Illumination lens adjustment method, multi-charged particle beam drawing apparatus, and program

Abstract

PURPOSE: To provide a method capable of at least one of improving current density distribution, reducing local beam distortion, reducing local beam blur, and reducing local misalignment.CONSTITUTION: An adjustment method of an illumination lens according to one aspect of the present invention includes: a step of variably setting a lens value of the illumination lens that guides a multi-charged particle beam to a blanking aperture array mechanism in which a plurality of opening parts are formed and each beam of the multi-charged particle beam passing through the plurality of opening parts is individually blanked and controlled; the steps of: a step of measuring a maximum movement amount from a reference positional relationship in a range in which a total current amount of a beam group passing through the plurality of opening parts for each positional relationship does not become less than a threshold while relatively moving the positional relationship between the multi-charged particle beam and the plurality of opening parts from the reference positional relationship for each lens value; and a step of determining and outputting the lens value of the illumination lens using a measured maximum movement amount for each lens value.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] One aspect of the present invention relates to an illumination lens adjustment method, a multi-charged particle beam lithography apparatus, and a program, and relates to, for example, an illumination lens adjustment technique in multi-beam lithography. [Background technology]

[0002] Lithography technology, which is responsible for the advancement of miniaturization of semiconductor devices, is the only extremely important process in semiconductor manufacturing that generates patterns. In recent years, with the increasing integration density of LSIs, the circuit line width required for semiconductor devices has been getting finer year by year. Here, electron beam (EB) lithography technology has inherently excellent resolution, and lithography is carried out using an electron beam to draw on wafers, etc.

[0003] For example, there is a lithography system that uses multiple beams. Compared to lithography using a single electron beam, using multiple beams allows for the irradiation of many beams at once, thereby significantly improving throughput. In such a 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 of which is blanked, and the unblocked beams are reduced in size by an optical system, deflected by a deflector, and irradiated onto the desired position on the sample.

[0004] In multi-beam lithography, multiple beams are individually blanked during lithography. Therefore, a blanking control mechanism is installed to individually control the blanking of the multiple beams. Therefore, the beams used for lithography are those that have passed through the blanking control mechanism. Furthermore, to shorten the lithography time, a beam with a larger current is required. The current amount is determined by the illumination system lenses that guide the multiple beams to the blanking control mechanism. Therefore, conventionally, the lens values ​​of the illumination system lenses are set to maximize the total current of the multiple beams that have passed through the blanking control mechanism. However, this method has been found to sometimes not optimize the current density distribution. Furthermore, it has been found that some beams may still have anomalies in their exit angles. As a result, problems such as local beam distortion, beam blur, and / or misalignment of the beam array on the sample surface have been encountered. Therefore, improvements in the current density distribution and reductions in local beam distortion, beam blur, and / or misalignment are required.

[0005] Here, two aperture sets are arranged, and assuming that the electron beam is incident perpendicularly, the spot diameter of each beam of the multi-beam can be selected by changing the positional relationship between the two sets. The two aperture sets are then aligned so that the current value is maximized between the apertures that result in the selected spot diameter (see, for example, Patent Document 1). However, there is no mention of the positional relationship between the formed multi-beam and the blanking control mechanism, which changes depending on the lens value. Also disclosed is a method in which some of the multi-beams are turned on, a blanking aperture array is scanned, a current amount map is created based on the beam current detection results by a detector and the position of the blanking aperture array, and the position of the blanking aperture array is adjusted based on the current amount map for each on-beam, allowing the multi-beam to pass through the blanking aperture array (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-171713 [Patent Document 2] Japanese Patent Application Publication No. 2019-121730 Summary of the Invention [Problem to be solved by the invention]

[0007] One aspect of the present invention provides a method that can improve current density distribution, reduce local beam distortion, reduce local beam blur, and / or reduce local misalignment. [Means for solving the problem]

[0008] A method for adjusting an illumination lens according to one aspect of the present invention includes the steps of: a step of variably setting a lens value of an illumination lens that guides the multi-charged particle beam to a blanking aperture array mechanism that has a plurality of apertures formed therein and that individually controls blanking of each beam of the multi-charged particle beam passing through the plurality of apertures; a step of measuring, for each lens value, a maximum amount of movement from the reference positional relationship within a range in which the total amount of current of the beam group passing through the plurality of openings for each positional relationship does not become less than a threshold value while relatively moving the positional relationship between the multi-charged particle beam and the plurality of openings from the reference positional relationship; determining and outputting a lens value of the illumination lens using the maximum amount of movement for each measured lens value; The present invention is characterized by the following.

[0009] The method further includes a step of illuminating, with the illumination lens, a shaping aperture array substrate disposed between the illumination lens and the blanking aperture array mechanism and having a plurality of openings formed therein, with the charged particle beam; Preferably, the multi-charged particle beam is formed by passing portions of the charged particle beam through a plurality of openings in a shaping aperture array substrate.

[0010] Furthermore, it is preferable that the lens value of the illumination lens is determined using only the maximum movement amount for each lens value as a parameter.

[0011] Alternatively, the method may further include a step of measuring a total current amount of the beam group passing through the plurality of openings of the blanking aperture array mechanism for each lens value and each positional relationship, The lens value of the illumination lens is preferably determined using the maximum movement amount for each lens value and the total current amount for each lens value as parameters.

[0012] Alternatively, the method may further include a step of measuring a current density distribution of a group of beams passing through a plurality of openings of the blanking aperture array mechanism for each lens value, It is preferable that the lens value of the illumination lens be determined using as parameters the maximum movement amount for each lens value and the current density distribution minimum value ratio for each lens value, which is the ratio of the minimum value to the maximum value obtained in the measured current density distribution.

[0013] Alternatively, a step of measuring a total current amount of a group of beams passing through a plurality of openings of a blanking aperture array mechanism for each lens value and each positional relationship; measuring a current density distribution of a group of beams passing through a plurality of openings of a blanking aperture array mechanism for each lens value; Furthermore, The lens value of the illumination lens is preferably determined using the following parameters: the maximum movement amount for each lens value, the total current amount for each lens value, and the minimum value ratio of the current density distribution for each lens value, which is the ratio of the minimum value to the maximum value obtained in the measured current density distribution.

[0014] A multi-charged particle beam writing apparatus according to one aspect of the present invention comprises: an emission source that emits a charged particle beam; an illumination lens that refracts the charged particle beam; a shaping aperture array substrate having a plurality of first openings formed therein, the shaping aperture array substrate being irradiated with the charged particle beam refracted by the illumination lens, and a portion of the charged particle beam passing through the plurality of first openings to form a multi-charged particle beam; a blanking aperture array mechanism in which a plurality of second openings are formed and which controls blanking of each beam of the multi-charged particle beam passing through the plurality of second openings individually; a moving mechanism that moves the shaping aperture array substrate and the blanking aperture array mechanism relative to each other; a current amount measuring mechanism that measures a total current amount of the beam group passing through the plurality of second apertures; a stage on which a sample can be placed, the sample being irradiated with a group of beams passing through the plurality of second openings to form a pattern; a setting unit that variably sets the lens value of the illumination lens; a displacement measurement unit that measures, for each lens value, a maximum displacement from a reference positional relationship within a range in which the total amount of current of the beam group passing through the plurality of second openings for each positional relationship does not become less than a threshold value while relatively displacing the positional relationship between the shaping aperture array substrate and the blanking aperture array mechanism from a reference positional relationship; a determination unit that determines a lens value of the illumination lens using the maximum movement amount for each measured lens value; It is preferable to have the following.

