Multi-charged particle beam irradiation apparatus, multi-charged particle beam irradiation method, correction map creation apparatus, and correction map creation method

Abstract

This system corrects positional and dimensional misalignments in patterns formed by multi-beam irradiation, including beams with misalignment, while also suppressing a decrease in resolution. [Solution] The drawing apparatus includes a correction map creation unit that calculates the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one surrounding pixel based on the amount of positional displacement of the beam irradiated to the pixel and the position of the pattern arranged within the pixel, and creates a correction map in which the modulation rates are defined; and an irradiation amount correction unit that calculates a corrected irradiation amount by adding a value obtained by multiplying the modulation rate of the beam to the pixel defined in the correction map by the amount of beam irradiation to the pixel, and a value obtained by multiplying the modulation rate of the beam to the surrounding pixels in the modulation rate map by the amount of beam irradiation to the related pixels of the surrounding pixels as described above.

Description

[Technical Field]

[0001] The present invention relates to a multi-charged particle beam irradiation apparatus, a multi-charged particle beam irradiation method, a correction map creation apparatus, and a correction map creation method. [Background technology]

[0002] With the increasing integration of LSIs, the circuit line widths required for semiconductor devices are becoming smaller year by year. To form the desired circuit patterns on semiconductor devices, a method is employed in which a high-precision original pattern (mask, or reticle, especially in the case of steppers and scanners) formed on silica is reduced and transferred onto a wafer using a reduction projection exposure system. The high-precision original pattern is drawn using an electron beam lithography system, employing so-called electron beam lithography technology.

[0003] Multibeam lithography systems can significantly improve throughput compared to single-beam systems because they can irradiate many beams at once. In a multibeam lithography system using a blanking aperture array, for example, an electron beam emitted from a single electron gun is passed through a shaping aperture array with multiple apertures to form multiple beams. Each of the multiple beams passes through its corresponding blanker in the blanking aperture array. The blanking aperture array has electrode pairs for individually deflecting the beams, with apertures for beam passage formed between the electrode pairs. By fixing one electrode of the electrode pair (blanker) at ground potential and switching the other electrode between ground potential and other potentials, blanking deflection of the passing electron beam is performed. The electron beam deflected by the blanker is shielded, while the undeflected electron beam is irradiated onto the substrate.

[0004] In multi-beam lithography, beam misalignment can occur due to optical system distortion, deviation from the design values of the shaping aperture array that forms the multi-beam, the Coulomb effect, and the like. When misalignment occurs in the beams that make up the multi-beam, there was a problem that the drawn pattern would also be misaligned in position and dimension. Therefore, it is desirable to correct the positional deviation and dimensional deviation of the pattern formed by irradiating the beam with misalignment.

[0005] In Patent Document 1, separately from the irradiation amount map (bitmap), a modulation rate map is created in which the modulation rate after distribution is defined for each pixel and the modulation rate showing the relationship with the distribution source is defined for the surrounding pixels, and the irradiation amount map and the modulation rate map are synthesized to obtain a corrected irradiation amount, and by irradiating the pixel corresponding to the beam with the corrected irradiation amount, it is described that the positional deviation and dimensional deviation of the pattern formed by irradiating the multi-beam including the beam with misalignment are corrected.

[0006] FIG. 10 and FIG. 11 show examples of performing irradiation amount distribution for correcting positional deviation and dimensional deviation by the above-described conventional method. As shown in FIG. 10, when on-grid where the edge of the pattern coincides with the pixel boundary, the irradiation amount of the 3×3 pixel pattern is distributed to the 4×4 pixel region. On the other hand, as shown in FIG. 11, when off-grid where the edge of the pattern does not coincide with the pixel boundary, the irradiation amount of the 3×3 pixel pattern is distributed to the 5×5 pixel region. Thus, there was a problem that the resolution of the edge was reduced due to the wasteful distribution of the irradiation amount.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention has been made in view of the above conventional problems, and corrects the positional deviation and dimensional deviation of a pattern formed by irradiation with a multi-beam including a beam in which a positional deviation has occurred, and suppresses a decrease in resolution. An object is to provide a multi-charged particle beam irradiation apparatus, a multi-charged particle beam irradiation method, a correction map creation apparatus, and a correction map creation method.

Means for Solving the Problems

[0009] A multi-charged particle beam irradiation apparatus according to one aspect of the present invention calculates the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one surrounding pixel for each pixel that constitutes an irradiation unit region per beam of the multi-charged particle beam, based on the amount of misalignment of the beam irradiated to the pixel and the position of the pattern arranged within the pixel, by modulating the beam irradiation amount to the pixel and the beam irradiation amount to at least one surrounding pixel to correct the misalignment of the pattern formed by the misaligned beam irradiated to the pixel. The calculated modulation rate of the beam to the pixel is defined at the position of the pixel, and the modulation rate of the beam to at least one surrounding pixel is defined in relation to the pixel. The system includes: a correction map creation unit that creates a correction map in which the modulation rate is defined for the irradiation area to which a multi-charged particle beam is irradiated, as defined at the position of one pixel; a shot data creation unit that calculates the beam irradiation amount to each pixel; an irradiation amount correction unit that calculates a corrected irradiation amount for each pixel by adding a value obtained by multiplying the modulation rate of the beam to the pixel defined in the correction map by the beam irradiation amount to the pixel, and a value obtained by multiplying the modulation rate of the beam to at least one pixel defined at the position of the pixel in the correction map as the surrounding at least one pixel by the beam irradiation amount to the pixel associated with that at least one pixel; and an irradiation unit that irradiates the sample surface with a multi-charged particle beam so that the beam of the corrected irradiation amount irradiates the corresponding pixels, respectively.

