JP2017143235A - Multi-charged particle beam lithography device and multi-charged particle beam lithography method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of lithography accuracy even in the case where a shot size of a multi-beam is changed.SOLUTION: A multi-charged particle beam lithography device according to one embodiment of the present invention comprises: a data region discrimination part for discriminating a data region based on a boundary of pixels and boundaries of an irradiation region of a multi-beam and a stripe region; a deflection coordinate adjustment part for adjusting deflection coordinates of the multi-beam in such a manner that the boundary of the pixels corresponds to the boundary of the irradiation region; a correction part for distributing the irradiation amount of beams corresponding to pixels within the data region calculated based on lithography data to one or more beams based on a positional relationship between each beam of the multi-beam and a pixel within the data region and calculating a corrected irradiation amount by adding the distributed irradiation amounts in each of the beams; and a lithography part for deflecting the multi-beam based on the adjusted deflection coordinates, radiating the beams of the corrected irradiation amount and drawing a pattern.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a multi charged particle beam writing apparatus and a multi charged particle beam writing method.

  With the high integration of LSI, the circuit line width of semiconductor devices has been further miniaturized. As a method of forming an exposure mask for forming a circuit pattern on these semiconductor devices (the one used in a stepper or scanner is also referred to as a reticle), an electron beam lithography technique having excellent resolution is used. Yes.

  Since the drawing apparatus using a multi-beam can irradiate many beams at one time (one shot) as compared with the case of drawing with one electron beam, the throughput can be greatly improved. In the multi-beam drawing apparatus, for example, an electron beam emitted downward from an electron gun passes through an aperture member having a plurality of holes to form a multi-beam.

  In such a multi-beam drawing apparatus, the shot size may change for each drawing adjustment / each apparatus due to an error in the attachment position of the aperture member, an error in the size of the hole formed in the aperture member, or the like. When drawing is performed without considering the change in the shot size, there is a problem in that the drawing accuracy is deteriorated due to expansion / reduction of the entire layout or deterioration of pattern joining accuracy.

JP 2006-251207 A Special table 2012-527765 gazette Japanese Patent No. 5270891 JP, 2015-162504, A JP 2009-88848 A

  The present invention has been made in view of the above-described conventional situation, and provides a multi-charged particle beam drawing apparatus and a multi-charged particle beam drawing method capable of preventing deterioration of drawing accuracy even when a multi-beam shot size is changed. This is the issue.

  A multi-charged particle beam drawing apparatus according to one aspect of the present invention divides a drawing region of a substrate into a mesh shape, a pixel boundary, a multi-charged particle beam irradiation region, and the drawing region at a predetermined width in a predetermined direction. A deflection coordinate adjustment for adjusting a deflection coordinate of the multi-charged particle beam so as to associate the boundary of the pixel with the boundary of the irradiation region based on the boundary of the stripe region. The irradiation dose of the beam corresponding to the pixel in the data area calculated based on the drawing data based on the positional relationship between the unit, each beam of the multi-charged particle beam, and the pixel in the data area is 1 A correction unit that distributes the above-mentioned beams and calculates a corrected irradiation amount by adding the distributed irradiation amounts in each of the beams, and the adjusted deflection coordinates. Deflecting the multi charged particle beam Te, a drawing unit for drawing a pattern by irradiating a beam of the corrected dose is one with a.

  In the multi-charged particle beam drawing apparatus according to one aspect of the present invention, the correction unit defines, for each pixel in the data area, a correction map that defines a ratio of distributing a beam irradiation amount corresponding to the pixel to surrounding beams. And calculating the corrected dose.

  In the multi-charged particle beam drawing apparatus according to one aspect of the present invention, the correction unit calculates the correction irradiation amount for each pixel from the barycentric position of the pixel, the irradiation amount of the beam corresponding to the pixel, and the barycentric position. It is characterized by calculating.

  In the multi-charged particle beam drawing apparatus according to one aspect of the present invention, when the data region determination unit determines that the data region is larger than the irradiation region of the multi-charged particle beam, the irradiation region within the data region It is characterized by complementing shot data corresponding to a location located outside.

  A multi-charged particle beam drawing apparatus according to an aspect of the present invention includes a stage on which the substrate is placed and moved, and a plurality of openings, and the multi-charged particle beam drawing device passes through the plurality of openings to allow the charged particle beam to pass therethrough. An aperture member that forms a particle beam, a blanking plate in which a plurality of blankers for switching on and off of the corresponding beams among the multi-charged particle beams are arranged, and a beam that is turned on by the plurality of blankers are collected together A deflector for deflecting to follow the movement of the stage, and tracking control for deflecting the beam to the first drawing position and drawing the beam irradiation position to follow the movement of the stage while drawing for a predetermined time, After a predetermined time has passed, reset the beam deflection to return the beam to the direction opposite to the stage movement direction. A deflection control unit that controls the deflector, the deflection control unit deflecting the beam to the second drawing position after drawing at the first drawing position, and performing drawing and tracking control, After drawing at the second drawing position, the beam is deflected to the third drawing position to perform drawing and tracking control.