[0015] A program according to one aspect of the present invention comprises: a process of variably setting a lens value of an illumination lens that guides the multi-charged particle beam to a blanking aperture array mechanism that has a plurality of apertures formed therein and that individually controls blanking of each beam of the multi-charged particle beam passing through the plurality of apertures; a process of measuring a maximum amount of movement from the reference positional relationship within a range in which the total amount of current of the beam group passing through the plurality of openings for each positional relationship does not become less than a threshold value while relatively moving the positional relationship between the multi-charged particle beam and the plurality of openings from the reference positional relationship for each lens value; A process of storing the maximum movement amount for each measured lens value in a storage device; a process of reading out the maximum movement amount for each lens value stored in the storage device, determining the lens value of the illumination lens using the read-out maximum movement amount for each lens value, and outputting the lens value; to be executed by the computer. [Effects of the Invention]

[0016] According to one aspect of the present invention, at least one of an improvement in current density distribution, a reduction in local beam distortion, a reduction in local beam blur, and a reduction in local positional deviation can be achieved. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a conceptual diagram showing a configuration of a drawing device according to a first embodiment. [Figure 2] FIG. 2 is a conceptual diagram showing the configuration of a shaping aperture array substrate according to the first embodiment. [Figure 3] 2 is a cross-sectional view showing the configuration of a blanking aperture array mechanism in the first embodiment. FIG. [Figure 4] FIG. 2 is a conceptual diagram for explaining an example of a drawing operation in the first embodiment. [Figure 5] 3 is a diagram showing an example of a multi-beam irradiation area and a pixel to be written in the first embodiment. FIG. [Figure 6] FIG. 2 is a diagram for explaining an example of a multi-beam writing operation according to the first embodiment. [Figure 7] FIG. 10 is a diagram showing an example of the relationship between the lens value of the illumination system lens, the current density distribution, and the maximum value of the total current amount in a comparative example to the first embodiment. [Figure 8] FIG. 10 is a diagram showing an example of a beam array shape on a sample surface in a comparative example to the first embodiment. [Figure 9] FIG. 10 is a diagram showing an example of a beam trajectory in a comparative example to the first embodiment. [Figure 10] FIG. 2 is a flowchart showing an example of main steps of the writing method according to the first embodiment. [Figure 11]3 is a diagram showing an example of the positional relationship between a shaping aperture array substrate and a blanking aperture array mechanism according to the first embodiment. FIG. [Figure 12] FIG. 4 is a diagram showing an example of the relationship between the total current amount and the shift position in the first embodiment. [Figure 13] FIG. 4 is a diagram for explaining how to measure a margin in the first embodiment. [Figure 14] FIG. 4 is a diagram for explaining parameter values ​​relating to the total current amount in the case where the total current amount is included in the parameters according to the first embodiment. [Figure 15] FIG. 4 is a diagram for explaining parameter values ​​relating to current density in the case where current density is included in the parameters according to the first embodiment. [Figure 16] FIG. 3 is a diagram for explaining a method for measuring a current density in the first embodiment. [Figure 17] FIG. 4 is a diagram showing an example of the relationship between the illumination system lens value, the margin, and the current density according to the first embodiment. [Figure 18] FIG. 2 is a diagram showing an example of a beam array shape on a sample surface in the first embodiment. [Figure 19] FIG. 2 is a diagram showing an example of beam illumination by an illumination system lens according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] In the following embodiments, a configuration using an electron beam will be described as an example of a charged particle beam, but the charged particle beam is not limited to an electron beam and may be a beam using charged particles such as an ion beam.

[0019] Embodiment 1 FIG. 1 is a conceptual diagram showing the configuration of a lithography apparatus according to the first embodiment. In FIG. 1, the lithography apparatus 100 includes a lithography mechanism 150 and a control circuit 160. The lithography apparatus 100 is an example of a multi-charged particle beam lithography apparatus and also an example of a multi-charged particle beam exposure apparatus. The lithography mechanism 150 includes an electron lens barrel 102 (electron beam column) and a lithography chamber 103. Inside the electron lens barrel 102, an electron gun 201, an illumination lens 202, a shaping aperture array substrate 203, a blanking aperture array mechanism 204, a reduction lens 205, a limiting aperture substrate 206, an objective lens 207, a main deflector 208, a sub-deflector 209, a drive mechanism 212, and a drive mechanism 214 are arranged.

[0020] An XY stage 105 is disposed within the patterning chamber 103. A sample 101, such as a mask, which will be the patterned substrate during patterning (exposure) is disposed on the XY stage 105. The sample 101 includes an exposure mask used in manufacturing a semiconductor device, or a semiconductor substrate (silicon wafer) on which a semiconductor device is manufactured. The sample 101 also includes a mask blank coated with resist and on which nothing has yet been patterned. A mirror 210 for measuring the position of the XY stage 105 is also disposed on the XY stage 105.

[0021] Furthermore, a Faraday cup 106 is placed on the XY stage 105. Note that, although the example in Fig. 1 shows a case where the Faraday cup 106 is placed on the XY stage 105, the present invention is not limited to this. The Faraday cup 106 may be placed in any position downstream of the blanking aperture array mechanism 204 in the beam traveling direction and at a position where the entire multi-beam can be detected.

[0022] The control system circuit 160 includes a control computer 110, a memory 112, a deflection control circuit 130, an aperture position control circuit 131, digital-to-analog conversion (DAC) amplifier units 132 and 134, a lens control circuit 136, a current amount detection circuit 137, a stage control mechanism 138, a stage position measurement device 139, and storage devices 140 and 142 such as magnetic disk drives. The control computer 110, the memory 112, the deflection control circuit 130, the aperture position control circuit 131, the lens control circuit 136, the current amount detection circuit 137, the stage control mechanism 138, the stage position measurement device 139, and storage devices 140 and 142 are interconnected via a bus (not shown). The deflection control circuit 130 is connected to the 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 a deflection control circuit 130 via a DAC amplifier 134. The group of electromagnetic lenses, including the illumination lens 202, the reduction lens 205, and the objective lens 207, is controlled by a lens control circuit 136.

[0023] The position of the XY stage 105 is controlled by driving motors (not shown) for each axis controlled by a stage control mechanism 138. A stage position measuring device 139 receives light reflected from a mirror 210 and measures the position of the XY stage 105 based on the principle of laser interferometry.

[0024] The position of the shaping aperture array substrate 203 is movable by a drive mechanism 212 controlled by the aperture position control circuit 131. The shaping aperture array substrate 203 moves in a direction on a plane perpendicular to the central axis of the multibeams 20. Similarly, the position of the blanking aperture array mechanism 204 is movable by a drive mechanism 214 controlled by the aperture position control circuit 131. The blanking aperture array mechanism 204 moves in a direction on a plane perpendicular to the central axis of the multibeams 20. With such a mechanism, the relative positional relationship between the shaping aperture array substrate 203 and the blanking aperture array mechanism 204 can be changed by moving either one or both of them. In other words, the movement mechanisms such as the drive mechanisms 212 and 214 move the shaping aperture array substrate 203 and the blanking aperture array mechanism 204 relatively in a direction perpendicular to the central axis of the trajectory of the multibeams 20. The driving mechanism 212 may further move the shaping aperture array substrate 203 in the direction of the central axis (z direction) of the multi-beam 20. Similarly, the driving mechanism 214 may further move the blanking aperture array mechanism 204 in the direction of the central axis (z direction) of the multi-beam 20.

