Multi-charged particle beam drawing apparatus, multi-charged particle beam drawing method, and readable recording medium having a program recorded thereon

Abstract

A multi-charged particle beam lithography apparatus according to one aspect of the present invention is characterized by comprising: a calculation processing unit that performs calculation processing of the temperature rise caused by heat generated by irradiating each grid region in a processing region corresponding to a beam array region being supplied to a target grid region which is one of the plurality of grid regions, the calculation processing being performed by convolution processing using the dose representative value of each of the grid regions and a heat spread function representing heat spread generated in the grid region; an effective temperature calculation unit that performs a repetitive process of repeatedly performing the calculation processing while moving the position of the processing region in a second direction on a bar region, and calculates representative values of the plurality of temperature rises obtained by performing the repetitive process a plurality of times until the target grid region reaches a position at the other end from one end in the second direction of the processing region, as the effective temperature of the target grid region; and a dose correction unit that corrects the doses of the plurality of beams irradiated to each of the target grid regions using the effective temperature.

Description

Technical Field

[0001] The present invention relates to a multi-charged particle beam drawing apparatus, a multi-charged particle beam drawing method, and a readable recording medium recording a program, and more particularly to a method for correcting resist heating caused by multi-beam drawing. Background Art

[0002] Lithography technology, which is responsible for the progress of miniaturization of semiconductor devices, is an extremely important process that is the only one to generate patterns in the semiconductor manufacturing process. In recent years, with the high integration of LSIs, the circuit line widths required for semiconductor devices have been miniaturized year by year. Here, electron beam (e-beam) drawing technology has excellent resolution in nature, and an e-beam is used to draw on a wafer or the like.

[0003] For example, there is a drawing apparatus using multiple beams. Compared with the case of drawing with a single e-beam, by using multiple beams, a larger number of beams can be irradiated at one time, and the production volume can be greatly increased. In such a multi-beam type drawing apparatus, for example, an e-beam emitted from an electron gun is passed through a mask having a plurality of holes to form multiple beams, blanking control is performed respectively, and each unobstructed beam is reduced by an optical system and deflected by a deflector to be irradiated to a desired position on a specimen.

[0004] Here, in drawing using an e-beam, if it is desired to irradiate irradiation energy with a higher density e-beam in a short time, there is a problem of a phenomenon called resist heating occurring: the substrate temperature overheats, the resist sensitivity changes, and the line width accuracy deteriorates. For example, in single-beam drawing, a method is adopted in which the influence of the temperature rise of each past emission of one beam is accumulated to determine the dose correction amount of the current emission. However, in multi-beam drawing, since multiple beams are used, in the method of accumulating the influence of the temperature rise of each past emission and each beam, the calculation amount becomes huge. In addition, in multi-beam drawing, since multiple beams are simultaneously emitted, it is necessary to consider the influence of the temperature rise of other multiple beams from a wide range of regions that are simultaneously irradiated.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-503837 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] One aspect of the present invention provides an apparatus and a method for correcting resist heating without accumulating the influence of the temperature rise of each emission and each beam in multi-beam drawing.

[0010] Means for solving problems

[0011] A multi-charged particle beam imaging device according to one embodiment of the present invention irradiates a multi-charged particle beam onto an imaging area on a sample surface, and is characterized by comprising:

[0012] a dividing unit for dividing the drawing area into a plurality of grid areas in the first direction and in a second direction, which is a moving direction of the worktable along each of the plurality of strip areas, formed by dividing the drawing area in the first direction according to the size of the beam array area of the multiple charged particle beams on the sample surface;

[0013] a dose representative value calculation unit that calculates, for each of the divided grid areas, representative values of a plurality of doses generated by irradiating the grid area with a plurality of beams as the dose representative value;

[0014] a calculation processing unit that performs calculation processing of a temperature rise caused by heat generated by irradiating the beam to each of the grid areas within the treatment area corresponding to the beam array area and being supplied to a grid area of interest, which is one of the plurality of grid areas, the calculation processing being performed by convolution processing using the dose representative value for each of the grid areas and a heat spread function representing heat spread generated in the grid area;

[0015] an effective temperature calculation unit that performs an iterative process of repeatedly performing the calculation process while moving the position of the processing area in the second direction on the strip area, and calculates representative values of a plurality of the temperature increases obtained by performing the iterative process a plurality of times until the focus grid area moves from one end of the processing area in the second direction to the other end, as the effective temperature of the focus grid area;

[0016] a dose correction unit that corrects the dose of the plurality of beams irradiating each of the grid areas of interest using the effective temperature; and

[0017] The drawing mechanism draws a pattern on the sample using the multiple charged particle beams of the respectively calibrated doses.

[0018] A multi-charged particle beam drawing method according to one embodiment of the present invention is characterized in that:

[0019] The sample drawing area is divided into a plurality of grid areas in each of the plurality of strip areas divided in the first direction by the size of the beam array area of the multi-charged particle beam on the sample surface in the first direction, and in the second direction, which is the moving direction of the worktable along each of the strip areas.

[0020] For each of the divided grid regions, calculate statistical values of a plurality of doses generated by irradiating a plurality of beams within the grid region as dose statistical values.

[0021] Perform a calculation process for calculating the rising temperature caused by heat generated by irradiating each of the above grid regions in the processing region corresponding to the above beam array region being supplied to a target grid region that is one of the above plurality of grid regions. The above calculation process is a convolution process using the above dose statistical value of each of the above grid regions and a heat diffusion function representing the heat diffusion generated by the grid region.

[0022] Perform a repetitive process of repeatedly performing the above calculation process while moving the position in the second direction on the above bar region, and calculate representative values of the above plurality of rising temperatures obtained by performing the above repetitive process multiple times until the target grid region reaches the position at the other end from one end in the second direction of the above processing region, that is, the effective temperature of the target grid region.

[0023] Use the above effective temperature to correct the doses of the plurality of beams irradiating each of the above target grid regions.

[0024] Use the multi-charged particle beams with the above doses corrected respectively to draw a pattern on the above specimen.

[0025] A readable recording medium recording a program according to one aspect of the present invention, for causing a computer to execute the following steps:

[0026] A step of dividing the drawing region of the specimen into a plurality of grid regions within each of the bar regions of a plurality of bar regions divided in the first direction by the size of the beam array region of the multi-charged particle beam on the specimen surface in the first direction, in the first direction and the second direction which is the moving direction of the workbench along each of the bar regions;

[0027] A step of, for each of the divided grid regions, calculating statistical values of a plurality of doses generated by irradiating a plurality of beams within the grid region as dose statistical values;

[0028] A step of performing a calculation process for calculating the rising temperature caused by heat generated by irradiating each of the above grid regions in the processing region corresponding to the above beam array region being supplied to a target grid region that is one of the above plurality of grid regions. The above calculation process is a convolution process using the above dose statistical value of each of the above grid regions and a heat diffusion function representing the heat diffusion generated by the grid region;

[0029] A step of performing an iterative process of repeatedly performing the above calculation process while moving the position in the second direction on the above bar-shaped area, and respectively calculating representative values of the plurality of above rising temperatures obtained by performing the above iterative process multiple times until the above target grid area reaches a position at the other end from one end in the second direction of the above processing area, that is, the effective temperature of the above target grid area; and

[0030] A step of correcting the dose of the plurality of beams irradiated to each of the above target grid areas using the above effective temperature.

[0031] Advantages of the Invention

[0032] According to one aspect of the present invention, in multi-beam lithography, it is possible to correct resist heating without accumulating the influence of temperature rise for each emission and each beam. Brief Description of the Drawings

[0033] Figure 1 It is a conceptual diagram showing the configuration of the lithography apparatus according to Embodiment 1.

[0034] Figure 2 It is a conceptual diagram showing the configuration of the shaped aperture array substrate according to Embodiment 1.

[0035] Figure 3 It is a cross-sectional view showing the configuration of the blanking aperture array mechanism according to Embodiment 1.

[0036] Figure 4 It is a top view conceptual diagram showing a part of the configuration within the diaphragm area of the blanking aperture array mechanism according to Embodiment 1.

[0037] Figure 5 It is a diagram showing an example of the individual blanking mechanism according to Embodiment 1.

