first position error, which is the distortion of the beam array; calculating a second position error, which is the drawing position error when a first multiple drawing is applied, in which the beam array is drawn overlappingly while shifting it in a first direction perpendicular to the direction of continuous movement, and a second multiple drawing is applied, in which the beam array is drawn overlappingly while shifting it in a second direction orthogonal to the first direction, based on the first position error; calculating a second distortion component, which is the adjustable distortion component of the beam array when the first multiple drawing and the second multiple drawing are applied, based on the first distortion component, which is the distortion component of the beam array that can be adjusted by adjusting the optical elements of the multibeam lithography apparatus; comparing the second position error and the second distortion component; and adjusting the beam array shape by adjusting the optical elements based on the comparison result. [Effects of the Invention]

[0008] According to the present invention, drawing accuracy can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] It is a schematic diagram of a multi-charged particle beam lithography apparatus according to an embodiment of the present invention. [Figure 2] It is a plan view of a shaping aperture member. [Figure 3] It is a diagram for explaining an example of a lithography operation. [Figure 4] It is a diagram showing an example of an irradiation region of a multi-beam and a pixel to be lithographed. [Figure 5] It is a diagram for explaining an example of a lithography operation. [Figure 6] It is a diagram for explaining an example of a lithography operation. [Figure 7] (a) and (b) are diagrams showing examples of lithography methods for multiple lithography. [Figure 8] (a) to (d) are diagrams showing examples of lithography methods for multiple lithography. [Figure 9] It is a diagram for explaining an example of a lithography operation. [Figure 10] (a) to (c) are diagrams showing examples of reduction of beam position error by multiple lithography. [Figure 11] It is a flowchart for explaining a beam adjustment method according to an embodiment. [Figure 12] It is a diagram showing an example of a beam array shape. [Figure 13] (a) and (b) are graphs showing the distribution of the amount of displacement. [Figure 14] (a) and (b) are graphs showing adjustable strain components. [Figure 15] It is a graph showing the distribution of the amount of displacement after adjustment. [Embodiments for Carrying Out the Invention]

[0010] Hereinafter, embodiments of the present invention will be described based on the drawings. In the embodiments, as an example of the beam, a configuration using an electron beam will be described. However, the beam is not limited to an electron beam, and other charged particle beams such as an ion beam may be used.

[0011] FIG. 1 is a schematic configuration diagram of a drawing apparatus according to an embodiment. As shown in FIG. 1, the drawing apparatus 100 includes a drawing unit W and a control unit C. The drawing apparatus 100 is an example of a multi-charged particle beam drawing apparatus. The drawing unit W includes an electron optical column 102 and a drawing chamber 103. In the electron optical column 102, an electron source 201, an illumination lens 202, a shaping aperture array substrate 203, a blanking aperture array substrate 204, a reduction lens 205, a limiting aperture member 206, an objective lens 207, deflectors 208, 209, and a detector 211 that constitute a multi-beam generation mechanism are arranged.

[0012] An XY stage 105 is arranged in the drawing chamber 103. A substrate 101 to be drawn is arranged on the XY stage 105. The substrate 101 is, for example, a mask blank or a semiconductor substrate (silicon wafer).

[0013] A mark 106 and a mirror 210 for position measurement are arranged on the XY stage 105.

[0014] The control unit 160 includes a control computer 110, a deflection control circuit 130, a detection circuit 132, a lens control circuit 134, a stage position detector 139, and a storage unit 140. Drawing data is input from the outside and stored in the storage unit 140. Usually, information on a plurality of graphic patterns for drawing is defined in the drawing data. Specifically, for each graphic pattern, a graphic code, coordinates, size, etc. are defined.

[0015] The control computer 110 includes a distortion measurement unit 112, an optical system adjustment unit 114, a data processing unit 116, and a drawing control unit 118. Each part of the control computer 110 may be constituted by hardware such as an electric circuit, or may be constituted by software such as a program that executes these functions. Alternatively, it may be constituted by a combination of hardware and software.

[0016] The stage position detector 139 irradiates a laser, receives the reflected light from the mirror 210, and detects the position of the XY stage 105 by the laser interference method.

[0017] Figure 2 is a conceptual diagram showing the configuration of the molded aperture array substrate 203. As shown in Figure 2, the molded aperture array substrate 203 has openings 22 formed in a vertical (y-direction) m row × horizontal (x-direction) n column (m, n ≥ 2) arrangement at a predetermined arrangement pitch. Each opening 22 is formed as a rectangle or circle of the same dimensions and shape.