[0025] Data on the amount of current detected by the Faraday cup 106 is output to a current amount detection circuit 137, converted into digital data by the current amount detection circuit 137, and then output to the control computer 110. The Faraday cup 106 is, for example, simultaneously irradiated with the entire multibeam 20 and measures the amount of current for the entire multibeam 20. Alternatively, it is simultaneously irradiated with some beam groups of the multibeam 20 and measures the amount of current for these beam groups.

[0026] The control computer 110 includes a rasterization processing unit 50, a shot data generation unit 52, a lens value setting unit 54, a current amount measurement unit 56, a shift processing unit 60, a judgment unit 62, a margin measurement unit 63, a judgment unit 64, a current density distribution creation unit 66, a parameter calculation unit 68, a lens value determination unit 70, a drawing control unit 72, and a transfer processing unit 74. Each of the "~ units" such as the rasterization processing unit 50, shot data generation unit 52, lens value setting unit 54, current amount measurement unit 56, shift processing unit 60, judgment unit 62, margin measurement unit 63, judgment unit 64, current density distribution creation unit 66, parameter calculation unit 68, lens value determination unit 70, drawing control unit 72, and transfer processing unit 74 has a processing circuit. Such a processing circuit includes, for example, an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each of the "~ units" may use a common processing circuit (the same processing circuit) or different processing circuits (separate processing circuits). Information input and output to and from the rasterization processing unit 50, shot data generation unit 52, lens value setting unit 54, current amount measurement unit 56, shift processing unit 60, judgment unit 62, margin measurement unit 63, judgment unit 64, current density distribution creation unit 66, parameter calculation unit 68, lens value determination unit 70, drawing control unit 72, and transfer processing unit 74, as well as information being calculated, are stored in memory 112 each time.

[0027] The drawing operation of the drawing apparatus 100 is controlled by a drawing control unit 72. In other words, the drawing control unit 72 (an example of a control circuit) controls the drawing mechanism 150. In addition, a transfer process of the irradiation time data of each shot to the deflection control circuit 130 is controlled by a transfer processing unit 74.

[0028] 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 on a plurality of figure patterns that constitute the chip pattern. Specifically, for each figure pattern, for example, the coordinates of each vertex are defined in the order in which the figure is formed. Alternatively, for each figure pattern, for example, a figure code, coordinates, size, etc. are defined.

[0029] 1 shows the configuration necessary for explaining the first embodiment. The drawing device 100 may also include other configurations that are normally required.

[0030] FIG. 2 is a conceptual diagram showing the configuration of a shaping aperture array substrate in the first embodiment. In FIG. 2, holes (openings) 22 are formed in a matrix of p columns (y direction) by q columns (x direction) (p, q≧2) at a predetermined arrangement pitch in shaping aperture array substrate 203. The example in FIG. 2 shows, for example, a case where 512×512 columns of holes 22 are formed in the vertical and horizontal directions (x, y directions). The number of holes 22 is not limited to this. For example, 32×32 columns of holes 22 may be formed. Each hole 22 is formed as a rectangle of the same size and shape. Alternatively, it may be a circle of the same diameter. A portion of electron beam 200 passes through each of these multiple holes 22, thereby forming multiple beams 20. In other words, shaping aperture array substrate 203 forms multiple beams 20.

[0031] FIG. 3 is a cross-sectional view showing the configuration of the blanking aperture array mechanism according to the first embodiment. As shown in FIG. 3, the blanking aperture array mechanism 204 includes a blanking aperture array substrate 31, which is made of a semiconductor substrate such as silicon, and is disposed on a support base 33. In a central membrane region 330 of the blanking aperture array substrate 31, passage holes 25 (openings) for passing through each beam of the multi-beams 20 are formed at positions corresponding to the holes 22 of the shaping aperture array substrate 203 shown in FIG. 2. Pairs of control electrodes 24 and counter electrodes 26 (blankers: blanking deflectors) are disposed at positions facing each other across the corresponding passage holes 25 among the plurality of passage holes 25. Furthermore, a control circuit 41 (logic circuit) is disposed inside the blanking aperture array substrate 31 near each passage hole 25, which applies a deflection voltage to the control electrode 24 for each passage hole 25. The counter electrodes 26 for each beam are connected to ground.

[0032] An amplifier (an example of a switching circuit), not shown, is disposed within the control circuit 41. As an example of the amplifier, a CMOS (Complementary MOS) inverter circuit serving as a switching circuit is disposed. To the input (IN) of the CMOS inverter circuit, either an L (low) potential (e.g., ground potential) that is lower than the threshold voltage or an H (high) potential (e.g., 1.5 V) that is equal to or higher than the threshold voltage is applied as a control signal. In the first embodiment, 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 corresponding beam is deflected by an electric field due to the potential difference with the ground potential of the counter electrode 26, and is controlled so that the beam is turned OFF by being shielded by the limiting aperture substrate 206. On the other hand, when an H potential is applied to the input (IN) of the CMOS inverter circuit (active state), the output (OUT) of the CMOS inverter circuit becomes the ground potential, and there is no potential difference with the ground potential of the opposing electrode 26, so the corresponding beam is not deflected, and the beam is controlled to be ON by passing through the limiting aperture substrate 206. Blanking control is performed by this deflection.

[0033] Next, a specific example of the operation of the drawing mechanism 150 will be described. An electron beam 200 emitted from an electron gun 201 (emission source) is refracted by an illumination lens 202 and ideally illuminates the entire shaping aperture array substrate 203 almost perpendicularly. A plurality of rectangular holes 22 (openings) are formed in the shaping aperture array substrate 203, and the electron beam 200 illuminates an area including all of the holes 22. Portions of the electron beam 200 irradiated onto the positions of the holes 22 pass through the holes 22 of the shaping aperture array substrate 203, thereby forming, for example, a rectangular multibeam (multiple electron beams) 20. The multibeam 20 passes through corresponding blankers of a blanking aperture array mechanism 204. Each blanker performs blanking control on the beams passing through it so that the beams are turned on for a set drawing time (irradiation time). In other words, the blanking aperture array mechanism 204 individually controls blanking of each of the multiple child beams 20 passing through the multiple passage holes 25 .

[0034] The multi-beams 20 that pass through the blanking aperture array mechanism 204 are reduced by the reduction lens 205 and travel toward a central hole formed in the limiting aperture substrate 206. Here, the electron beams deflected by the blankers of the blanking aperture array mechanism 204 are shifted from the central hole of the limiting aperture substrate 206 and are blocked by the limiting aperture substrate 206. On the other hand, the electron beams that are not deflected by the blankers of the blanking aperture array mechanism 204 pass through the central hole of the limiting aperture substrate 206 as shown in FIG. 1. In this way, the limiting aperture substrate 206 blocks each beam that is deflected by the blankers of the blanking aperture array mechanism 204 to be in a beam-off state. Then, each beam of one shot is formed by the beams that pass through the limiting aperture substrate 206 from when the beams are turned on until when they are turned off. The multibeams 20 that have passed through the limiting aperture substrate 206 are focused by the objective lens 207 to form a pattern image with the desired reduction ratio, and the entire multibeams 20 that have passed through the limiting aperture substrate 206 are deflected in the same direction by the main deflector 208 and the sub-deflector 209, and each beam is irradiated onto its respective irradiation position on the sample 101. Furthermore, for example, when the XY stage 105 is moving continuously, tracking control is performed by the main deflector 208 so that the beam irradiation position follows the movement of the XY stage 105. Ideally, the multibeams 20 that are irradiated at one time are arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of holes 22 in the shaping aperture array substrate 203 by the desired reduction ratio described above.