[0010] A multi-charged particle beam irradiation method according to one aspect of the present invention involves the steps of: for each pixel that constitutes an irradiation unit region per beam of the multi-charged particle beam, calculating the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one pixel surrounding the pixel, based on the amount of misalignment of the beam irradiated to the pixel and the position of the pattern arranged within the pixel, by modulating the beam irradiation amount to the pixel and the beam irradiation amount to at least one pixel surrounding the pixel, in order to correct the misalignment of the pattern formed by the misaligned beam irradiated to the pixel; and for each pixel, defining the calculated modulation rate of the beam to the pixel at the position of the pixel, and relating the calculated modulation rate of the beam to at least one pixel surrounding the pixel to the pixel. The method comprises the steps of: creating a correction map in which a modulation rate is defined for an irradiation region irradiated with a multi-charged particle beam so as to be defined for the position of at least one pixel surrounding the pixel; calculating the beam irradiation amount to each pixel; calculating a corrected irradiation amount for each pixel by adding the value obtained by multiplying the modulation rate of the beam to the pixel defined in the correction map by the beam irradiation amount to the pixel, and the value obtained by multiplying the modulation rate of the beam to the at least one pixel defined as the position of the pixel in the correction map by the beam irradiation amount to the pixel associated with the at least one pixel; and irradiating the sample surface with a multi-charged particle beam so that the beam of the corrected irradiation amount is irradiated to the corresponding pixels.

[0011] A correction map creation device according to one aspect of the present invention calculates the modulation rate of the beam to a pixel and the modulation rate of the beam to at least one pixel surrounding the pixel for each pixel that constitutes an irradiation unit area per beam of a multi-charged particle beam, based on the amount of misalignment of the beam irradiated to the pixel and the position of the pattern arranged within the pixel, by modulating the amount of beam irradiation to the pixel and the amount of beam irradiation to at least one pixel surrounding the pixel, in order to correct the misalignment of the pattern formed by the beam that is misaligned when irradiated to the pixel. The calculated modulation rate of the beam to the pixel is defined at the position of the pixel, and the modulation rate of the beam to at least one pixel surrounding the pixel is defined at the position of at least one pixel surrounding the pixel in relation to the pixel, and so on, and outputs a correction map in which the modulation rate is defined for the irradiation area irradiated by a multi-charged particle beam.

[0012] A method for creating a correction map according to one aspect of the present invention comprises the steps of: calculating, for each pixel that constitutes an irradiation unit region per beam of a multi-charged particle beam, the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one pixel surrounding the pixel, based on the amount of misalignment of the beam irradiated to the pixel and the position of the pattern arranged within the pixel, by modulating the amount of beam irradiation to the pixel and the amount of beam irradiation to at least one pixel surrounding the pixel, in order to correct the misalignment of the pattern formed by the beam that is misaligned and irradiated to the pixel; and creating and outputting a correction map in which the modulation rates are defined for the irradiation region irradiated by the multi-charged particle beam, such that for each pixel, the calculated modulation rate of the beam to the pixel is defined at the position of the pixel, and the calculated modulation rate of the beam to at least one pixel surrounding the pixel is defined at the position of at least one pixel surrounding the pixel in relation to the pixel. [Effects of the Invention]

[0013] According to the present invention, it is possible to correct positional and dimensional deviations of patterns formed by irradiation with a multi-beam system that includes beams with misalignment, while suppressing a decrease in resolution. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram of a drawing apparatus according to an embodiment of the present invention. [Figure 2] This is a plan view of a molded aperture array substrate. [Figure 3] This is a diagram illustrating an example of drawing operation. [Figure 4] This is a flowchart illustrating the drawing method according to the same embodiment. [Figure 5] This figure shows the positional misalignment correction using the comparative example. [Figure 6] (a) and (b) are diagrams showing examples of positional displacement. [Figure 7] This figure shows the positional misalignment correction according to the same embodiment. [Figure 8] (a) and (b) are diagrams showing examples of positional displacement. [Figure 9] (a) and (b) are diagrams showing examples of positional displacement. [Figure 10] This figure shows an example of how the irradiation dose is distributed. [Figure 11] This figure shows an example of how the irradiation dose is distributed. [Modes for carrying out the invention]

[0015] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0016] As shown in Figure 1, the drawing apparatus 100 according to this embodiment comprises a drawing unit 150 and a control unit 160. The drawing apparatus 100 is an example of a multi-charged particle beam lithography apparatus. The drawing unit 150 has an electron-optical tube 102 and a drawing chamber 103. Inside the electron-optical tube 102 are an electron gun 201, an illumination lens 202, a molded aperture array substrate 203, a blanking aperture array substrate 204, a reduction lens 205, a limiting aperture member 206, an objective lens 207, and a deflector 208.

