Multi-charged particle beam lithography method and multi-charged particle beam lithography apparatus

Abstract

This invention provides a multi-beam lithography method that can reduce positional shifts caused by deviations in the linear component of the beam array shape. [Solution] The method is characterized by comprising the steps of: calculating a magnification correction amount for the beam array shape using a first coefficient that indicates a displacement component in a first direction which is the direction in which the stage is continuously moved in the acquired beam array shape; calculating a rotation correction amount for the beam array shape using a second coefficient that indicates a displacement component in a second direction which is orthogonal to the first direction; calculating a modulation dose amount for each unit region of a plurality of unit regions in which the stripe region is divided into a mesh-like structure based on either a third coefficient that indicates a displacement component in the first direction or a fourth coefficient that indicates a displacement component in the second direction; and performing either a rotation correction or magnification correction of the beam array shape, and modulating the dose amount for each unit region using the modulation dose amount.

Description

[Technical Field]

[0001] The present invention relates to a multi-charged particle beam lithography method and a multi-charged particle beam lithography apparatus, and more particularly to a method for correcting beam array misalignment occurring on the substrate surface in a multi-beam lithography apparatus. [Background technology]

[0002] Lithography technology, which drives the miniaturization of semiconductor devices, is an extremely important process in semiconductor manufacturing, being the only process that generates patterns. In recent years, with the increasing integration of LSIs, the circuit line width required for semiconductor devices has been decreasing year by year. Electron beam lithography technology inherently possesses superior resolution, and is used to draw patterns on wafers and other materials.

[0003] For example, there are lithography systems that use multiple beams. Compared to lithography with a single electron beam, using multiple beams allows for the irradiation of many beams at once, significantly improving throughput. In such a multi-beam lithography system, for example, an electron beam emitted from an electron gun is passed through a mask with multiple holes to form multiple beams. Each beam is then blanked, and the unshielded beams are reduced by an optical system, deflected by a deflector, and irradiated to the desired position on the sample.

[0004] Here, in multi-beam lithography, it is important for the lithography accuracy to accurately connect the beam arrays irradiated on the substrate. Therefore, before lithography, mark scanning is performed to measure the shape of the beam array on the substrate (see, for example, Patent Document 1). Among the deviations in the beam array shape, the linear component has been corrected by adjusting the intensity and distribution of the magnetic field by a magnetic lens or the like. However, since the magnetic element has hysteresis, after correcting the beam array shape, a confirmation measurement of the shape is performed. If there is a deviation at that time, readjustment is required. It takes about several tens of minutes to measure the beam array shape. Further, it takes about several tens of minutes for shape correction. During these operations, the apparatus cannot be operated, so there is a problem that the influence on the operation rate of the apparatus is large.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] One aspect of the present invention provides a lithography method and a lithography apparatus capable of reducing a positional deviation associated with a deviation of a linear component of a beam array shape in multi-beam lithography.

Means for Solving the Problems

[0007] A multi-charged particle beam lithography method according to one aspect of the present invention includes: a step of obtaining a beam array shape of a multi-charged particle beam; a step of calculating a magnification correction amount of the beam array shape using a first coefficient indicating a deviation component that deviates in a first direction proportional to a design coordinate in a first direction parallel to a direction in which drawing is performed while continuously moving a stage on which a sample is placed for the obtained beam array shape; A step of calculating a rotation correction amount for the beam array shape using a second coefficient that indicates a displacement component that shifts in a second direction perpendicular to the first direction, proportional to the design coordinates of the acquired beam array shape in the first direction, A step of calculating the modulation dose amount for each unit region of a plurality of unit regions into which the stripe region is divided into a mesh-like structure, based on at least one of a third coefficient that indicates a displacement component that shifts in the first direction in proportion to the design coordinates of the acquired beam array shape in the second direction, and a fourth coefficient that indicates a displacement component that shifts in the second direction in proportion to the design coordinates of the acquired beam array shape in the second direction, The process involves using two or more objective lenses to perform at least one of the following: rotational correction of the beam array shape according to the rotational correction amount, and magnification correction of the beam array shape according to the magnification correction amount, and modulating the dose amount for each unit region using the modulation dose amount. A process of drawing a pattern on a sample with a multi-charged particle beam that has undergone at least one of the rotational correction of the beam array shape and the magnification correction of the beam array shape, and the modulation of the dose amount, It is characterized by having the following features.

[0008] Furthermore, the process of calculating the modulation dose is as follows: A step of calculating the first modulation coefficient for each unit region using a third coefficient, A step of calculating the second modulation coefficient for each unit region using the fourth coefficient, A step of calculating the modulation dose for each unit region using the dose for each unit region and at least one of the first and second modulation coefficients, It is preferable to have this feature.

[0009] Furthermore, it is preferable that the objective lens includes an electrostatic lens.

[0010] Furthermore, it is preferable to further include a step of adjusting one of the crossover position and focus position of the multi-charged particle beam using a different electrostatic lens than the electrostatic lens.

[0011] Furthermore, it is preferable to set an upper limit on the rotational compensation amount.

[0012] A multi-charged particle beam lithography apparatus according to one aspect of the present invention is: A source that emits a multi-charged particle beam, An acquisition unit for acquiring the beam array shape of a multi-charged particle beam, A magnification correction amount calculation unit calculates a magnification correction amount for the beam array shape using a first coefficient that indicates a shift component in a first direction proportional to the design coordinates in a first direction parallel to the direction in which the acquired beam array shape is drawn while the stage on which the sample is placed is continuously moved, A rotation correction amount calculation unit calculates a rotation correction amount for the beam array shape using a second coefficient that indicates a displacement component that shifts in a second direction perpendicular to the first direction in proportion to the design coordinates of the acquired beam array shape in the first direction, and A modulation dose calculation unit calculates the modulation dose for each unit region of a plurality of unit regions into which the stripe region is divided into a mesh-like structure, based on at least one of a third coefficient that indicates a shift component that shifts in the first direction in proportion to the design coordinates of the beam array shape acquired in the second direction, and a fourth coefficient that indicates a shift component that shifts in the second direction in proportion to the design coordinates of the beam array shape acquired in the second direction. A dose modulation unit that modulates the dose amount for each unit region using the modulated dose amount, An objective lens that performs at least one of the following: magnification correction of the beam array shape according to the magnification correction amount, and rotational correction of the beam array shape according to the rotational correction amount, A drawing mechanism for drawing a pattern on a sample with a multi-charged particle beam that has undergone at least one of the following: beam array shape magnification correction, beam array shape rotation correction, and dose modulation. It is characterized by having the following features. [Effects of the Invention]

[0013] According to one aspect of the present invention, positional displacement due to deviations in the linear component of the beam array shape in multibeam lithography can be reduced. [Brief explanation of the drawing]

[0014] [Figure 1] This is a conceptual diagram showing the configuration of the drawing device in Embodiment 1. [Figure 2] This is a conceptual diagram showing the configuration of the molded aperture array substrate in Embodiment 1. [Figure 3] This is a cross-sectional view showing the configuration of the blanking aperture array mechanism in Embodiment 1. [Figure 4] This is a conceptual diagram illustrating an example of the drawing operation in Embodiment 1. [Figure 5] This figure shows an example of the multi-beam irradiation area and the pixels to be drawn in Embodiment 1. [Figure 6] This figure shows the parameters of the linear component in Embodiment 1. [Figure 7] This is a flowchart illustrating an example of the main steps of the drawing method in Embodiment 1. [Figure 8] This figure shows an example of a relationship table in Embodiment 1. [Figure 9] This figure shows an example of the beam position in Embodiment 1. [Figure 10] This figure illustrates the rotation amount θ and magnification m of the beam array shape in Embodiment 1. [Figure 11] This figure shows an example of the state in which the beam array rotation correction and magnification correction have been performed in Embodiment 1. [Figure 12] This is a diagram illustrating how to correct the YY term component in Embodiment 1. [Figure 13] This is a diagram illustrating how to correct the XY term components in Embodiment 1. [Figure 14] This figure illustrates an example of multibeam lithography operation in Embodiment 1. [Figure 15] This figure shows an example of a positional misalignment when drawing is performed according to Embodiment 1. [Figure 16] This is a conceptual diagram showing the configuration of the drawing device in Embodiment 2. [Figure 17]This figure shows an example of a relationship table in Embodiment 2. [Modes for carrying out the invention]

[0015] In the following embodiments, an electron beam configuration will be 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.