[0035] Fig. 4 is a conceptual diagram for explaining an example of the writing operation in embodiment 1. As shown in Fig. 4, the writing region 30 (bold line) on the sample 101 is virtually divided, for example, in the y direction into a plurality of rectangular stripe regions 32 with a predetermined width. The example in Fig. 4 shows a case where the writing region 30 on the sample 101 is divided, for example, in the y direction, into a plurality of stripe regions 32 with a width that is substantially the same as the size of the designed irradiation region 34 (writing field) that can be irradiated with a single irradiation of the multibeam 20.

[0036] 4 shows a case where each stripe region 32 is written once, but this is not limiting. Each stripe region 32 may also be written multiple times. Multiple writing with a degree of multiplicity of N (N-pass multiple writing) may be performed, in which the same stripe region 32 is written N times by moving the stage N times (N passes) in the x direction or the −x direction (N is an integer greater than or equal to 2). When performing N-pass multiple writing, it is preferable to overlap the stripe regions 32 by shifting the positions of the stripe regions 32 in the y direction in each pass. The shift amount per pass is preferably, for example, 1 / N of the width of the stripe region 32.

[0037] Furthermore, the above-described position shift is not limited to the y direction, but may also be applied to the x direction. Next, an example of the drawing operation will be described.

[0038] First, the XY stage 105 is moved and adjusted so that the irradiation area 34 of the multi-beam 20 is positioned at the left end of the first stripe region 32 or further to the left. Then, when writing the first stripe region 32, the XY stage 105 is moved, for example, in the -x direction, thereby relatively progressing writing in the x direction. The XY stage 105 is moved continuously at a constant speed, for example.

[0039] After the first stripe region 32 has been written, the stage position is moved in the -y direction by the width of the stripe region 32. As a result, the written stripe region 32 is shifted in the y direction by the width of the stripe region 32.

[0040] Next, the irradiation area 34 of the multi-beam 20 is adjusted to be located at the left end of the second stripe area 32, or at a position further to the left. Then, by moving the XY stage 105, for example, in the -x direction, writing proceeds relatively in the x direction. In this way, writing of the second stripe area 32 is completed. By repeating the same process thereafter, writing of all the stripe areas 32 is completed.

[0041] 4 shows the case where each stripe region 32 is written in the same direction, but this is not limiting. For example, the stripe region 32 to be written next to the stripe region 32 written in the x direction may be written in the -x direction by moving the XY stage 105 in the x direction, for example. By writing while alternating directions in this way, the stage movement time can be shortened, and ultimately the writing time can be shortened. In one shot, multiple shot patterns, up to the same number as the holes 22, are formed at once by the multi-beams formed by passing through each hole 22 in the shaping aperture array substrate 203.

[0042] FIG. 5 shows an example of a multibeam irradiation area and a target pixel for drawing in the first embodiment. In FIG. 5, the stripe area 32 is divided into a plurality of mesh areas, for example, based on the beam size of the multibeam 20. Each mesh area corresponds to a target pixel 36 (beam irradiation unit area, irradiation position). The size of the target pixel 36 is not limited to the beam size and may be any size regardless of the beam size. For example, the size may be 1 / n (n is an integer greater than or equal to 1) of the beam size. The example of FIG. 5 shows a case where the target region for drawing on the sample 101 is divided, for example, in the y direction, into a plurality of stripe areas 32, each having a width substantially equal to the size of the irradiation region 34 (drawing field) that can be irradiated with one irradiation of the multibeam 20. The size of the rectangular irradiation region 34 in the x direction can be defined by the number of beams in the x direction multiplied by the beam pitch in the x direction. The size of the rectangular irradiation region 34 in the y direction can be defined by the number of beams in the y direction multiplied by the beam pitch in the y direction. In the example of Figure 5, for example, a 512 x 512 array of multi-beams is shown as an 8 x 8 array of multi-beams. A plurality of pixels 28 (beam drawing positions) that can be irradiated with one shot of the multi-beams 20 are shown within the irradiation area 34. The pitch between adjacent pixels 28 is the inter-beam pitch of each of the multi-beams. A rectangular area surrounded 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 of Figure 5, each sub-irradiation area 29 is shown as being composed of, for example, 4 x 4 pixels.

[0043] FIG. 6 is a diagram illustrating an example of a multi-beam writing operation in the first embodiment. The example of FIG. 6 illustrates a case where writing is performed in each sub-irradiation region 29 with four different beams. The example of FIG. 6 also illustrates a writing operation in which the XY stage 105 continuously moves at a speed of a distance L corresponding to eight beam pitches while writing one-quarter of each sub-irradiation region 29 (one corresponding to the number of beams used for irradiation). In the writing operation illustrated in the example of FIG. 6, for example, while the XY stage 105 moves the distance L corresponding to eight beam pitches, the sub-deflector 209 sequentially shifts the irradiation position (pixel 36) to write (expose) four different pixels in the same sub-irradiation region 29, thereby firing four shots of the multi-beam 20 in a shot cycle T. While writing (exposing) these four pixels, the main deflector 20 collectively deflects the entire multi-beam 20, causing the irradiation region 34 to follow the movement of the XY stage 105 so that the relative position of the irradiation region 34 to the sample 101 does not shift due to the movement of the XY stage 105. In other words, tracking control is performed. When one tracking cycle is completed, tracking is reset and the system returns to the previous tracking start position. Note that since the drawing of the first pixel row from the right in each sub-irradiation area 29 has been completed, after tracking reset, the sub-deflector 209 first deflects the beam in the next tracking cycle to align (shift) the drawing position of the beam so that the drawing of an undrawn pixel row in each sub-irradiation area 29, for example, the second pixel row from the right, is drawn. By repeating this operation during drawing of the stripe area 32, the position of the irradiation area 34 of the multi-beam 20 sequentially moves as shown in the irradiation areas 34a, 34b, 34c, ... 34o shown in the lower diagram of Figure 4, and drawing is performed.

[0044] As described above, multibeams 20 are formed by illuminating shaping aperture array substrate 203 with electron beam 200 via illumination lens 202. The formed multibeams 20 are then guided to blanking aperture array mechanism 204 by illumination lens 202. The amount of current in multibeam 20 depends on illumination lens 202 that guides the multibeams to blanking aperture array mechanism 204.

[0045] Conventionally, the lens value (input value to the target lens, which means the current value flowing through the coil of the electromagnetic lens if the lens is an electromagnetic lens, or the voltage value applied to the electrode of the electrostatic lens if the lens is an electrostatic lens) that maximizes the total current amount of the multi-beams that have passed through the blanking control mechanism has been set for the illumination lens. However, it has been found that this method sometimes does not optimize the current density distribution.

[0046] FIG. 7 is a diagram showing an example of the relationship between the lens value of the illumination system lens, the current density distribution, and the maximum value of the total current amount in a comparative example of the first embodiment. In FIG. 7, the vertical axis shows the current distribution minimum value ratio, which is the ratio of the minimum value to the maximum value of the current density distribution. The horizontal axis shows the relative value of the lens value. In the example of FIG. 7, the relative lens value is shown based on the lens value at which the total current amount of the multi-beams 20 is maximum. As shown in the example of FIG. 7, it can be seen that there are lens values ​​at which the current distribution minimum value ratio is larger than when the illumination system lens is set to the lens value at which the total current amount of the multi-beams 20 is maximum.