[0018] The electron beam 200 emitted from the electron source 201 illuminates the entire molded aperture array substrate 203 almost vertically through the illumination lens 202. The electron beam 200 illuminates a region containing multiple apertures 22. As the electron beam 200 passes through the multiple apertures 22 of the molded aperture array substrate 203, a multi-beam 20 is formed, for example, having a rectangular beam array.

[0019] The blanking aperture array substrate 204 has through holes formed in it to match the positions of each opening 22 of the molded aperture array substrate 203. Each through hole is fitted with a pair of electrodes (blankers). The multibeam 20 passes through each corresponding through hole in the blanking aperture array substrate 204.

[0020] The electron beam passing through each aperture is independently controlled for each beam to either a beam-on or beam-off state by the voltage applied to the blanker. When the beam is on, the opposing electrodes of the blanker are controlled to the same potential, and the blanker does not deflect the beam. When the beam is off, the opposing electrodes of the blanker are controlled to different potentials, and the blanker deflects the beam. In this way, multiple blankers perform blanking deflection of their respective beams from among the multi-beams that have passed through the multiple apertures 22 of the molded aperture array substrate 203.

[0021] The multi-beams 20 that have passed through the blanking aperture array substrate 204 are reduced by the reduction lens 205, and with all beams turned on, they ideally pass through the same point on the limiting aperture member 206. The beam trajectories are adjusted using an alignment coil (not shown) so that this point is located within the central opening of the limiting aperture member 206.

[0022] Here, the beam controlled to the beam-off state is deflected by the blanker of the blanking aperture array substrate 204 and follows a trajectory that passes outside the opening of the limiting aperture member 206, and is therefore shielded by the limiting aperture member 206. On the other hand, the beam controlled to the beam-on state is not deflected by the blanker and passes through the opening of the limiting aperture member 206. In this way, the on / off state of the beam is controlled by the blanking control of the blanking plate 204.

[0023] The limiting aperture member 206 shields each beam that has been deflected by multiple blankers to the beam-off state. Then, the beam that has passed through the limiting aperture member 206, formed from the time the beam is turned on until it is turned off, forms a multi-beam for one shot.

[0024] The multi-beam 20, having passed through the limiting aperture member 206, is focused by the objective lens 207 and projected onto the substrate 101 at a desired reduction ratio. The deflectors 208 and 209 each deflect the entire multi-beam by the same direction and distance. The amount of deflection of the deflectors 208 and 209 is controlled independently. The irradiation position of the multi-beam on the substrate 101 is controlled by the deflectors 208 and 209.

[0025] During drawing, the XY stage 105 is controlled to move continuously at a predetermined speed. At this time, the beam irradiation position is controlled by the deflector 208 so that it follows the movement of the XY stage 105. The simultaneously irradiated multi-beams are ideally aligned at a pitch obtained by multiplying the array pitch of the multiple apertures 22 of the molded aperture array substrate 203 by the desired reduction ratio described above. During drawing, the multi-beam 20 performs a raster scan drawing operation in which the position control by deflection exposes all pixels defined on the substrate 101. If the beam is over a pixel that does not contain a pattern, the beam is controlled to be off by blanking control.

[0026] Figure 3 is a conceptual diagram illustrating the drawing operation. As shown in Figure 3, the drawing area 30 on the substrate 101 is virtually divided into multiple stripe-shaped areas 32 with a predetermined width in the y-direction, for example. When drawing these stripe areas, first, the XY stage 105 is moved to adjust the irradiation area (beam array) 34 that can be irradiated with a single multi-beam irradiation to the left end of the first stripe area 32, and then drawing is started.

[0027] When drawing the first stripe region 32, the XY stage 105 is continuously moved at a constant speed in the -x direction, thereby drawing the substrate 101 relatively in the +x direction. After the drawing of the first stripe region 32 is completed, the XY stage 105 stops. Next, the stage position is moved in the -y direction by the stripe width to adjust the beam array 34 so that it is positioned at the right edge of the second stripe region 32. Subsequently, the XY stage 105 is continuously moved at a constant speed in the +x direction, thereby drawing the substrate 101 toward the -x direction.

[0028] In the third stripe region 32, drawing is performed in the +x direction, and in the fourth stripe region 32, drawing is performed in the -x direction. It would also be possible to draw each stripe region 32 in the same direction, but in this case, an additional operation to return the stage position after drawing is required, which increases the drawing time.