[0016] Embodiment 1. Figure 1 is a conceptual diagram showing the configuration of a lithography apparatus in Embodiment 1. In Figure 1, the lithography apparatus 100 includes a lithography mechanism 150 and a control system circuit 160. The lithography apparatus 100 is an example of a multi-charged particle beam lithography apparatus and an example of a multi-charged particle beam exposure apparatus. The lithography mechanism 150 includes an electron tube 102 (electron beam column) and a lithography chamber 103. Inside the electron tube 102 are an electron gun 201, an illumination lens 202, a shaped aperture array substrate 203, a blanking aperture array mechanism 204, a reduction lens 205, a limiting aperture substrate 206, an electromagnetic lens 207 which is an objective lens, a main deflector 208, a secondary deflector 209, a detector 107, and multiple electrostatic lenses 212, 214, 216 which are objective lenses.

[0017] An XY stage 105 is placed inside the drawing chamber 103. Samples 101, such as masks, which will be the substrates to be drawn on during drawing (exposure), 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. Samples 101 also include mask blanks with resist coated on them but with no drawings yet. A mirror 210 for measuring the position of the XY stage 105 is also placed on the XY stage 105.

[0018] A mark 106 for measuring the beam position is further placed on the XY stage 105. The mark 106 may be transmissive or reflective. If the mark 106 is reflective, a detector 107 placed above the mark detects secondary electrons emitted when the mark 106 is irradiated with the beam. The mark pattern may be the same as conventional patterns. For example, a dot pattern or a cross pattern is preferable. If the mark 106 is transmissive, it is detected by a detector (not shown) inside the mark 106. In the case of transmissive, for example, apertures for detecting the beam one by one or several at a time are formed on the upper surface of the mark 106.

[0019] The control system circuit 160 includes a control computer 110, memory 112, deflection control circuit 130, electrostatic lens control circuit 131, digital-to-analog converter (DAC) amplifier units 132 and 134, lens control circuit 136, stage control mechanism 138, stage position measuring instrument 139, and storage devices 140, 142, and 144 such as magnetic disk drives. The control computer 110, memory 112, deflection control circuit 130, electrostatic lens control circuit 131, lens control circuit 136, stage control mechanism 138, stage position measuring instrument 139, and storage devices 140, 142, and 144 are connected to each other via a bus (not shown). The deflection control circuit 130 is connected to DAC amplifier units 132 and 134 and a blanking aperture array mechanism 204. The sub-deflector 209 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 130 via the DAC amplifier 132. The main deflector 208 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 130 via the DAC amplifier 134. The lens group, including the illumination lens 202, the reduction lens 205, and the objective lens (electromagnetic lens) 207, is controlled by the lens control circuit 136.

[0020] Each of the multiple electrostatic lenses 212, 214, and 216 is composed of three or more electrode substrates, each with an opening in the center. Ground potential is applied to the upper and lower electrode substrates. A control potential V is applied to the middle electrode substrate. Each of the multiple electrostatic lenses 212, 214, and 216 is controlled by the electrostatic lens control circuit 131. The following description, including Figure 1, will explain the case using electrostatic lenses 212, 214, and 216, which are three-stage objective lenses, but is not limited to this. If the focus shift due to the rotation and magnification correction of the beam array is within an acceptable range or if the focus shift is ignored, electrostatic lens 216 can be omitted, and two-stage electrostatic lenses 212 and 214 can be arranged. Therefore, it is sufficient to arrange two or more stages of electrostatic lenses.

[0021] The position of the XY stage 105 is controlled by the drive of motors on each axis (not shown) controlled by the stage control mechanism 138. The stage position measuring instrument 139 measures the position of the XY stage 105 by receiving reflected light from the mirror 210 using the principle of laser interferometry.

[0022] The signal detected by detector 107 is converted into digital data by a detection circuit (not shown) and then output to control computer 110.

[0023] The control computer 110 includes a beam array shape acquisition unit 50, a determination unit 51, a rotation correction amount calculation unit 52, a magnification correction amount calculation unit 54, a control value calculation unit 56, a control value setting unit 58, a modulation dose amount calculation unit 61, a dose modulation unit 64, a drawing data processing unit 70, a drawing control unit 72, and a transfer processing unit 74. The modulation dose calculation unit 61 comprises a modulation coefficient calculation unit 60, a modulation coefficient calculation unit 62, and a modulation dose calculation processing unit 63. Each of the "~ section," such as the beam array shape acquisition section 50, determination section 51, rotation correction amount calculation section 52, magnification correction amount calculation section 54, control value calculation section 56, control value setting section 58, modulation coefficient calculation section 60, modulation coefficient calculation section 62, modulation dose amount calculation section 61 (modulation coefficient calculation section 60, modulation coefficient calculation section 62, and modulation dose amount calculation processing section 63), dose modulation section 64, drawing data processing section 70, drawing control section 72, and transfer processing section 74, has a processing circuit. Such a processing circuit includes, for example, an electrical circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each of the "~ section" may use a common processing circuit (the same processing circuit) or different processing circuits (separate processing circuits). Information input to and output to the beam array shape acquisition unit 50, determination unit 51, rotation correction amount calculation unit 52, magnification correction amount calculation unit 54, control value calculation unit 56, control value setting unit 58, modulation dose amount calculation unit 61 (modulation coefficient calculation unit 60, modulation coefficient calculation unit 62, and modulation dose amount calculation processing unit 63), dose modulation unit 64, drawing data processing unit 70, drawing control unit 72, and transfer processing unit 74, as well as information being calculated, is stored in the memory 112 each time.

[0024] The drawing operation of the drawing device 100 is controlled by the drawing control unit 72. Furthermore, the transfer process of the irradiation time data for each shot to the deflection control circuit 130 is controlled by the transfer processing unit 74.

[0025] Furthermore, drawing data (chip data) is input from outside the drawing device 100 and stored in the storage device 140. The chip data defines information about multiple graphic patterns that constitute the chip pattern. Specifically, for each graphic pattern, for example, the graphic code, coordinates, and size are defined.

[0026] Here, Figure 1 shows the configuration necessary to explain Embodiment 1. The drawing device 100 may also have other configurations that are normally necessary.

[0027] Figure 2 is a conceptual diagram showing the configuration of a molded aperture array substrate in Embodiment 1. In Figure 2, the molded aperture array substrate 203 has p rows horizontally (x direction) × q rows vertically (y direction) (p,q≧2) holes (openings) 22 formed in a matrix at a predetermined arrangement pitch. In the example of Figure 2, for example, it shows a case where 512 × 512 rows of holes 22 are formed in the vertical and horizontal (x,y directions). The number of holes 22 is not limited to this. For example, 32 × 32 rows of holes 22 may be formed. Each hole 22 is formed as a rectangle of the same dimensions and shape. Alternatively, they may be circles of the same diameter. A portion of the electron beam 200 passes through each of these multiple holes 22 to form a multi-beam 20. In other words, the molded aperture array substrate 203 forms and emits a multi-beam 20. The molded aperture array substrate 203 is an example of a multi-beam emission source or multi-beam formation mechanism.