[0038] Figure 6 It is a conceptual diagram for explaining an example of the lithography operation according to Embodiment 1.

[0039] Figure 7 It is a diagram showing an example of the irradiation area of the multi-beams and the pixels to be lithographed according to Embodiment 1.

[0040] Figure 8 It is a diagram for explaining an example of the multi-beam lithography operation according to Embodiment 1.

[0041] Figure 9 It is a diagram showing an example of the relationship between the temperature distribution and the temperature caused by irradiating a single beam to an area of one beam pitch amount in the comparative example according to Embodiment 1.

[0042] Figure 10 It is a diagram showing an example of the relationship between the temperature distribution and the temperature caused by simultaneously irradiating multi-beams according to Embodiment 1.

[0043] Figure 11 It is a flowchart showing an example of the main process of the drawing method of Embodiment 1.

[0044] Figure 12 It is a diagram showing an example of the processing grid of Embodiment 1.

[0045] Figure 13 It is a diagram for explaining the calculation method of the effective temperature of Embodiment 1.

[0046] Figure 14 It is a diagram for explaining a part of the calculation formula of the effective temperature of Embodiment 1.

[0047] Figure 15 It is a diagram showing an example of the calculation formula of the thermal expansion function of Embodiment 1.

[0048] Figure 16 It is a diagram for explaining another part of the calculation formula of the effective temperature of Embodiment 1.

[0049] Figure 17 It is a diagram for explaining another part of the calculation formula of the effective temperature of Embodiment 1.

[0050] Figure 18 It is a diagram for explaining another part of the calculation formula of the effective temperature of Embodiment 1.

[0051] Figure 19 It is a diagram showing an example of the relationship between the line width CD and the temperature of Embodiment 1.

[0052] Figure 20 It is a diagram showing an example of the relationship between the line width CD and the dose of Embodiment 1.

[0053] Figure 21 It is a diagram for explaining the stage speed curve of Embodiment 2.

[0054] Figure 22 It is a diagram showing an example of the calculation formula of the thermal expansion function of Embodiment 2. Detailed Embodiments

[0055] Hereinafter, in the embodiments, as an example of a charged particle beam, the configuration using an electron beam will be described. However, the charged particle beam is not limited to an electron beam, and may also be a beam using charged particles such as an ion beam.

[0056] [Embodiment 1]

[0057] Figure 1 It is a conceptual diagram showing the configuration of the drawing apparatus of Embodiment 1. In Figure 1In this case, the drawing apparatus 100 includes a drawing mechanism 150 and a control system circuit 160. The drawing apparatus 100 is an example of a multi-charged particle beam drawing apparatus and is also an example of a multi-charged particle beam exposure apparatus. The drawing mechanism 150 includes an electron column 102 (electron beam column) and a drawing chamber 103. Inside the electron column 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, and a sub-deflector 209 are arranged. Inside the drawing chamber 103, an XY stage 105 is arranged. On the XY stage 105, a specimen 101 such as a mask which becomes a drawing object substrate during drawing (exposure) is arranged. The specimen 101 includes an exposure mask for manufacturing a semiconductor device or a semiconductor substrate (silicon wafer) for manufacturing a semiconductor device, etc. In addition, a resist is coated on the specimen 101. For example, the specimen 101 includes a mask blank coated with a resist on which no drawing has been performed yet. On the XY stage 105, a mirror 210 for position measurement of the XY stage 105 is also arranged.

[0058] The control system circuit 1 sixty has a control computer 110, a memory 112, a deflection control circuit 130, digital-to-analog conversion (DAC) amplifier units 132, 134, a lens control circuit 136, a stage control mechanism 138, a stage position detector 139, and storage devices 140, 142, 144 such as a disk device. The control computer 110, the memory 112, the deflection control circuit 130, the lens control circuit 136, the stage control mechanism 138, the stage position detector 139, and the storage devices 140, 142, 144 are interconnected via a bus (not shown). The DAC amplifier units 132, 134 and the blanking aperture array mechanism 204 are connected to the deflection control circuit 130. The sub-deflector 209 is composed of electrodes with four or more poles, and each electrode is controlled by the deflection control circuit 130 via each DAC amplifier 132. The main deflector 208 is composed of electrodes with four or more poles, and each electrode is controlled by the deflection control circuit 130 via each DAC amplifier 134. The stage position detector 139 receives the reflected light from the mirror 210, and thereby measures the position of the XY stage 105 using the principle of laser interferometry.

[0059] The pattern density calculation unit 50, dose calculation unit 52, segmentation unit 53, dose representative value calculation unit 54, tracking cycle time calculation unit 56, convolution calculation processing unit 57, effective temperature calculation unit 58, modulation rate calculation unit 60, correction unit 62, irradiation time data generation unit 72, data processing unit 74, transmission control unit 79, and drawing control unit 80 are configured in the control computer 110. Each of the "~ units" such as the pattern density calculation unit 50, dose calculation unit 52, segmentation unit 53, dose representative value calculation unit 54, tracking cycle time calculation unit 56, convolution calculation processing unit 57, effective temperature calculation unit 58, modulation rate calculation unit 60, correction unit 62, irradiation time data generation unit 72, data processing unit 74, transmission control unit 79, and drawing control unit 80 has a processing circuit. Such a processing circuit includes, for example, a 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 may also use different processing circuits (different processing circuits). Information input / output and information during operation with respect to the pattern density calculation unit 50, dose calculation unit 52, segmentation unit 53, dose representative value calculation unit 54, tracking cycle time calculation unit 56, convolution calculation processing unit 57, effective temperature calculation unit 58, modulation rate calculation unit 60, correction unit 62, irradiation time data generation unit 72, data processing unit 74, transmission control unit 79, and drawing control unit 80 are each stored in the memory 112 every time.

[0060] The drawing operation of the drawing device 100 is controlled by the drawing control unit 80. In addition, the transmission process of the irradiation time data for each emission to the deflection control circuit 130 is controlled by the transmission control unit 79.

[0061] In addition, chip data is input from the outside of the drawing device 100 and stored in the storage device 140. The drawing data includes chip data and drawing condition data. In the chip data, for each graphic pattern, for example, a graphic code, coordinates, dimensions, etc. are defined. In addition, the drawing condition data includes information indicating the multiplicity and the stage speed.

[0062] In addition, the related data described later for calculating the modulation rate for correcting the resist heating is stored in the storage device 144.

[0063] Here, in Figure 1 the configuration required for explaining Embodiment 1 is described. For the drawing device 100, other required configurations may generally be provided.

[0064] Figure 2 is a conceptual diagram showing the configuration of the shaping aperture array substrate of Embodiment 1. In Figure 2In the forming aperture array substrate 203, holes (openings) 22 are formed in a matrix with a specified arrangement pitch, with p columns in the longitudinal (y direction) and q columns in the transverse (x direction) (p, q ≥ 2). In Figure 2 the example of, for example, it shows a case where holes 22 are formed in 500 columns × 500 rows in the horizontal and vertical (x, y directions). The number of holes 22 is not limited to this. Each hole 22 is formed as a rectangle with the same size and shape. Alternatively, it can also be a circle with the same diameter. A part of the electron beam 200 passes through these multiple holes 22 respectively, thereby forming a multi-beam 20. In other words, the forming aperture array substrate 203 forms the multi-beam 20.

[0065] Figure 3 is a cross-sectional view showing the configuration of the blanking aperture array mechanism of Embodiment 1.

[0066] Figure 4 is a top view conceptual diagram showing a part of the configuration within the diaphragm region of the blanking aperture array mechanism of Embodiment 1. Additionally, in Figure 3 and Figure 4 the positional relationship of the control electrode 24, the counter electrode 26, the control circuit 41, and the pad 343 is not consistently described. As Figure 3 shown, the blanking aperture array mechanism 204 has a blanking aperture array substrate 31 made of a semiconductor substrate such as silicon disposed on the support table 33. In the diaphragm region 330 at the center of the blanking aperture array substrate 31, through holes 25 (openings) for allowing the respective beams of the multi-beam 20 to pass through are formed at positions corresponding to the respective holes 22 of the forming aperture array substrate 203 shown in Figure 2 . And for each of the multiple through holes 25, a set of a control electrode 24 and a counter electrode 26 (blanker: blanking deflector) are respectively disposed at positions facing each other across the through hole 25. In addition, a control circuit 41 (logic circuit; unit) for applying a deflection voltage to the control electrode 24 for each through hole 25 is disposed inside the blanking aperture array substrate 31 near each through hole 25. The counter electrode 26 for each beam is grounded.