[0029] Figure 4 shows an example of a multi-beam irradiation area and pixels to be drawn. In Figure 4, the stripe area 32 is set with multiple control grids 27 arranged in a grid pattern at a pitch corresponding to the beam size of the multi-beam on the surface of the substrate 101. For example, an arrangement pitch of about 10 nm is preferable.

[0030] Multiple control grids 27 become the ideal irradiation position (ideal position) with no misalignment of the multi-beam. The array pitch of the control grids 27 is not limited to the same size as the beam size, but can be any size that can be controlled as the deflection position of the deflector 209. Then, multiple pixels 36 are set up, virtually divided into a mesh shape with the same size as the array pitch of the control grids 27, centered on each control grid 27.

[0031] Each pixel 36 represents an irradiation unit area per beam of the multibeam. In the example in Figure 4, the drawing area of ​​the substrate 101 is shown to be divided in the y-direction into multiple stripe areas 32 with a width size equal to the size of the beam array 34 (drawing field) that can be irradiated with one multibeam 20 irradiation. The size of the beam array 34 in the x-direction is the value obtained by multiplying the inter-beam pitch in the x-direction of the multibeam by the number of beams in the x-direction. The size of the beam array 34 in the y-direction is the value obtained by multiplying the inter-beam pitch in the y-direction of the multibeam by the number of beams in the y-direction.

[0032] Figure 4 shows an example of an 8x8 multibeam array. Note that the multibeam array is not limited to 8x8; 512x512 arrays or other configurations can be used as appropriate. Within the beam array 34, multiple pixels 28 (beam drawing positions) that can be illuminated in a single multibeam shot are shown as black-filled pixels. In other words, the pitch between adjacent pixels 28 becomes the pitch between each beam of the designed multibeam array. Here, the area corresponding to the beam pitch is defined as the sub-illumination area 29. In the example in Figure 4, each sub-illumination area 29 consists of 4x4 pixels.

[0033] When drawing each stripe region 32, the XY stage 105 moves in the x direction, and the beam array is deflected by the deflector 209 so that the pixels exposed in each shot move (scan) in the y direction, and the drawing is performed using a raster scan method in which the shot beams are continuously irradiated in sequence.

[0034] When drawing each stripe region 32, the beam position is controlled by deflectors 208 and 209 in parallel with the continuous movement of the XY stage 105 in the x-direction, exposing all pixels on the substrate 101 the same number of times. At this time, deflector 208 controls the switching of exposed pixels and controls the deflection of the beam position so that the beam being exposed follows the continuous movement of the substrate 101 (stage tracking). Deflector 209 deflects the beam array within the range of the sub-irradiation region 29 when switching exposed pixels. This operation is the drawing method called raster scanning described earlier, and a specific example is shown in Figure 5.

[0035] Figure 5 shows an example where four multibeams exist in the x-direction and are arranged at intervals of four times the beam size. There may also be four rows or different rows of multibeams in the y-direction, but since each row of multibeams draws a region with a beam pitch width corresponding to the width of the sub-irradiation area 29, Figure 5 can be thought of as showing one row of beam arrays and the pixels they should expose in a multi-row multibeam array.

[0036] In the example shown in Figure 5, the process is repeated in which, while the stage moves continuously in the -x direction, each beam exposes a row of four pixels in the y direction, and then the beam moves in the +x direction to expose another row. As described above, while each beam exposes four pixels in one row, the deflector 208 performs a stage tracking operation that continuously changes in accordance with the movement of the stage to keep the position of the beam array in the x direction on the substrate 101 immobile, while the deflector 209 applies deflection to switch the pixels being exposed in the y direction. The large movement of the beam in the +x direction after exposing one row is performed by a tracking reset operation, which stops the stage tracking and returns the amount of deflection of the deflector 208 to the amount of deflection at the start of stage tracking.

[0037] In Figure 5, pixel groups are separated by regions corresponding to the beam pitch width. When the beam moves to a different row, it moves to a region with a different pitch width. This movement is achieved by controlling the amount of deflection applied in the x-direction by the deflector 209. In other words, the raster scan operation is performed by the deflector 208 performing tracking deflection and the deflector 209 performing deflection within the sub-irradiation region 29. In the exposure process shown in Figure 5, only some pixels are exposed in the regions corresponding to the first three pitch widths from the left, but all pixels in the regions corresponding to the pitch widths to the right are exposed by repeating the process. Therefore, immediately after the start of exposure, three beam pitch regions are incompletely exposed. To prevent the actual drawing area from falling into this area, the drawing operation is started from the region to the left of the drawing area.