[0017] An XY stage 105 is located inside the drawing chamber 103. Samples 101, such as mask blanks, which will be the substrates to be drawn on, are placed on the XY stage 105. Samples 101 include exposure masks used when manufacturing semiconductor devices, or semiconductor substrates (silicon wafers) on which semiconductor devices are manufactured. A mirror 210 for measuring the position of the XY stage 105 is also located on the XY stage 105.

[0018] The control unit 160 includes a control computer 110, a memory 112, a deflection control circuit 130, a stage position detector 139, and storage devices 140, 142, and 144 such as magnetic disk drives. The control computer 110, memory 112, deflection control circuit 130, stage position detector 139, and storage devices 140, 142, and 144 are connected to each other via a bus (not shown). Drawing data is input from an external source and stored in the storage device 140 (storage unit).

[0019] The control computer 110 includes a position shift data acquisition unit 50, a correction map creation unit 51, a graphic data acquisition unit 52, a shot data creation unit 53, an irradiation dose correction unit 54, a drawing control unit 60, and a data processing unit 61. The functions of each part of the control computer 110 may be configured as hardware such as electrical circuits, or as software such as programs that execute these functions. Information input to and output from each part of the control computer 110 and information being calculated are stored in the memory 112 each time.

[0020] Figure 2 is a conceptual diagram showing the configuration of the molded aperture array substrate 203. Multiple openings 22 are formed in a matrix in the vertical (y-direction) and horizontal (x-direction) directions at predetermined arrangement pitches. For example, 512 vertical x 512 horizontal openings 22 are formed. Each opening 22 is a rectangle or circle of the same dimensions.

[0021] The blanking aperture array substrate 204 has through holes formed in it to match the positions of each opening 22 in the molded aperture array substrate 203. Each through hole is fitted with a pair of electrodes (blankers: blanking deflectors). An amplifier that applies voltage is connected to one of the two electrodes for each beam, and the other is grounded. The electron beam passing through each through hole is deflected independently by the voltage applied to the pair of electrodes. Blanking control is performed by this deflection of the electron beam.

[0022] Next, the operation of the drawing unit 150 in the drawing device 100 will be described. The electron beam 200 emitted from the electron gun 201 (emitting unit) illuminates the entire molded aperture array substrate 203 almost vertically by the illumination lens 202. As the electron beam 200 passes through multiple openings 22 in the molded aperture array substrate 203, a multibeam consisting of multiple individual beams 20a to 20e is formed. The beam array shape of the multibeam is, for example, rectangular. Each individual beam of the multibeam passes through its corresponding blanker in the blanking aperture array substrate 204. Each blanker deflects the individual beam as it passes through.

[0023] The multi-beams that have passed through the blanking aperture array substrate 204 are reduced by the reduction lens 205 and travel toward the central opening formed in the limiting aperture member 206. Individual beams deflected by the blankers of the blanking aperture array substrate 204 are moved away from the central opening of the limiting aperture member 206 and are shielded by the limiting aperture member 206. On the other hand, individual beams that are not deflected by the blankers pass through the central opening of the limiting aperture member 206.

[0024] In this way, the limiting aperture member 206 shields the individual beams that have been deflected by the blanker 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 the beam for one shot.

[0025] The multi-beams that have passed through the limiting aperture member 206 are focused by the objective lens 207 to form a pattern image with a desired reduction ratio, which is then deflected together by the deflector 208 and irradiated onto the sample 101. For example, when the XY stage 105 is moving continuously, the deflector 208 tracks the beam irradiation position so that it follows the movement of the XY stage 105. The position of the XY stage 105 is measured by irradiating a laser from the stage position detector 139 towards the mirror 210 on the XY stage 105 and using the reflected light.

[0026] The multi-beams irradiated at once will ideally be arranged 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. The drawing device 100 performs the drawing operation using a raster scan method in which shot beams are irradiated sequentially, and when drawing a desired pattern, the necessary beams are controlled to turn ON by blanking control according to the pattern.

[0027] As shown in Figure 3, the drawing area 31 of the sample 101 is virtually divided into multiple stripe-shaped areas 35 with a predetermined width in the y direction, for example. For example, the XY stage 105 is moved to adjust the irradiation area 34 that can be irradiated with a single multi-beam irradiation to be located at the left end of the first stripe area 35, and drawing is started. By moving the XY stage 105 in the -x direction, drawing can be advanced relatively in the +x direction.

[0028] After the first stripe area 35 has been drawn, the stage position is moved in the -y direction to adjust the illuminated area to be located at the right edge of the second stripe area 35, and drawing begins. Then, by moving the XY stage 105, for example, in the +x direction, drawing is performed in the -x direction.

[0029] Drawing time can be reduced by alternating directions while drawing, such as drawing in the +x direction for the third stripe region 35 and in the -x direction for the fourth stripe region 35. However, it is not limited to alternating directions; each stripe region 35 can also be drawn in the same direction.

[0030] The striped area 35 is virtually divided into multiple mesh areas (pixels). The size of each mesh area (pixel) is, for example, approximately the beam size. Each mesh area (pixel) represents the irradiation unit area for one individual beam in a multi-beam system.