[0067] In addition, as Figure 4As shown, each control circuit 41 is connected to parallel wirings for control signals of n bits (e.g., 10 bits). In addition to the parallel wirings for n-bit irradiation time control signals (data), each control circuit 41 is also connected to wirings for clock signals, read signals, emission signals, power supplies, etc. These wirings can also use a part of the parallel wirings. For each of the individual beams that make up the multi-beam 20, an individual blanking mechanism 47 is formed by the control electrode 24, the counter electrode 26, and the control circuit 41. In addition, in Embodiment 1, as a data transmission method, for example, a shift register method is used. In the shift register method, the multi-beam 20 is divided into multiple groups for each of the multiple beams, and multiple shift registers for multiple beams within the same group are connected in series. Specifically, the multiple control circuits 41 formed in an array in the diaphragm area 330 are grouped at a specified pitch, for example, in the same row or the same column. As Figure 4 shown, the groups of control circuits 41 within the same group are connected in series. And the signals from the pads 343 arranged for each group are transmitted to the control circuits 41 within the group.

[0068] Figure 5 FIG. is an example showing an individual blanking mechanism of Embodiment 1. In Figure 5 , an amplifier 46 (an example of a switching circuit) is arranged within the control circuit 41. In Figure 5 the example, as an example of the amplifier 46, a CMOS (Complementary MOS) inverter circuit that is a switching circuit is arranged. Either an L (low) potential (e.g., ground potential) below the threshold voltage or an H (high) potential (e.g., 1.5 V) above the threshold voltage is applied as a control signal to the input (IN) of the CMOS inverter circuit. In Embodiment 1, in a state where 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 is a positive potential (Vdd), and the corresponding beam 20 is deflected by the electric field generated by the potential difference with the ground potential of the counter electrode 26 and is blocked by the aperture limiting substrate 206, thereby controlling the beam to be cut off. On the other hand, in a state where an H potential is applied to the input (IN) of the CMOS inverter circuit (activated state), the output (OUT) of the CMOS inverter circuit becomes the ground potential, and the potential difference with the ground potential of the counter electrode 26 disappears and the corresponding beam 20 is not deflected. Therefore, through the aperture limiting substrate 206, the beam is controlled to be turned on. Blanking control is performed through such deflection.

[0069] Then, each individual blanking mechanism 47 controls the irradiation time of the emission for each beam individually using a counter circuit (not shown) according to the irradiation time control signal transmitted for each beam.

[0070] Next, a specific example of the operation of the drawing mechanism 150 will be described. The electron beam 200 emitted from the electron gun 201 (emission source) illuminates the entire shaping aperture array substrate 203 substantially vertically through the illumination lens 202. A plurality of rectangular holes 22 (openings) are formed in the shaping aperture array substrate 203, and the electron beam 200 illuminates the area including all the plurality of holes 22. Each part of the electron beam 200 that irradiates the positions of the plurality of holes 22 passes through the plurality of holes 22 of the shaping aperture array substrate 203, respectively. Thus, for example, a multi-beam (a plurality of electron beams) 20 having a rectangular shape is formed. This multi-beam 20 passes into the blanker (first deflector: individual blanking mechanism 47) corresponding to the blanking aperture array mechanism 204 respectively. Each of these blankers performs blanking control on the beam passing through individually during the set drawing time (irradiation time) to make the beam in the on state.

[0071] The multi-beam 20 after passing through the blanking aperture array mechanism 204 is reduced by the reduction lens 205 and travels toward the hole formed at the center of the limiting aperture substrate 206. Here, the position of the electron beam deflected by the blanker of the blanking aperture array mechanism 204 deviates from the hole at the center of the limiting aperture substrate 206 and is blocked by the limiting aperture substrate 206. On the other hand, the electron beam not deflected by the blanker of the blanking aperture array mechanism 204 passes through the hole at the center of the limiting aperture substrate 206 as Figure 1 shown. In this way, the limiting aperture substrate 206 blocks each beam deflected by the individual blanking mechanism 47 into the beam cut-off state. Then, each beam of one emission is formed by using the beam that has passed through the limiting aperture substrate 206 and is formed from the beam on state to the beam cut-off state. The multi-beam 20 that has passed through the limiting aperture substrate 206 is focused by the objective lens 207 to form a pattern image with a desired reduction ratio. The entire multi-beam 20 that has passed through the limiting aperture substrate 206 is deflected in the same direction by the main deflector 208 and the sub-deflector 209 and irradiated onto the respective irradiation positions on the specimen 101 of each beam. In addition, for example, when the XY stage 105 moves continuously, the multi-beam 20 is deflected by the main deflector 208 so that the irradiation position of the beam follows the movement of the XY stage 105, thereby performing tracking control. The multi-beam 20 irradiated once is ideally arranged at intervals obtained by multiplying the arrangement interval of the plurality of holes 22 of the shaping aperture array substrate 203 by the above-mentioned desired reduction ratio.

[0072] Figure 6 is a conceptual diagram for explaining an example of the drawing operation of Embodiment 1. As Figure 6As shown, the drawing area 30 of the sample 101 is, for example, virtually divided into a plurality of long strip-shaped areas 32 with a predetermined width in the y direction. First, the XY worktable 105 is moved and adjusted so that the irradiation area 34 that can be irradiated by the emission of the multi-beam 20 once is located at the left end or further to the left of the first strip-shaped area 32, and the drawing is started. When drawing the first strip-shaped area 32, the XY worktable 105 is moved in the -x direction, for example, so that the drawing is relatively performed in the x direction. The XY worktable 105 moves continuously, for example, at a constant speed. After the drawing of the first strip-shaped area 32 is completed, the worktable position is moved in the -y direction, and this time the XY worktable 105 is moved in the x direction, for example, so that the drawing is performed in the -x direction in the same manner. By repeating this action, each strip-shaped area 32 is drawn in sequence. By drawing while alternating the direction, the drawing time can be shortened. However, the drawing is not limited to this method of alternately changing the direction while drawing. Each strip area 32 may also be drawn in the same direction. When the XY stage 105 is moved at a constant speed, the continuous movement speed may be varied for each strip. In a single shot, multiple beams formed by the apertures 22 of the shaped aperture array substrate 203 are used to form a maximum of a number of shot patterns, equal to the number of apertures 22.

[0073] Figure 7 : is a diagram showing an example of the irradiation area of the multi-beam and the pixels to be drawn according to the first embodiment. Figure 7 In the embodiment, the strip area 32 is divided into a plurality of grid areas in a grid shape, for example, by the beam size of the multi-beam 20. Each of these grid areas becomes a pixel 36 (unit irradiation area, irradiation position or depiction position) for depicting the object. The size of the pixel 36 for depicting the object is not limited to the beam size, and can also be composed of any size that is unrelated to the beam size. For example, it can be composed of a size of 1 / a (a is an integer greater than 1) of the beam size. Figure 7 In the example of , the case where the drawing area 30 of the sample 101 is divided into a plurality of strip areas 32 with a width dimension substantially the same as the dimension of the irradiation area 34 (beam array area) that can be irradiated by irradiation of the multi-beam 20 once, for example, in the y direction is shown. The dimension of the rectangular irradiation area 34 in the x direction can be defined as the number of beams in the x direction × the spacing between beams in the x direction. The dimension of the rectangular irradiation area 34 in the y direction can be defined as the number of beams in the y direction × the spacing between beams in the y direction. In Figure 7In the example, for instance, the illustration of the multi-beam of 500 columns × 500 rows is omitted and shown as a multi-beam of 8 columns × 8 rows. Also, within the irradiation region 34, a plurality of pixels 28 (the depicted positions of the beams) that can be irradiated by the emission of the multi-beam 20 in one pass are shown. The pitch between adjacent pixels 28 on the specimen surface is the pitch between the respective beams of the multi-beam 20. A rectangular region surrounded in the x and y directions by the size of the beam pitch constitutes one sub-irradiation region 29 (pitch unit). Each sub-irradiation region 29 includes one pixel 28. In Figure 7 the example, for example, the pixel at the upper left corner of each sub-irradiation region 29 is shown as the pixel 28 located at the depicted position of the beam. Each sub-irradiation region 29 is constituted by, for example, 10 × 10 pixels. In Figure 7 the example, for instance, each sub-irradiation region 29 of 10 × 10 pixels is omitted and shown as, for example, 4 × 4 pixels.