[0028] Figure 3 is a cross-sectional view showing the configuration of the blanking aperture array mechanism in Embodiment 1. As shown in Figure 3, the blanking aperture array mechanism 204 has a blanking aperture array substrate 31 made of a semiconductor substrate such as silicon placed on a support base 33. In the membrane region 330 in the center of the blanking aperture array substrate 31, through holes 25 (openings) for the passage of each beam of the multi-beam 20 are opened at positions corresponding to each hole 22 of the molded aperture array substrate 203 shown in Figure 2. Then, a set of control electrodes 24 and counter electrodes 26 (blankers: blanking deflectors) are placed at positions opposite each other across the corresponding through holes 25. In addition, a control circuit 41 (logic circuit) that applies a deflection voltage to the control electrode 24 for each through hole 25 is placed inside the blanking aperture array substrate 31 near each through hole 25. The counter electrodes 26 for each beam are connected to ground.

[0029] An amplifier (an example of a switching circuit), not shown in the diagram, is placed inside the control circuit 41. As an example of an amplifier, a CMOS (Complementary MOS) inverter circuit, which acts as a switching circuit, is placed inside. Either an L (low) potential (e.g., ground potential) that is lower than the threshold voltage, or an H (high) potential (e.g., 1.5V) that is higher than the threshold voltage, is applied as a control signal to the input (IN) of the CMOS inverter circuit. In Embodiment 1, when an L potential is applied to the input (IN) of the CMOS inverter circuit, the output (OUT) of the CMOS inverter circuit applied to the control circuit 41 becomes a positive potential (Vdd), and the electric field caused by the potential difference with the ground potential of the counter electrode 26 deflects the corresponding beam, which is then shielded by the limiting aperture substrate 206 to turn the beam OFF. On the other hand, when a high potential is applied to the input (IN) of the CMOS inverter circuit (active state), the output (OUT) of the CMOS inverter circuit becomes ground potential, and the potential difference with the ground potential of the counter electrode 26 disappears, so the corresponding beam is not deflected, and the control is made so that the beam turns ON when it passes through the limiting aperture substrate 206. Blanking control is performed by this deflection.

[0030] Next, a specific example of the operation of the drawing mechanism 150 will be described. The electron beam 200 emitted from the electron gun 201 (emission source) illuminates the entire molded aperture array substrate 203 almost vertically by the illumination lens 202. Multiple rectangular holes 22 (openings) are formed in the molded aperture array substrate 203, and the electron beam 200 illuminates the area containing all of the multiple holes 22. Each portion of the electron beam 200 irradiated at the location of the multiple holes 22 passes through each of the multiple holes 22 in the molded aperture array substrate 203, thereby forming, for example, a rectangular multi-beam (multiple electron beams) 20. These multi-beams 20 pass through the corresponding blankers of the blanking aperture array mechanism 204. Each of these blankers individually blanks the passing beam so that the beam remains ON for a set drawing time (irradiation time).

[0031] The multi-beam 20 that has passed through the blanking aperture array mechanism 204 is reduced by the reduction lens 205 and travels toward the central hole formed in the limiting aperture substrate 206. Here, the electron beam deflected by the blanker of the blanking aperture array mechanism 204 is moved away from the central hole in the limiting aperture substrate 206 and is shielded by the limiting aperture substrate 206. On the other hand, the electron beam that was not deflected by the blanker of the blanking aperture array mechanism 204 passes through the central hole in the limiting aperture substrate 206 as shown in Figure 1. In this way, the limiting aperture substrate 206 shields each beam that has been deflected by the blanker of the blanking aperture array mechanism 204 to the beam-OFF state. Then, each beam of one shot is formed by the beam that has passed through the limiting aperture substrate 206 from the time the beam is turned ON until it is turned OFF. The multi-beams 20 that have passed through the limiting aperture substrate 206 are focused by the objective lens (electromagnetic lens) 207 to form a pattern image with a desired reduction ratio. The main deflector 208 and sub-deflector 209 then deflect the entire multi-beams 20 that have passed through the limiting aperture substrate 206 in the same direction, illuminating each beam at its respective irradiation position on the sample 101. Furthermore, for example, when the XY stage 105 is moving continuously, the main deflector 208 performs tracking control so that the beam irradiation position follows the movement of the XY stage 105. Ideally, the multi-beams 20 irradiated at one time will be arranged at a pitch obtained by multiplying the array pitch of the multiple holes 22 in the molded aperture array substrate 203 by the desired reduction ratio described above.

[0032] Figure 4 is a conceptual diagram illustrating an example of the drawing operation in Embodiment 1. As shown in Figure 4, the drawing area 30 (thick line) of the sample 101 is virtually divided into multiple stripe-shaped areas 32 with a predetermined width in the y direction, for example. The example in Figure 4 shows a case where the drawing area 30 of the sample 101 is divided into multiple stripe areas 32 with a width size substantially the same as the size of the designed irradiation area 34 (drawing field) that can be irradiated with one multi-beam 20 irradiation in the y direction. The size of the irradiation area 34 of the designed multi-beam 20 in the x direction can be defined by the number of beams in the x direction × the beam pitch in the x direction. The size of the rectangular irradiation area 34 in the y direction can be defined by the number of beams in the y direction × the beam pitch in the y direction.

[0033] First, the XY stage 105 is moved to adjust the position of the irradiation area 34 of the multi-beam 20 to the left edge of the first stripe area 32, or even further to the left, and the first stripe area 32 is drawn. When drawing the first stripe area 32, the drawing progresses relatively in the x direction by moving the XY stage 105, for example, in the -x direction. The XY stage 105 is moved continuously at a constant speed, for example. After the drawing of the first stripe area 32 is completed, the stage position is moved in the -y direction by the width of the stripe area 32.

[0034] Next, the illumination area 34 of the multi-beam 20 is adjusted to be located at the left edge of the second stripe area 32, or even further to the left, and the drawing of the second stripe area 32 is performed by moving the XY stage 105, for example, in the -x direction, thereby relatively advancing the drawing in the x direction.

[0035] Furthermore, while the example in Figure 4 shows the case where each stripe region 32 is drawn in the same direction, this is not the only option. For example, for the stripe region 32 to be drawn after the stripe region 32 drawn in the x direction, the XY stage 105 can be moved, for example, in the x direction, so that the drawing is performed in the -x direction. By drawing while alternating directions in this way, the stage movement time can be shortened, and consequently, the drawing time can be shortened. In a single shot, the multi-beam formed by passing through each hole 22 of the molded aperture array substrate 203 forms up to the same number of shot patterns as each hole 22 at once.

[0036] Furthermore, while the example in Figure 4 shows the case where the stage is moved once for the drawing process of each stripe area, this is not the only option. It is also preferable to perform multiple drawing (multiple-path drawing) by moving the stage multiple times over the same position. In that case, for example, it is preferable to perform multiple drawing while shifting in the y direction by an amount equal to 1 / n of the width of the stripe area. Alternatively, it is also preferable to perform multiple drawing (in-path multiple drawing) in which the same position is drawn multiple times with different beams during a single stage movement.