[0047] Fig. 8 is a diagram showing an example of the beam array shape on the sample surface in a comparative example of embodiment 1. As shown in the example of Fig. 8, it can be seen that the beam position is largely shifted inward locally at one of the four corners of the beam array, causing local beam distortion in the beam array.

[0048] 9 is a diagram showing an example of a beam trajectory in a comparative example of the first embodiment. In FIG. 9, an electron beam refracted by an illumination lens causes some of the formed multi-beams to collide with the wall surface of the opening of the blanking aperture array mechanism while passing through. This causes the shape of the locally shaped beam to be chipped. This is detected as a local positional deviation on the sample surface, and the distance to the sample surface changes due to the positional deviation, resulting in a shift in the focal position, resulting in beam blur.

[0049] As described above, it has been found that conventional methods not only fail to optimize the current density distribution, but also may cause local distortion of the beam array shape, beam blur, and / or positional deviation. Therefore, in the first embodiment, the lens value is determined not by the total current amount, but by mainly using another method. This will be explained in detail below.

[0050] Fig. 10 is a flowchart showing an example of main steps of the writing method according to the embodiment 1. In Fig. 10, the writing method according to the embodiment 1 carries out a series of steps including a reference positioning step (S102), an illumination system lens value setting step (S110), a current measuring step (S112), a determination step (S114), a shifting step (S116), a margin measuring step (S118), a determination step (S120), a parameter calculating step (S122), a lens value determining step (S124), an illumination system lens value setting step (S126), a positioning step (S130), and a writing step (S140).

[0051] In the reference position alignment step (S102), under the control of aperture position control circuit 131, drive mechanism 212 drives shaping aperture array substrate 203 to place shaping aperture array substrate 203 at the designed position. Similarly, under the control of aperture position control circuit 131, drive mechanism 214 drives blanking aperture array mechanism 204 to place blanking aperture array mechanism 204 at the designed position. This determines the reference positional relationship (reference position) between shaping aperture array substrate 203 and blanking aperture array mechanism 204. In addition, using an alignment coil (not shown) that is arranged closer to electron gun 201 than shaping aperture array substrate 203, the beam trajectory is adjusted so that the central axis of the beam trajectory is ideally perpendicular to shaping aperture array substrate 203 and blanking aperture array mechanism 204.

[0052] In the illumination system lens value setting step (S110), the lens value setting unit 54 variably sets the lens value of the illumination lens 202, which guides the multibeams 20 to the blanking aperture array mechanism 204, which individually controls blanking of each beam of the multibeams 20 passing through the multiple passage holes 25. Here, one of multiple lens values ​​prepared in advance is set. For example, it is preferable to prepare multiple lenses before and after a designed lens value. Specifically, the operation is as follows: The lens value setting unit 54 sets the lens of the illumination lens 202 in the lens control circuit 136. The lens control circuit 136 controls the illumination lens 202 to match the set lens value. Specifically, a current corresponding to the lens value is passed through the coil of the electromagnetic lens.

[0053] In the current measurement step (S112), the current amount measurement unit 56 measures the total current amount of the beam group passing through the multiple passage holes 25 of the blanking aperture array mechanism 204 for each lens value and for each positional relationship. Specifically, the operation is as follows. The current amount measurement unit 56 measures the current amount of the multi-beams 20 that have passed through the blanking aperture array mechanism 204 in the current relative positional relationship between the shaping aperture array substrate 203 and the blanking aperture array mechanism 204. Specifically, the operation is as follows. First, the XY stage 105 is moved to a position where the Faraday cup 106 can receive the multi-beams 20. Then, the Faraday cup 106 is irradiated with the multi-beams 20 that have passed through the blanking aperture array mechanism 204. The Faraday cup 106 (an example of a current amount measurement mechanism) measures the total current amount of the beam group passing through the multiple passage holes 25 of the blanking aperture array mechanism 204. The measurement data corresponding to the current amount of the multi-beams 20 measured by the Faraday cup 106 is converted into digital data of the current amount by the current amount measurement circuit 137 and output to the control computer 110. The current amount measurement unit 56 measures the current amount of the multi-beams 20 by inputting the current amount measured by the Faraday cup 106 via the current amount measurement circuit 137. If the Faraday cup 106 can measure the current amounts of all the multi-beams 20 at once, the measured value is measured as the total current amount of the multi-beams 20. If the Faraday cup 106 measures the current amount of each of some of the beam groups of the multi-beams 20, the sum of the values ​​measured for each beam group is measured as the total current amount of the multi-beams 20.

[0054] In the determination step (S114), the determination unit 62 determines whether current measurement has been completed at all shift positions. If current measurement has been completed at all shift positions, the process proceeds to the margin measurement step (S118). If current measurement has not been completed at all shift positions, the process proceeds to the shift step (S116).

[0055] In the shift step (S116), shift processing unit 60 controls one or both of drive unit 212 and drive unit 214 via aperture position control circuit 131 to shift the position of one or both of shaping aperture array substrate 203 and blanking aperture array mechanism 204. As a result, one or both of shaping aperture array substrate 203 and blanking aperture array mechanism 204 are shifted in a direction perpendicular to the designed central axis of the trajectory of multibeam 20. Therefore, ideally, one or both of shaping aperture array substrate 203 and blanking aperture array mechanism 204 are shifted in a direction perpendicular to the central axis of the trajectory of multibeam 20.

[0056] 11 is a diagram showing an example of the positional relationship between the shaping aperture array substrate and the blanking aperture array mechanism in embodiment 1. Each beam 10 of multibeam 20 is formed to the size of hole 22 in shaping aperture array substrate 203. The size of passage hole 25 in blanking aperture array mechanism 204 is larger than the size of each beam 10. Therefore, the total shift amount only needs to be the size of passage hole 25 in blanking aperture array mechanism 204. If the shift is made any greater than this, each beam 10 will deviate from passage hole 25 in blanking aperture array mechanism 204.

[0057] Therefore, the size of the passage hole 25 is divided into a plurality of shift amounts, and a plurality of shift positions at intervals of the shift amounts are set. In other words, the shift processing unit 60 moves the relative position between the shaping aperture array substrate 203 and the blanking aperture array mechanism 204 by the shift amount. Here, for example, the blanking aperture array mechanism 204 is moved from the reference position, for example, to the left (-x direction) by one shift amount. Then, the process returns to the current measurement step (S112), and each step from the current measurement step (S112) to the shift step (S116) is repeated until current measurement is completed at all shift positions.

[0058] FIG. 12 is a diagram showing an example of the relationship between the total current amount and the shift position in the first embodiment. In FIG. 12, the vertical axis represents the total current amount of the multi-beam 20. The horizontal axis represents the shift amount of the shaping aperture array substrate 203 and the blanking aperture array mechanism 204 from the reference position (coordinate 1). For example, while the position of the shaping aperture array substrate 203 is fixed, the position of the blanking aperture array mechanism 204 is shifted by the shift amount. The blanking aperture array mechanism 204 is shifted back and forth in the x direction from the reference position. Similarly, it is shifted back and forth in the y direction from the reference position. Then, the total current amount is measured at each shift position. FIG. 12 shows, for example, the x direction.