[0074] Figure 8 is a diagram for explaining an example of the multi-beam drawing operation of Embodiment 1. In Figure 8 the example, the situation of irradiating each sub-irradiation region 29 on the surface of the specimen 101 by 10 different beams is shown. Further, in Figure 8 the example, the drawing operation is shown in which, during the period of drawing 1 / 10 (one divided by the number of beams for irradiation) of the region within each sub-irradiation region 29, the XY stage 105 continuously moves, for example, at a speed of moving a distance L of 25 beam pitches. In Figure 8 In the drawing operation shown in the example, for instance, it is shown that while the XY stage 105 moves a distance L of 25 beam pitches, the irradiation position (pixel 36) is sequentially shifted by the sub-deflector 209, and within the emission cycle time t trk-cycle 10 multi-beams 20 are emitted 10 times to draw (expose) different 10 pixels within the same sub-irradiation region 29. During the period of drawing (exposing) these 10 pixels, the entire multi-beam 20 is deflected by the main deflector 208 all at once, thereby causing the irradiation region 34 to follow the movement of the XY stage 105 so that the relative position between the irradiation region 34 and the specimen 101 does not shift due to the movement of the XY stage 105. In other words, tracking control is performed. Therefore, in each tracking control, the distance L deflected all at once by the main deflector 208 is the tracking distance.

[0075] When the tracking loop for one time ends, tracking reset is performed and the previous tracking start position is returned. In addition, since the drawing of the first pixel row from the top of each sub-irradiation area 29 is completed, after the tracking reset is performed, in the next tracking loop, first, the sub-deflector 209 is deflected so that the drawing position of the beam coincides (shifts) in order to draw the pixel columns of, for example, the second row from the top that have not been drawn in each sub-irradiation area 29. Thus, at each tracking reset, the pixel columns to be drawn next are changed. During the execution of 10 times of tracking control, each pixel 36 in each sub-irradiation area 29 is drawn once. In the drawing of the bar area 32, by repeating this operation, as Figure 6 shown, the position of the irradiation area 34 moves in sequence according to the cases of the irradiation areas 34a to 34o, and the drawing of this bar area 32 is performed.

[0076] In Figure 8 the example of, the sub-irradiation area 29 on the sample surface at the lower right corner of the irradiation area 34 with a width W becomes a position shifted by a distance L to the left from the lower right corner of the irradiation area 34 in the second tracking control. Therefore, the sub-irradiation area 29 located at the lower right corner of the irradiation area 34 in the first tracking control is drawn by other beams at a position separated by a distance L to the left from the lower right corner of the irradiation area 34 in the second tracking control. Here, it is drawn by beams separated by, for example, 25 in the -x direction from the beam at the lower right corner.

[0077] For example, in the drawing process where the multiplicity of each stage 1 path is set to 2, each pixel 36 in each sub-irradiation area 29 can be drawn twice through 20 times of tracking control.

[0078] Figure 9 is a diagram showing an example of the relationship between the temperature distribution and the temperature caused by irradiating one beam to an area of one beam pitch in the comparative example of Embodiment 1. In Figure 9 it, the vertical axis represents the temperature and the horizontal axis represents the temperature distribution. As Figure 9 shown, the foot area of the temperature distribution caused by irradiating one beam is wide. Therefore, it affects a wide range. However, as the influence on the foot area, the temperature rise caused by one beam is at most as small as below 0.01 °C.

[0079] Figure 10 is a diagram showing an example of the relationship between the temperature distribution and the temperature caused by simultaneously irradiating multiple beams in Embodiment 1. In Figure 10 it, the vertical axis represents the temperature and the horizontal axis represents the temperature distribution. The temperature rise caused by one beam is at most below 0.01 °C, but for example, when simultaneously irradiating 500 × 500 = 250,000 beams, as Figure 10As shown, the temperature rises caused by the respective beams overlap in the foot-of-mountain region. As a result, for example, when 500 × 500 = 250,000 beams are irradiated simultaneously, a significant temperature rise occurs in the foot-of-mountain region.

[0080] Techniques related to predicting and correcting the heating effect in a single-beam-based one-beam drawing are known, but there is no precedent for correcting the heating effect in a multi-beam drawing method in which, for example, 250,000 or more beams are simultaneously emitted at each stage path. Calculating the heat generated by each of, for example, 250,000 beams in the same way as a single beam is unrealistic in terms of the amount of calculation.

[0081] In multi-beams, the current density J is extremely small compared to a single beam in, for example, the VSB method, so the temperature rises slowly. And during this period, the temperature distribution caused by one emission spreads by several tens of μm. Therefore, even if the emission data and dose data within the bar are divided and summarized to a certain extent, sufficient accuracy can be obtained. In addition, as described above, in multi-beam drawing, the raster scan method is used, so the position is determined according to time. Therefore, if the dose data and the drawing speed (table speed or tracking cycle time) are determined, the rising temperature is determined. A simpler correction can be performed compared to the VSB method of drawing that requires both position and time.

[0082] Therefore, in Embodiment 1, the dose information of the bar region 32 is assigned to a certain M × N pixel information including the target grid for which the temperature should be obtained. For the target grid, using the dose information before and after this region and parameters such as the tracking cycle time that determine the progress speed of the drawing as inputs, the temperature at the time of each of the multiple beam irradiations is calculated. Then, its statistical value (for example, the average value) is used as the effective temperature for correction. Hereinafter, a specific description will be given.

[0083] Figure 11 is a flowchart showing an example of the main part processes of the drawing method of Embodiment 1. In Figure 11 the drawing method of Embodiment 1 implements a series of processes including a pattern density calculation process (S102), a dose calculation process (S104), a processing grid division process (S106), a tracking cycle time calculation process (S108), a dose representative value calculation process (S110), a convolution calculation process (S111), an effective temperature calculation process (S112), a modulation rate calculation process (S114), a correction process (S118), an irradiation time data generation process (S120), a data processing process (S122), and a drawing process (S124).

[0084] First, for each bar region 32, the drawing data is read out from the storage device 140.

[0085] As the pattern density calculation step (S102), the pattern density calculation unit 50 calculates the pattern density ρ (area density of the pattern) for each pixel 36 within the target bar-shaped region 32. For each bar-shaped region 32, the pattern density calculation unit 50 creates a pattern density map using the calculated pattern density ρ of each pixel 36. The pattern density of each pixel 36 is defined as each element of the pattern density map. The created pattern density map is stored in the storage device 144.

[0086] As the dose calculation step (S104), the dose calculation unit 52 calculates the dose (irradiation amount) for irradiating each pixel 36. For example, the dose can be calculated as a value obtained by multiplying a preset reference irradiation dose Dbase by the proximity effect correction irradiation coefficient Dp and the pattern density ρ. Thus, it is preferable that the dose is obtained in proportion to the area density of the pattern calculated for each pixel 36. For the proximity effect correction irradiation coefficient Dp, the drawing region (here, for example, the bar-shaped region 32) is hypothetically divided into a plurality of adjacent grid regions (grid regions for proximity effect correction calculation) in a grid pattern with a specified size. The size of the adjacent grid region is preferably set to about 1 / 10 of the influence range of the proximity effect, for example, set to about 1 μm. Then, the drawing data is read from the storage device 140, and for each adjacent grid region, the pattern area density ρ' of the pattern disposed within the adjacent grid region is calculated.

[0087] Next, for each adjacent grid region, the proximity effect correction irradiation coefficient Dp for correcting the proximity effect is calculated. Here, the size of the grid region for calculating the proximity effect correction irradiation coefficient Dp does not need to be the same as the size of the grid region for calculating the pattern area density ρ'. In addition, the correction model and calculation method of the proximity effect correction irradiation coefficient Dp can also be the same as those used in the conventional single-beam drawing method.

