Method for calculating efficient temperature of multi-charged particle radiation region, multi-charged particle radiation method, readable recording medium with non-transitory recording

Abstract

The purpose of the present invention is to provide a method capable of correcting the thermalization of a resist without performing a huge calculation that accumulates the influence of each emission and the temperature rise of each beam in a multi-charged particle beam drawing. Provided is a method for calculating the effective temperature of a multi-charged particle beam drawing region, for each of a plurality of mesh regions obtained by dividing a drawing region of a sample irradiated with a multi-charged particle beam in a drawing traveling direction and in a direction linearly independent of the drawing traveling direction. Calculating, as a dose representative value, a representative value of a dose of a beam irradiating the inside of the mesh region (S108); a kernel and dose representative value is convolved by the speed of a stage on which the sample is placed and the size of a beam array region on the surface of the sample of the multi-charged particle beam in the direction of travel. A representative value of a rising temperature imparted to each of the plurality of mesh regions by heat caused by beam irradiation is calculated as an effective temperature for each of the plurality of mesh regions (S112).

Description

Technical Field

[0001] The present invention relates to a method for calculating the effective temperature of a multi-charged particle beam drawing area, a multi-charged particle beam drawing device, a multi-charged particle beam drawing method and a program (or a readable recording medium that non-temporarily records the program), for example, to a method for correcting the heating of a resist generated during multi-beam drawing. Background Art

[0002] The photolithography technology that supports the miniaturization of semiconductor devices is an extremely important process for generating unique patterns in the semiconductor manufacturing process. In recent years, with the high integration of LSI, the circuit line width required by semiconductor devices has been miniaturized year by year. Here, the electron beam (electron beam) drawing technology has an inherently excellent resolution and uses an electron beam to draw on a wafer or the like.

[0003] For example, there is a drawing device using multiple beams. Compared with the case of drawing with a single electron beam, by using multiple beams, many beams can be irradiated at one time, so the throughput can be greatly improved. In the drawing device of the multi-beam method, for example, the electron beam emitted from the electron gun is passed through a mask having multiple holes to form multiple beams, and each beam that is not shielded is blanked and reduced in the optical system, deflected by a deflector, and irradiated to a desired position on the sample.

[0004] Here, in the depiction using electron beams, there is the following problem: if the amount of irradiation energy is to be irradiated in a short time with a higher density electron beam, a phenomenon called resist heating occurs in which the substrate temperature is overheated, the resist sensitivity changes, and the line width accuracy deteriorates (for example, refer to Patent Document 1). For example, in single-beam depiction, a method is adopted to accumulate the effect of a beam on the temperature rise of each past shot to determine the dose correction amount of the current shot. However, in multi-beam depiction, since multiple beams are used, the amount of calculation becomes huge in the method of accumulating the effect of each past shot and the temperature rise of each beam. In addition, in multi-beam depiction, since multiple beams are emitted simultaneously, it is necessary to consider the effect of the temperature rise from multiple other beams located in a large area that is irradiated simultaneously.

[0005] Prior art literature

[0006] Patent Literature

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

[0008] Technical problem to be solved by the invention

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

[0010] Means for solving technical problems

[0011] A method for calculating an effective temperature of a region drawn by a multi-charged particle beam according to one embodiment of the present invention is characterized in that:

[0012] For each of a plurality of grid areas formed by dividing a drawing area of ​​a sample irradiated by a multi-charged particle beam in a drawing progress direction and a direction linearly independent of the drawing progress direction, a representative value of the dose of the beam irradiating the grid area is calculated as a representative dose value,

[0013] By performing convolution processing on a kernel determined by the speed of a stage on which a sample is placed and the size of a beam array area on the surface of a sample of a multi-charged particle beam in a depicted direction of travel and a dose representative value, representative values ​​of the temperature rise imparted to each of a plurality of grid areas by the heat caused by beam irradiation are calculated and output as respective effective temperatures of the plurality of grid areas.

[0014] A multi-charged particle beam mapping method according to one embodiment of the present invention,

[0015] The pattern is drawn on the sample using the correction amount calculated using the effective temperature obtained by the above-mentioned effective temperature calculation method.

[0016] By using the effective temperature in each of the plurality of grid areas, a correction amount for correcting the dose of the plurality of beams irradiating the grid area of ​​interest, which is one of the plurality of grid areas, or the pattern data of the figure drawn in the grid area of ​​interest is calculated;

[0017] Use the correction amount to draw a pattern on the sample.

[0018] A readable recording medium that non-transitorily records a program for causing a computer to execute, in one embodiment of the present invention, non-transitorily records a program for causing a computer to execute the following functions:

[0019] A function of calculating, for each of a plurality of grid areas formed by dividing a drawing area of ​​a sample irradiated by a multi-charged particle beam in a drawing progress direction and a direction linearly independent of the drawing progress direction, a representative value of the dose of the beam irradiating the grid area as a representative dose value; and

[0020] A function that calculates, as representative values of the effective temperatures of multiple grid regions, representative values of the temperature rises imparted to each of the multiple grid regions by the heat caused by beam irradiation through convolution processing of a kernel determined by the speed of the stage on which the sample is placed and the size of the beam array region in the drawing travel direction on the surface of the sample of the multi-charged particle beam.