  The multi charged particle beam drawing apparatus according to an aspect of the present invention adds a shot for irradiating the pixel when a positional deviation between the pixel and a beam corresponding to the pixel is a predetermined amount or more.

  The multi-charged particle beam drawing apparatus according to one aspect of the present invention adds a shot when the center of the pixel is not included in the beam corresponding to the pixel.

  A multi-charged particle beam drawing method according to an aspect of the present invention includes a pixel boundary obtained by dividing a drawing region of a substrate into a mesh shape, a multi-charged particle beam irradiation region, and the drawing region divided in a predetermined width toward a predetermined direction. Determining a data region based on the boundary of the stripe region, adjusting a deflection coordinate of the multi-charged particle beam so as to associate the boundary of the pixel and the boundary of the irradiation region, and the multi-charge Based on the positional relationship between each beam of the particle beam and the pixel in the data area, the irradiation amount of the beam corresponding to the pixel in the data area calculated based on the drawing data is distributed to one or more beams. , Calculating a corrected dose by adding the distributed dose in each beam, and a multi-charged particle beam based on the adjusted deflection coordinates Deflect, a step of drawing a pattern by irradiating a beam of the corrected dose is one with a.

  The multi-charged particle beam writing method according to one aspect of the present invention performs tracking control for following the movement of a stage on which the substrate is placed, and resets beam deflection after a predetermined time has elapsed. And returning the beam to the direction opposite to the stage moving direction, deflecting the beam to the first drawing position to perform drawing and tracking control, and after drawing at the first drawing position, The drawing and tracking control is performed by deflecting to the second drawing position, and after the drawing at the second drawing position, the beam is deflected to the third drawing position to perform the drawing and tracking control.

  In the multi-charged particle beam drawing method according to an aspect of the present invention, when a positional deviation between the pixel and the beam corresponding to the pixel is a predetermined amount or more, a shot for irradiating the pixel is added.

  According to the present invention, it is possible to prevent deterioration in drawing accuracy even when the shot size of a multi-beam changes.

It is a schematic block diagram of the drawing apparatus which concerns on embodiment of this invention. (A) (b) is a figure which shows the structural example of an aperture member. It is a figure explaining an example of drawing operation. It is a figure which shows an example of the irradiation area | region of a multibeam, and a drawing object pixel. It is a flowchart explaining the drawing method by embodiment of this invention. It is a figure which shows the irradiation area | region of the multi-beam where the beam size changed. It is a figure which shows the example of correction | amendment of irradiation amount. (A)-(d) is a figure which shows the shot by a comparative example. (A)-(d) is a figure which shows the example of the shot by embodiment. It is a figure which shows the example of determination of a data area. It is a figure which shows the adjustment example of a deflection coordinate. It is a figure which shows the example of correction | amendment of irradiation amount. It is a figure which shows the example of correction | amendment of irradiation amount. (A)-(c) is a figure explaining the process in the case of taking a data area large. It is a figure which shows the example of tracking operation | movement. (A) (b) is a figure which shows the example of the positional relationship of a pixel mesh and a beam mesh.

  Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and a beam using charged particles such as an ion beam may be used.

  FIG. 1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to an embodiment. In FIG. 1, the drawing apparatus 100 includes a drawing unit 150 and a control unit 160. The drawing apparatus 100 is an example of a multi charged particle beam drawing apparatus.

  The drawing unit 150 includes an electron column 102 and a drawing chamber 103. In the electron beam column 102, an electron gun 201, an illumination lens 202, an aperture member 203, a blanking plate 204, a reduction lens 205, a limiting aperture member 206, an objective lens 207, and a deflector 208 are arranged.

  In the drawing chamber 103, an XY stage 105 capable of continuous movement is disposed. On the XY stage 105, a mask substrate 101 to be drawn at the time of drawing is arranged. The mask substrate 101 includes an exposure mask for manufacturing a semiconductor device, or a semiconductor substrate (silicon wafer) on which the semiconductor device is manufactured. Further, the mask substrate 101 includes mask blanks to which a resist is applied and nothing is drawn yet. On the XY stage 105, a mirror 210 for measuring the position of the XY stage 105 is further arranged.

  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, 144, and 146 such as a magnetic disk device. These are connected to each other via a bus. In the storage device 140, drawing data is input from the outside and stored.