[0088] Then, for each bar-shaped region 32, the dose calculation unit 52 creates a dose map (1) using the calculated dose of each pixel 36. The dose of each pixel 36 is defined as each element of the dose map (1). In the above example, the case where the dose is calculated as the absolute value multiplied by the reference irradiation dose Dbase is shown, but it is not limited thereto. The reference irradiation dose Dbase can also be assumed to be 1, and the dose can be calculated as a relative value with respect to the reference irradiation dose Dbase. In other words, it can also be the case where the dose is calculated as a coefficient value obtained by multiplying the proximity effect correction irradiation coefficient Dp and the pattern density ρ. The created dose map (1) is stored in the storage device 144.

[0089] As the process of dividing the grid (S106), the dividing unit 53 (dividing processing circuit) divides each strip region, which is obtained by dividing the drawing region of the sample in the y direction (first direction) by the size of the beam array region of the multi-charged particle beam on the sample surface, into a plurality of grid regions in the y direction and in the x direction (second direction), which is the moving direction of the workbench along each strip region. Specifically, the dividing unit 53 (dividing processing circuit) divides each strip region 32 into a plurality of processing grids (grid regions) in the y direction (first direction) and in the x direction (second direction) orthogonal to the y direction, respectively, with a size of 1 / N of the size W of the beam array region (N is an integer of 2 or more).

[0090] Figure 12 FIG. is an example of the processing grid of Embodiment 1. As described above, the drawing region 30 of the sample 101 is divided into a plurality of strip regions 32 in the y direction by the size W of the irradiation region 34 (beam array region) of the multi-beam 20 on the surface of the sample 101. And each strip region 32 is divided into a plurality of processing grids (grid regions) 39 with a size of 1 / N of the size W of the irradiation region 34 (beam array region) (N is an integer of 2 or more). The size s of each processing grid 39 is composed of a size larger than the sub-irradiation region 29 of the beam pitch size.

[0091] In Embodiment 1, the size s of the processing grid 39 is preferably set to the tracking distance L, for example. The tracking distance L is k times (k is a natural number) the beam pitch size on the surface of the sample 101. The tracking distance L is set to 25 times the beam pitch size in the above example. Therefore, the size s of the processing grid 39 is preferably set to a size of 25 beam pitch amounts, for example. Thus, the size s of the processing grid 39 is a size larger than the beam pitch size on the surface of the sample 101. Furthermore, the processing grid 39 is a region sufficiently large with respect to the pixel 36 that is the unit region for irradiating each beam.

[0092] As the tracking cycle time calculation process (S108), the tracking cycle time calculation unit 56 calculates the tracking cycle time t trk-cycle . The tracking cycle time t trk-cycle As shown in the following formula (1), it can be obtained by dividing the tracking distance L by the workbench speed v. Here, the speed v in the case of moving at a constant speed during the drawing of the strip region 32 using the XY workbench 105 is used. In addition, since the size s of the processing grid 39 = L, as shown in the following formula (1-1), the tracking cycle time t trk-cycle can be obtained by dividing the size s of the processing grid 39 by the workbench speed v. In addition, since the size s of the processing grid 39 is 1 / N of the width W of the beam array region, that is, the width of the strip region 32, the tracking cycle time t trk-cycleAs shown in the following formula (1-1), it can be obtained by dividing 1 / N of the width W of the beam array region by the table speed v.

[0093]

Formula 1

[0094] (1-1)t trk-cycle = L / v = s / v = (W / N) / v

[0095] As the dose representative value calculation process (S110), the dose representative value calculation unit 54 (dose statistical value calculation circuit) calculates, for each divided processing grid 39, a representative value of a plurality of doses based on a plurality of beams irradiated within the processing grid 39 as the dose representative value D. A plurality of sub-irradiation regions 29 are included within the processing grid 39. As described above, each sub-irradiation region 29 is irradiated by a plurality of different beams. In the above example, for example, a plurality of pixels 36 are included within the processing grid 39 irradiated by 10 different beams separated by 25 beam pitches in the x direction. Here, a representative value (dose representative value Dij) of the dose defined among all the pixels 36 within the processing grid 39 is calculated. As the representative value, for example, an average value, a maximum value, a minimum value, or a median value can be cited. Here, as the dose representative value Dij, for example, the average value, i.e., the average dose, is calculated. The dose representative value calculation unit 54 creates a dose representative value map using the calculated dose representative value Dij of each processing grid 39. The dose of each processing grid 39 is defined as each element of the dose representative value map. i represents the index in the x direction of the processing grid 39. j represents the index in the y direction of the processing grid 39. The created dose representative value map is stored in the storage device 144.

[0096] As the convolution calculation process (S111), the convolution calculation processing unit 57 performs a calculation process of the rising temperature caused by the heat generated by irradiating the beam to each processing grid 39 within the processing region corresponding to the beam array region being provided to the target grid region which is one of the plurality of processing grids 39. This calculation process is performed by a convolution process using the dose representative value of each processing grid 39 and a heat spread function representing the heat spread generated by the processing grid 39.

[0097] As the effective temperature calculation process (S112), the effective temperature calculation unit 58 (effective temperature calculation circuit) performs a repetitive process of repeatedly performing the above-described calculation process while moving the position of the processing area corresponding to the beam array area in the x-direction on the bar-shaped area, and calculates representative values of a plurality of rising temperatures obtained by performing such repetitive processes multiple times until the processing grid 39 reaches from one end to the other end in the x-direction of this processing area as the effective temperature of the target grid area. Specifically, the effective temperature calculation unit 58 (effective temperature calculation circuit) calculates the effective temperature for each processing grid 39 using the dose statistical value Dij of each processing grid 39 and the heat spread function PSF representing the heat spread generated in each grid. The heat spread function PSF can be defined by the following formula (1-2) as a general heat diffusion equation, for example.

[0098]

Equation 2

[0099] (1-2)

[0100] A function representing the surface temperature of the quartz glass substrate obtained from Equation (1-2) can be used. Here, λ represents the thermal diffusivity of the substance for temperature diffusion. An example of the solution to the above equation will be described later as the explanation of Equation (3-1).

[0101] While moving the rectangular area in the x-direction by the size s of the processing grid 39 on the target bar-shaped area 32, a convolution process is performed to calculate the rising temperature caused by the heat generated by irradiating each processing grid 39 in the processing area, which is a rectangular area of the same size as the beam array area composed of N×N processing grids 39, being provided to the target grid area, using the dose statistical value Dij and the heat spread function PSF, until the target grid area is included in the rectangular area. The effective temperature calculation unit 58 performs such a process N times from the position where the target grid area is at one end in the x-direction within the rectangular area to the position at the other end. Then, the effective temperature calculation unit 58 calculates the statistical value of the results of such N convolution processes as the effective temperature T(k, l).

[0102] Figure 13 It is a diagram for explaining the method of calculating the effective temperature of Embodiment 1. The effective temperature T(k, l) can be defined by the formula (2) shown Figure 13 In the bar-shaped area 32, M processing grids 39 are arranged in the x-direction and N processing grids 39 are arranged in the y-direction. In Equation (2), the processing grid 39 in the l-th row in the y-direction and the k-th column in the x-direction among the plurality of processing grids 39 in the bar-shaped area 32 is represented as the target grid area.

[0103] In Equation (2), i represents the index in the x direction in the dose statistical value mapping. The index i in the x direction of the processing grid 39 defined as the left end of the bar region 32 is 0.

[0104] j represents the index in the y direction in the dose statistical value mapping. The index j in the y direction of the processing grid 39 defined as the lowermost part of the bar region 32 is 0.

[0105] N represents the number of grids in the longitudinal direction (y direction) of the input dose mapping for effective temperature calculation.

[0106] M represents the number of grids in the transverse direction (x direction) of the input dose mapping for effective temperature calculation.

[0107] (k, l) represents the index (reference number) of the processing grid (region of interest grid) for calculating the effective temperature T within the (M×N) processing grids.

[0108] Dij: represents the dose statistical value of the processing grid 39 assigned to the index (k, l) in the dose statistical value mapping. (μC / cm^2)

[0109] m represents the tracking reset numbers from the (l - N + 1)-th to the l-th before the beam array region (N×N) passes through the region of interest grid (k, l). When m = l - N + 1, the region of interest grid is at the right end of the (N×N) beam array region. When m = l, the region of interest grid is at the left end.

