Method of calculating opening correction amount of aperture array substrate, aperture array substrate, blanking aperture array substrate, multi charged particle beam writing apparatus, and multi charged particle beam writing method

Abstract

To improve the accuracy of drawing using multiple beams by correcting the position and dimension of an aperture of an aperture array substrate.SOLUTION: According to another aspect of the present invention, there is provided a method of calculating a correction amount of positions or dimensions of a plurality of apertures of an aperture array substrate having the plurality of apertures through which multiple charged particle beams pass, the method including measuring a deviation amount distribution which is a distribution of an amount of deviation of each beam in a beam array of the multiple charged particle beams from a predetermined position or a predetermined current density, and dividing the beam array into a predetermined number of block regions based on the deviation amount distribution; A representative value of the deviation amount corresponding to each block region is calculated, and a correction amount of the position or the dimension of the corresponding opening of the aperture array substrate is calculated for each block region based on the representative value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for calculating an aperture correction amount for an aperture array substrate, an aperture array substrate, a blanking aperture array substrate, a multi-charged particle beam lithography apparatus, and a multi-charged particle beam lithography method. [Background technology]

[0002] As LSIs become more highly integrated, the circuit line widths used in semiconductor devices are becoming finer every year. To form the desired circuit patterns for semiconductor devices, a method is adopted in which a high-precision master pattern (called a mask, or a reticle, especially when used in steppers and scanners) formed on a light-shielding film on a glass substrate is reduced and transferred onto a wafer using a reduction projection exposure system. To create high-precision master patterns, a technique known as electron beam lithography is used, in which a resist pattern is formed using an electron beam writing system. Alternatively, a method known as direct wafer writing is sometimes used, in which a pattern is formed on a resist coated on a wafer using an electron beam.

[0003] In a multi-beam lithography device using a blanking aperture array substrate, which is one type of multi-beam lithography device, for example, an electron beam emitted from a single electron gun is passed through a shaping aperture array substrate with multiple apertures to form multiple beams (multiple electron beams). Downstream of the shaping aperture array substrate is a blanking aperture array substrate. The blanking aperture array substrate has, for each beam of the multi-beam, an electrode pair (blanker) for individually deflecting the beam and an aperture formed between the electrode pair for passing the beam, which are arranged in an array on the blanking aperture array substrate. The blanking aperture array substrate switches the blanking deflection of the passing beam on and off by controlling the electrode pairs corresponding to each beam of the multi-beam to the same potential or to different potentials. The multi-beams formed by the shaping aperture array substrate pass through the passage holes between the corresponding blankers on the blanking aperture array substrate. The optical column of the multi-beam writing device is configured so that the electron beam deflected by the blanker is blocked by being deflected from the beam path toward the substrate to be exposed, and the undeflected electron beam is irradiated onto the substrate along the path.

[0004] In multi-beam lithography, deviations of each beam from its ideal position and its current density from its target value affect the lithography accuracy and throughput. The positions of each beam in the multi-beam array have a systematic distribution of misalignment due to optical distortion aberrations and other factors. Beam misalignment causes shifts and waviness in the edge position of the exposed pattern, degrading the pattern position, dimensions, and edge roughness. The current density of each beam in the multi-beam array has a systematic distribution that reflects the current density distribution of the beams illuminating the shaped aperture array substrate. Differences in current density among the multi-beam beams can be corrected by modulating the beam irradiation time so that each beam delivers the correct dose to the substrate being lithographed, regardless of current density. However, this correction requires a longer irradiation time for beams with lower current densities, which extends the shot cycle of multi-beam lithography and increases the lithography time.

[0005] To alleviate these problems, a technique is known in which the positional deviation and current density deviation of each beam of a multi-beam are predicted in advance, and the positions and sizes of the openings in the shaped aperture array substrate are distributed in advance to compensate for these deviations. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-030567 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-080155 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-041055 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the error distribution of the irradiation position and current density of each beam of the multi-beam pattern varies depending on the adjustment status of the multi-beam lithography device and individual differences in components such as the cathode, and therefore does not become the same as the predicted error distribution. If the actual error distribution differs from the predicted distribution, the distribution imparted to the position and size of the apertures on the molded aperture array substrate may increase the actual error rather than reducing it. In other words, the error caused by aperture correction on the molded aperture array substrate may be larger than the actual (pre-correction) error. Furthermore, the beam error observed as the difference between the actual distribution and the aperture correction based on the predicted distribution may be a more complex distribution than the actual distribution.

[0008] In electron beam lithography systems, it is necessary to measure the beam position on the sample surface for optical system adjustment. This is done as follows: A mark for beam position detection is placed at the height of the substrate to be exposed, i.e., on the sample surface, and the beam is scanned over the mark to detect reflected electrons from the mark. By acquiring the amount of reflected electrons for each beam deflection, the change in the amount of reflected electrons due to beam scanning is obtained as a scan waveform. The scan waveform is then analyzed to calculate the mark edge position and determine the mark position. In multi-beam lithography systems, the beam position measurement accuracy is low when scanning a single beam because the current of each beam is small. Therefore, by scanning the mark with multiple beams grouped together, high position measurement accuracy can be achieved by measuring the average position of the grouped beams. In this case, it is preferable for the grouped beams to have a uniform positional deviation and the same current density for scan waveform analysis. When using a shaped aperture array substrate with conventional aperture correction, if the predicted error distribution matches the actual error distribution, the grouped beams have a uniform positional deviation and current density. However, if they do not match, the grouped beams may have a larger or more complex error distribution than actual.

[0009] In addition, a technique is known in which, by applying the same shift amount to the beam-passing apertures in the blanking aperture array substrate as the positions of the apertures in the shaping aperture array substrate, each beam of a multi-beam system can be aligned with the center of the apertures in the blanking aperture array substrate when the positions of the apertures in the shaping aperture array substrate are shifted. However, because the blanking aperture array substrate contains built-in wiring and control circuits for beam deflection, shifting the positions of the apertures in the blanking aperture array substrate may require changing the positions of the wiring and control circuits. If the positions of the apertures in the shaping aperture array substrate and the blanking aperture array substrate are continuously shifted to match the predicted beam error amount, it would be necessary to continuously shift the positions of the wiring and control circuits on the blanking aperture array substrate, making design changes more difficult.