[0038] In this example, multiple pixels are sequentially exposed in the +y direction during the tracking period, but this is not the only way. For example, as shown in Figure 6, sequential exposure in the +x direction is also possible.

[0039] Within a multi-beam system, some beams may shift in their irradiation position due to optical system aberrations, causing distortion in the beam array shape. To average out the positional errors of each beam, multiplexing is performed, dividing the required irradiation dose into multiple drawing (exposure) passes.

[0040] For example, a Y-direction shifted multiple drawing (first multiple drawing) is performed so that one stripe partially overlaps with another stripe. Figure 7(a) shows an example where the Y coordinate of the stripe area is shifted by 1 / 2 the width of the stripe area, so that one stripe partially overlaps with another stripe. In the example shown in Figure 7(a), one area is exposed twice, so the multiplicity is 2.

[0041] Figure 7(b) shows an example of Y-direction shifted multiple drawing with a multiplicity of 4. In this example, the stripe of the N+1th path is shifted in the +Y direction by 1 / 4 of the width of the stripe area relative to the stripe of the Nth path. In the example shown in Figure 7(b), one area is drawn overlapping four times, so the multiplicity is 4. The multiplicity n is an integer of 2 or greater, and the amount of shift when the multiplicity is n is 1 / n of the width of the stripe area. n can be set to a predetermined value depending on the drawing conditions.

[0042] Furthermore, for example, the beam array is divided into multiple regions of the same predetermined width in the x-direction (drawing direction, scanning direction), and while one stripe region is being drawn, X-direction shifted multiple drawing (second multiple drawing) is performed in which beams from different divided regions draw the same location on the same spot.

[0043] For example, as shown in Figure 8(a), the beam array 34 is divided into two sub-beam arrays, region R1 and region R2. As shown in Figures 8(b) and 8(c), the shaded areas in the figures are irradiated by the beam from region R1, and then by the beam from region R2. Therefore, one region is drawn twice, resulting in a multiplicity of 2.

[0044] The raster scanning method in this case is shown in Figure 9. In this example, exposure is performed using two beams (c, d) arranged with a pitch of 4 pixels in the X direction. After exposing two rows of pixels consisting of 4 pixels in the Y direction, the exposure of two rows of pixels in a region with a different beam pitch width is repeated, thereby exposing all pixels with the two beams (c, d).

[0045] If four beams are arranged in the X direction with a pitch of 4 pixels, exposure can be performed in parallel with the exposure of beams (c, d) using two other beams (a, b) as shown in Figure 9. In this case, while drawing the stripe, pixels exposed by the upstream beam, for example beams (a, b), are re-exposed by the downstream beams (c, d), so that all pixels in the stripe are exposed twice. In other words, by dividing the beam array into two in the X direction and controlling them, all pixels are exposed twice. In this example, beams (a, b) belong to region R1 in Figures 8(a)-(c), and beams (c, d) belong to region R2.

[0046] As shown in Figure 8(d), when the beam array 34 is divided into eight regions R1 to R8, the multiplicity of the multiplexing becomes 8. Note that the number of divisions and the multiplicity can be set to a predetermined integer of 2 or more depending on the drawing conditions.

[0047] For simplicity, we assume here that the multiplicity of the X-direction shift is sufficiently greater than the multiplicity of the Y-direction shift. Under this assumption, the strain component dependent on the X position within the beam array is sufficiently averaged, leaving only the Y-position dependent component in the second position error component and second strain component, which will be described later. These can then be expressed as a one-dimensional function of the Y position. Note that this embodiment is not limited to the above assumption, and the beam array strain may also be treated as a two-dimensional function of the X and Y positions.

[0048] When the beam array has distortion as shown in Figure 10(a), the X-direction shifted multiplexing makes the X-position dependent error nearly uniform, as shown in Figure 10(b). Furthermore, by combining this with the Y-direction shifted multiplexing, the Y-position dependent error is reduced, as shown in Figure 10(c).

[0049] The inventors of the present invention have found that, when adjusting the beam array distortion of a multi-beam system, the final drawing accuracy can be effectively improved by adjusting the optical system to suppress position error components other than those that can be reduced by X-direction shifted multiple drawing and Y-direction shifted multiple drawing.