[0110] n represents the tracking reset numbers from the 0-th to the m-th.

[0111] For the first tracking control (tracking cycle), no tracking reset has been performed, so the tracking reset number is zero. For the second tracking control, one tracking reset has been performed, so the tracking reset number is 1.

[0112] PSF(n, m, k - i, l - j) represents the thermal spread function.

[0113] Figure 14 It is a diagram showing part of the calculation formula for the effective temperature in Embodiment 1. In Figure 14In [Equation (2)], the part enclosed by the dashed line represents the calculation part of the convolution process. In the calculation part of the convolution process in [Equation (2)], a convolution process is performed to calculate the temperature rise caused by the heat generated by irradiating each grid region in a rectangular region 35 having the same size as the beam array region composed of N×N processing grids 39 and supplying the heat to the grid region of interest with index (k, l). A rectangular region 35 is used where the left end of the rectangular region 35 is the n-th column of the processing grid 39 and the right end is the (n+N−1)-th column of the processing grid 39. Therefore, N×N processing grids 39 corresponding to those from the n-th column to the (n+N−1)-th column in the x direction and from the 0-th row to the (N−1)-th row in the y direction are arranged within the rectangular region 35.

[0114] Figure 15 FIG. is an example of an equation for calculating the thermal spread function for explaining Embodiment 1. The thermal spread function PSF(n, m, k−i, l−j) is defined by the equation shown in Figure 15 Equation (3-1). Based on the initial condition where the same heat is given to the volume obtained by multiplying the grid size by Rg on the substrate surface by beam irradiation, and under the boundary condition that it is infinite in the XY direction and semi-infinite in the substrate depth direction in the Z direction, the above heat conduction equation is solved, whereby Equation (3-1) can be obtained.

[0115] The notations that are the same as those in [Equation (2)] in the thermal spread function PSF(n, m, k−i, l−j) represent the same notations as in [Equation (2)]. Figure 15 The thermal spread function PSF(n, m, k−i, l−j) shown in FIG. defines a case where the XY stage 105 moves at a constant speed in the direction opposite to the drawing direction, for example, the -x direction. As shown in Figure 15 FIG., the thermal spread function PSF(n, m, k−i, l−j) is defined using the tracking cycle time obtained from the speed v of the XY stage 105.

[0116] In Equation (3-1), Rg represents the range of a 50 kV electron beam in quartz. For example, the range Rg=(0.046 / ρ)E is used. 1.75 .

[0117] ρ represents the density of the substrate (quartz) (for example, 2.2 g / cm^3).

[0118] σn,m represents a function determined by the number of times (m−n) of tracking reset from the n-th to the m-th. The function σn,m is defined as Equation (3-3).

[0119] The function A is defined as Equation (3-2).

[0120] In Equation (3-2), V represents the acceleration voltage of the electron beam.

[0121] Cp represents the specific heat of the substrate (quartz) (e.g., 0.77 J / g / K).

[0122] In Equation (3-3), λ represents the thermal diffusivity of the substrate (quartz) (e.g., 0.0081 cm^2 / sec).

[0123] (m - n) represents the number of times of tracking reset performed from the nth to the mth time.

[0124] t trk-cycle represents the tracking cycle time. The tracking cycle time t trk-cycle is represented by Equation (3-4). It is the same as Equation (1).

[0125] v stage represents the stage speed v.

[0126] Usually, in a multi-beam lithography apparatus, it is optimized such that the stage speed v within the stage path stage =(constant), and the emission is completed within the time between trackings (10 emissions in the previous example). Since the tracking distance L (=W / N) is followed at the stage speed, the tracking cycle time t trk-cycle can be defined by Equation (1-1).

[0127] Figure 16 is a diagram for explaining another part of the calculation formula of the effective temperature in Embodiment 1. For Figure 14 the convolution process described in, while moving the rectangular region 35 from the left end (n = 0) of the bar region 32 in the x-direction by the size s of the processing grid 39, the convolution process is performed until the region of interest grid of the index (k, l) is included in the rectangular region 35 (n = m). Figure 16 The calculation part enclosed by the dashed line in Equation (2) shown represents this kind of processing. In Figure 16 the example of, the case where the rectangular region 35 is moved until the region of interest grid of the index (k, l) is located at the right end of the rectangular region 35 is shown. In this state, the left end of the rectangular region 35 is in the (k - N + 1)th column and the right end is in the kth column.

[0128] Figure 17 is a diagram for explaining another part of the calculation formula of the effective temperature in Embodiment 1.

[0129] Figure 18 is a diagram for explaining another part of the calculation formula of the effective temperature in Embodiment 1. In Figure 18 specifically, the processing performed by the calculation part Figure 17 is expressed by an equation.

[0130] For Figure 16 the processing shown, asFigure 17 As shown, N processes are performed from the position at one end, i.e., the right end, of the rectangular region 35 in the x-direction within the attention grid region to the position at the other end, i.e., the left end. In other words, as Figure 18 shown, the process shown in Figure 16 is performed from n = 0 to n = m = k - N + 1, the process shown in Figure 16 is performed from n = 0 to n = m = k - N + 2, the process shown in Figure 16 is performed from n = 0 to n = m = k - N + 3, ……, the process shown in Figure 16 is performed from n = 0 to n = m = k for N processes, and their sum is calculated. Since N processing grids 39 are arranged in the x-direction in the rectangular region 35, N processes are performed from the right end to the left end of the attention grid region within the rectangular region 35. Figure 17 The calculation part enclosed by the dashed line in the formula (2) shown in Figure 18 represents such a process. Then, the statistical value of the results of N convolution processes is calculated as the effective temperature T(k, l).

[0131] In addition, the number of divisions of the rectangular region and the number of calculation processes do not have to be the same. That is, it can also be divided into N, and the number of calculation processes can be set to be smaller than N (downsampling). In addition, it can also be divided into N and distributed (upsampling) to a number of grids larger than N.

[0132] The effective temperature T(k, l) is not limited to the average value, and can also be the maximum value, minimum value or median value of the results of N convolution processes. More preferably, it is the median value. Further preferably, it is the average value.

[0133] The position of the attention grid region is changed, and for each position (i, j) of the processing grid 39, the effective temperature T(i, j) is obtained.

[0134] As described above, in the first embodiment, instead of calculating the temperature rise for each emission and each beam, the effective temperature T(i, j) per processing grid 39 is calculated using the dose statistical value Dij of the processing grid 39. The effective temperature T(i, j) can be calculated for each of the processing grids 39 that are sufficiently large compared to the pixels 36 that are the unit regions irradiated by the beam for each emission. Therefore, the calculation amount can be greatly reduced.

[0135] As the modulation rate calculation step (S114), the modulation rate calculation unit 60 calculates the modulation rate α(x) of the dose depending on the effective temperature T.

[0136] Figure 19 This is a diagram showing an example of the relationship between the line width CD and temperature in Embodiment 1. In Figure 19 it, the vertical axis represents the line width CD (Critical Dimension), and the horizontal axis represents the temperature. As Figure 19 shown, it can be seen that as the temperature of the resist increases, the deviation of the line width CD also increases. There is a linear relationship for the CD variation ΔCD / ΔT [nm / K] based on the heating effect. This value varies depending on the resist type and substrate type, so experiments are conducted on them to obtain it. Therefore, an approximate formula for the CD change amount ΔCD per unit temperature ΔT is obtained. Such correlation data (1) is input from the outside and stored in the storage device 144.

[0137] Figure 20 This is a diagram showing an example of the relationship between the line width CD and dose in Embodiment 1. In Figure 20 it, the vertical axis represents the line width CD, and the horizontal axis represents the dose. In the Figure 20 example, the horizontal axis is represented logarithmically. As Figure 20 shown, the line width CD depends on the pattern density, and as the dose increases, the line width CD also increases. Experiments are conducted to obtain the relationship ΔCD / ΔD between the CD variation and the dose depending on each resist type, substrate type, and each pattern density. Then, an approximate formula for the CD change amount ΔCD per unit dose is obtained. Such correlation data (2) is input from the outside and stored in the storage device 144.