[0031] When drawing the sample 101 with a multibeam, as described above, the multibeam, which becomes a shot beam, is continuously irradiated one pixel at a time by moving the beam deflection position of the deflector 208 while following the movement of the XY stage 105 during the tracking operation. Then, which beam of the multibeam irradiates which pixel on the sample 101 is determined by the drawing sequence.

[0032] Using the beam pitch between adjacent beams in the x and y directions of the multibeam, the region on the surface of sample 101 with a beam pitch (x direction) × beam pitch (y direction) between adjacent beams in the x and y directions is composed of an n × n pixel region (subpitch region). For example, if the XY stage 105 moves by the beam pitch (x direction) in the -x direction during one tracking operation, n pixels are drawn while shifting the irradiation position with one beam in the x or y direction (or diagonal direction). In the next tracking operation, the other n pixels within the same n × n pixel region are similarly drawn with a beam different from the one described above. In this way, by drawing n pixels with different beams in n tracking operations, all pixels in one n × n pixel region are drawn. The same operation is performed for other n × n pixel regions within the multibeam irradiation area, and a pattern is drawn.

[0033] Figure 4 is a flowchart showing the drawing method according to this embodiment. This drawing method includes a graphic data acquisition step (S1), a shot data creation step (S2), a positional shift data acquisition step (S3), a correction map creation step (S4), a correction step (S5), and a drawing step (S6).

[0034] Before performing the drawing process, the amount of beam misalignment at each pixel when multiple beams are irradiated onto the surface of the sample 101 is measured. A measurement substrate coated with resist is placed on the stage 105, multiple beams are irradiated onto it, and the irradiation position is measured. For example, one pixel at a time, or multiple pixels separated from each other to a degree that does not cause measurement problems, can be drawn according to the drawing sequence, and the beam irradiation position of the pixels on the measurement substrate can be measured using a position measuring device. By calculating the difference between the design position and the measured position, the amount of misalignment for each pixel can be measured. This operation is repeated to measure the amount of beam misalignment for all pixels. Alternatively, the amount of beam misalignment for all pixels can be determined by measuring the amount of misalignment for each beam and assigning the amount of beam misalignment corresponding to each pixel. The obtained misalignment data is input from an external source and stored in the storage device 144.

[0035] In the graphic data acquisition process (S1), the graphic data acquisition unit 52 reads and acquires drawing data (graphic data) from the storage device 140. For example, the graphic data acquisition unit 52 reads the corresponding drawing data from the storage device 140 for each stripe area.

[0036] In the shot data creation process (S2), the shot data creation unit 53 receives drawing data and calculates the area density of the patterns arranged within each pixel or group of pixels. For example, the shot data creation unit 53 assigns multiple graphic patterns defined in the drawing data to corresponding pixels. Then, the shot data creation unit 53 calculates the area density of the graphic patterns arranged within each pixel or group of pixels.

[0037] The shot data creation unit 53 calculates the beam irradiation amount for each pixel. For example, the beam irradiation amount for each pixel is calculated by multiplying the pattern area density by the reference irradiation amount. The multiple pixels that define the irradiation amount and the multiple mesh regions that define the area density of the pattern may be the same size or may be composed of different sizes. If they are composed of different sizes, the area density can be interpolated by linear interpolation or the like before determining each irradiation amount. The irradiation time can be defined by dividing the irradiation amount by the current density.

[0038] In the positional displacement data acquisition process (S3), the positional displacement data acquisition unit 50 reads the positional displacement data stored in the storage device 144 and inputs (acquires) the amount of positional displacement for each pixel.

[0039] In the correction map creation process (S4), the correction map creation unit 51 calculates the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one surrounding pixel for each pixel, in order to correct the positional and dimensional deviations (CD deviations) of the pattern formed by the misaligned beam irradiated onto the pixel. The correction map creation unit 51 then creates and outputs a modulation rate map (correction map) in which the modulation rates are defined for the drawing area drawn by the multi-beam, defining the calculated modulation rate of the beam to the pixel at the position of the pixel, and defining the calculated beam distribution amount (modulation rate) to at least one surrounding pixel in relation to the pixel at the position of at least one surrounding pixel that will receive the distribution.

[0040] Figure 5 illustrates a method for correcting misalignment. Figure 5 shows the case where beam a, irradiated onto a pixel at coordinate (x,y), experiences a misalignment of Δx in the x-direction and Δy in the y-direction. To correct the misalignment of the pattern formed by the misaligned beam a to a position that matches the pixel at coordinate (x,y), the amount of irradiation due to the misalignment is distributed to pixels on the opposite side of the direction from the surrounding pixels that were misaligned. In the example in Figure 5, the amount of irradiation due to the misalignment of the pixel at coordinate (x,y+1) is distributed to the pixel at coordinate (x,y-1). The amount of irradiation due to the misalignment of the pixel at coordinate (x+1,y) is distributed to the pixel at coordinate (x-1,y-1). The amount of irradiation due to the misalignment of the pixel at coordinate (x+1,y+1) is distributed to the pixel at coordinate (x-1,y-1).

[0041] When the beam shifts, for each surrounding pixel where a portion of the beam overlaps, the area of ​​the shift (the area of ​​the overlapping beam) is divided by the beam area, and this ratio is calculated as the distribution amount (beam modulation rate) to the pixels located on the opposite side of the overlapping pixel.