  The control computer 110 includes a data area determination unit 50, a deflection coordinate adjustment unit 52, a correction map creation unit 54, a shot data creation unit 56, a correction unit 58, and a drawing control unit 60. These functions may be configured by hardware such as an electric circuit, or may be configured by software. When configured by software, a program that realizes at least some of the functions may be stored in a recording medium and read and executed by a computer having a CPU. The recording medium is not limited to a removable medium such as a magnetic disk or an optical disk, but may be a fixed recording medium such as a hard disk device or a memory. Information such as calculation results in the control computer 110 is stored in the memory 112 each time.

  2A and 2B are conceptual diagrams illustrating a configuration example of the aperture member 203. FIG. In FIG. 2A, the aperture member 203 has vertical (y direction) m rows × horizontal (x direction) n rows (m, n ≧ 2) holes (openings) 22 in a matrix at a predetermined arrangement pitch. Is formed. For example, 512 × 512 rows of holes 22 are formed in the vertical and horizontal directions (x and y directions). Each hole 22 is formed of a rectangle having the same dimensions. The hole 22 may be circular.

  When a part of the electron beam 200 passes through each of the plurality of holes 22, the multi-beams 20a to 20e are formed. Here, an example in which two or more holes 22 are arranged in both the vertical and horizontal directions (x and y directions) is shown, but the present invention is not limited to this. For example, either one of the vertical and horizontal directions (x and y directions) may be a plurality of rows and the other may be only one row.

  The arrangement of the holes 22 is not limited to the case where the vertical and horizontal directions are arranged in a lattice pattern as shown in FIG. For example, as shown in FIG. 2B, the holes in the k-th row in the vertical direction (y direction) and the rows in the k + 1-th row are shifted by a dimension a in the horizontal direction (x direction). Also good. Similarly, the holes in the vertical (y direction) k + 1-th row and the k + 2-th row may be arranged so as to be shifted in the horizontal direction (x direction) by a dimension b.

  In the blanking plate 204, through-holes (openings) for passing the beams of the multi-beams are opened at positions corresponding to the holes 22 of the aperture member 203 shown in FIGS. Then, a set of blanking deflection electrodes (blankers: blanking deflectors) is disposed across each passing hole. A deflection voltage based on a control signal from the deflection control circuit 130 is applied to one of the two electrodes, and the other is grounded.

  The electron beams 20a to 20e passing through the respective through holes are independently deflected by a blanker, and blanking control is performed. In this way, the plurality of blankers perform blanking deflection of the corresponding beams among the multi-beams that have passed through the plurality of holes 22 (openings) of the aperture member 203.

  FIG. 3 is a conceptual diagram illustrating an example of a drawing operation. As shown in FIG. 3, the drawing area 30 of the mask substrate 101 is virtually divided into a plurality of strip-like stripe areas 32 having a predetermined width in the y direction, for example.

  First, the XY stage 105 is moved and adjusted so that the irradiation region 34 that can be irradiated by one irradiation of the multi-beam 20 is positioned at the left end of the first stripe region 32 or further on the left side. Is started. When drawing the first stripe region 32, the drawing is relatively advanced in the x direction by moving the XY stage 105 in the −x direction, for example. For example, the XY stage 105 is continuously moved at a predetermined speed.

  After the drawing of the first stripe region 32 is completed, the stage position is moved in the −y direction, and the irradiation region 34 is relatively positioned in the y direction at the right end of the second stripe region 32 or further to the right. This time, the XY stage 105 is moved in the x direction, for example, so that the drawing is similarly performed in the −x direction.

  In the third stripe region 32, drawing is performed in the x direction, and in the fourth stripe region 32, drawing is performed while alternately changing the orientation, such as drawing in the −x direction. Can be shortened. However, the drawing is not limited to the case of alternately changing the direction, and when drawing each stripe region 32, the drawing may be advanced in the same direction. In one shot, a plurality of shot patterns having the same number as each hole 22 are formed at a time by the multi-beam formed by passing through each hole 22 of the aperture member 203.

  FIG. 4 is a diagram illustrating an example of a multi-beam irradiation region and a drawing target pixel. In FIG. 4, the stripe region 32 is divided into a plurality of mesh regions 40 having a mesh shape with, for example, a multi-beam size. Each mesh area 40 is a drawing target pixel (drawing position). The size of the drawing target pixel is not limited to the beam size. For example, the beam size may be 1 / n (n is an integer of 1 or more). In the example of FIG. 4, the drawing region of the mask substrate 101 has a plurality of stripes with a width size smaller than the size (shot size) of the irradiation region 34 that can be irradiated by one irradiation of the multi-beams 20a to 20e, for example, in the y direction. The case where it is divided into regions 32 is shown. The width of the stripe region 32 is not limited to this, and may be, for example, n times as large as the irradiation region 34 (n is an integer of 1 or more).