[0037] Figure 5 shows an example of the multi-beam irradiation area and the pixels to be drawn in Embodiment 1. In Figure 5, the stripe area 32 is divided into multiple mesh areas, for example, by the beam size of the multi-beam 20. Each of these mesh areas becomes the pixels 36 to be drawn (beam irradiation unit area, irradiation position). The size of the pixels to be drawn 36 is not limited to the beam size and may be composed of any size regardless of the beam size. For example, it may be composed of a size of 1 / n (where n is an integer of 1 or more) of the beam size. In the example of Figure 5, the drawing area of ​​the sample 101 is shown as being divided into multiple stripe areas 32 in the y direction, for example, with a width size that is substantially the same as the size of the irradiation area 34 (drawing field) that can be irradiated with one irradiation of the multi-beam 20. The size of the rectangular irradiation area 34 in the x direction can be defined by the number of beams in the x direction × the beam pitch in the x direction. The size of the rectangular irradiation area 34 in the y direction can be defined by the number of beams in the y direction × the beam pitch in the y direction. In the example in Figure 5, for example, a 512x512-row multibeam is shown as an 8x8-row multibeam. Within the irradiation area 34, multiple pixels 28 (beam drawing positions) that can be irradiated in one shot of the multibeam 20 are shown. The pitch between adjacent pixels 28 becomes the inter-beam pitch of the multibeam. A rectangular area enclosed by the size of the inter-beam pitch in the x and y directions constitutes one sub-irradiation area 29 (pitch cell area). In the example in Figure 5, each sub-irradiation area 29 is shown as being composed of, for example, 4x4 pixels.

[0038] Figure 6 shows the parameters of the linear component in Embodiment 1. In Figure 6, the rectangular beam array shape of the design is shown by a dotted line. In the example in Figure 5, the x and y directions are shown with the center of the rectangular beam array shape as the origin. The XX linear component represents the displacement component that shifts in the x direction in proportion to the x coordinate of the design. Specifically, it represents the displacement component in the x direction that widens (or narrows) in the x direction relative to the beam array shape of the design. The YY linear component represents the displacement component that shifts in the y direction in proportion to the y coordinate of the design. Specifically, it represents the displacement component in the y direction that widens (or narrows) in the y direction relative to the beam array shape of the design. The XY linear component represents the displacement component that shifts in the x direction in proportion to the y coordinate of the design. Specifically, it represents the oblique displacement component that shifts in the x direction while maintaining the y direction relative to the beam array shape of the design. The YX linear component represents the displacement component that shifts in the y direction in proportion to the x coordinate of the design. Specifically, it represents the oblique displacement component that shifts in the y direction while maintaining the x direction relative to the beam array shape of the design. Then, a linear component parameter (first-order approximation coefficient) that depends on the amount of displacement in the x-direction, proportional to the design x-coordinate, is defined as C. XX This is shown. The linear component parameter C depends on the amount of displacement in the y-direction, which is proportional to the design y-coordinate. YY This is shown. The linear component parameter C depends on the amount of displacement in the x-direction that is proportional to the design y-coordinate. XY This is shown. The linear component parameter C depends on the amount of displacement in the y direction, which is proportional to the design x coordinate. YX This is shown.

[0039] The amount of displacement X of the x-coordinate of each point in the beam array shape with the beam array center as the origin can be approximated by the following equation (1-1) using the design coordinates (x,y) with the beam array center as the origin. Similarly, the amount of displacement Y of the y-coordinate of each point in the beam array shape with the beam array center as the origin can be approximated by the following equation (1-2) using the design coordinates (x,y) with the beam array center as the origin. (1-1) X=C XX ·x+C XY ·y (1-2) Y=C YX ·x+C YY ·y

[0040] Figure 7 is a flowchart showing an example of the main steps of the drawing method in Embodiment 1. In Figure 7, the drawing method in Embodiment 1 performs a series of steps: relationship table creation step (S102), beam array shape acquisition step (S104), first-order approximation coefficient calculation step (S106), determination step (S108), rotation correction amount calculation step (S110), magnification correction amount calculation step (S112), control value calculation step (S114), control value setting step (S116), correction step (S118), dose map creation step (S120), modulation dose amount calculation step (S130), dose modulation step (S136), and drawing step (S140). The modulation dose amount calculation step (S130) performs the modulation coefficient calculation step (S132) and the modulation dose amount calculation processing step (S134) as internal steps.

[0041] As part of the relationship table creation process (S102), a relationship table is created for the cases where the rotation amount of the beam array shape described later becomes θ, the magnification becomes m, and the voltages V1 of electrostatic lens 212, V2 of electrostatic lens 214, and V3 of electrostatic lens 216 are varied, respectively, so that the focus position is on the substrate surface. The data for creating such a relationship table can be obtained by experiment or simulation. The multi-beam 20 is irradiated, and for example, a condition matrix of voltages V1, V2, and V3 is created, and the rotation amount θ of the beam array shape, magnification m, and focus position are measured for each condition. From these measurement results, the set of V1, V2, and V3 in which the rotation amount becomes θ and the magnification becomes m under the condition that the focus position is at the desired position is determined.

[0042] Figure 8 shows an example of a relationship table in Embodiment 1. In the example in Figure 8, a V1 table for electrostatic lens 212, a V2 table for electrostatic lens 214, and a V3 table for electrostatic lens 216 are shown. In each table, the vertical axis shows the rotation amount θ1, θ2, .... The horizontal axis shows the magnification m1, m2, .... The voltage V1 (V2, or V3) for giving the desired rotation amount θ and magnification m is defined. The created relationship table is stored in the storage device 144. The relationship table may be created in the drawing device 100 and stored in 4 of the storage device 14, or it may be created offline, input to the drawing device 100, and stored in the storage device 144.

[0043] As a beam array shape acquisition step (S104), first, multiple positions within the beam array are measured using the mark 106. Specifically, for example, when using a reflective mark, the position of the irradiated beam (or beam group) is measured from a secondary electron image obtained by scanning the mark 106 with a beam group consisting of one or multiple adjacent beams and detecting the secondary electrons reflected from the mark 106 with the detector 107. For example, the positions of 5x5 beams within the beam array, including the beams at the four corners of the beam array, are measured. The selection of beams or beam groups can be performed by the blanking aperture array mechanism 204. The position of a beam group can be determined by measuring, for example, the center position of the beam group. Alternatively, the position of each beam in the beam group can be measured and the average value can be taken as the position of the beam group. From the measurement results of each position, the amount obtained by subtracting the average value of the positional displacement of each position is defined as the positional displacement of each beam from its design position. Alternatively, the positional displacement of each beam may be obtained from the positional displacement distribution caused by the beam array shape obtained from the drawing results.

[0044] Figure 9 shows an example of beam positions in Embodiment 1. In the example in Figure 9, the position of the beam (or beam group) in the design and the amount of deviation from there are shown. In the example in Figure 9, for example, 5x5 beam positions are shown.

[0045] As the first-order approximation coefficient calculation step (S106), the beam array shape acquisition unit 50 approximates the displacement amounts dx(i) and dy(i) at a plurality of positions by the above-described expressions (1-1) and (1-2), and calculates the linear component parameters (first-order approximation coefficients) C XX , C XY , C YX , C YY .

[0046] As the determination step (S108), the determination unit 51 determines whether the values of C YX , C XX among the calculated linear component parameters are greater than the threshold value Δth. If not, it proceeds to the drawing step (S120) assuming no correction is necessary. If so, it proceeds to the rotation correction amount calculation step (S110).