[0138] The modulation rate calculation unit 60 reads the correlation data (1) and (2) from the storage device 144, and calculates the dose change amount ΔD per unit temperature ΔT depending on the pattern density as the modulation rate α(x) of the dose depending on the effective temperature T. The modulation rate α(x) depending on the pattern density ρ is defined by the following formula (5).

[0139] (5) α(x) = (ΔCD / ΔT) / (ΔCD / ΔD) ρ = (ΔD / ΔT) ρ

[0140] As a correction process (S118), the correction unit 62 (dose correction circuit) uses the effective temperature T(i, j) to correct the doses of the multiple beams irradiating each grid region of interest. The correction amount can be obtained as a value obtained by multiplying the effective temperature T(i, j) by the modulation rate α(x). The corrected dose D′(x) can be obtained by the following formula (6). x represents the index of the pixel 36. (i, j) represents the index of the processing grid. In addition, for the pattern density ρ, the pattern density of the pixel 36 to be targeted can be used.

[0141] (6) D′(x) = D(x) - T(i, j)·α(x)

[0142] Then, for each bar region 32, the correction unit 62 creates a dose map (2) using the corrected dose D′(x) of each pixel 36 that has been calculated. The dose D′(x) of each pixel 36 is defined as each element of the dose map (2). Thus, the corrected (modulated) dose distribution D′(x) is obtained. That is, the CD size that can return the temperature rise amount according to the design size can be obtained. The created dose map (2) is stored in the storage device 144.

[0143] As the irradiation time data generation process (S120), the irradiation time data generation unit 72 calculates, for each pixel 36, the irradiation time t of the electron beam for irradiating the pixel 36 with the calculated corrected dose D′(x). The irradiation time t can be calculated by dividing the dose D′(x) by the current density J. When the dose D(x) before correction defined in the dose map (1) is a relative value (dose coefficient value) with respect to the reference irradiation dose Dbase calculated assuming the reference irradiation dose Dbase is 1, the dose statistical value Dij of each processing grid 39 is also calculated as a relative value with respect to the reference irradiation dose Dbase. Therefore, the effective temperature T(i, j) of each processing grid 39 is also calculated as a relative value with respect to the reference irradiation dose Dbase. Therefore, in this case, the irradiation time t can be calculated by dividing the value obtained by multiplying the dose D′(x) by the reference irradiation dose Dbase by the current density J.

[0144] The irradiation time t of each pixel 36 is calculated as a value within the maximum irradiation time Ttr that can be irradiated by one emission of the multi-beam 20. The irradiation time t of each pixel 36 is converted into grayscale value data of 0 to 1023 grayscales with the maximum irradiation time Ttr set to, for example, 1023 grayscales (10 bits). The grayscaled irradiation time data is stored in the storage device 142.

[0145] As the data processing process (S122), the data processing unit 74 rearranges the irradiation time data in the emission order according to the drawing order, and also rearranges it in the data transfer order considering the arrangement order of the shift registers of each group.

[0146] As the drawing process (S124), under the control of the drawing control unit 80, the transfer control unit 79 transfers the irradiation time data to the deflection control circuit 130 in the emission order. The deflection control circuit 130 outputs a blanking control signal to the blanking aperture array mechanism 204 in the emission order, and outputs a deflection control signal to the DAC amplifier units 132, 134 in the emission order. Then, the drawing mechanism 150 draws a pattern on the specimen 101 using the multi-beam 20 with the dose D′(x) corrected using the effective temperature T(i, j) respectively.

[0147] In the above example, the case where the bar regions 32 where the calculation of the end dose D′(x) ends are sequentially subjected to drawing processing is described. For example, during the drawing processing of a certain bar region 32, the dose D′(x) of the bar region 32 that is one before or two before the bar region 32 in the drawing processing is calculated in parallel. In other words, the case where the calculation of the dose D′(x) is performed in parallel with the drawing processing is described. However, it is not limited thereto. As a preprocessing before starting the drawing processing, the effective temperature T(i, j) and / or the dose D′(x) may also be performed.

[0148] As described above, according to Embodiment 1, in multi-beam drawing, it is possible to correct the resist heating without accumulating the influence of the temperature rise for each emission and each beam.

[0149] [Embodiment 2]

[0150] In Embodiment 1, the case where the XY stage 105 moves in the direction opposite to the drawing direction at a constant speed during the drawing of the bar region 32 is described, but it is not limited thereto. In Embodiment 2, the case where the XY stage 105 moves at a variable speed is described. The configuration of the drawing apparatus 100 according to Embodiment 2 is the same as Figure 1 the same. In addition, the main part processes of the drawing method according to Embodiment 2 are the same as Figure 11 the same. Hereinafter, the content other than the points specifically described is the same as that of Embodiment 1.

[0151] Figure 21 is a diagram for explaining the table speed curve according to Embodiment 2. In Figure 21 , the case where the speed of the XY stage 105 changes at a prescribed interval in the x direction is shown. The information of such a speed curve is stored in the storage device 144. The speed curve can be calculated within the drawing apparatus 100, or can be calculated outside the drawing apparatus 100 and input to the drawing apparatus 100. In the case of calculating within the drawing apparatus 100, a speed calculation unit (not shown) may be arranged in the control computer 110.

[0152] Figure 22 is a diagram for explaining an example of the calculation formula of the thermal spread function according to Embodiment 2. The thermal spread function PSF(n, m, k-i, l-j) is defined by the formula (3-1) shown in Figure 22 . In Figure 22 , the formula (3-1) and the formula (3-2) are the same as Figure 15 the same. The thermal spread function PSF(n, m, k-i, l-j) according to Embodiment 2 defines the case where the XY stage 105 moves variably in the direction opposite to the drawing direction, for example, the -x direction in the x direction which becomes the drawing direction. As Figure 22As shown, the thermal expansion function PSF(n, m, k-i, l-j) is defined using the tracking cycle time obtained from the speed v of the XY stage 105.

[0153] In the case where the XY stage 105 moves variably, the function σn,m is defined in Equation (7-1). Further, the tracking cycle time can be defined as the value obtained by dividing the tracking distance L (=W / N) by the stage speed v. The size s of the processing grid 39 is set to the tracking distance L. Therefore, the tracking cycle time t p trk-cycle is defined by Equation (7-2).

[0154] v p stage represents the variable stage speed v. p represents the position of the constant speed interval within the variable speed curve. The stage speed v p stage is preferably set to be able to change the speed in units of the tracking distance L, for example. However, it is not limited thereto. The speed can also be changed during tracking. In this case, the constant speed interval is set smaller than the tracking distance L.

[0155] (m - n) represents the number of times of tracking reset from the nth to the mth.

[0156] In the case of using the XY stage 105 variably, since the speed changes for each interval, the tracking cycle time changes. Therefore, in the case of using the XY stage 105 variably, as shown in Equation (7-1), within the path of the function σn,m, different from the case of constant speed, the sum of each tracking cycle time t p trk-cycle from p = 1 to P = (m - n) is multiplied by 4λ.

[0157] When calculating the effective temperature T of Embodiment 2, it is the same as Embodiment 1 except for the thermal expansion function used.

[0158] As described above, according to Embodiment 2, even in the case of variable-speed drawing, in multi-beam drawing, the influence of the temperature rise of each emission and each beam is not accumulated, and the resist heating can be corrected.

[0159] In the above-described embodiments, the case where the size s of the processing grid 39 is made to coincide with the tracking distance L has been described, but it is not limited thereto. The thermal expansion caused by heat transfer depends only on the distance between the concerned grid and the grid size regarded as the uniform irradiation dose (= time, for raster scanning).

[0160] Therefore, as the imaginary tracking distance for calculating the effective temperature, the size s of the processing grid 39 can be used. Therefore, the value obtained by dividing the size s of the processing grid 39 by the stage speed v can be used as the computationally assumed tracking cycle time. Therefore, the calculation formula of the above thermal expansion function can be directly used.

[0161] Therefore, the size s of the processing grid 39 may also be different from the tracking distance L. For example, it is preferable to set the size s of the processing grid 39 to a value smaller than the tracking distance L. Thereby, the time resolution of the temperature diffusion and the spatial resolution of the dose distribution in the effective temperature calculation formula become higher, and thus the accuracy of the effective temperature can be improved. However, since the smaller the grid size, the greater the calculation amount of the effective temperature, in practice, it is sufficient to define the size s of the processing grid 39 with the tracking distance L.