[0050] The beam adjustment and drawing method according to this embodiment will be explained in accordance with the flowchart shown in Figure 11.

[0051] The strain measurement unit 112 measures the strain of the multi-beam beam array (step S1). For example, a portion of the multi-beams is grouped together, and a mark 106 on the XY stage 105 is scanned using a deflector 208 or deflector 209, and electrons reflected from the mark 106 are detected by the detector 211. For each amount of deflection during scanning, the detection circuit 132 transmits the amount of electrons detected by the detector 211 to the control computer 110.

[0052] The strain measurement unit 112 acquires a scan waveform from the detected electron quantity and deflection amount, and calculates the position of the grouped beams based on the position of the XY stage 105. The position of the XY stage 105 is detected by the stage position detector 139. Another beam of the multibeam is grouped, and the position of the beam is calculated using the same method. By repeating this, the beam position is determined for each grouped beam, and a beam array shape as shown in Figure 12 can be obtained. The amount of positional displacement (first position error) is small at the center of the beam array, but the amount of positional displacement (first position error) increases at the outer periphery (four corners) of the beam array.

[0053] In this embodiment, the amount of positional displacement (second positional error) considering the above-mentioned X-direction shifted multiple drawing and Y-direction shifted multiple drawing is calculated and determined (step S2). For example, if the X-direction shift multiplicity is sufficiently large, the strain component dependent on the X position is sufficiently averaged, so only the Y-coordinate dependence of the strain component remains. When the range distribution of the X-direction and Y-direction positional displacement amounts within the beam array is summarized for each Y-coordinate, it is as shown in Figure 13(a). For example, consider the case where the multiplicity of the Y-direction shifted multiple drawing is 4. When the averaging of the shifted multiple drawing is considered, the range distribution of the X-direction and Y-direction positional displacement amounts is as shown in Figure 13(b).

[0054] The strain measurement unit 112 approximates, for example, the beam array shown in Figure 12 with the following polynomial.

[0055] X = a0 + a1x + a2y + a3x 2 +a4xy+a5y 2 Y = b0 + b1x + b2y + b3x 2 +b4xy+b5y 2

[0056] In adjusting the optical elements such as electromagnetic lenses and electrostatic lenses that constitute the optical system of a drawing device, consider the case where there are multiple distortion components corrected by an adjustable optical element, and the number of adjustable optical elements is small compared to the degrees of freedom of the distortion components. Here, the adjustable distortion component is called the first distortion component. For example, if there are four adjustable optical elements as shown below, the number of adjustable components is small compared to the 12 distortion coefficients, so it is not possible to adjust to an ideal shape without beam array distortion, and except in special cases, it is not possible to make both the position error components a1 and b2 zero. Adjust element 1: a1+b2 Adjust element 2: a2-b1 Adjust element 3: a3+b5 Adjust element 4: a5-b3

[0057] Here, the description of element 1 above indicates that when adjustments are made to element 1, both a1 and b2 components of the beam array's position error components fluctuate by the same magnitude. Given the above constraints, one possible adjustment is to ensure that the two dependent components of a1 and b2, a2 ​​and b1, a3 and b5, and a5 and b3 are all the same magnitude, so that some of the position error components of the beam array distortion do not become excessively large. However, this adjustment method does not take into account the errors reduced by applying the first and second multiplex drawing methods, and is not the optimal method for reducing the position error (second position error) when multiplex drawing is applied.

[0058] When the multiplicity of the X-direction shift is sufficiently large, the X-position dependence of the position error can be ignored. Therefore, coefficients that depend only on the x-coordinate (a1, a3, b1, b3, etc.) and coefficients that depend symmetrically with respect to the x-coordinate (a4, b4, etc.) can be ignored. Thus, of the 12 coefficients, only four should be considered during adjustment: a2, b2, a5, and b5, excluding the shift components a0 and b0.

[0059] According to this embodiment, in order to reduce the position error (second position error) when multiple drawing is applied, it is sufficient to adjust the distortion components (a2, b2, a5, b5) other than the error components that are reduced by applying Y-direction shifted multiple drawing and X-direction shifted multiple drawing. It is shown that all distortion components that need to be adjusted can be adjusted by adjusting the four elements 1 to 4.