[0047] As the rotation correction amount calculation step (S110), the rotation correction amount calculation unit 52 calculates the rotation correction amount Δθ of the beam array shape using the linear component parameter C YX (the second coefficient) indicating the displacement component that shifts in the y direction (the second direction) in proportion to the design coordinates in the x direction (the first direction) of the acquired beam array shape. The rotation correction amount Δθ can be defined by the following expression (2). (2) Δθ = tan -1 (-C YX )

[0048] In Embodiment 1, for example, the x direction (the first direction) is a direction parallel to the drawing direction when each of the plurality of stripe regions 32 into which the drawing region 30 of the sample 101 is divided into strip shapes is drawn. For example, the y direction (the second direction) is a direction orthogonal to the x direction.

[0049] FIG. 10 is a diagram for explaining the rotation amount θ and magnification m of the beam array shape in Embodiment 1. In FIG. 10, the coordinates of the lower right corner of the beam array are ((C XX -C XY +1)A, (C YX -C YY -1)A). The coordinates of the lower left corner are ((-C XX -C XY-1)A,(-C YX -C YY -1)A) can be defined. If the rotation angle is the inclination θ from the x-axis, then tanθ can be defined by the following equation (3). (3) tanθ=C YX / (C XX +1) ≈ C YX

[0050] C XX It is sufficiently small. Therefore, tanθ ≈ C YX It can be defined (approximated) as follows. To perform rotation correction, rotate in the opposite direction as shown in equation (4). (4) tan(-θ)=-C YX / (C XX +1) ≈ -C YX

[0051] Since the rotational compensation amount Δθ = -θ, the rotational compensation amount Δθ can be defined by equation (2).

[0052] As a magnification correction amount calculation step (S112), the magnification correction amount calculation unit 54 calculates a linear component parameter C that indicates the shift component of the acquired beam array shape that is shifted in the x-direction in proportion to the design coordinates in the x-direction (first direction) parallel to the direction in which the XY stage 105 on which the sample 101 is placed is drawn while continuously moving the XY stage 105. XX The magnification correction amount Δm of the beam array shape is calculated using (the first coefficient). The magnification correction amount Δm can be defined by the following equation (5). (5) Δm = 1 / C XX

[0053] In Figure 10, if A is the x-direction dimension from the center position of the design beam array, then the coordinates of the x-direction end passing through the center position of the acquired beam array are (A·C XX It can be defined as (,0). The coordinates of the -x end passing through the center position of the acquired beam array are (-A·C XX It can be defined as ,0). Therefore, the y-direction dimension L passing through the center position of the measured beam array can be defined by the following equation (6). (6) L=2A·C XX

[0054] Therefore, the acquired beam array magnification can be defined as L / 2A when the design beam array magnification is set to 1, so C XX It can be defined as follows. The magnification correction amount Δm should be the reciprocal of the magnification of the acquired beam array. Therefore, the magnification correction amount Δm can be defined by the following equation (5).

[0055] As part of the control value calculation process (S114), the control value calculation unit 56 reads the current control rotation angle θ and magnification m stored in the memory device 144 and calculates the optimal rotation angle θ′=θ+Δθ and magnification m′=m+Δm to correct the beam array shape. It also reads the relationship table stored in the memory device 144 and calculates the voltages V1, V2, and V3 of each electrostatic lens 212, 214, and 216 corresponding to the calculated rotation amount θ′ and magnification m′ by referring to the relationship table.

[0056] As part of the control value setting process (S116), the control value setting unit 58 outputs the calculated voltages V1, V2, and V3 to the electrostatic lens control circuit 131. The electrostatic lens control circuit 131 sets voltage V1 to the control voltage for electrostatic lens 212, voltage V2 to the control voltage for electrostatic lens 214, and voltage V3 to the control voltage for electrostatic lens 216.

[0057] As part of the correction process (S118), two or more electrostatic lenses 212, 214 perform at least one of the following: rotational correction of the beam array shape according to the rotational correction amount and magnification correction of the beam array shape according to the magnification correction amount. Here, we show the case where both are performed.

[0058] Figure 11 shows an example of the state in which rotational correction and magnification correction have been performed on the beam array in Embodiment 1. As a result of adjusting the magnification in the x-direction, the dimension in the x-direction passing through the center position of the beam array can be made to match the design dimension, as shown in Figure 11. In addition, as a result of adjusting the rotation, the displacement component that shifts in the y-direction in proportion to the design coordinate in the x-direction can be corrected, as shown in Figure 11.

[0059] Furthermore, the focus position of the multi-beam 20 is adjusted using a different electrostatic lens 216 from the two or more electrostatic lenses 212, 214. Although the case of adjusting the focus position has been described here, the crossover position may also be adjusted. For example, the final crossover position may be adjusted.

[0060] In Embodiment 1, the beam array shape is corrected using electrostatic lenses 212 and 214 that do not produce hysteresis, resulting in good reproducibility and eliminating the need for shape verification.

[0061] As shown in Figure 11, the displacement component that shifts in the y direction in proportion to the design coordinate in the y direction (YY term component) and the displacement component that shifts in the x direction in proportion to the design coordinate in the y direction (XY term component) remain. In Embodiment 1, the amount of displacement of the YY term component and the XY term component is reduced by dose modulation.

[0062] In the dose map creation process (S120), the drawing data processing unit 70 reads chip pattern data (drawing data) from the storage device 140 and performs rasterization. Specifically, it calculates the pattern density (pattern area density) for each of the 36 pixels.

[0063] Next, the drawing data processing unit 70 calculates a proximity effect correction dose Dp(x) for each nearby mesh region to correct for the proximity effect. The unknown proximity effect correction dose Dp(x) can be defined by a threshold model for proximity effect correction, similar to conventional methods, using the backscattering coefficient η, the dose threshold Dth of the threshold model, the pattern area density ρ″, and the distribution function g(x). The proximity effect correction dose Dp(x) is calculated as a relative value normalized with the reference dose Dbase set to 1.

[0064] Next, the drawing data processing unit 70 calculates the incident irradiation amount D(x) (dose amount) for each pixel to irradiate that pixel. The incident irradiation amount D(x) can be calculated, for example, by multiplying the reference irradiation amount Dbase by the proximity effect correction irradiation amount Dp and the pattern area density ρ'. The reference irradiation amount Dbase can be defined, for example, as Dth / (1 / 2+η). As a result, the incident irradiation amount D(x) for each pixel, corrected for proximity effects, can be obtained based on the layout of multiple graphic patterns defined in the drawing data. Alternatively, the drawing data processing unit 70 may define the incident irradiation amount D(x) for each pixel as an incident irradiation amount D(x) normalized with the reference irradiation amount Dbase set to 1. In this case, the incident irradiation amount D(x) can be calculated, for example, by multiplying the proximity effect correction irradiation amount Dp and the pattern area density ρ'.

[0065] Next, the drawing data processing unit 70 creates a dose map whose elements are the incident irradiation amount D(x) of each pixel 36. In other words, each pixel (position) (x,y) and its incident irradiation amount D(x) are associated and defined. The created dose map is stored in the storage device 142. The drawing data processing unit 70 creates a dose map for the entire drawing area 30 where drawing processing is performed according to the drawing data (chip data).

[0066] When performing multiple draw operations, a dose map is created for each draw operation.

[0067] As a modulation dose calculation step (S130), the modulation dose calculation unit 61 calculates a linear component parameter C that indicates a shift component that is proportional to the design coordinates of the acquired beam array shape in the y direction (second direction) and shifts in the x direction (first direction), for example. YY (The third coefficient) and a linear component parameter C that indicates a displacement component that shifts, for example, in the y-direction (second direction), proportional to the design coordinates of the acquired beam array shape in the y-direction (second direction). XYBased on (the fourth coefficient) and at least one of the following, the modulation dose amount for each pixel 36 (unit area) of the stripe region, which is divided into a mesh, is calculated. Specifically, it works as follows.