[0059] In the margin measurement step (S118), the margin measurement unit 63 (movement amount measurement unit) moves the positional relationship between the multibeam 20 and the multiple passage holes 25 relative to a reference positional relationship in a direction perpendicular to the central axis of the trajectory of the multibeam 20 for each lens value, and measures a margin (maximum movement amount) from the reference positional relationship within a range in which the total current amount of the multibeam 20 (beam group) passing through the multiple passage holes 25 for each positional relationship does not fall below a threshold value Mth. The threshold value Mth is preferably set, for example, in the range of 99.0 to 99.9% of the total current amount at the reference position (coordinate 1). More preferably, it is set in the range of 99.5 to 99.8% of the total current amount at the reference position (coordinate 1). For example, it is set to 99.7% of the total current amount at the reference position (coordinate 1). This value corresponds to the proportion of the total current amount when, for example, several sequences at the periphery of the multibeam 20 do not reach the sample surface. The margin in the x direction is measured as the sum of the margin (1) in the -x direction from the reference position (coordinate 1) and the margin (2) in the +x direction from the reference position (coordinate 1). Similarly, the margin in the y direction is measured as the sum of the margin (1) in the -y direction from the reference position (coordinate 1) and the margin (2) in the +y direction from the reference position (coordinate 1). The measured margin for each lens value is stored in, for example, the storage device 142.

[0060] FIG. 13 is a diagram for explaining how to measure a margin in the first embodiment. In FIG. 13, it is checked whether the total current amount at each shift position in, for example, the -x direction from the reference position (coordinate 1) is equal to or greater than the threshold value Mth. Then, the amount of movement to the shift position just before the one where the total current amount becomes less than the threshold value Mth is set as margin (1). Similarly, it is checked whether the total current amount at each shift position in, for example, the +x direction from the reference position (coordinate 1) is equal to or greater than the threshold value Mth. Then, the amount of movement to the shift position just before the one where the total current amount becomes less than the threshold value Mth is set as margin (2). The same applies to the y direction.

[0061] As described above, the margin (maximum movement amount) for the lens value can be measured.

[0062] In the determination step (S120), the determination unit 64 determines whether current measurement has been completed for all preset lens values. If current measurement has been completed for all lens values, the process proceeds to the parameter calculation step (S122). If current measurement has not been completed for all shift positions, the process returns to the current measurement step (S112), where the setting value of the illumination lens 202 is changed to a lens value for which current measurement has not yet been performed, out of the multiple preset lens values, and the current measurement step (S112) through the determination step (S120) are repeated until current measurement has been completed for all lens values.

[0063] In the parameter calculation step (S122), the parameter calculation unit 68 calculates the value of a parameter function f using only the margin a for each lens value as a parameter. Such parameter function f is defined by the following equation (1-1). Note that the coefficient P is defined as the reciprocal of the design margin A and is defined by equation (1-2). i indicates the index of the lens value. (1-1) f(i)=P·a(i) (1-2) P=1 / A

[0064] As described above, there are margins in the x direction and the y direction. As the margin a(i), the statistical value of both, for example, the average value, the maximum value, or the minimum value may be used. Alternatively, the total value of both may be used as the margin a(i). Alternatively, as the margin a(i), one of the two preset values may be used. For example, the margin in the x direction is used.

[0065] Alternatively, the parameter calculation unit 68 calculates the value of the parameter function f using, as parameters, the margin a(i) for each lens value and the total current amount b(i) for each lens value. Such a parameter function f is defined by the following formula (2-1). Note that the coefficient P may be defined as the reciprocal of the design margin. i indicates the index of the lens value. The function Q(b) is defined by the following formulas (2-2) and (2-3) using the design value B of the total current amount. The total current amount b(i) for each lens value uses the total current amount measured at the reference position for each lens value. Alternatively, the maximum value among a plurality of total current amounts measured at the same lens value may be used. (2-1) f(i)=P·a(i)+Q(b(i)) (2-2) Q(b(i))=(2B-b(i)) / B (when b(i)≧B) (2-3) Q(b(i))=b(i) / B (when b(i)<B)

[0066] FIG. 14 is a diagram for explaining the parameter value regarding the total current amount when the total current amount in Embodiment 1 is included in the parameter. When the total current amount b(i) for each lens value is less than B, the larger the total current amount b(i), the more the function Q(b) rises toward 1. And when the total current amount b(i)=B, the function Q(b) becomes 1. When the total current amount b(i)>B, the larger the total current amount b(i), the more the function Q(b) descends toward 0.

[0067] Alternatively, the parameter calculation unit 68 calculates the value of a parameter function f using as parameters a margin a(i) for each lens value and a current density distribution minimum value ratio c(i) for each lens value, which is the ratio (%) of the minimum value to the maximum value obtained in the measured current density distribution. Such parameter function f is defined by the following equation (3-1). Note that the coefficient P is preferably defined as the reciprocal (1 / A) of the design margin A. i represents the index of the lens value. The function R(c) is defined by the following equation (3-2). The current density distribution for each lens value is the current density distribution measured at a reference position. Alternatively, the current density distribution with the smallest difference between the maximum and minimum values ​​may be used among multiple current density distributions measured at the same lens value. (3-1) f(i)=P·a(i)+R(c(i)) (3-2) R(c)=c(i)·100

[0068] The current density distribution minimum value ratio c(i), which indicates the ratio of the minimum value to the maximum value obtained in the current density distribution, may be defined as a ratio (= minimum value / maximum value) instead of a percentage. In that case, it goes without saying that R(c) = c(i).

[0069] 15 is a diagram for explaining parameter values ​​related to current density when the current density is included in the parameters in embodiment 1. As the current density distribution minimum value ratio c(i) for each lens value increases, the function R(c) increases toward 1.

[0070] When the current density is included in the parameter function f, the current density distribution of the beam group passing through the plurality of passage holes 25 of the blanking aperture array mechanism 204 is measured for each lens value. Specifically, the operation is as follows.

[0071] FIG. 16 is a diagram illustrating a method for measuring current density in the first embodiment. In FIG. 16, the beam array constituting the multibeam 20 is divided into a plurality of blocks 21 in a lattice pattern. Each block 21 includes m×m beams, where m is an integer equal to or greater than 2. Then, for each lens value, in a current measurement step (S112) in which the relative positional relationship between the shaping aperture array substrate 203 and the blanking aperture array mechanism 204 is at a reference position, the current amount measurement unit 56 further measures the current amount for each block. With the beam groups other than the target block turned off, the beam group of the target block is received by the Faraday cup 106, and the current amount is measured by the Faraday cup 106. Detection data corresponding to the current amount of the multibeam 20 detected by the Faraday cup 106 is converted into digital current amount data by the current amount measurement circuit 137 and output to the control computer 110.

[0072] The current density distribution creating unit 66 then creates the current density distribution of the multi-beams 20 by inputting the current amount for each block measured by the Faraday cup 106 via the current amount measuring circuit 137 .

[0073] In this way, the current density distribution for each lens value is measured.