[0010] The present invention aims to provide a method for calculating the amount of aperture correction for an aperture array substrate, an aperture array substrate, a blanking aperture array substrate, a multi-charged particle beam drawing device, and a multi-charged particle beam drawing method, which can correct the position and dimensions of the openings in the aperture array substrate to improve the accuracy of drawing using multiple beams. [Means for solving the problem]

[0011] A method for calculating an aperture correction amount for an aperture array substrate according to one aspect of the present invention is a method for calculating correction amounts for the positions or dimensions of a plurality of apertures in an aperture array substrate having a plurality of apertures through which a multi-charged particle beam passes, the method comprising: measuring a deviation amount distribution, which is a distribution of deviation amounts from a predetermined position or a predetermined current density, of each beam in a beam array of the multi-charged particle beam; dividing the beam array into a predetermined number of block regions based on the deviation amount distribution; calculating a representative value of the deviation amount corresponding to each block region; and calculating a correction amount for the position or dimension of the corresponding aperture in the aperture array substrate for each block region based on the representative value.

[0012] An aperture array substrate according to one aspect of the present invention has a plurality of apertures whose positions or dimensions are corrected based on the correction amounts calculated by the above-described method for calculating aperture correction amounts for an aperture array substrate.

[0013] A blanking aperture array substrate according to one aspect of the present invention corrects the positions of a plurality of apertures based on the correction amount calculated by the above-described method for calculating aperture correction amount for an aperture array substrate, and includes a blanker that performs blanking deflection of each beam of the multi-charged particle beam passing through each aperture in accordance with the corrected position of each aperture, and a control circuit that applies voltage to the blanker.

[0014] A multi-charged particle beam writing apparatus according to one embodiment of the present invention comprises: a beam source that emits a charged particle beam; a shaping aperture array substrate that is divided into regions and has a plurality of first openings formed on a block basis, the first openings being shifted in position or having different dimensions; the charged particle beam is irradiated onto an area including the entire plurality of first openings, and multiple beams are formed by portions of the charged particle beam passing through each of the plurality of first openings; a blanking aperture array substrate that has a plurality of second openings formed thereon, through which corresponding beams of the multiple beams pass, and each second opening is provided with a blanker that performs blanking deflection of the beam; and a deflector that collectively deflects the beams that have passed through the plurality of second openings and adjusts the beam irradiation position on the substrate to be written.

[0015] A multi-charged particle beam writing method according to one embodiment of the present invention comprises the steps of: emitting a charged particle beam; irradiating the charged particle beam onto a shaping aperture array substrate having a plurality of first openings formed thereon, each of which is blocked by region and whose positions or dimensions are shifted in block units; forming multi-beams by allowing a portion of the charged particle beam to pass through each of the plurality of first openings; controlling the on / off of each beam using a blanking aperture array substrate having a plurality of second openings formed thereon, through which corresponding beams of the multi-beams pass, and each second opening having a blanker provided at each second opening for blanking deflection of the beam; and deflecting the beams that have passed through the plurality of second openings collectively using a deflector, and irradiating the beams onto a substrate to be written. [Effects of the Invention]

[0016] According to the present invention, the positions and dimensions of the openings in the aperture array substrate can be corrected, thereby improving the accuracy of drawing using multiple beams. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram of a multi-charged particle beam writing apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a plan view of a shaped aperture array substrate. [Figure 3] FIG. 2 is a cross-sectional view showing the configuration of a blanking aperture array substrate. [Figure 4] FIG. 10 is a schematic diagram of a control circuit in a blanking aperture array substrate. [Figure 5] FIG. 2 is a configuration diagram of an input / output circuit and a cell array circuit. [Figure 6] FIG. 2 is a schematic diagram of an individual blanking mechanism. [Figure 7] 10 is a flowchart illustrating a method for manufacturing a shaped aperture array substrate in which the positions and dimensions of the openings are corrected. [Figure 8] FIG. 10A is a diagram showing an example of a beam position deviation distribution, and FIGS. 10B and 10C are diagrams showing examples of block division of the position deviation amount. [Figure 9] FIG. 10 is a diagram illustrating an example of mark scanning. [Figure 10] FIG. 10A is a diagram showing an example of a beam position deviation distribution, and FIGS. 10B and 10C are diagrams showing examples of block division of the position deviation amount. [Figure 11] FIG. 10(a) is a diagram showing an example of a current density distribution, and FIG. 10(b) is a diagram showing an example of a representative value of the current density for each block. [Figure 12] 10A and 10B are diagrams illustrating an example of position correction of an individual blanking mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments, a configuration using an electron beam as an example of a charged particle beam will be described. However, the charged particle beam is not limited to an electron beam, and an ion beam may also be used.

[0019] Fig. 1 is a schematic diagram of a lithography apparatus according to an embodiment. As shown in Fig. 1, the lithography apparatus 100 includes a lithography unit 150 and a control unit 160. The lithography apparatus 100 is an example of a multi-charged particle beam lithography apparatus. The lithography unit 150 includes an electron lens barrel 102 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 substrate 204, a reduction lens 205, a limiting aperture member 206, an objective lens 207, and a deflector 208 are arranged.

[0020] An XY stage 105 and a detector 108 are arranged in the patterning chamber 103. A substrate 101 to be patterned is arranged on the XY stage 105. A resist to be exposed to an electron beam is applied to the upper surface of the substrate 101. The substrate 101 is a mask blank to be processed into a photomask, or a semiconductor substrate (silicon wafer) to be processed into a semiconductor device. A mark substrate 104, a Faraday cup 106, and a mirror 210 for measuring the stage position are arranged on the XY stage 105. The output of the Faraday cup 106 is sent to the control computer 110 via an amplifier 134.