  In the irradiation region 34, a plurality of pixels 24 (beam drawing positions) that can be irradiated by one irradiation of the multi-beams 20a to 20e are shown. In other words, the pitch between adjacent pixels 24 is the pitch between the beams of the multi-beam. In the example of FIG. 4, one sub-pitch region 26 is configured by a square region that is surrounded by four adjacent pixels 24 and includes one pixel 24 of the four pixels 24. FIG. 4 shows a case where each sub-pitch region 26 is composed of 4 × 4 pixels.

  Next, the operation of the drawing unit 150 will be described. The electron beam 200 emitted from the electron gun 201 (emission part) illuminates the entire aperture member 203 almost vertically by the illumination lens 202. When the electron beam 200 passes through the plurality of holes 22 of the aperture member 203, for example, a plurality of rectangular electron beams (multi-beams) 20a to 20e are formed. The multi-beams 20a to 20e pass through the corresponding blankers of the blanking plate 204, respectively. The blankers individually deflect the passing electron beam 20 so that the beam is turned on only during the calculated drawing time (irradiation time), and the beam is turned off otherwise.

  The multi-beams 20 a to 20 e that have passed through the blanking plate 204 are reduced by the reduction lens 205 and travel toward a central hole formed in the limiting aperture member 206. The electron beam deflected so that the beam is turned off by the blanker of the blanking plate 204 is displaced from the center hole of the limiting aperture member 206 (blanking aperture member), and is blocked by the limiting aperture member 206. On the other hand, the electron beam that has not been deflected by the blanker of the blanking plate 204 (deflected so as to be turned on) passes through the hole at the center of the limiting aperture member 206.

  A beam of one shot is formed by the beam that has passed through the limiting aperture member 206 formed from when the beam is turned on to when the beam is turned off. 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, and each beam (the entire multi-beam 20) is deflected together in the same direction by the deflector 208, and the mask Irradiation is performed on each drawing position (irradiation position) on the substrate 101.

  When the XY stage 105 is continuously moving, tracking control is performed by the deflector 208 so that the drawing position (irradiation position) of the beam follows the movement of the XY stage 105. Laser is irradiated from the stage position detector 139 toward the mirror 210 on the XY stage 105, and the position of the XY stage 105 is measured using the reflected light. The multi-beams irradiated at a time are ideally arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of holes of the aperture member 203 by the desired reduction ratio described above.

  The drawing apparatus 100 sequentially and sequentially irradiates a plurality of pixels (pixels 24 in FIG. 4) with a multi-beam as a shot beam while following the movement of the XY stage 105 during each tracking operation while shifting the drawing position. The drawing operation is performed using the raster scan method.

  FIG. 5 is a flowchart illustrating a drawing method according to the embodiment. This drawing method includes a data area determination step S102, a deflection coordinate adjustment step S104, a correction map creation step S106, a drawing data acquisition step S202, a shot data creation step S204, a correction step S206, and a drawing step S208. Prepare.

  In the drawing data acquisition step S202, the shot data creation unit 56 reads and acquires drawing data (graphic data) from the storage device 140. The shot data creation unit 56 reads corresponding drawing data from the storage device 140 for each stripe region, for example.

  In the shot data creation step S204, the shot data creation unit 56 uses the drawing data to calculate the area density of the pattern arranged inside each pixel (or for each of a plurality of pixel groups). For example, the shot data creation unit 56 assigns a plurality of graphic patterns defined in the drawing data to corresponding pixels. Then, the shot data creation unit 56 calculates the area density of the graphic pattern to be arranged for each pixel.

  In addition, the shot data creation unit 56 calculates the beam irradiation amount to the pixel for each pixel. Here, the irradiation amount of the electron beam per shot (or irradiation time T: also referred to as shot time or exposure time) is calculated for each pixel. The reference dose (or irradiation time T) is preferably obtained in proportion to the calculated area density of the pattern. It is preferable that the finally calculated irradiation amount is a corrected irradiation amount obtained by correcting the dimensional variation for a phenomenon causing dimensional variation such as a proximity effect, a fogging effect, and a loading effect (not shown) by the irradiation amount. The irradiation time can be defined by a value obtained by dividing the irradiation amount D by the current density J.

  The shot data creation unit 56 calculates an irradiation amount for each pixel on the assumption that the beam is reduced at a predetermined reduction rate (for example, 200%). However, due to an error in the attachment position of the aperture member 203, an error in the size of the hole 22 formed in the aperture member 203, and the like, the reduction ratio of the beam changes, and the shot size (beam size) changes.