[0074] Alternatively, the parameter calculation unit 68 calculates the value of a parameter function f using the margin a(i) for each lens value, the total current b(i) for each lens value, and the current density distribution minimum value ratio c(i) for each lens value as parameters. Such parameter function f is defined by the following equation (4). The values ​​of each term on the right-hand side are as described above. (4) f(i)=P·a(i)+Q(b(i))+R(c(i))

[0075] In the lens value determination step (S124), lens value determination unit 70 uses the margin for each measured lens value to determine and output the lens value of illumination lens 202. Specifically, the operation is as follows. The lens value determination unit 70 determines the lens value of the illumination lens 202 using the function f of the equation (1-1) that uses only the margin a(i) for each lens value as a parameter. Alternatively, the lens value determination unit 70 determines the lens value of the illumination lens 202 using the margin a(i) for each lens value and the total current amount b(i) for each lens value as parameters, using the function f of equation (2-1). Alternatively, the lens value determination unit 70 determines the lens value of the illumination lens 202 using the margin a(i) for each lens value and the current density distribution minimum value ratio c(i) for each lens value as parameters, using the function f in equation (3-1). Alternatively, the lens value determination unit 70 determines the lens value of the illumination lens 202 using the margin a(i) for each lens value, the total current amount b(i) for each lens value, and the current density distribution minimum value ratio c(i) for each lens value as parameters, using the function f of equation (4).

[0076] Specifically, lens value determination unit 70 determines the lens value for which the value of function f is largest as the lens value of illumination lens 202. When the lens value of illumination lens 202 is determined based only on margin a(i) for each lens value, the lens value for illumination lens 202 may be determined as the lens value for illumination lens 202 with the largest margin, without calculating function f. The determined lens value is output to lens control circuit 136.

[0077] In the illumination system lens value setting step (S126), lens control circuit 136 sets the input lens value as the lens value of illumination lens 202. Lens control circuit 136 controls illumination lens 202 to match the set lens value. Specifically, a current corresponding to the lens value is passed through the coil of the electromagnetic lens.

[0078] In the alignment step (S130), under the control of aperture position control circuit 131, drive mechanism 212 drives shaping aperture array substrate 203 to place shaping aperture array substrate 203 at the designed position. Similarly, under the control of aperture position control circuit 131, drive mechanism 214 drives blanking aperture array mechanism 204 to place blanking aperture array mechanism 204 at the designed position. In other words, alignment is performed so as to return shaping aperture array substrate 203 and blanking aperture array mechanism 204 to their reference positions. Alternatively, the shaping aperture array substrate 203 and the blanking aperture array mechanism 204 may be aligned so as to achieve the positional relationship of the shift position at which the total amount of current is maximized for the set lens value.

[0079] FIG. 17 is a diagram showing an example of the relationship between the illumination system lens value, margin, and current density in the first embodiment. In the upper diagram of FIG. 17, the vertical axis represents the margin amount, and the horizontal axis represents the illumination system lens value. In the lower diagram of FIG. 17, the vertical axis represents the current density distribution minimum value ratio, and the horizontal axis represents the illumination system lens value. Note that the illumination system lens value is shown as a relative value with respect to the lens value that maximizes the total current amount. As shown in FIG. 17, the current density distribution minimum value ratio is larger when the illumination system lens is set to the lens value that maximizes the margin than when the illumination system lens is set to the lens value that maximizes the total current amount regardless of the margin. This indicates that the current density uniformity is improved when the illumination system lens is set to the lens value that maximizes the margin.

[0080] 18 is a diagram showing an example of the beam array shape on the sample surface in the first embodiment. As shown in Fig. 18, it can be seen that the beam position deviation that occurred locally at one of the four corners of the beam array has been improved. Therefore, it can be seen that the local beam distortion of the beam array has been suppressed.

[0081] In the comparative example, even if the beam contacts the passage hole of the blanking aperture array mechanism and is displaced on the sample surface due to charging, as shown in FIG. 9, the displaced beam is still detected by the Faraday cup 106. Therefore, no change in the total current amount was observed even when such a local phenomenon occurred. In contrast, in the first embodiment, lens values ​​with a large margin are selected. This means that lens values ​​are selected that do not reduce the total current amount even when the positional relationship between the beam and the passage hole 25 of the blanking aperture array mechanism 204 is shifted. In other words, this indicates that the entire multibeam 20 is incident toward the passage hole 25 of the blanking aperture array mechanism 204 in a nearly parallel, e.g., nearly perpendicular, form. Therefore, even if the positional relationship between the shaping aperture array substrate 203 and the blanking aperture array mechanism 204 is shifted, the total current amount can remain large. Therefore, according to the first embodiment, it is possible to avoid the phenomenon shown in FIG. 9, in which some beams, incident at an excessively oblique angle due to refraction by the illumination system lens, contact the wall surface of the passage hole 25. This makes it possible to suppress or reduce local distortion of the beam array, thereby suppressing or reducing beam blur due to local beam position shift and / or focus shift.

[0082] 19 is a diagram showing an example of beam illumination using an illumination system lens in the first embodiment. The example in FIG. 19 shows a case where the entire multibeam 20 is incident parallel and obliquely on the passage holes of the blanking aperture array mechanism. This can occur when the illumination system lens is disposed obliquely. Even in such a case, according to the first embodiment, lens values ​​that allow the entire multibeam 20 to be incident parallel can be selected, thereby avoiding the above-mentioned local distortion of the beam array.

[0083] As described above, the drawing process is carried out after the adjustment of the illumination lens 202. A specific description will be given below.

[0084] In the drawing step (S140), first, the rasterization processing unit 50 reads out chip pattern data (drawing data) from the storage device 140 and performs rasterization processing. Specifically, the pattern density (pattern area density) is calculated for each pixel 36.

[0085] Next, the shot data generation unit 52 calculates, for each pixel 36, an irradiation dose D to be applied to that pixel 36. The irradiation dose D may be calculated, for example, by multiplying a preset reference irradiation dose Dbase by a proximity effect-corrected irradiation dose Dp and a pattern area density ρ. The proximity effect-corrected irradiation dose Dp is given as a relative value normalized with the reference irradiation dose Dbase set to 1. In this way, the irradiation dose D is preferably calculated in proportion to the pattern area density calculated for each pixel 36. For the proximity effect-corrected irradiation dose Dp, the drawing region (e.g., the stripe region 32) is virtually divided into a plurality of proximity mesh regions (mesh regions for calculating proximity effect correction) of a predetermined size in a mesh pattern. The size of the proximity mesh region is preferably set to approximately 1 / 10 of the range of influence of the proximity effect, for example, approximately 1 μm. Then, the drawing data is read from the storage device 140, and for each proximity mesh region, a pattern density ρ' (pattern area density) of the pattern to be arranged within the proximity mesh region is calculated.

[0086] Next, a proximity effect correction dose Dp for correcting the proximity effect is calculated for each proximity mesh region. Here, the size of the mesh region for calculating the proximity effect correction dose Dp does not need to be the same as the size of the mesh region for calculating the pattern density ρ'. Furthermore, the correction model for the proximity effect correction dose Dp and its calculation method may be the same as the method used in the conventional single-beam writing method.

[0087] Then, the shot data generation unit 52 calculates, for each pixel 36, the irradiation time t of the electron beam for making the calculated irradiation dose D incident on that pixel 36. The irradiation time t can be calculated by dividing the irradiation dose D by the current density J. In this way, a dose map (actually an irradiation time map) is created in which irradiation time data (shot data) for each pixel 36 is defined.

[0088] When multiple writing is performed, a dose map (actually, an irradiation time map) is created for each of the multiple writing processes. In other words, a dose map (actually, an irradiation time map) is created for each stripe layer. The created irradiation time data is stored in the storage device 142 in shot order.