[0021] A mark 104M (see FIG. 9) for beam calibration is formed on the mark substrate 104. The mark 104M is formed on a base made of, for example, silicon, and is made of a material with a higher electron reflectivity, such as metal, and has a shape with edges in two perpendicular directions, such as a cross shape. The mark 104M is scanned with an electron beam in a direction perpendicular to the edges and is used to detect the beam position and blur amount. The detector 108 detects a reflected electron signal from the mark 104M when the cross of the mark 104M is scanned with the electron beam.

[0022] The control unit 160 has a control computer 110, a deflection control circuit 130, a detection circuit 132, an amplifier 134, a stage position detector 139, and a memory unit 140. Drawing data is input from the outside and stored in the memory unit 140. The drawing data defines information on multiple graphic patterns to be drawn. Specifically, a graphic code, coordinates, size, etc. are defined for each graphic pattern. The drawing data may also include other information, such as irradiation dose control information.

[0023] The control computer 110 has an area density calculation unit 111, an irradiation time calculation unit 112, a data processing unit 113, and a writing control unit 114. Each unit of the control computer 110 may be configured with hardware such as an electric circuit, or may be configured with software such as a program that executes these functions, or may be configured with a combination of hardware and software.

[0024] The stage position detector 139 irradiates the mirror 210 with a laser, receives the light reflected from the mirror 210, and detects the position of the XY stage 105 by laser interference.

[0025] Figure 2 is a conceptual diagram showing the configuration of shaping aperture array substrate 203. Shaping aperture array substrate 203 is a plate-like member, and as shown in Figure 2, a plurality of openings 203a are formed along the vertical direction (y direction) and horizontal direction (x direction) within the surface of shaping aperture array substrate 203. Each opening 203a is rectangular or circular in shape.

[0026] An electron beam 200 emitted from an electron gun 201 (beam source) illuminates a shaping aperture array substrate 203 via an illumination lens 202. The electron beam 200 illuminates an area of ​​the shaping aperture array substrate 203 that includes all of the apertures 203a. A portion of the electron beam 200 passes through the multiple apertures 203a in the shaping aperture array substrate 203, and the remaining beam is stopped by the shaping aperture array substrate 203, thereby forming multiple electron beams, i.e., a multibeam 20. The shape of each beam (individual beam) that makes up the multibeam 20 follows the shape of the apertures 203a in the shaping aperture array substrate 203, and is, for example, rectangular.

[0027] 3, the blanking aperture array substrate 204 has a support base 204a and a semiconductor substrate 204b made of silicon or the like provided on the support base 204a. The central portion of the semiconductor substrate 204b is thinly shaved from the backside, forming a thin membrane region 204c. The membrane region 204c is surrounded by a thick outer peripheral region, and the semiconductor substrate 204b is held on the backside of the outer peripheral region on the support base 204a. The central portion of the support base 204a is open, and the membrane region 204c is located in the open region of the support base 204a.

[0028] In the membrane region 204c, a plurality of beam passage holes H are formed in alignment with the respective positions of the plurality of openings 203a of the shaping aperture array member 203. A blanker 50 consisting of a pair of electrodes 51, 52 is disposed in each passage hole H, and one of the multi-beams passes between the pair of electrodes and through the passage hole H. The blanker 50 switches the deflection of the beam passing through the passage hole H on and off by grounding one electrode 52 and keeping it at ground potential, and switching the other electrode 51 to ground potential or a potential other than ground potential. In this way, the blanker 50 performs blanking control, setting each of the multi-beams to either a beam-on or beam-off state. The principle of blanking control is described below.

[0029] When one individual beam of the multi-beams is controlled to a beam-on state, the opposing electrodes 51 and 52 of the blanker 50 are controlled to the same potential, and the blanker 50 does not deflect the beam passing through the passage hole H. When the beam is controlled to a beam-off state, the opposing electrodes 51 and 52 of the blanker 50 are controlled to different potentials, and the blanker 50 deflects the beam passing through the passage hole H.

[0030] The multi-beams 20 that have passed through the blanking aperture array substrate 204 are reduced in size by the reduction lens 205 and travel towards the central opening formed in the limiting aperture member 206 .

[0031] Here, the beam controlled to the beam-off state is deflected by the blanker 50 and passes through a trajectory outside the opening of the limiting aperture member 206, and is therefore blocked by the limiting aperture member 206. On the other hand, the beam controlled to the beam-on state is not deflected by the blanker 50 and passes through the opening of the limiting aperture member 206. The beam trajectory is adjusted by an alignment coil (not shown) so that the beam controlled to the beam-on state is positioned within the opening of the limiting aperture member 206. In FIG. 1, the trajectories of the multi-beams in the beam-on state are adjusted so that they converge to a single point at the position of the limiting aperture member 206. However, it is preferable to adjust the alignment coil so that this single point is located at the center of the opening of the limiting aperture member 206. In this way, the on / off state of each beam of the multi-beam is controlled by a combination of the on / off operation of the deflection of the blanker 50 and the blocking of the beam by the limiting aperture. In other words, blanking control is performed.

[0032] The multibeams 20 that have passed through the limiting aperture member 206 are focused by the objective lens 207 and formed as a pattern image with a desired reduction ratio on the substrate 101. Ideally, the multibeams are aligned on the substrate 101 at a pitch obtained by multiplying the arrangement pitch of the plurality of openings 203a in the shaping aperture array substrate 203 by the desired reduction ratio described above. Each beam (all of the multibeams that are in a beam-on state) that has passed through the limiting aperture member 206 is deflected collectively in the same direction by the deflector 208 and irradiated at a desired position on the substrate 101 with the beams focused on the surface of the substrate 101.