[0060] The strain measurement unit 112 determines the adjustable strain component (second strain component) for positional error when multi-layer drawing is applied, from the strain components (first strain component) of coefficients a2, b2, a5, and b5 that should be considered during adjustment. In this case, the first strain component is as shown in Figure 14(a). The model of the positional displacement distribution that can be adjusted by the coefficients a2, b2, a5, and b5 when XY direction shift multi-layer drawing is applied (second strain component) is as shown in Figure 14(b).

[0061] The strain measurement unit 112 compares the displacement distribution in Figure 13(b) with the strain components that can be adjusted using the coefficients a2, b2, a5, and b5 in Figure 14(b), and calculates an evaluation value to assess the adjustment range (room for adjustment) (step S3). For example, the displacement distribution in Figure 13(b) is fitted to the displacement distribution model in Figure 14(b) using the least squares method (scaling coefficient), and the result is calculated as the evaluation value.

[0062] If the evaluation value is above a predetermined threshold (step S4_No), the lens control circuit 134 adjusts the optical element (step S5). Steps S1 to S5 are repeated until the evaluation value falls below the threshold. Figure 15 shows the simulation results of the range distribution of positional displacement in the X and Y directions, taking into account shifted multiple drawing, after the adjustment is complete. It can be seen that the contribution of the second distortion component is largely removed, and good positional accuracy is achieved.

[0063] Subsequently, a pattern is drawn on the substrate 101 using the adjusted multibeam (step S6). For example, the data processing unit 116 reads the drawing data from the storage unit 140 and calculates the pattern area density ρ(x) within each pixel 36. For each pixel 36, the data processing unit 116 calculates the incident irradiation amount D(x) (dose amount, exposure amount) by multiplying the preset reference irradiation amount by the pattern area density ρ(x) and the proximity effect correction coefficient. For each shot, the data processing unit 116 calculates the irradiation amount for each beam (individual beam) of the multibeam. For example, the data processing unit 116 calculates the irradiation amount by dividing the incident irradiation amount D(x) of the pixel irradiated by the individual beam by the multiplicity of the shifted multiply drawing.

[0064] The drawing unit W draws patterns on the substrate 101 using X-direction shifted multiple drawing and Y-direction shifted multiple drawing. The drawing control unit 118 converts the irradiation amount of each beam into irradiation time data and transfers it to the deflection control circuit 130. The deflection control circuit 130 controls the on / off state of each blanker of the blanking aperture array substrate 204 based on the irradiation time data.

[0065] Thus, according to this embodiment, in beam array distortion error adjustment, the optical system can be adjusted to suppress the error obtained by subtracting the position error component reduced by the shifted multiplex drawing method, thereby improving drawing accuracy.

[0066] It should be noted that the present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiments. Moreover, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0067] 100 Drawing device 110 Control Computer 112 Strain measurement section 114 Optical system adjustment section

Claims

1. A method for adjusting the beam array shape in a multibeam lithography apparatus that performs multiple-beam multi-drawing on a drawing area of ​​a substrate while continuously moving a stage on which the substrate is placed, The first position error, which is the distortion of the beam array, is measured. Based on the first position error, a second position error is calculated, which is the drawing position error when a first multiple drawing is applied, in which the beam array is drawn overlappingly while shifting it in a first direction perpendicular to the direction of continuous movement, and a second multiple drawing is applied, in which the beam array is drawn overlappingly while shifting it in a second direction orthogonal to the first direction. Based on the first strain component, which is the strain component of the beam array that can be adjusted by adjusting the optical elements of the multibeam lithography apparatus, the second strain component, which is the adjustable strain component of the beam array when the first multiplex lithography and the second multiplex lithography are applied, is calculated. A method for adjusting a multibeam lithography apparatus, comprising comparing the second position error with the second strain component, and adjusting the optical element based on the comparison result to adjust the beam array shape.

2. The multibeam lithography adjustment method according to claim 1, wherein the first strain component is determined based on the coefficients of a polynomial that approximates the first position error.

3. A method for adjusting a multibeam lithography apparatus according to claim 1 or 2, comprising: fitting the second position error with the second strain component to obtain an evaluation value; and adjusting the optical element so that the evaluation value is less than a predetermined value.

4. A multi-beam lithography method comprising using a multi-beam lithography apparatus in which the optical elements have been adjusted according to the multi-beam lithography apparatus adjustment method described in claim 1 or 2, to irradiate a substrate with the multi-beams and draw a pattern.

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