[0042] For example, in the example of FIG. 5, when the pixel size (beam size) is set to 1, the area shifted to the pixel at coordinates (x + 1, y + 1) is Δx × Δy. The area shifted to the pixel at coordinates (x, y + 1) is (1 - Δx) × Δy. The area shifted to the pixel at coordinates (x + 1, y) is Δx × (1 - Δy). The area remaining in the pixel at coordinates (x, y) is (1 - Δx) × (1 - Δy).

[0043] However, in the example of FIG. 5, without considering the edge position of the actually drawn pattern, the beam irradiation amount (modulation rate) distributed to the surrounding pixels is calculated based only on the beam position shift amount. Therefore, the beam irradiation amount may be excessively distributed to the surrounding pixels, and the resolution of the edge may be degraded (see FIG. 11).

[0044] Therefore, in the present embodiment, the center-of-gravity position of the pattern within the pixel is calculated as information on the edge position, and the amount of shift of the center-of-gravity of the pattern within the pixel from the pixel center is obtained. Then, by shifting the beam position shift amount by the amount of shift of the center-of-gravity position, the modulation rate considering the edge position is calculated.

[0045] The correction map creation unit 51 uses the beam irradiation amount d for each pixel calculated in the shot data creation process to calculate the center-of-gravity position (x’ g , y’ g ) of the pattern within the pixel for each pixel. As an example of the calculation method, when the right edge of the pattern exists within the pixel, x’ g = d x / 2 can be obtained. When the left edge of the pattern exists within the pixel, x’ g = 1 - d x / 2 can be obtained. When the upper edge of the pattern exists within the pixel, y’ g = d y / 2 can be obtained. When the lower edge of the pattern exists within the pixel, y’ g = 1 - d y / 2 can be obtained. Here, d x is the contribution of the beam irradiation amount in the x direction, d y is the contribution of the beam irradiation amount in the y direction, and d x × dy is set to d. The method for calculating the centroid position of the pattern within the pixel from the beam exposure d per pixel is not limited to this, and d x = d y = √d or other calculation methods such as approximating it, and the centroid position of the pattern within the pixel may be determined by other calculation methods.

[0046] Note that the centroid position (x’ g , y’ g ) is such that the lower left vertex of the pixel is the origin (0, 0), and the x - direction size and y - direction size of the pixel are each set to 1. Also, the beam exposure d is a value in the range of 0 ≤ d ≤ 1 and corresponds to the pattern area density multiplied by the reference exposure. When the beam exposure d = 1, the entire pixel is occupied by the pattern. When the beam exposure d = 0, there is no pattern in this pixel.

[0047] When the beam exposure d satisfies 0 < d < 1, at least one of the upper, lower, left, or right edges exists within the pixel. Which edge of the pattern in the pixel exists can be determined from the beam exposures of the surrounding pixels. For example, when the beam exposure of the pixel to the left, upper left, or lower left of the pixel to be calculated is 1, a right - hand edge of the pattern exists in the pixel to be calculated. When the beam exposure of the pixel to the lower left, lower, or lower right of the pixel to be calculated is 1, an upper edge of the pattern exists in the pixel to be calculated.

[0048] For example, as shown in FIG. 6(a), when the graphic pattern P is arranged, the correction map creation unit 51 calculates, for the pixel at the coordinates (x, y), the amount of deviation Δx g , y g ) in the x - direction of the centroid position (x’ g , y’ g ) of the pattern within the pixel as viewed from the pixel center position (x g and the amount of deviation Δy g in the y - direction.

[0049] The correction map creation unit 51 shifts the beam displacement amount Δx and Δy, which are the displacement amounts Δx and Δy of the beam a irradiated to the pixel at coordinates (x,y) shown in the example of Figure 5, by the amount of the centroid displacement, as shown in Figure 6(b). The shifted beam displacement amounts Δx' and Δy' are as follows. Δx' = Δx + Δx g Δy' = Δy + Δy g

[0050] Shifting the beam misalignment by the centroid misalignment can result in over-distribution or negative distribution of the irradiation dose. Therefore, the correction map creation unit 51 introduces the following limiter to process the beam misalignment amounts Δx' and Δy' to within geometrically valid values ​​of beam misalignment amounts Δx'' and Δy''. Δx”=min(max(Δx',0),1) Δy”=min(max(Δy',0),1)

[0051] As shown in Figure 7, the correction map creation unit 51 calculates the beam irradiation amount (modulation rate) to be distributed to the surrounding pixels using the beam position shift amounts Δx'' and Δy''.

[0052] For example, in the example in Figure 7, the area shifted to the pixel at coordinates (x+1, y+1) is Δx"×Δy", and from this value, the distribution amount (beam modulation rate) to distribute to the pixel at coordinates (x-1, y-1) for correction can be determined.

[0053] Similarly, the area shifted to the pixel at coordinate (x, y+1) is (1-Δx") × Δy"), and from this value, the distribution amount (beam modulation rate) to be distributed to the pixel at coordinate (x, y-1) for correction can be determined.

[0054] The area shifted to the pixel at coordinate (x+1,y) is Δx"×(1-Δy)", and from this value, the distribution amount (beam modulation rate) to be distributed to the pixel at coordinate (x-1,y) for correction can be determined.