[0068] As part of the modulation coefficient calculation process (S132), the modulation coefficient calculation unit 60 calculates a linear component parameter C that represents the shift component of the acquired beam array shape in the y direction, proportional to the design coordinates of the acquired beam array shape in the y direction. YY Using the (third coefficient), the modulation coefficient Δ for each pixel 36 of the multiple pixels 36 (unit region) into which the stripe region 32 is divided into a mesh is calculated. YY Calculate the (first modulation coefficient).

[0069] Figure 12 is a diagram illustrating how the YY term component is corrected in Embodiment 1. In Figure 12, the modulation coefficient Δ is the ratio of the displacement in the y-direction from the pixel 36 by the irradiation position of each beam of the multi-beam 20. YY It is calculated as follows. For example, if the y-direction size of pixel 36 is 1, the length of the shift in the y-direction is the modulation coefficient Δ. YY This corresponds to the YY term component, which changes depending on the position in the y-direction when the center of the designed beam array is taken as the origin. Similarly, the modulation coefficient Δ YY This also changes depending on the position in the y-direction from the center of the beam array. Therefore, the modulation coefficient Δ changes for each pixel's y-position on the surface of sample 101. YY The modulation coefficient Δ is calculated for each pixel at the y-position, with the y-center of the stripe region 32 being the origin in the y-direction. As shown in Figure 4, for example, if the y-direction width of the stripe region 32 and the y-direction size of the beam array region are the same, then for each stripe region 32, the modulation coefficient Δ is calculated for each pixel at the y-position, with the y-center of the stripe region 32 being the origin in the y-direction. YY The modulation coefficient Δ is calculated. If the y-coordinate is the same, the YY term components will be the same even if it shifts in the x-direction, so similarly, YY The same value is obtained. Also, in each stripe region 32, the modulation coefficient Δ between the same positions YY Since the values ​​will be the same, if we calculate for the pixels of one stripe region 32, we can reuse the results for the pixels of the other stripe regions 32.

[0070] Next, the modulation coefficient calculation unit 62 calculates a linear component parameter C that represents the shift component that shifts in the x-direction in proportion to the design coordinates in the y-direction of the acquired beam array shape. XY Using (the fourth coefficient), the modulation coefficient Δ for every 36 pixels is calculated. XY Calculate the (second modulation coefficient).

[0071] Figure 13 is a diagram illustrating how to correct the XY term component in Embodiment 1. In Figure 13, the modulation coefficient Δ is the ratio of the displacement in the x-direction from the pixel 36 at the irradiation position of each beam of the multi-beam 20. XY It is calculated as follows. For example, if the x-direction size of pixel 36 is 1, the length of the displacement in the x-direction is the modulation coefficient Δ. XY This corresponds to the modulation coefficient Δ. The XY term component changes depending on the position in the y direction when the center of the designed beam array is taken as the origin, so similarly, XY This also changes depending on the position in the y-direction from the center of the beam array. Therefore, the modulation coefficient Δ changes for each pixel's y-position on the surface of sample 101. XY The modulation coefficient Δ is calculated as follows: Similar to the case described above, for example, if the y-direction width of the stripe region 32 and the y-direction size of the beam array region are the same, then for each stripe region 32, the y-direction center of the stripe region 32 is taken as the y-origin, and the modulation coefficient Δ is calculated for each pixel at its y-position. XY The modulation coefficient Δ is calculated. If the y-coordinate is the same, the XY term components will be the same even if it shifts in the x-direction, so similarly, XY The same value is obtained. Also, in each stripe region 32, the modulation coefficient Δ between the same positions XY Since the values ​​will be the same, if we calculate for the pixels of one stripe region 32, we can reuse the results for the pixels of the other stripe regions 32.

[0072] As a modulation dose calculation process (S134), the modulation dose calculation processing unit 63 calculates the incident irradiation amount D(x) for each pixel 36 and the modulation coefficient Δ YY and modulation coefficient Δ XY The modulation dose is calculated for every 36 pixels using at least one of the following.

[0073] First, dose modulation is performed to correct the YY term component. As shown in Figure 12, the modulated dose amount d'(i,j), which is the modulated dose amount of the target pixel (i,j) for correcting the YY term component, is calculated using the dose amount d(i,j) of each pixel defined in the dose map. The modulated dose amount d'(i,j) is calculated by defining the x and y coordinates with the center of the design beam array as the origin, and Δ YY When >0, it can be defined by the following equation (7-1): Δ YY When < 0, it can be defined by the following equation (7-2). (7-1) d′(i,j)=(1-Δ YY )d(i,j)+Δ YY d(i,j+1) (7-2) d′(i,j)=(1-Δ YY )d(i,j)+Δ YY d(i,j-1)

[0074] Next, dose modulation is performed to correct the XY term components. As shown in Figure 13, the modulated dose amount d'(i,j), which is the modulated dose amount of the target pixel (i,j) for correcting the XY term components, is calculated using the dose amount d(i,j) of each pixel after correction of the YY term components. The modulated dose amount d'(i,j) is calculated by defining the x and y coordinates with the design beam array center as the origin, and Δ XY When >0, it can be defined by the following equation (8-1): Δ XY When < 0, it can be defined by the following equation (8-2). (8-1) d'(i,j)=(1-Δ XY )d(i,j)+Δ XY d(i+1,j) (8-2) d′(i,j)=(1-Δ XY )d(i,j)+Δ XY d(i-1,j)

[0075] In Embodiment 1, two or more objective lenses are used to perform rotational correction of the beam array shape according to the rotational correction amount, and magnification correction of the beam array shape according to the magnification correction amount, and the modulation of the dose amount is performed for each pixel using the modulation dose amount. This will be explained below.

[0076] As part of the dose modulation process (S136), the dose modulation unit 64 modulates the dose amount for each pixel using the modulated dose amount d'(i,j). Specifically, it replaces the dose amount d(i,j) before modulation with the modulated dose amount d'(i,j), which is the dose amount after modulation.

[0077] The drawing data processing unit 70 creates a modulation dose map using the dose amount of each pixel after modulation and stores it in the storage device 142.

[0078] In the drawing process (S140), the drawing data processing unit 70 first calculates the irradiation time for each pixel 36 using the modulated irradiation amount D(x) (dose amount) defined in the modulation dose map. The irradiation time for each pixel 36 can be calculated by dividing the irradiation amount D(x) of that pixel by the current density J. If the irradiation amount D(x) defined in the modulation dose map is normalized with a reference irradiation amount Dbase of 1, the irradiation time for each pixel 36 can be calculated by multiplying the irradiation amount D(x) by the reference irradiation amount Dbase and dividing the result by the current density J.

[0079] The drawing data processing unit 70 then rearranges the obtained irradiation time data for each pixel 36 in shot order and stores it in the storage device 142. The transfer processing unit 74 then transfers the irradiation time data in shot order to the deflection control circuit 130.

[0080] Then, under the control of the drawing control unit 72, the drawing mechanism 150 draws a pattern on the sample 101 with a multi-beam 20 that has undergone at least one of the rotation correction of the beam array shape and the magnification correction of the beam array shape, as well as modulation of the dose amount. Here, when drawing, the pattern is drawn on the sample 101 with a multi-beam 20 that has undergone rotation correction of the beam array shape, magnification correction of the beam array shape, and further modulation of the dose amount. The drawing mechanism 150 draws a pattern on the sample 101 while moving continuously relative to it in the x direction.