  FIG. 6 shows an example of the relationship between the pixel 40 for which the shot data creation unit 56 calculates the irradiation amount and the multi-beam irradiation region 34 whose beam size has changed. The pixel 40 is indicated by a broken line. FIG. 6 shows an example in which the multi-beam is composed of four beams. As shown in FIG. 6, when the size of each beam of the multi-beam changes, one beam is located across a plurality of pixels 40, and the boundary of the irradiation region 34 and the boundary of the pixel 40 do not match. Therefore, it is necessary to correct the irradiation amount of each pixel 40 in consideration of a change in beam size.

  For example, as shown in FIG. 7, the beam B corresponding to the pixel at the coordinate (x, y) is adjacent to the pixel at the coordinate (x, y), and the adjacent coordinates (x, y + 1), (x + 1, y), It is located on the pixel (x + 1, y + 1). Therefore, the irradiation dose distributed to the beam B is obtained from the irradiation dose of each pixel and the ratio of the overlapping areas, and the irradiation dose distributed from each pixel is summed to calculate the corrected irradiation dose of the beam B.

  For example, the ratio of the area where the beam B overlaps the pixel at coordinates (x, y) (= overlapping area / area of one pixel) is A10, and the irradiation amount of the pixel at coordinates (x, y) is D10. . Similarly, the ratio of the area where the beam B overlaps the pixel at coordinates (x, y + 1), (x + 1, y), (x + 1, y + 1) is set to A11, A12, A13, coordinates (x, y + 1), (x + 1), respectively. , Y) and (x + 1, y + 1) are set as D11, D12, and D13, respectively. In this case, the correction dose of the beam B is obtained by D10 × A10 + D11 × A11 + D12 × A12 + D13 × A13. In this way, the corrected dose of each beam is calculated.

  Consider a case where a shot is performed while shifting by half the irradiation area size. FIGS. 8A to 8D show a case where a shot is performed by simply shifting the irradiation area size by ½. Since the boundary of the irradiation region 34 and the boundary of the pixel 40 do not coincide with each other, the positional relationship between the beam and the pixel 40 is different in each shot of FIGS. How to stride is different. Therefore, the distribution ratio of the irradiation amount to adjacent pixels differs between shots. That is, the irradiation amount correction maps that define the distribution ratio of the irradiation amount to the adjacent pixels are different in FIGS. 8A to 8D, and the calculation cost of the correction processing increases.

  Therefore, in the present embodiment, the shot position (deflection coordinate) is adjusted so that the boundary of the irradiation region 34 coincides with the boundary of the pixel 40. 9A to 9D show examples of shot position adjustment according to the present embodiment. FIGS. 9A and 9B are the same as FIGS. 8A and 8B. In this example, in the shot shown in FIG. 9C, the boundary of the irradiation region 34 and the boundary of the pixel 40 are made to coincide. By the position adjustment, for example, the + x side end of the shot irradiation region in FIG. 9A and the −x side end of the shot irradiation region in FIG. 9C overlap.

  9 (a) and 9 (c), the positional relationship between each beam and the pixel 40 (how to straddle adjacent pixels) is the same in FIGS. 9A and 9C, and the distribution ratio of the dose to the adjacent pixels is the same. It will be the same. Therefore, FIGS. 9A and 9C can use a common dose correction map. Similarly, FIGS. 9B and 9D can use a common dose correction map. That is, if a combination of two correction maps, that is, the dose correction map in FIG. 9A and the dose correction map in FIG. 9B, is created, this can be used repeatedly thereafter. Since a common correction map can be used repeatedly, the calculation cost of correction processing can be reduced. In the data area determination step S102, the deflection coordinate adjustment step S104, and the correction map creation step S106, such correction map creation processing is performed.

  It is preferable to execute the data area determination step S102 to the correction map creation step S106 as a pre-process for performing the drawing process.

  Before the drawing process is performed, the beam size at each pixel when the multi-beam is irradiated onto the surface of the mask substrate 101 is measured in advance to determine the irradiation region size. A measurement substrate coated with a resist (not shown) can be placed on the stage 105 and irradiated with multi-beams to determine the irradiation region size. The beam size data and the irradiation area size data are stored in the storage device 144.

  In the data area determination step S102, the data area determination unit 50 determines the data area corresponding to the irradiation area 34 among the pixel data using the irradiation area size data. For example, in the stripe region 32, the boundary of the data region is matched (matched) with the boundary of the nearest pixel 40 so as to be smaller than the actual irradiation region size. For example, the shaded area in FIG. 10 is the data area.

  In the deflection coordinate adjustment step S104, the deflection coordinate adjustment unit 52 adjusts the deflection coordinates so that the boundary of the irradiation region 34 and the boundary of the pixel 40 coincide with each other based on the boundary of the data region specified in step S102. For example, as shown in FIG. 11, the deflection coordinates are adjusted in the −x direction.