[0033] Irradiation of the substrate 101 with the multibeams is possible whether the XY stage 105 is stationary or moving continuously. When the XY stage 105 is moving continuously, the stage position detector 139 measures the amount of change in the stage position, and using the result, the deflector 208 is used to continuously change the position of the multibeams so that they follow the movement of the XY stage 105. This is called stage tracking deflection. Stage tracking deflection makes it possible to fix the position of the multibeams on the substrate 101. At least while the substrate 101 is being irradiated with the beams, stage tracking deflection is performed to control the position of each beam of the multibeams on the substrate 101 so that it remains stationary.

[0034] The blanking aperture array substrate 204 includes the blanker 50 and the passage holes H described above, as well as a control circuit for applying a desired voltage to the blanker 50. As shown in FIG. 4, this control circuit includes an input / output circuit 31 and a cell array circuit 34.

[0035] As shown in FIG. 5, the cell array circuit 34 is provided with a plurality of cells that constitute individual blanking mechanisms 40 that drive blankers 50. FIG. 5 shows an example of a blanking aperture array substrate having 262,144 cell array circuits and blankers, each consisting of 512 rows and 512 columns. One individual blanking mechanism 40 drives one blanker 50. The input / output circuit 31 outputs data received from the deflection control circuit 130 to the cell array circuit 34. For example, the input / output circuit 31 includes an input / output circuit 31a that outputs data to the individual blanking mechanisms 40 arranged on one half of the cell array circuit 34, and an input / output circuit 31b that outputs data to the individual blanking mechanisms 40 arranged on the other half.

[0036] The input / output circuit 31 is provided with a plurality of selectors 320 (demultiplexers). The selectors 320 receive blanking control data that defines the on / off state of each beam via the amplifiers 310, and output the data from the corresponding output lines. A plurality of individual blanking mechanisms 40 are connected in series to each output line.

[0037] The selector 320 has, for example, eight output lines row1 to row8, and each output line is connected to 256 individual blanking mechanisms 40. By arranging 64 selectors 320 in each of the input / output circuits 31a and 31b, blanking control data can be transferred to 512 × 512 individual blanking mechanisms 40 that make up the cell array circuit 34.

[0038] 6, the individual blanking mechanism 40 includes a shift register 41, a pre-buffer 42, a buffer 43, a data register 44, a NAND circuit 45, and an amplifier 46. The shift register 41 transfers data output from the shift register of the preceding cell to the shift register of the succeeding cell in accordance with a clock signal (SHIFT).

[0039] The pre-buffer 42 stores the blanking control data for the cell output from the shift register 41 in accordance with the clock signal (LOAD1).

[0040] The buffer 43 takes in and holds the output value of the pre-buffer 42 in accordance with the clock signal (LOAD2).

[0041] The data register 44 receives and holds the output value of the buffer 43 in accordance with the clock signal (LOAD3).

[0042] An output signal of the data register 44 and a shot enable signal (SHOT_ENABLE) are input to the NAND circuit 45. An output signal of the NAND circuit 45 is applied to an electrode 51 of a blanker 50 via an amplifier 46 (driver amplifier).

[0043] When the output signal of the data register 44 and the shot enable signal are both high, the output of the NAND circuit 45 goes low, electrodes 51 and 52 have the same potential, the blanker 50 does not deflect the beam, and the beam is turned on. When at least one of the output signal of the data register 44 and the shot enable signal is low, the output of the NAND circuit 45 goes high, electrodes 51 and 52 have different potentials, the blanker 50 deflects the beam, and the beam is turned off.

[0044] The shot enable signal is input to the NAND circuits 45 of all the individual blanking mechanisms 40, and by setting the shot enable signal to Low, all beams can be turned off regardless of the output signal of the data register 44.

[0045] While the shot enable signal is maintained at high, the beam is switched on / off by the output of the data register 44. That is, when the blanking control data is 1 (high), the beam is turned on, and when the blanking control data is 0 (low), the beam is turned off. After transferring the blanking control data to the individual blanking mechanism 40, the shot enable signal is set to high for the duration of the irradiation time, so that the desired beam can be turned on for the specified irradiation time and irradiated onto the sample. By combining such blanking control with beam position control by the main deflector 208 and the sub-deflector 209, writing using multiple beams can be performed.

[0046] In a multi-beam lithography device, the electron optical system is adjusted before lithography. In this adjustment process, a method is used in which the position and resolution of the multi-beams are measured by scanning the multi-beams over the mark 104M. In the case of a lithography device with a large number of multi-beams, the mark 104M is scanned with beams formed by grouping some of the multi-beams. This method makes it possible to adjust, for example, the focal position of the multi-beams (see, for example, JP 2018-67605 A).

[0047] In this embodiment, a shaping aperture array substrate 203 is used, which is manufactured by shifting the position and dimensions of the apertures 203a so as to reduce the error distribution of the beam array current density distribution and the beam position on the sample surface as predicted in advance. At this time, the position and dimensions of the apertures 203a are corrected in units of blocks with a predetermined arrangement. In other words, the amount of correction is determined for each block, and the same correction amount is applied to the apertures within the block. Furthermore, the arrangement of these blocks is set so that the beam group that scans the mark 104M for beam adjustment is included (fitted).

[0048] 7 is a flowchart illustrating a method for manufacturing a shaping aperture array substrate in which the positions and dimensions of the openings are corrected. Before the positions and dimensions of the openings are corrected, the shaping aperture array substrate has openings of the same size arranged at equal intervals.

[0049] In the block placement determination step (S1), the placement of blocks that correct the positions and dimensions of the apertures in the shaping aperture array substrate is determined. For example, a multi-beam beam array is divided into regions such as 7x7, 8x8, or 9x9, and the divided regions are defined as blocks. A rectangular shape is preferable for the blocks. Once the number of blocks is determined, the placement of the blocks is also determined. Furthermore, the size of each block does not have to be the same. For example, if the number of beam arrays in the X direction is not divisible by the number of blocks in the X direction, the size of at least one block in the X direction will be different from the size of the other blocks. The placement of the blocks is determined so that each block includes a partial array used for mark scanning.