[0055] The area remaining for the pixel at coordinate (x,y) is (1-Δx") × (1-Δy"), and from this value, the modulation rate of the beam at the pixel at coordinate (x,y) can be determined.

[0056] As described above, the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one surrounding pixel to which the beam will be distributed are calculated for each pixel. The correction map creation unit 51 creates and outputs a modulation rate map (correction map) in which the modulation rates are defined for the drawing area drawn by the multibeam, so as to define the calculated modulation rate of the beam to the pixel at the position of the pixel, and the calculated modulation rate of the beam to at least one surrounding pixel to which the beam will be distributed is defined in relation to the pixel at the position of at least one such surrounding pixel.

[0057] In the correction step (S5), the correction map (modulation rate map) created in the correction map creation step (S4) is applied to the irradiation amount for each pixel calculated in the shot data creation step (S2) to determine the corrected irradiation amount. Specifically, the irradiation amount correction unit 54 calculates a corrected irradiation amount for each pixel by adding the following: a value obtained by multiplying the modulation rate of the beam to the pixel defined in the modulation rate map by the beam irradiation amount to the pixel, and a value obtained by multiplying the modulation rate of the beam to at least one surrounding pixel (peripheral pixel), defined at the position of the pixel in the modulation rate map as a pixel associated with distribution, by the beam irradiation amount to the pixel associated with that at least one pixel. The method for calculating the corrected irradiation amount can be the method described in Japanese Patent Application Publication No. 2016-119423, etc.

[0058] In this case, it is preferable that the corrected irradiation dose be an irradiation dose that is corrected by the irradiation dose for dimensional changes caused by phenomena that cause dimensional changes, such as proximity effect, fogging effect, and loading effect.

[0059] The corrected irradiation amount for each pixel is defined in the corrected irradiation amount map and stored in the storage device 142.

[0060] In the drawing process (S6), the drawing unit 150 uses a multi-beam system to draw a pattern on the sample 101 so that the corrected irradiation amount beam is irradiated to each corresponding pixel. First, the data processing unit 61 converts the corrected irradiation amount into irradiation time and rearranges it in the order of shots according to the drawing sequence. The rearranged irradiation time array data is then output to the deflection control circuit 130.

[0061] The deflection control circuit 130 outputs irradiation time array data to the blanking aperture array substrate 204 for each shot. Then, under the control of the drawing control unit 60, the drawing unit 150 performs drawing for the corresponding irradiation time for each shot of each beam.

[0062] In this embodiment, the modulation rate (the amount of beam distributed to surrounding pixels) is determined by considering not only the beam displacement but also the centroid position of the pattern within the pixel. This reduces wasted distribution and suppresses a decrease in resolution.

[0063] In the above embodiment, an example was described in which the centroid position of the pattern within a pixel is calculated from the beam irradiation amount. However, the centroid positions based on the state of adjacent pixels may be pre-created in a table and the centroid position may be determined by referring to the table. Alternatively, the shot data creation unit 53 may calculate the centroid position when calculating the area density of the pattern arranged inside each pixel and store the centroid position data in the storage unit.

[0064] In the above embodiment, an example was described in which the beam displacement amount is shifted based on the centroid position of the pattern within the pixel. However, the beam displacement amount may also be shifted based on the size (shape) or edge position of the pattern within the pixel.

[0065] For example, the correction map creation unit 51 determines the pixel size L in the x direction for each pixel. x , and the pixel size L in the y direction y Using the beam irradiation amount d for each pixel, the size L' in the x-direction of the pattern within the pixel is determined. x and size L' in the y direction y To find L' x =dx L x , L' y =d y L y This can be calculated using the following method. Furthermore, the method for calculating the size of the pattern within a pixel from the beam irradiation amount d for each pixel is not limited to this, d x =d y The size of the pattern within the pixel can also be determined using other calculation methods, such as approximating it as =√d.

[0066] Note that the pixel size in the x-direction is L. x , y-direction size L y If we set both to 1, the beam irradiation amount d is a value in the range of 0 ≤ d ≤ 1, and therefore the size L' in the x-direction of the pattern within the pixel. x and size L' in the y direction y Also, 0≦L' x ≤1 and ≤L' y The value is in the range of ≤1.

[0067] The correction map creation unit 51 calculates the area that overlaps with surrounding pixels when the pattern of size obtained by the above calculation is shifted by the amount of positional displacement defined in the positional displacement data.

[0068] For example, if the geometric pattern is arranged as shown in Figure 6(a), the in-pixel pattern at coordinates (x,y) obtained by the above calculation will be as shown in Figure 8(a). The size L' of the in-pixel pattern in the x direction. x and size L' in the y direction y From this, the shape of the pattern within the pixel is determined, and this shape and the pixel center position (x g ,y g From this, the edge position of the pattern within the pixel is determined. Figure 8(b) shows the case where the beam irradiated onto the pixel at coordinate (x,y) undergoes a positional shift of Δx in the x direction and Δy in the y direction, similar to the examples in Figure 5 and Figure 6(b).

[0069] The correction map creation unit 51 calculates the positional displacement Δx', which corresponds to the amount by which the in-pixel pattern extends beyond the pixel at coordinate (x,y) in the x direction, and the positional displacement Δy', which corresponds to the amount by which it extends beyond the pixel in the y direction, using the following formulas.