  In the correction map creation step S106, a correction map for distributing the dose to adjacent pixels is created. When a shot is performed while shifting by half the irradiation area size, two types of correction maps are created. Similarly, when a shot is performed while shifting by 1/3 of the irradiation area size, three types of correction maps that are used repeatedly are created. Further, when a shot is performed while shifting the irradiation area size (one time), one type of correction map is created. The created correction map is stored in the storage device 146.

  In order to reduce resources by reducing the number of correction maps to be created, for example, in the shots shown in FIGS. 9B and 9D, the shot position is set so that the boundary of the irradiation region 34 and the boundary of the pixel 40 coincide with each other. May be adjusted. Thereby, in all the shots, the positional relationship between each beam and the pixel 40 (how to straddle adjacent pixels) is the same, and a common dose correction map can be used. Similarly, when the shot is performed while shifting by 1/3 of the irradiation area size, the shot position of each shot is adjusted so that a common irradiation amount correction map can be used for all shots, and the boundary between the irradiation area 34 and the pixel Forty boundaries may be matched. Alternatively, the shot position may be adjusted so that two types of correction maps are used.

  Thus, after creating a correction map as pre-processing, actual drawing processing is started. As described above, first, in the drawing data acquisition step S202, drawing data is read from the storage device 140 for each stripe area, and then in the shot data creation step S204, the beam irradiation amount for each pixel is calculated.

  Next, in the correction step S206, the correction unit 58 distributes the irradiation amount of each pixel to adjacent pixels based on the irradiation amount distribution ratio defined in the correction map. The correction unit 58 adds the doses distributed from the adjacent pixels, and calculates the corrected dose of each pixel (beam). Thus, pixel data is reconstructed by correcting the irradiation amount of each pixel.

  Further, the correction unit 58 corrects the irradiation amount to the adjacent pixels in order to correct the positional deviation and the dimensional deviation of the pattern formed by the beam having a positional deviation caused by the distortion of the electron beam after the reconstruction of the pixel data. May be distributed. For example, as shown in FIG. 12, a beam corresponding to a pixel at coordinates (x, y) is added to a pixel at coordinates (x, y) and adjacent coordinates (x, y + 1), (x + 1, y), ( When the pixel is located on the pixel at x + 1, y + 1), the irradiation amount of the pixel at the coordinate (x, y) is allocated to a pixel adjacent to the opposite side of the overlapping pixel according to the ratio of the overlapping area. For example, the dose corresponding to the area ratio overlapping with the pixel at coordinates (x, y + 1) is allocated to the pixel at coordinates (x, y-1). Then, the corrected dose is obtained by adding the doses allocated from adjacent pixels.

  Note that the number of beams corresponding to one pixel is not necessarily limited to one, and may be two or more. In addition, there may be one that does not allocate the irradiation amount of the beam corresponding to one pixel to other beams.

  In the drawing step S208, the drawing unit 150 draws a pattern on the mask substrate 101 using a multi-beam so that each beam is irradiated to the corresponding pixel by the correction dose. The drawing control unit 60 converts the corrected dose into the irradiation time, rearranges the shots in the order of the drawing sequence, and outputs the irradiation time data to the deflection control circuit 130. The deflection control circuit 130 controls the blanker of the blanking plate 204 and the deflection amount of the deflector 208 for each shot based on the irradiation time data. In addition, the drawing control unit 60 outputs the deflection coordinates adjusted by the deflection coordinate adjustment unit 52 to the deflection control circuit 130. Thereby, the deflection amount of the deflector 208 is controlled so that the boundary of the irradiation region of the multi-beam and the boundary of the pixel coincide.

  As described above, according to the present embodiment, even when the beam size changes, it is possible to prevent the deterioration of the drawing accuracy by distributing the pixel irradiation amount and correcting the irradiation amount of each beam. In addition, a data area is determined (limited) so that the boundary of the irradiation area 34 and the boundary of the pixel 40 coincide with each other, and the deflection coordinates are adjusted so as to match the boundary. Therefore, a correction map for correcting the irradiation amount is provided. It can be shared between shots, and the time and resources required for the correction map creation process can be reduced.

  In the above embodiment, a plurality of sets of at least one correction map to be used repeatedly may be created according to the global position dependency on the mask substrate 101 or the like.

  In the above-described embodiment, an example in which correction processing is performed twice, that is, correction of the dose for reconstructing pixel data and correction of the dose for correcting the positional deviation and dimensional deviation of the pattern to be formed. Although described, these may be performed together in one correction process. For example, with the ideal shot (calculated shot before dose correction) and the actual shot (shot after dose correction), match the area (dose) and the center of gravity, Calculate.

Description will be made by paying attention to the pixel 40A shown in FIG. The pixel 40A is assumed to be overlapped by three beams B1, B2, and B3 whose positions are shifted due to the change in the beam size, and the irradiation amounts of the respective beams are D ₁ , D ₂ , and D ₃ . At this time, the corrected dose D of the pixel 40A is calculated so that the following relational expression is satisfied.