[0050] For example, if the number of beams used for mark scanning is 32 × 32, the multi-beam consisting of 512 × 512 beams is divided into 8 × 8 blocks. In this case, one block contains 64 × 64 beams, so the 32 × 32 beams used for scanning, that is, the partial array, is contained in one block.

[0051] In the step (S2) of measuring the error amount distribution of beams in the multi-beam, either the positional deviation amount distribution of the irradiation position of each beam of the multi-beam or the current density distribution is measured as the error amount distribution. When performing positional correction of the opening of the shaping aperture array substrate, the positional deviation amount distribution is measured. When performing dimensional correction of the opening of the shaping aperture array substrate, the current density distribution is measured. When performing both positional and dimensional correction of the opening of the shaping aperture array substrate, both the positional deviation amount distribution and the current density distribution are measured. The measurements are preferably performed using an apparatus equipped with the corrected shaping aperture array substrate or multiple apparatuses with the same configuration as the apparatus equipped with the corrected shaping aperture array substrate, and the correction amount is determined from the average value. In the error amount distribution measurement step (S2), the lithography apparatus is equipped with a shaping aperture array substrate before the aperture correction. Alternatively, when a shaping aperture array substrate after the aperture correction is equipped, the correction amount applied to the aperture is subtracted to calculate the positional deviation amount distribution and the current amount distribution.

[0052] One method for measuring the distribution of misalignment of each beam in a multi-beam system is to perform multi-beam lithography. A resist-coated test substrate (mask blank) is irradiated with the multi-beams to write a pattern for beam irradiation position evaluation. The test substrate is then developed or further etched, and the resulting pattern position is measured using a position measurement device. The lithography is performed using the step-and-repeat method. In multi-beam step-and-repeat lithography, the stage on which the test substrate is placed is fixed, and the multi-beams are scanned across the test substrate using a deflection less than the beam pitch to expose an area on the test substrate that is the same size as the beam array. In this lithography method, the alignment of the beams in the beam array matches the alignment of the positions on the sample surface exposed by each beam, so the alignment of the beams in the beam array is transferred as the alignment of the written pattern. Therefore, by measuring the alignment of the written pattern with a position measurement device, the relative alignment of the beams in the beam array during lithography can be determined.

[0053] When measuring the position of a written pattern using a position measurement device, it is preferable for the pattern size to be relatively large, as this will result in higher measurement accuracy. It is preferable for the pattern size to be larger than the beam pitch. In this case, one pattern is exposed using multiple beams, and the average position of the multiple beams that write the periphery of the pattern is measured as the positional deviation of the written pattern. By arranging such patterns in a grid pattern in an area the size of the beam array and performing step-and-repeat writing, the relative positional deviation distribution of the beams within the beam array can be determined from the results of position measurement of the pattern formed by writing.

[0054] FIG. 8(a) shows an example of the distribution of the amount of positional deviation obtained from the result of drawing on the evaluation substrate.

[0055] As another method for measuring the beam position deviation distribution within the multi-beam, the mark 104M may be scanned using the multi-beam to measure the mark position, and the beam position deviation may be calculated from the apparent deviation of the measured mark position. A specific example is shown below. First, multiple measurement points for the position deviation within the multi-beam are determined. This arrangement does not have to correspond to the arrangement of the blocks in the block determination step (S1). For example, a 5 x 5 point arrangement within the multi-beam is used. The multi-beams included in the area including each measurement point are grouped, and the grouped beams are set as a partial array (on-beam area).

[0056] Next, the XY stage 105 carrying the mark 104M is moved so that the mark 104M is positioned at a designed irradiation position of the partial array (on-beam region) corresponding to one of the measurement points. The position of the XY stage 105 at this time is detected by a stage position detector 139, allowing for accurate control of the position of the mark 104M. Next, as shown in FIG. 9 , with only the partial array (on-beam region) of the multi-beam turned on, the deflector 208 is used to scan across the edge of the mark 104M, while the detector 108 detects electrons reflected from the mark 104M. For each deflection amount during scanning, the detection circuit 132 transmits the amount of reflected electrons from the mark 104M detected by the detector 108 to the control computer 110. For each deflection amount during scanning, the control computer 110 acquires the deflection amount and the detected amount of reflected electrons as a scan waveform, and then calculates the edge position of the mark 104M from the scan waveform and calculates the position of the mark 104M in the deflection coordinate system. If the beam of the partial array scanning mark 104M is misaligned from the ideal position, the position of the mark detected in this manner will be detected as having a misalignment with the opposite sign of the amount of beam misalignment. For example, if the beam of the partial array is misaligned by 5 nm in the X direction, mark 104M will be observed to be misaligned by -5 nm in the X direction during mark scanning. Taking this into consideration, the amount of misalignment of the beam of the partial array can be calculated as the amount of misalignment with the opposite sign of the apparent misalignment of the mark position observed during mark scanning.

[0057] Next, the position of the partial array is calculated in the same way using a partial array at another measurement point. By repeating this process, the position of the partial array (on-beam area) at each measurement point within the beam array can be determined. By subtracting the average value of each partial array position from the position of each partial array, the relative beam position deviation distribution at each measurement point within the beam array can be calculated.

[0058] FIG. 10(a) shows an example in which beam position measurement is performed by mark scanning in the partial array (on-beam area) at each position for 5 × 5 points in the multi-beam, and the beam position deviation distribution in the multi-beam is calculated.