[0081] Figure 14 is a diagram illustrating an example of multi-beam drawing operation in Embodiment 1. The example in Figure 14 shows a case where each sub-irradiation area 29, enclosed by the beam pitch and including one beam irradiation position of each multi-beam 20, is drawn with four different beams. The example in Figure 14 also shows a drawing operation in which the XY stage 105 moves continuously at a speed that moves a distance L equivalent to 8 beam pitches while drawing 1 / 4 (1 of the number of beams used for irradiation) of the area within each sub-irradiation area 29. The example in Figure 14 shows a case where each sub-irradiation area 29 is composed of, for example, 4x4 pixels. In the drawing operation shown in the example in Figure 14, for example, while the XY stage 105 moves a distance L equivalent to 8 beam pitches, the irradiation position (pixel 36) is sequentially shifted by the sub-deflector 209, and the multi-beam 20 is used for 4 shots in a shot cycle T to draw (expose) four different pixels 36 within the same sub-irradiation area 29. While the four pixels 36 are being drawn (exposed), the entire multi-beam 20 is deflected collectively by the main deflector 208 to prevent the irradiation area 34 from shifting relative to the sample 101 due to the movement of the XY stage 105, thereby causing the irradiation area 34 to follow the movement of the XY stage 105. In other words, tracking control is performed. After one tracking cycle is completed, the tracking is reset and returned to the previous tracking start position. Since the drawing of the first pixel row from the right in each sub-irradiation area 29 has been completed, after the tracking reset, in the next tracking cycle, the sub-deflector 209 first deflects the beam to adjust (shift) its drawing position so that it can draw, for example, the second pixel row from the right in each sub-irradiation area 29 that has not yet been drawn. By repeating this operation while the stripe area 32 is being drawn, the position of the irradiation area 34 (34a~34o) of the multi-beam 20 moves sequentially, as shown in the lower part of Figure 4, and drawing is performed.

[0082] Figure 15 shows an example of the positional misalignment state when drawing is performed in Embodiment 1. As described above, the beam array shape can be corrected from the state shown in the upper part of Figure 15 to the state shown in the middle part of Figure 15 by rotation correction and magnification correction. Then, a dose distribution equivalent to the dose distribution obtained when the beam array shape is corrected to the state shown in the lower part of Figure 15 by dose modulation can be obtained by drawing using the beam array shape shown in the middle part of Figure 15 and the irradiation dose modulation described above.

[0083] In the example described above, if rotational correction is performed to correct the YX term component, the XY term component increases. Even when correcting the XY term component by dose modulation, it is desirable that the amount of deviation is not too large. Therefore, as a modification of Embodiment 1, it is also preferable to set an upper limit Δθmax for the rotational correction amount Δθ. Thus, if the value calculated by equation (2) exceeds the upper limit Δθmax, the rotational correction amount Δθ is limited to Δθmax and defined by the following equation (9). (9) Δθ = Δθmax

[0084] In this case, the correction of the YX term component is incomplete. However, by performing continuous movement drawing in the x-direction, as shown in Figure 4, the irradiation areas 34 (34a~34o) of the multi-beam 20 overlap while shifting their position in the x-direction with each tracking reset. Therefore, the positional shift of the YX term component is averaged out by each shot with each tracking reset. As a result, even if an upper limit is set on the rotation correction amount Δθ, the beam array shape can be brought closer to the beam array shape of the design.

[0085] As described above, according to Embodiment 1, it is possible to reduce positional deviations caused by shifts in the linear component of the beam array shape in multibeam lithography.

[0086] Embodiment 2. Embodiment 1 describes a case where rotational correction and magnification correction are performed using electrostatic lenses 212, 214 as two or more objective lenses, but the invention is not limited to this. Embodiment 2 describes a case where an air-core coil, which is an electromagnetic lens, is used instead of an electrostatic lens for rotational correction. Note that the electromagnetic lens is not limited to an air-core coil, but one with low hysteresis is preferred.

[0087] Figure 16 is a conceptual diagram showing the configuration of the drawing apparatus in Embodiment 2. Figure 16 is the same as Figure 1, except that the air-core coil control circuit 135 is located there, and the air-core coil 218 is located there instead of the electrostatic lens 212. The example in Figure 16 shows the air-core coil 218 being located between the reduction lens 205 and the limiting aperture substrate 206, but it is not limited to this. It may be located between the blanking aperture array mechanism 204 and the sample 101.

[0088] The air-core coil 218 is controlled by the air-core coil control circuit 135. The main steps of the drawing method in Embodiment 2 are the same as in Figure 7. Any points not specifically described below may be the same as in Embodiment 1.

[0089] In the relationship table creation process (S102), a relationship table is created for the case where the beam array shape is rotated by a rotation amount θ, the magnification is set to m, and the excitation current I1 of the air-core coil 218, the voltage V2 of the electrostatic lens 214, and the voltage V3 of the electrostatic lens 216 are varied with respect to the rotation amount θ and magnification m, respectively, in order to set the focus position to the substrate plane. The data for creating such a relationship table can be obtained by experimentation or simulation. The multi-beam 20 is irradiated, and for example, first the air-core coil 218 is rotated by a rotation amount θ of the beam array shape. In that state, the electrostatic lens 214 is used to enlarge or reduce the beam array shape to a magnification m. As a result the focus position shifts from the substrate 101 plane, so the electrostatic lens 216 is used to adjust the focus position to the substrate 101 plane. The image magnification and image focus are shifted by adjusting the image rotation. The image focus and image rotation angle are shifted by adjusting the image magnification. The image rotation angle and image magnification are shifted by adjusting the image focus. Therefore, this adjustment is repeated multiple times to find the excitation current I1 and voltages V2 and V3 that result in a state where the deviations of the three parameters—rotation amount, magnification, and focus position—are smaller than the acceptable range. The same adjustment is performed while varying the rotation amount θ and magnification m.

[0090] Figure 17 shows an example of a relationship table in Embodiment 2. In the example in Figure 17, an excitation current I1 table for the air-core coil 218, a V2 table for the electrostatic lens 214, and a V3 table for the electrostatic lens 216 are shown. In each table, the vertical axis shows the amount of rotation θ1, θ2, .... The horizontal axis shows the magnification m1, m2, .... The excitation current I1 (voltage V2 or V3) to achieve the desired amount of rotation θ and magnification m is defined. The created relationship table is stored in the storage device 144. The relationship table may be created within the drawing device 100 and stored in the storage device 144, or it may be created offline, input to the drawing device 100, and stored in the storage device 144.

[0091] The beam array shape acquisition step (S104), the first-order approximation coefficient calculation step (S106), the determination step (S108), the rotation correction amount calculation step (S110), and the magnification correction amount calculation step (S112) are the same as in Embodiment 1.

[0092] As part of the control value calculation process (S114), the control value calculation unit 56 reads the current rotation amount θ, magnification m, and relationship table stored in the memory device 144, and calculates the excitation current I1 of the air-core coil 218 and the voltages V2 and V3 of each electrostatic lens 214 and 216 corresponding to the rotation amount θ and magnification m calculated by referring to the relationship table.

[0093] As part of the control value setting process (S116), the control value setting unit 58 outputs the calculated excitation current I1 to the air-core coil control circuit 135. The air-core coil control circuit 135 sets the excitation current I1 to the excitation current for the air-core coil 218. The control value setting unit 58 also outputs the calculated voltages V2 and V3 to the electrostatic lens control circuit 131. The electrostatic lens control circuit 131 sets voltage V2 to the control voltage for the electrostatic lens 214 and voltage V3 to the control voltage for the electrostatic lens 216.