  For other pixels, the same equation as above is established, and the corrected dose of each pixel is calculated so that a plurality of equations are established. In this way, by correcting the irradiation amount so that the area (irradiation amount) and the center of gravity are matched, it is possible to correct the positional deviation and dimensional deviation of the pattern as well as the reconstruction of the pixel data.

  In the data area determination step S102 of the above embodiment, the data area determination unit 50 may determine the data area so as to be larger than the size of the irradiation area 34. For example, as shown in FIG. 14A, the data region DR is made larger than the irradiation region 34 in the + x direction and the + y direction (right direction and upward direction in the drawing). At this time, since shots at the boundary portion outside the irradiation region 34 on the + x side and + y side, which are indicated by the hatched portion in FIG. 14B, are separately required, the shot data creation unit 56 uses the shot data at this boundary portion. To complement. As shown in FIG. 14C, a beam for performing shots in the −x direction and −y direction (lower left in the figure) is used for the shot of the complemented shot data.

  In the present embodiment, the dose and the like are corrected using the correction map. However, the correction calculation may be performed using a correction formula or the like without necessarily using the map.

  The drawing apparatus 100 allows each beam to be moved so that the irradiation target pixel of each beam does not shift due to the movement of the XY stage 105 during multi-beam irradiation on the mask substrate 101 arranged on the movable XY stage 105. Irradiation of each beam is performed while performing a tracking operation following the stage movement. When one or more shots are completed, the tracking operation is reset, each beam is turned back, the deflection position is shifted to the next irradiation target pixel, and similarly, each beam is irradiated while performing the tracking operation. .

  In the conventional tracking control, as shown in FIG. 15, tracking is continued from time t = 0 to t = T at a position A0 on the substrate. During time T, the stage moves by a distance L. By resetting the tracking at time t = T, the beam is turned back in the direction opposite to the stage moving direction. After the settling time Ts of the DAC amplifier elapses, the next tracking is started for the position A1.

  For the position A1, tracking is continued from time t = T + Ts to t = 2T + Ts. During this time, the stage moves by a distance L. The beam is turned back by resetting the tracking at the time of t = 2T + Ts, and after the settling time Ts of the DAC amplifier has elapsed, the next tracking is started for the position A2. Thereafter, such an operation is repeated.

  In the conventional tracking operation, the distance between the shots (for example, the distance from the position A0 to the position A1, the distance from the position A1 to the position A2) is constant, and the tracking reset distance (distance for returning the beam) is also constant. ing. On the other hand, in the above embodiment, since the shot position (deflection coordinate) is adjusted so that the boundary of the irradiation region 34 coincides with the boundary of the pixel 40, the distance between shots may not be constant, and tracking reset is performed. The distance may not be constant.

  The drawing apparatus 100 obtains the beam deflection coordinates P and the corrected irradiation dose adjusted so as to associate the boundary of the irradiation region 34 with the boundary of the pixel 40, and determines shot data. The deflection control circuit 130 reads the shot data, calculates the tracking reference position P-L0 from the deflection coordinates P and the stage position L0 at the start of tracking, and starts the tracking operation.

  In order to use the entire irradiation region 34 and use a large tracking range, an offset term may be added when calculating the tracking reference position P-L0.

  After the adjustment of the deflection coordinates, as shown in FIG. 16A, a pixel 40B whose pixel center is not included in the beam mesh due to a large deviation between the pixel mesh (broken line in the figure) and the beam mesh (solid line in the figure). Can occur. When a desired dose amount is given to such a pixel 40B with the beam B4, the dose amount needs to be extremely large, and the drawing time per shot becomes long. The drawing on the mask substrate 101 includes a large number of shots, which greatly affects the total drawing time.

  Therefore, when the positional deviation between the pixel mesh and the beam mesh is equal to or larger than a predetermined amount, for example, when a pixel 40B is generated in which the pixel center is not included in the beam mesh, the center of the pixel 40B as shown in FIG. It is preferable to add a shot that fits within the beam mesh. The total drawing time is shorter when one shot is added than when the drawing time per shot is increased.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

20 Multi-beam 22 Hole 32 Stripe area 50 Data area determination part 52 Deflection coordinate adjustment part 54 Correction map creation part 56 Shot data creation part 58 Correction part 60 Drawing control part 100 Drawing apparatus 101 Mask substrate 102 Electron barrel 103 Drawing room 105 XY Stage 110 Control computer 112 Memory 130 Deflection control circuit 139 Stage position detector 140, 142, 144, 146 Storage device 150 Drawing unit 160 Control unit 200 Electron beam 201 Electron gun 202 Illumination lens 203 Aperture member 204 Blanking plate 205 Reduction lens 206 Limiting aperture member 207 Objective lens 208 Deflector 210 Mirror