[0059] Next, in the step (S2) of measuring the error amount distribution of beams within the multibeam, we will show how to measure the current density distribution within the beam array. First, multiple measurement points for the current density distribution within the beam array are determined. This arrangement does not need to correspond to the block arrangement in the block determination step (S1). For example, a 5x5 or 16x16 arrangement within the beam array can be used. A partial array of the multibeam (on-beam area) is set in the area containing each measurement point. Only the partial array of the multibeam to be measured is turned on, and the beam current of the partial array reaching the Faraday cup 106 is measured. Then, the current of the partial array is converted to the average current density of the beams in the partial array using the designed beam size on the sample surface or the beam size on the sample surface calculated from the previously measured aperture dimensions of the shaping aperture and the reduction ratio of the optical system, and the number of beams belonging to the partial array. The partial array (on-beam area) that is turned on is switched to measure the current distribution at all measurement points, and the current density distribution within the beam array is calculated. As such, the current density distribution cannot be measured directly; it is a quantity estimated from the beam current and aperture dimensions. Therefore, the current density distribution described below is an effective current density distribution that includes the effect of any deviation from the design value of the opening dimensions of the shaping aperture.

[0060] Current density measurement of a partial array can be completed in a shorter time than beam position measurement using partial array mark scanning, so a larger number of measurement points can be used. For a multi-beam consisting of 512 x 512 beams, current density distribution measurement can be performed using, for example, 16 x 16 measurement positions, with the size of the partial array assigned to each measurement position being 32 x 32. In this case, the partial arrays are adjacent to each other with no gaps. This measurement can determine the current density distribution in the form of a color map, for example, as shown in Figure 11(a).

[0061] In the aperture correction amount calculation step (S3 in Fig. 7), the amount of correction for the aperture position is calculated using the misalignment amount distribution obtained in the error amount distribution measurement step (S2), and the amount of correction for the aperture dimension is calculated using the current density distribution. In either case, a representative value of the error amount is determined for each block determined in S1 from the error amount distribution obtained in the error amount distribution measurement step (S2), and this is set as the aperture correction amount for each block.

[0062] We will now describe an example of calculating the amount of correction for the aperture position. First, we will show an example where the number of error measurement points is greater than the number of blocks, i.e., where there are multiple measurement points per block. When the misalignment distribution is measured for a large number of measurement points, as in Figure 8(a), each block determined in step S1 contains multiple measurement points. In this case, it is advisable to calculate the average error amount for each block at the measurement points included in that block and use this as the correction amount for that block. Figure 8(b) shows an example where the blocks determined in step S1 are 8 x 8, and Figure 8(c) shows an example where the blocks are 4 x 4. In Figures 8(b) and 8(c), the representative value for each block is displayed at the measurement point. Although there are multiple apertures within a block, Figures 8(b) and 8(c) show that the amount of correction for the aperture position is uniform within the block and discontinuous between blocks. The amount of correction for each block in Figure 8 can also be the median value rather than the average value of the errors at the measurement points included in the block.

[0063] The aperture position correction amount Δs is expressed by the following equation. In the following equation, i and j are subscripts that identify the blocks in the beam array. X indicates the measured position deviation amount. kis the coordinate of the measurement point belonging to block (i, j).

[0064]

number

[0065] Next, we will show an example where the number of measurement points is less than or equal to the number of blocks. The amount of misalignment measured by mark scanning has fewer measurement points than the amount of misalignment obtained from the drawing results of the evaluation board due to measurement time constraints. Therefore, the number of measurement points is often less than or equal to the number of blocks. In this case, the amount of misalignment X measured by mark scanning is m (x i ) to find X(x k )=f Xm (x k ) and using the polynomial whose coefficients are determined by fitting, estimate the amount of positional deviation at more evaluation points than the measurement results, and determine a representative value for each block from one or preferably multiple evaluation points belonging to each block.

[0066] A specific example is shown below. When the misalignment distribution is measured for 5 x 5 measurement points as shown in Figure 10(a), this misalignment distribution is fitted with a polynomial, for example, a cubic polynomial. Furthermore, from the fitting results, 16 x 16 evaluation points, which is more than the number of blocks, are set and the misalignment amount at each evaluation point is calculated. Next, for each block, the average misalignment amount of the evaluation points contained in the block is calculated and this is used as the representative value for that block. Figure 10(b) shows an example where the blocks determined in S1 are 8 x 8, and Figure 10(c) shows an example where the blocks are 4 x 4. Figures 10(b) and 10(c) show the representative values ​​for each block for each evaluation point.

[0067] In this way, the error amount X(x k ) is fitted with a polynomial function f to find the evaluation points x′, which are greater than the number of measurement points. k Error in X(x' k ) amount can be estimated to calculate the correction amount for each block.

[0068]

number

[0069] Next, we will explain how to calculate the aperture dimension correction amount. Figure 11(a) contains 16 × 16 measurement data points, which is more than the number of blocks. Therefore, for 8 × 8 or 4 × 4 blocks, the current density for each block can be determined by taking the average of the measurement data contained in each block, as in Equation 1 above. However, empirically, current density distributions are often expressed by quadratic polynomials. Therefore, a quadratic function is set as a distribution that is expected to be reproducible across different lithography systems and cathodes. This function is used to fit the measurement data. By setting evaluation points that are the same as the measurement points or different from the measurement points and calculating the error amount at the evaluation points from the fitting results, we can obtain correction amounts that are expected to be reproducible. Figure 11(b) shows the results of determining the current density at 16 × 16 evaluation points, calculating the current density at the evaluation points from the fitting results, and calculating a representative current density value for each 8 × 8 block. This method is similar to Equation 2 above in that it calculates a representative value for each block from the fitting results. Alternatively, without using fitting, the average current density at the measurement points belonging to a block can be used as the representative value for the block, as in Equation 1. In addition, the representative value of the current density for each block can be the average value of the current density or the median value. k ) instead of the normalized current density distribution J(x k ) / J0 and its representative value for each block, where J0 is the design value of the current density.

[0070] Next, as shown in the following formula, the opening area correction amount Δa is calculated using the representative value of the current density for each block, and the opening area correction amount Δa is used to calculate the dimension correction amount Δw. In the following formula, i and j are subscripts that identify the block. k indicates the coordinates of the measurement or evaluation point belonging to block (i, j). a0 is the design aperture size, J0 is the design current density, J(xk ) indicates the measured current density. The calculated aperture area correction ratio Δa(i,j) / a0 is shown in Figure 11(b). Because there are multiple apertures within a block, Figure 11(b) shows that the aperture size correction amount is uniform within the block and discontinuous between blocks.