[0162] The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

[0163] In addition, parts that are not directly required in the description of the present invention, such as the device configuration and control method, etc., are omitted from the description, but the required device configuration and control method can be appropriately selected and used. For example, the description of the control unit configuration for controlling the drawing device 100 is omitted, but of course, the required control unit configuration can be appropriately selected and used.

[0164] In addition, all multi-charged particle beam drawing devices and multi-charged particle beam drawing methods that have the elements of the present invention and can be appropriately designed and modified by those skilled in the art are included in the scope of the present invention.

[0165] Industrial Applicability

[0166] Relates to a multi-charged particle beam drawing device and a multi-charged particle beam drawing method, and can be used, for example, in a method for correcting resist heating generated in multi-beam drawing.

[0167] Explanation of Symbols

[0168] 20: Multi-beam; 22: Hole; 24: Control electrode; 25: Through hole; 26: Opposing electrode; 28, 36: Pixel; 29: Sub-irradiation area; 30: Drawing area; 32: Bar area; 34: Irradiation area; 35: Rectangular area; 39: Processing grid; 41: Control circuit; 46: Amplifier; 47: Individual blanking mechanism; 50: Pattern density calculation unit; 52: Dose calculation unit; 53: Division unit; 54: Dose representative value calculation unit; 56: Tracking cycle time calculation unit; 58: Effective temperature calculation unit; 60: Modulation rate calculation unit; 62: Correction unit; 72: Irradiation time data generation unit; 74: Data processing unit; 79: Transmission control unit; 80: Drawing control unit; 100: Drawing device; 101: Specimen; 102: Electron gun barrel; 103: Drawing chamber; 105: XY stage; 110: Control computer; 112: Memory; 130: Deflection control circuit; 132, 134: DAC amplifier unit; 136: Lens control circuit; 138: Stage control mechanism; 139: Stage position detector; 140, 142, 144: Storage device; 150: Drawing mechanism; 160: Control system circuit; 200: Electron beam; 201: Electron gun; 202: Illumination lens; 203: Shaping aperture array substrate; 204: Blanking aperture array mechanism; 205: Reduction lens; 206: Aperture limiting substrate; 207: Objective lens; 208: Main deflector; 209: Sub-deflector; 210: Mirror; 330: Diaphragm area; 343: Pad.

Claims

1. A multi-charged particle beam lithography apparatus that irradiates a multi-charged particle beam onto a lithography region on a sample surface, characterized in that, Comprising: A dividing unit that divides each strip region formed by dividing the above-described drawing region in the first direction of the beam array region of the multi-charged particle beam on the above-described sample surface in the first direction into a plurality of grid regions in the first direction and in the second direction, which is the moving direction of the workbench along each strip region; A dose representative value calculation unit that calculates, for each divided grid region, the average value, maximum value, minimum value, or median value of the plurality of doses generated by irradiating a plurality of beams within the grid region as the dose representative value; A calculation processing unit that performs a calculation process of the rising temperature caused by heat generated by irradiating each of the above-described grid regions within the processing region corresponding to the above-described beam array region being supplied to a target grid region, which is one of the above-described plurality of grid regions. The above-described calculation process is performed by a convolution process using the above-described dose representative value of each of the above-described grid regions and a function obtained as the solution of a heat diffusion equation representing the heat diffusion generated by the grid region; An effective temperature calculation unit that performs a repetitive process of repeatedly performing the above-described calculation process while moving the position of the above-described processing region in the second direction on the above-described strip region, and calculates, respectively, the average value, maximum value, minimum value, or median value of the plurality of above-described rising temperatures obtained by performing the above-described repetitive process multiple times until the above-described target grid region reaches the position at the other end from one end in the second direction of the above-described processing region, as the effective temperature of the above-described target grid region; A dose correction unit that corrects the doses of the plurality of beams irradiating each of the above-described target grid regions using the above-described effective temperature; And A drawing mechanism that draws a pattern on the above-described sample using the multi-charged particle beam with the above-described respectively corrected doses.

2. The multi-charged particle beam drawing device according to claim 1, wherein The above-described processing region is a region having the same size as the above-described beam array region.

3. The multi-charged particle beam drawing device according to claim 1, wherein The above-described drawing mechanism has a movable workbench for mounting the above-described sample, The above-described function represents a case where the workbench moves at a constant speed in the opposite direction of the second direction within the above-described strip.

4. The multi-charged particle beam drawing device according to claim 1, wherein The above-described drawing mechanism has a movable workbench for mounting the above-described sample, The above-described function represents a case where the workbench moves variably in the opposite direction of the second direction.

5. The multi-charged particle beam drawing device according to claim 1, wherein The above-described drawing mechanism includes: A workbench for mounting the above-described sample and capable of moving; and A deflector that performs tracking control to deflect the above-described multi-charged particle beam to follow the movement of the above-described workbench, As the size of the above-described grid region, the tracking distance for performing tracking control is used.

6. The multi-charged particle beam drawing device according to claim 5, wherein The above-described function is represented by a tracking cycle time obtained from the speed of the above-described workbench.

7. The multi-charged particle beam drawing device according to claim 5, wherein The above tracking distance is k times the beam pitch dimension on the above sample surface, where k is a natural number.

8. The multi-charged particle beam drawing apparatus according to claim 1, wherein The size of the above grid region is larger than the beam pitch dimension on the above sample surface.

9. A multi-charged particle beam drawing method, characterized in that In each strip region obtained by dividing the drawing region of the sample in the first direction by the size of the beam array region of the multi-charged particle beam on the sample surface in the first direction, the region is divided into a plurality of grid regions in the first direction and in the second direction which is the moving direction of the worktable along each strip region, For each of the divided grid regions, calculate the average value, maximum value, minimum value or median value of the plurality of doses generated by irradiating the plurality of beams in the grid region as the dose statistical value, Perform a calculation process for the rising temperature caused by the heat generated by irradiating each of the above grid regions in the processing region corresponding to the above beam array region being supplied to a target grid region which is one of the above plurality of grid regions. The above calculation process is a convolution process using the above dose statistical value of each of the above grid regions and a function obtained as the solution of the heat diffusion equation representing the heat spread generated by the grid region, Perform a repetitive process of repeatedly performing the above calculation process while moving the position in the second direction on the above strip region, and calculate the average value, maximum value, minimum value or median value of the above plurality of rising temperatures obtained by performing the above repetitive process multiple times until the target grid region reaches the position at the other end from one end in the second direction of the above processing region, that is, the effective temperature of the target grid region, Use the above effective temperature to correct the doses of the plurality of beams irradiating each of the above target grid regions, Use the multi-charged particle beam with the above doses corrected respectively to draw a pattern on the above sample.

10. A readable recording medium having a program recorded thereon, characterized in that, This program is used to cause a computer to execute the following steps: A step of dividing the drawing region of the sample into a plurality of grid regions in the first direction and in the second direction which is the moving direction of the worktable along each strip region, where each strip region is obtained by dividing the drawing region of the sample in the first direction by the size of the beam array region of the multi-charged particle beam on the sample surface in the first direction; A step of calculating the average value, maximum value, minimum value or median value of the plurality of doses generated by irradiating the plurality of beams in each of the divided grid regions as the dose statistical value; A step of performing a calculation process for the rising temperature caused by the heat generated by irradiating each of the above grid regions in the processing region corresponding to the above beam array region being supplied to a target grid region which is one of the above plurality of grid regions. The above calculation process is a convolution process using the above dose statistical value of each of the above grid regions and a function obtained as the solution of the heat diffusion equation representing the heat spread generated by the grid region; A step of performing an iterative process of repeatedly performing the above calculation process while moving the position in the second direction on the above bar-shaped area, and respectively calculating the average value, maximum value, minimum value, or median value of the plurality of above-mentioned rising temperatures obtained by performing the above iterative process multiple times until the above-mentioned grid area of interest reaches the position at the other end from one end of the above-mentioned second direction of the above-mentioned processing area, that is, the effective temperature of the above-mentioned grid area of interest; and A step of correcting the dose of the plurality of beams irradiated to each of the above-mentioned grid areas of interest using the above-mentioned effective temperature.

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