Claims (10)

The data area is determined based on the boundary of the pixel obtained by dividing the drawing area of the substrate into a mesh shape, the irradiation area of the multi-charged particle beam, and the boundary of the stripe area obtained by dividing the drawing area by a predetermined width in a predetermined direction. A data area determination unit;
A deflection coordinate adjusting unit that adjusts the deflection coordinates of the multi-charged particle beam so as to associate the boundary of the pixel and the boundary of the irradiation region;
Based on the positional relationship between each beam of the multi-charged particle beam and the pixel in the data area, the irradiation amount of the beam corresponding to the pixel in the data area calculated based on the drawing data is one or more beams. A correction unit that calculates a corrected dose by adding the distributed dose in each beam, and
A drawing unit for drawing a pattern by deflecting a multi-charged particle beam based on the adjusted deflection coordinates and irradiating the beam of the corrected dose;
A multi-charged particle beam drawing apparatus.   The correction unit calculates, for each pixel in the data area, the correction dose using a correction map that defines a ratio of distributing a beam dose corresponding to the pixel to surrounding beams. The multi-charged particle beam drawing apparatus according to claim 1   The said correction | amendment part calculates the said corrected irradiation amount from the gravity center position of the said pixel for every pixel, and the irradiation amount and gravity center position of the beam corresponding to the said pixel, The said correction radiation amount is characterized by the above-mentioned. Multi charged particle beam lithography system.   When the data area determination unit determines that the data area is larger than the irradiation area of the multi-charged particle beam, the data area determination unit supplements shot data corresponding to a position located outside the irradiation area in the data area. The multi-charged particle beam drawing apparatus according to any one of claims 1 to 3. A stage for placing and moving the substrate;
A plurality of openings, and an aperture member that forms a multi-charged particle beam by passing a charged particle beam through the plurality of openings;
Among the multi-charged particle beams, a blanking plate in which a plurality of blankers for switching on and off of the corresponding beams is disposed,
A deflector that deflects the beams turned on by the plurality of blankers together to follow the movement of the stage;
While the beam is deflected to the first drawing position and drawing for a predetermined time, tracking control is performed so that the beam irradiation position follows the movement of the stage. After the predetermined time has elapsed, the beam deflection is reset and the beam is moved in the stage moving direction. A deflection control unit that controls the deflector so as to return to the opposite direction;
Further comprising
The deflection control unit performs drawing and tracking control by deflecting the beam to the second drawing position after drawing at the first drawing position, and performing drawing and tracking control after drawing at the second drawing position. 5. The multi-charged particle beam drawing apparatus according to claim 1, wherein the drawing and tracking control are performed while deflecting to a position.   The multi-charged particle according to claim 1, wherein a shot for irradiating the pixel is added when a positional deviation between the pixel and a beam corresponding to the pixel is equal to or greater than a predetermined amount. Beam drawing device.   The multi-charged particle beam drawing apparatus according to claim 6, wherein a shot is added when the center of the pixel is not included in a beam corresponding to the pixel. The data area is determined based on the boundary of the pixel obtained by dividing the drawing area of the substrate into a mesh shape, the irradiation area of the multi-charged particle beam, and the boundary of the stripe area obtained by dividing the drawing area by a predetermined width in a predetermined direction. Process,
Adjusting the deflection coordinates of the multi-charged particle beam so as to associate the boundary of the pixel and the boundary of the irradiation region;
Based on the positional relationship between each beam of the multi-charged particle beam and the pixel in the data area, the irradiation amount of the beam corresponding to the pixel in the data area calculated based on the drawing data is one or more beams. And calculating a corrected dose by adding the distributed dose in each beam, and
Deflecting a multi-charged particle beam based on the adjusted deflection coordinates, irradiating the beam of the corrected dose, and drawing a pattern;
A multi-charged particle beam writing method comprising: Performing tracking control for tracking the irradiation position of the multi-charged particle beam following the movement of the stage on which the substrate is placed, resetting the beam deflection after a predetermined time, and returning the beam to the direction opposite to the stage moving direction Further comprising
The beam is deflected to the first drawing position to perform drawing and tracking control, and after drawing at the first drawing position, the beam is deflected to the second drawing position to perform drawing and tracking control, and the second drawing is performed. The multi-charged particle beam writing method according to claim 8, wherein after writing at a position, the beam is deflected to a third drawing position to perform drawing and tracking control. 10. The multi-charged particle beam drawing method according to claim 8, wherein a shot for irradiating the pixel is added when a positional shift between the pixel and a beam corresponding to the pixel is a predetermined amount or more. .

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