[0071]

number

[0072] As described above, the aperture correction amounts (position correction amount, dimensional correction amount) can be determined from the measurement results for a single lithography tool. Based on these results, it is possible to manufacture a shaping aperture array substrate with corrected aperture positions and dimensions. However, the beam position deviation distribution and current density distribution will vary to some extent from tool to tool or each adjustment due to variations in the adjustment of the electron optical system and variations in the manufacturing of the electron optical lens barrel and cathode. Therefore, it is desirable to perform aperture correction using the average values ​​of the beam position deviation distribution and current density distribution measured using multiple lithography tools and cathodes as a distribution that is expected to be reproducible. In other words, it is desirable to perform aperture correction using the average value of multiple measurement results obtained by performing multiple cathode replacements and beam adjustments on a tool with the same configuration as the tool equipped with the shaping aperture array substrate with the corrected aperture, or multiple measurement results obtained on multiple tools with the same configuration.

[0073] Using the aperture correction amounts (position correction amount, dimensional correction amount) calculated for each block in this manner, apertures 203a are formed with positions and dimensions corrected for each block, and a shaping aperture array substrate 203 is fabricated (S4 in Figure 7). In the fabricated shaping aperture array substrate 203, the aperture array is divided into blocks, and the positions of the apertures 203a are shifted for each block. Within the same block, the apertures 203a are arranged at equal intervals, but the intervals between the apertures 203a at the block boundaries are different values. Furthermore, the dimensions of the apertures 203a differ from block to block.

[0074] The fabricated shaping aperture array substrate 203 is mounted on the drawing apparatus 100 shown in FIG. 1, and after adjusting the electron optical system, the substrate 101 is irradiated with multi-beams to draw a pattern.

[0075] If the positional deviation distribution and current density distribution of the multi-beam match or do not deviate significantly from the distributions predicted in advance, it is expected that the positional accuracy of the multi-beams irradiated onto the substrate 101 will be higher than when an uncorrected shaping aperture array substrate is used, because the positions and dimensions of the openings 203a in the shaping aperture array substrate 203 have been corrected, and that the pattern will be drawn with high precision. Also, because the uniformity of the current amount of each beam of the multi-beam is higher than when an uncorrected shaping aperture array substrate is used, the amount of current density distribution correction, i.e., the amount of irradiation time correction required to uniformize the amount of irradiation given by the multi-beams in one irradiation, will be reduced, thereby suppressing an increase in the shot cycle and improving drawing throughput.

[0076] During the pre-writing electron-optical system adjustment stage, the mark 104M is scanned with a partial beam array. Because the position or dimensions of the apertures 203a in the shaping aperture array substrate 203 are corrected for each block containing a partial array, the correction amount for each beam belonging to the partial beam array is uniform. Therefore, the mark scan waveform can be processed using the same conventional method used for a shaping aperture array substrate without aperture correction. Furthermore, even if the expected error distribution differs from the actual error distribution during or after the optical system adjustment, the error distribution within the partial array will not be worse than the actual error distribution. This allows for correction of block-by-block error distributions, which affect writing accuracy, while maintaining the reliability of the mark scan. Aperture correction is performed based on the state after beam adjustment, when the multi-beam position deviation distribution and current density distribution are minimized. However, before or during beam adjustment, the distributions may have larger deviations or may be different from these states. In particular, when adjusting the optical system, the positional deviation distribution and current density distribution of the multi-beam are measured in a state deviated from the optimal value in order to find the optimal value for the excitation amount of the lens or alignment coil. Therefore, it is important that the aperture correction does not adversely affect the mark scanning even in such a state, that is, even in a state where the distribution has a deviation larger than the distribution that determined the aperture correction amount or a different distribution.

[0077] Next, correction of the aperture position of the blanking aperture array substrate will be described. The blanking aperture array substrate 204 has a through hole H (second aperture) formed in alignment with the position of the aperture 203a of the shaping aperture array substrate 203. Therefore, correcting the position of the individual blanking mechanism 40, including the through hole H and the blanker 50, in accordance with the correction of the position of the aperture 203 of the shaping aperture array substrate 203 facilitates alignment of the multi-beam blanking aperture array with the aperture array when using a shaping aperture array substrate with the corrected aperture position. In this embodiment, as described above, the position of the aperture 203a of the shaping aperture array substrate 203 is corrected in units of blocks, and therefore the position of the individual blanking mechanism 40 is also corrected in units of blocks divided by the same number of blocks. When correcting the position of the individual blanking mechanism 40, as described below, it is preferable that the number of blocks determined in S1 of FIG. 7 be an even number × even number, i.e., 8 × 8, so that the LSI circuit of the blanking aperture array substrate 204 can be designed in units of blocks of the same size.

[0078] For example, as shown in FIG. 12, a blanking aperture array substrate 204 is fabricated by correcting the positions of the individual blanking mechanisms 40 on a block-by-block basis. The blanking aperture array substrate 204 is fabricated by creating an LSI chip or wafer with a control circuit and then processing it using MEMS to form a structure including a blanker and passage holes H. In other words, the design and fabrication of a blanking aperture array substrate involves two elements: the LSI wafer or chip and the MEMS wafer or chip. By correcting the positions of the individual blanking mechanisms 40 on a block-by-block basis, design changes to the LSI circuit can be accommodated by shifting the circuit and wiring for each block and modifying the wiring paths at block boundaries. In other words, because design changes other than shifting are limited to modifying the wiring paths at block boundaries, the amount of design change required for the LSI circuit is smaller than when the positions of the individual blanking mechanisms 40 are corrected independently, facilitating the design and fabrication of an LSI circuit for a blanking aperture array with shifted aperture positions. Similarly, design changes to the MEMS structure can be accommodated by shifting the MEMS structure in block units and changing the design of the MEMS structure at the block boundary, which makes it easy to design and manufacture a MEMS structure with corrected aperture positions.