[0070]

number

[0071] Furthermore, the correction map creation unit 51 processes the positional displacement amounts Δx' and Δy' to be limited to geometrically valid positional displacement amounts Δx'' and Δy'' using the following limiter. Δx”=min(max(Δx',0),1) Δy”=min(max(Δy',0),1)

[0072] The correction map creation unit 51 calculates the beam irradiation amount (modulation rate) to be distributed to surrounding pixels using the beam position shift amounts Δx'' and Δy'', similar to the example in Figure 7. The distribution amount to each pixel is the same as in the example in Figure 7, so its explanation is omitted here.

[0073] In this way, by considering not only the beam displacement but also the shape (size) of the pattern within the pixel to determine the modulation rate (the amount of beam distributed to surrounding pixels), it is possible to reduce wasted distribution and suppress the decrease in resolution.

[0074] Alternatively, the pattern shape based on the state of adjacent pixels may be pre-defined in a table, and the pattern shape may be determined by referring to this table. Furthermore, when the shot data creation unit 53 calculates the area density of the pattern arranged within each pixel, it may detect the in-pixel pattern shape and store it in the memory unit.

[0075] The modulation rate may be determined by considering both the centroid position and shape of the pattern within the pixel. For example, as shown in Figure 9(a), the correction map creation unit 51, in the same manner as above, determines the pixel center (x) for the pixel at coordinate (x,y). g ,y g The centroid position (x') of the pattern within the pixel as seen from ) g ,y' g Δx, the amount of displacement of the center of gravity in the x-direction. g and the displacement amount Δy in the y direction g Calculate.

[0076] Furthermore, the correction map creation unit 51 uses the same method as described above to determine the size L' in the x-direction of the pattern within the pixel. x and size L' in the y direction y We seek.

[0077] Figure 9(b), similar to Figures 5, 6(b), and 8(b), shows the case where a beam irradiated onto a pixel at coordinates (x,y) experiences a positional shift of Δx in the x-direction and Δy in the y-direction. The correction map creation unit 51 calculates the positional shift Δx', which corresponds to the amount the in-pixel pattern extends beyond the pixel at coordinates (x,y) in the x-direction, and the positional shift Δy', which corresponds to the amount it extends beyond in the y-direction, using the following formulas.

[0078]

number

[0079] Furthermore, the correction map creation unit 51 uses the above limiter to calculate geometrically effective positional displacement amounts Δx'' and Δy'' from the positional displacement amounts Δx' and Δy''. Using these positional displacement amounts Δx'' and Δy'', the distribution amount to surrounding pixels (beam modulation rate) is determined.

[0080] The correction map creation unit 51 calculates the beam irradiation amount (modulation rate) to be distributed to surrounding pixels using the beam position shift amounts Δx'' and Δy'', similar to the example in Figure 7. The distribution amount to each pixel is the same as in the example in Figure 7, so its explanation is omitted here.

[0081] By determining the modulation rate while considering both the centroid position and shape of the pattern within the pixel, the decrease in resolution can be suppressed even more effectively.

[0082] In the above embodiment, an example was described in which the centroid position and shape of the pattern within a pixel are calculated using the beam irradiation amount for each pixel. However, the centroid position and shape may also be determined from the edge positions of the pattern within a pixel. For example, the x-direction size of the pattern within a pixel can be determined from the right edge position and the left edge position of the pattern within a pixel. The y-direction size of the pattern within a pixel can be determined from the upper edge position and the lower edge position of the pattern within a pixel. The shape of the pattern within a pixel can be determined from the x-direction size and the y-direction size of the pattern within a pixel. In addition, the centroid position of the pattern within a pixel can be determined from the top, bottom, left, and right edge positions. Using these values, the beam irradiation amount (modulation rate) to be distributed to surrounding pixels can be calculated in the same manner as described above.

[0083] A portion of the calculations performed by the correction map creation unit 51 described above may be performed by an external device to the drawing device 100, and the calculation results may be input to the control computer 110.

[0084] In the above embodiment, an electron beam configuration was described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam; it may also be a beam using charged particles such as an ion beam.

[0085] In the above embodiment, a drawing device for drawing patterns on a substrate was described, but it can also be applied to other irradiation devices that irradiate an object with a beam, such as an inspection device.

[0086] 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 above 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]

[0087] 50 Position shift data acquisition unit 51 Correction Map Creation Section 52. Graphic Data Acquisition Unit 53 Shot Data Creation Section 54 Irradiance correction section 100 Drawing device 101 samples 102 Electro-optical lens barrel 103 Drawing room 105 XY Stages 110 Control Computer 150 Drawing section 160 Control Unit 201 Electron Gun 203 Molded aperture array substrate 204 Blanking Aperture Array Substrate 208 Deflector