[0089] Then, under the control of the drawing control unit 72, the drawing mechanism 150 uses the illumination lens 202 set to the lens value obtained by the above-mentioned method to irradiate the sample 101 with the multi-beam 20 that has passed through multiple passage holes 25 of the blanking aperture array mechanism 204, thereby drawing a pattern on the sample 101.

[0090] As described above, according to the first embodiment, it is possible to achieve at least one of improving the current density distribution, reducing local beam distortion, reducing local beam blur, and reducing local positional deviation.

[0091] Furthermore, the processing functions described in each of the above-mentioned embodiments may be executed by a computer, and a program for causing a computer to execute such processing functions may be stored in a non-transitory, tangible readable recording medium such as a magnetic disk device.

[0092] The lens group, such as the illumination lens 202, the reduction lens 205, and the objective lens 207 described in the embodiment, is not limited to electromagnetic lenses, but may be electric field lenses or a combination of electric field lenses and electromagnetic lenses.

[0093] Although the description of the device configuration, control method, and other parts not directly necessary for the explanation of the present invention have been omitted, the required device configuration and control method can be appropriately selected and used. For example, the description of the control unit configuration that controls the drawing device 100 has been omitted, but it goes without saying that the required control unit configuration can be appropriately selected and used.

[0094] In addition, all illumination lens adjustment methods, multi-charged particle beam writing apparatuses, and programs that include elements of the present invention and that can be appropriately modified by those skilled in the art are included within the scope of the present invention. [Explanation of symbols]

[0095] 20 Multibeam 22 holes 24 control electrode 25 Passing hole 26 Counter electrode 29 Sub-irradiation area 30 drawing area 32 stripe area 34 Irradiation area 36 pixels 40 areas 41 Control circuit 42 patterns 50 Rasterization processing unit 52 Shot data generation unit 54 Lens value setting section 56 Current measurement section 60 Shift processing section 62 Judgment section 63 Margin measurement section 64 Judgment section 66 Current density distribution creation section 68 Parameter calculation unit 70 Lens value determination unit 72 Drawing control unit 74 Transfer Processing Unit 100 drawing device 101 Sample 102 Electron Telescope 103 Drawing room 105 XY stage 106 Faraday Cup 110 Control computer 112 memory 130 Deflection control circuit 131 Aperture position control circuit 132,134 DAC amplifier unit 136 Lens control circuit 137 Current detection circuit 138 Stage Control Mechanism 139 Stage Position Measuring Instrument 140,142 Storage device 150 Drawing mechanism 160 Control Circuits 200 electron beam 201 Electron Gun 202 Lighting lens 203 Shaped Aperture Array Substrate 204 Blanking Aperture Array Mechanism 205 Reduction Lens 206 Limiting Aperture Substrate 207 Objective Lens 208 Main deflector 209 Sub deflector 210 Mirror 212,214 Drive mechanism 330 Membrane Region

Claims

1. a step of variably setting a lens value of an illumination lens that guides the multi-charged particle beam to a blanking aperture array mechanism that has a plurality of apertures formed therein and that individually controls blanking of each beam of the multi-charged particle beam passing through the plurality of apertures; a step of measuring, for each lens value, a maximum amount of movement from a reference positional relationship within a range in which a total amount of current of a beam group passing through the plurality of openings for each positional relationship does not become less than a threshold value while relatively moving a positional relationship between the multi-charged particle beam and the plurality of openings from the reference positional relationship; determining and outputting a lens value of the illumination lens using the maximum amount of movement for each measured lens value; A method for adjusting an illumination lens, comprising:

2. using the illumination lens to illuminate with a charged particle beam a shaped aperture array substrate disposed between the illumination lens and the blanking aperture array mechanism and having a plurality of openings formed therein; the multi-charged particle beam is formed by passing a portion of the charged particle beam through a plurality of openings in the shaping aperture array substrate; 2. The method for adjusting an illumination lens according to claim 1.

3. 3. The method for adjusting an illumination lens according to claim 1, wherein the lens value of the illumination lens is determined using only the maximum movement amount for each lens value as a parameter.

4. measuring a total current amount of the beam group passing through the plurality of openings of the blanking aperture array mechanism for each lens value and for each positional relationship; 3. The illumination lens adjustment method according to claim 1, wherein the lens value of the illumination lens is determined using the maximum movement amount for each lens value and the total current amount for each lens value as parameters.

5. measuring a current density distribution of a group of beams passing through the plurality of openings of the blanking aperture array mechanism for each lens value; 3. The illumination lens adjustment method according to claim 1, wherein the lens value of the illumination lens is determined using, as parameters, the maximum movement amount for each lens value and a current density distribution minimum value ratio for each lens value, which is the ratio of the minimum value to the maximum value obtained in the measured current density distribution.

6. measuring a total current amount of the beam group passing through the plurality of openings of the blanking aperture array mechanism for each lens value and for each positional relationship; measuring a current density distribution of a group of beams passing through the plurality of openings of the blanking aperture array mechanism for each lens value; Furthermore, 3. The illumination lens adjustment method according to claim 1, wherein the lens value of the illumination lens is determined using, as parameters, the maximum movement amount for each lens value, the total current amount for each lens value, and a current density distribution minimum value ratio for each lens value, which is the ratio of the minimum value to the maximum value obtained in the measured current density distribution.

7. an emission source that emits a charged particle beam; an illumination lens for refracting the charged particle beam; a shaping aperture array substrate having a plurality of first openings formed therein, the shaping aperture array substrate being irradiated with the charged particle beam refracted by the illumination lens, and a portion of the charged particle beam passing through the plurality of first openings to form a multi-charged particle beam; a blanking aperture array mechanism in which a plurality of second openings are formed, and which controls blanking of each beam of the multi-charged particle beam passing through the plurality of second openings individually; a moving mechanism that moves the shaping aperture array substrate and the blanking aperture array mechanism relatively; a current amount measuring mechanism that measures a total current amount of the beam group passing through the plurality of second openings; a stage on which a sample can be placed, the sample being irradiated with the group of beams passing through the plurality of second openings to form a pattern; a setting unit that variably sets a lens value of the illumination lens; a displacement measurement unit that measures, for each lens value, a maximum displacement from a reference positional relationship between the shaping aperture array substrate and the blanking aperture array mechanism within a range in which a total amount of current of a group of beams passing through the plurality of second openings for each positional relationship does not become less than a threshold value, while relatively displacing the positional relationship between the shaping aperture array substrate and the blanking aperture array mechanism from the reference positional relationship; a determination unit that determines a lens value of the illumination lens using a maximum movement amount for each measured lens value; A multi-charged particle beam drawing apparatus comprising:

8. a process of variably setting a lens value of an illumination lens that guides the multi-charged particle beam to a blanking aperture array mechanism that has a plurality of apertures formed therein and that individually controls blanking of each beam of the multi-charged particle beam passing through the plurality of apertures; a process of measuring a maximum amount of movement from a reference positional relationship within a range in which a total amount of current of a beam group passing through the plurality of openings for each positional relationship does not become less than a threshold value while relatively moving a positional relationship between the multi-charged particle beam and the plurality of openings from the reference positional relationship for each lens value; A process of storing the maximum movement amount for each measured lens value in a storage device; a process of reading out the maximum movement amount for each lens value stored in the storage device, determining the lens value of the illumination lens using the read-out maximum movement amount for each lens value, and outputting the lens value; A program that causes a computer to execute the following.

Images