[0079] Furthermore, blanking aperture arrays are complex chips with hundreds of thousands of individual blanking mechanisms and control circuits, but depending on whether the location of the LSI circuit malfunction or MEMS structure formation defect is at the block boundary or not, it becomes possible to determine whether the defect is due to a design change for shifting the aperture position or to an unrelated cause in the LSI manufacturing process or MEMS process. This makes it easier to manufacture and control the quality of blanking aperture arrays with shifted aperture positions.

[0080] In the above embodiment, an example has been described in which the positions and dimensions of the openings 203a of the shaping aperture array substrate 203 are corrected, but it is also possible to correct only either the position or the dimension. Also, in the blanking aperture array substrate 204, not only the position but also the dimension may be corrected, or only the dimension may be corrected.

[0081] According to the above embodiment, even if the aperture correction amount distribution and the actual beam error amount, i.e., the distribution of positional deviation or current density, do not match, the aperture correction can be prevented from making the error distribution within the grouped multi-beam worse than the actual one, thereby preventing the aperture correction from adversely affecting the mark scanning process even in such cases. Furthermore, it is possible to easily change the design of the wiring and control circuits within the blanking aperture substrate when correcting the aperture position of the blanking aperture array substrate.

[0082] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. For example, the present invention is not limited to a writing apparatus, but can also be applied to an inspection apparatus. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0083] 40 Individual blanking mechanism 50 Blanca 100 Drawing device 203 Shaped Aperture Array Substrate 204 Blanking aperture array substrate 104 Mark Board 106 Faraday Cup 108 detectors

Claims

1. A method for calculating a correction amount for positions or dimensions of a plurality of openings in an aperture array substrate having a plurality of openings through which a multi-charged particle beam passes, the method comprising: measuring a deviation distribution, which is a distribution of deviations from a predetermined position or a predetermined current density of each beam in a beam array of the multi-charged particle beam; Dividing the beam array into a predetermined number of block regions based on the deviation amount distribution, and calculating a representative value of the deviation amount corresponding to each block region; a method for calculating an amount of correction for an aperture of an aperture array substrate, the method comprising: calculating, for each of the block regions, an amount of correction for the position or size of the aperture of the corresponding aperture array substrate, based on the representative value;

2. 2. The method for calculating an aperture correction amount for an aperture array substrate according to claim 1, further comprising the steps of: irradiating a substrate to be irradiated with the multi-charged particle beam to draw an evaluation pattern; measuring the drawing position of the evaluation pattern; and determining the deviation amount distribution using the measurement results.

3. 2. The method for calculating an aperture correction amount for an aperture array substrate according to claim 1, further comprising the steps of: irradiating a mark with beams from an on-beam area in which beams from a portion of the beam array are turned on; detecting a reflected charged particle signal from the mark to calculate a position of the on-beam area; sequentially switching the on-beam areas to calculate positions of a plurality of on-beam areas; and determining the deviation amount distribution using the positions of the plurality of on-beam areas.

4. setting a plurality of measurement points within the beam array; Allocating block areas that are part of the beam array to each of the plurality of measurement points, and arranging the block areas adjacent to each other; 2. The method for calculating an aperture correction amount for an aperture array substrate according to claim 1, wherein the amount of current is measured at each of the plurality of measurement points to determine the deviation amount distribution.

5. 2. The method for calculating an aperture correction amount for an aperture array substrate according to claim 1, wherein the representative value is an average or median value of a plurality of positional deviation amounts within the block region.

6. 6. An aperture array substrate in which the positions or dimensions of a plurality of apertures are corrected based on the correction amounts calculated by the method for calculating aperture correction amounts for an aperture array substrate according to claim 1.

7. 6. A blanking aperture array substrate, comprising: a blanker for blanking deflection of each beam of the multi-charged particle beam passing through each aperture in accordance with the corrected position of each aperture; and a control circuit for applying a voltage to the blanker; the blanker correcting the positions of a plurality of apertures based on a correction amount calculated by the method for calculating an aperture correction amount for an aperture array substrate according to claim 1;

8. a beam source that emits a charged particle beam; a shaping aperture array substrate which is divided into blocks for each region, and in which a plurality of first openings whose positions are shifted or whose dimensions are different are formed in block units, and in which the charged particle beam is irradiated onto a region including all of the plurality of first openings, and in which parts of the charged particle beam pass through the plurality of first openings, thereby forming multiple beams; a blanking aperture array substrate in which a plurality of second apertures are formed, through which corresponding beams of the multi-beams pass, and in which blankers for blanking deflection of the beams are provided in the second apertures; a deflector that collectively deflects the beams that have passed through the plurality of second openings and adjusts the beam irradiation position on the substrate to be written; A multi-charged particle beam writing apparatus comprising:

9. 9. The multi-charged particle beam drawing apparatus according to claim 8, wherein the second openings are divided into blocks for each region, and the positions of the second openings are shifted in units of blocks.

10. emitting a charged particle beam; a step of irradiating the charged particle beam onto a shaping aperture array substrate, which is divided into blocks for each region and has a plurality of first openings formed thereon, the positions of which are shifted or which have different dimensions in block units, and forming a multi-beam by allowing portions of the charged particle beam to pass through the plurality of first openings; a step of controlling on / off of each beam using a blanking aperture array substrate in which a plurality of second apertures are formed, through which corresponding beams of the multi-beams pass, and in which blankers for blanking deflection of the beams are provided in each second aperture; using a deflector to collectively deflect the beams that have passed through the plurality of second openings, and irradiate the beams onto a substrate to be written; A multi-charged particle beam writing method comprising:

11. 11. The multi-charged particle beam writing method according to claim 10, wherein the second openings are divided into blocks for each region, and the positions of the second openings are shifted in units of blocks.

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