Claims

1. A correction map creation unit creates a correction map in which modulation rates are defined for an irradiation area irradiated by a multi-charged particle beam, such that for each pixel that constitutes an irradiation unit area per beam of a multi-charged particle beam, the amount of beam irradiation to the pixel and the amount of beam irradiation to at least one pixel surrounding the pixel are modulated to correct the misalignment of the pattern formed by the beam that is misaligned when irradiating the pixel, and the modulation rate of the beam to at least one pixel surrounding the pixel is calculated based on the amount of misalignment of the beam irradiated to the pixel and the position of the pattern arranged within the pixel, the calculated modulation rate of the beam to the pixel is defined at the position of the pixel, and the modulation rate of the beam to at least one pixel surrounding the pixel is defined in relation to the pixel and at the position of the at least one pixel surrounding the pixel, and so on. A shot data creation unit calculates the amount of beam irradiation to each pixel, For each pixel, an irradiation dose correction unit calculates a corrected irradiation dose by adding a value obtained by multiplying the modulation rate of the beam to the pixel defined in the correction map by the beam irradiation dose to the pixel, and a value obtained by multiplying the modulation rate of the beam to at least one pixel defined as the surrounding pixel at the position of the pixel in the correction map by the beam irradiation dose to the pixel associated with that at least one pixel. An irradiation unit that irradiates the sample surface with a multi-charged particle beam so that the corrected irradiation amount beam irradiates each corresponding pixel, A multi-charged particle beam irradiation device equipped with the following features.

2. The multi-charged particle beam irradiation apparatus according to claim 1, wherein the correction map creation unit calculates the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one pixel surrounding the pixel, based on the amount of positional displacement of the beam irradiated to the pixel and the centroid position of the pattern arranged within the pixel.

3. The multi-charged particle beam irradiation apparatus according to claim 2, wherein the correction map creation unit calculates the centroid position of a pattern arranged within the pixel using the amount of beam irradiation to the pixel.

4. The multi-charged particle beam irradiation apparatus according to claim 1, wherein the correction map creation unit calculates the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one pixel surrounding the pixel, based on the amount of positional displacement of the beam irradiated to the pixel and the edge position of the pattern arranged within the pixel.

5. The multi-charged particle beam irradiation apparatus according to claim 4, wherein the correction map creation unit calculates the edge position of a pattern arranged within the pixel using the amount of beam irradiation to the pixel.

6. The multi-charged particle beam irradiation apparatus according to claim 1, wherein the correction map creation unit calculates the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one pixel surrounding the pixel, based on the amount of positional displacement of the beam irradiated to the pixel and the centroid position and shape of the pattern arranged within the pixel.

7. The multi-charged particle beam irradiation apparatus according to claim 1, wherein the correction map creation unit has a limiter that processes the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one pixel surrounding the pixel to be within a predetermined range.

8. For each pixel that constitutes an irradiation unit region per beam of a multi-charged particle beam, the process involves calculating the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one surrounding pixel, based on the amount of misalignment of the beam irradiated to the pixel and the position of the pattern arranged within the pixel, by modulating the beam irradiation amount to the pixel and the beam irradiation amount to at least one surrounding pixel, in order to correct the misalignment of the pattern formed by the misaligned beam irradiated to the pixel. A step of creating a correction map in which modulation rates are defined for an irradiation area irradiated by a multi-charged particle beam, such that for each pixel, the calculated modulation rate of the beam to the pixel is defined at the position of the pixel, and the calculated modulation rate of the beam to at least one pixel surrounding the pixel is defined in relation to the pixel at the position of at least one pixel surrounding the pixel; For each pixel, the process involves calculating the amount of beam irradiation to that pixel, For each pixel, the process involves calculating a corrected irradiation amount by adding together a value obtained by multiplying the modulation rate of the beam to the pixel defined in the correction map by the beam irradiation amount to the pixel, and a value obtained by multiplying the modulation rate of the beam to at least one pixel defined in the correction map at the position of the pixel in question by the beam irradiation amount to the pixel associated with that at least one pixel. A step of irradiating the sample surface with a multi-charged particle beam so that the beam with the corrected irradiation amount is irradiated to each corresponding pixel, A multi-charged particle beam irradiation method comprising the following features.

9. A correction map creation device that creates and outputs a correction map in which modulation rates are defined for an irradiation region irradiated by a multi-charged particle beam, by modulating the amount of beam irradiation to the pixel and the amount of beam irradiation to at least one pixel surrounding the pixel to correct the misalignment of the pattern formed by the beam that is misaligned when irradiating the pixel, based on the amount of misalignment of the beam irradiated to the pixel and the position of the pattern arranged within the pixel, and defines the calculated modulation rate of the beam to the pixel at the position of the pixel, and defines the modulation rate of the beam to at least one pixel surrounding the pixel in relation to the pixel at the position of at least one pixel surrounding the pixel.

10. For each pixel that constitutes an irradiation unit region per beam of a multi-charged particle beam, the process involves calculating the modulation rate of the beam to the pixel and the modulation rate of the beam to at least one surrounding pixel, based on the amount of misalignment of the beam irradiated to the pixel and the position of the pattern arranged within the pixel, by modulating the beam irradiation amount to the pixel and the beam irradiation amount to at least one surrounding pixel, in order to correct the misalignment of the pattern formed by the misaligned beam irradiated to the pixel. A step of creating and outputting a correction map in which modulation rates are defined for an irradiation area irradiated by a multi-charged particle beam, such that for each pixel, the calculated modulation rate of the beam to the pixel is defined at the position of the pixel, and the calculated modulation rate of the beam to at least one pixel surrounding the pixel is defined in relation to the pixel at the position of at least one pixel surrounding the pixel, A method for creating a correction map that includes the following features.

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