[0094] In the correction process (S118), the combination of the electrostatic lens 214 and the air-core coil 218 performs rotational correction of the beam array shape according to the rotational correction amount and magnification correction of the beam array shape according to the magnification correction amount. Rotational correction is performed by the air-core coil 218 of the combination of the electrostatic lens 214 and the air-core coil 218. Magnification correction is performed by the electrostatic lens 214 of the combination of the electrostatic lens 214 and the air-core coil 218.

[0095] As a result, as shown in Figure 11, the dimension in the x-direction passing through the center position of the beam array can be made to match the design dimension. Furthermore, as a result of the rotation adjustment, as shown in Figure 11, the displacement component that shifts in the y-direction in proportion to the design coordinate in the x-direction can be corrected.

[0096] Furthermore, similar to Embodiment 1, the focus position of the multi-beam 20 is adjusted using a different electrostatic lens 216 than the electrostatic lens 214. While this description focuses on adjusting the focus position, the crossover position may also be adjusted. For example, the final crossover position may be adjusted.

[0097] In Embodiment 2, the beam array shape is corrected using an air-core coil 218 that does not produce hysteresis and an electrostatic lens 214 that also does not produce hysteresis, resulting in good reproducibility and the omission of shape verification operations.

[0098] The contents of each step from the dose map creation process (S120) onward are the same as in Embodiment 1.

[0099] The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

[0100] Furthermore, while descriptions of the device configuration, control methods, and other parts not directly necessary for explaining the present invention have been omitted, it goes without saying that the necessary device configuration and control methods can be appropriately selected and used. For example, although the control unit configuration for controlling the drawing device 100 has been omitted, it goes without saying that the necessary control unit configuration can be appropriately selected and used.

[0101] Furthermore, all multi-charged particle beam lithography apparatuses and multi-charged particle beam lithography methods that incorporate elements of the present invention and can be appropriately modified by those skilled in the art are included within the scope of the present invention. [Explanation of Symbols]

[0102] 10 beams 20 Multibeam 22 holes 23 electrodes 24 control electrodes 25 Passing hole 26 Counter electrode 36 pixels 29 Sub-irradiation area 32 Stripe Area 34 Irradiation area 41 Control circuits 50 Beam array shape acquisition unit 51 Judgment section 52 Rotation Correction Amount Calculation Unit 54 Magnification correction amount calculation section 56 Control Value Calculation Unit 58 Control Value Setting Unit 60 Modulation coefficient calculation unit 61 Modulation dose calculation unit 62 Modulation coefficient calculation unit 63 Modulation dose calculation processing unit 64. Dose Modulation Section 70 Drawing Data Processing Unit 72 Drawing Control Unit 74 Transfer Processing Unit 100 drawing device 101 samples 102 Electronic Microscope Tube 103 Drawing room 105 XY Stages 106 Mark 107 Detectors 110 Control Computer 112 memory 130 Deflection control circuit 131 Electrostatic lens control circuit 132,134 DAC Amplifier Unit 135 Air-core coil control circuit 136 Lens control circuit 138 Stage control mechanism 139 Stage position measuring instrument 140,142,144 Storage device 150 Drawing mechanism 160 Control System Circuits 200 electron beam 201 Electron Gun 202 Illumination Lens 203 Molded aperture array substrate 204 Blanking Aperture Array Mechanism 205 Reduction Lens 206 Limiting Aperture Substrate 207 Objective lens (electromagnetic lens) 208 Main deflector 209 Sub deflector 210 Mirror 212, 214, 216 Objective lenses (electrostatic lenses) 218 Objective lens (air-core coil) 330 Membrane area

Claims

1. A process for acquiring the beam array shape of a multi-charged particle beam, A step of calculating a magnification correction amount for the beam array shape using a first coefficient that indicates a shift component in the first direction that is proportional to the design coordinates in the first direction parallel to the direction in which the acquired beam array shape is drawn while the stage on which the sample is placed is continuously moved, A step of calculating a rotation correction amount for the beam array shape using a second coefficient that indicates a displacement component that shifts in a second direction perpendicular to the first direction in proportion to the design coordinates of the acquired beam array shape in the first direction, A step of calculating the modulation dose amount for each unit region of a plurality of unit regions into which the stripe region is divided into a mesh, based on at least one of a third coefficient that indicates a shift component that shifts in the first direction in proportion to the design coordinates of the beam array shape acquired in the second direction, and a fourth coefficient that indicates a shift component that shifts in the second direction in proportion to the design coordinates of the beam array shape acquired in the second direction, Using two or more objective lenses, perform at least one of the following: rotational correction of the beam array shape according to the rotational correction amount, and magnification correction of the beam array shape according to the magnification correction amount, and modulate the dose amount for each unit region using the modulation dose amount. A step of drawing a pattern on a sample with the multi-charged particle beam, which has been subjected to at least one of the rotation correction of the beam array shape and the magnification correction of the beam array shape, and the modulation of the dose amount. A multi-charged particle beam lithography method characterized by comprising the following features.

2. The process of calculating the modulation dose is as follows: A step of calculating the first modulation coefficient for each unit region using the third coefficient, A step of calculating a second modulation coefficient for each unit region using the fourth coefficient, A step of calculating the modulation dose for each unit region using the dose amount for each unit region and at least one of the first and second modulation coefficients, The multi-charged particle beam lithography method according to claim 1, characterized by having the following features.

3. The multi-charged particle beam lithography method according to claim 1, wherein the objective lens includes an electrostatic lens.

4. The multi-charged particle beam lithography method according to claim 3, further comprising the step of adjusting one of the crossover position and focus position of the multi-charged particle beam using a different electrostatic lens than the aforementioned electrostatic lens.

5. The multi-charged particle beam lithography method according to claim 1, characterized in that an upper limit is set for the rotation correction amount.

6. A source that emits a multi-charged particle beam, An acquisition unit for acquiring the beam array shape of the multi-charged particle beam, A magnification correction amount calculation unit calculates a magnification correction amount for the beam array shape using a first coefficient that indicates a shift component in the first direction that is proportional to the design coordinates in the first direction parallel to the direction in which the acquired beam array shape is drawn while the stage on which the sample is placed is continuously moved. A rotation correction amount calculation unit calculates a rotation correction amount for the beam array shape using a second coefficient that indicates a displacement component that shifts in a second direction perpendicular to the first direction in proportion to the design coordinates of the acquired beam array shape in the first direction, A modulation dose calculation unit calculates the modulation dose for each unit region of a plurality of unit regions into which the stripe region is divided into a mesh, based on at least one of a third coefficient that indicates a shift component that shifts in the first direction in proportion to the design coordinates of the beam array shape acquired in the second direction, and a fourth coefficient that indicates a shift component that shifts in the second direction in proportion to the design coordinates of the beam array shape acquired in the second direction. A dose amount modulation unit that modulates the dose amount for each unit region using the modulated dose amount, An objective lens that performs at least one of the following: magnification correction of the beam array shape according to the magnification correction amount, and rotational correction of the beam array shape according to the rotational correction amount. A drawing mechanism for drawing a pattern on a sample with the multi-charged particle beam, which has been subjected to at least one of the magnification correction of the beam array shape and the rotation correction of the beam array shape, and the modulation of the dose amount. A multi-charged particle beam lithography apparatus characterized by being equipped with the following features.

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