[0021] A non-transitory recording medium readable by a computer for a program of another aspect of the present invention, the non-transitory recording medium recording a program that causes a computer to execute the following functions:

[0022] The above functions;

[0023] A function that calculates a correction amount for correcting the dose of multiple beams that irradiate a target grid region, which is one of the multiple grid regions, in the multi-charged particle beam or the pattern data of a pattern drawn in the target grid region, using the effective temperature in each of the multiple grid regions; and

[0024] A function of drawing a pattern on the sample using the correction amount.

[0025] A multi-charged particle beam drawing apparatus according to one aspect of the present invention, comprising:

[0026] A dose representative value calculation circuit that calculates, for each of multiple grid regions obtained by dividing the drawing region of a sample irradiated with a multi-charged particle beam in the drawing travel direction and a direction linearly independent of the drawing travel direction, a representative value of the dose of the beam irradiating the grid region as a dose representative value;

[0027] An effective temperature calculation circuit that calculates, through convolution processing of a kernel determined by the speed of the stage on which the sample is placed and the size of the beam array region in the drawing travel direction on the surface of the sample of the multi-charged particle beam, representative values of the temperature rises imparted to each of the multiple grid regions by the heat caused by beam irradiation as the effective temperatures of the multiple grid regions;

[0028] A correction amount calculation circuit that calculates a correction amount for correcting the dose of multiple beams that irradiate a target grid region, which is one of the multiple grid regions, in the multi-charged particle beam or the pattern data of a pattern drawn in the target grid region, using the effective temperature in each of the multiple grid regions; and

[0029] A drawing mechanism that draws a pattern on the sample using the calculated correction amount.

[0030] Effects of the invention

[0031] According to one embodiment of the present invention, in multi-beam drawing, the influence of the temperature rise of each shot and each beam is not accumulated, and the thermalization of the resist can be corrected. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a conceptual diagram showing the structure of the rendering device in the first embodiment.

[0033] Figure 2 This is a conceptual diagram showing the structure of the formed aperture array substrate in Embodiment 1.

[0034] Figure 3 It is a cross-sectional view showing the structure of the blanking aperture array mechanism in the first embodiment.

[0035] Figure 4 This is a conceptual plan view showing a portion of the structure within the membrane region of the blanking aperture array mechanism according to the first embodiment.

[0036] Figure 5 This is a diagram showing an example of a separate blanking mechanism according to the first embodiment.

[0037] Figure 6 This is a conceptual diagram for explaining an example of the drawing operation in the first embodiment.

[0038] Figure 7 This is a diagram showing an example of a multi-beam irradiation area and rendering target pixels in the first embodiment.

[0039] Figure 8 This is a diagram for explaining an example of the multi-beam imaging operation in the first embodiment.

[0040] Fig. 9 This is a diagram showing an example of the relationship between the temperature distribution and the temperature caused by irradiating a region corresponding to one beam pitch with one beam in a comparative example of the first embodiment.

[0041] Fig.10 This is a diagram showing an example of the relationship between the temperature distribution and the temperature due to the simultaneous irradiation of multiple beams in the first embodiment.

[0042] Fig.11 This is a flowchart showing an example of the main process of the drawing method in the first embodiment.

[0043] Fig.12 This is a diagram showing an example of a processing grid in the first embodiment.

[0044] Fig.13 This is a diagram for explaining the calculation method of the effective temperature in the first embodiment.

[0045] Fig.14This is a diagram for explaining a part of the calculation formula of the effective temperature in the first embodiment.

[0046] Fig.15 This is a diagram for explaining an example of a calculation formula for the heat diffusion function in the first embodiment.

[0047] Fig.16 This is a diagram for explaining another part of the calculation formula of the effective temperature in the first embodiment.

[0048] Fig.17 This is a diagram for explaining another part of the calculation formula of the effective temperature in the first embodiment.

[0049] Fig.18 This is a diagram for explaining another part of the calculation formula of the effective temperature in the first embodiment.

[0050] Fig.19 This is a diagram for explaining an example of a virtual model of effective temperature in the first embodiment.

[0051] Fig. 20 This is a diagram for explaining an example of a kernel derivation process in the first embodiment.

[0052] Fig.21 This is a diagram showing another example of the kernel derivation process in Implementation Example 1.

[0053] Fig. 22 This is a diagram showing another example of the kernel derivation process in Implementation Example 1.

[0054] Fig.23 This is a diagram for explaining the kernel in Implementation Example 1.

[0055] Fig.24 This is a diagram showing an example of the relationship between the stage speed and the kernel in the first embodiment.

[0056] Fig.25 This is a diagram showing an example of the relationship between the moving direction dimension of the beam array and the kernel in the first embodiment.

[0057] Fig.26 This is a diagram showing another example of the relationship between the moving direction dimension of the beam array and the kernel in the first embodiment.

[0058] Fig. 27 This is a diagram showing an example of a kernel defined as a table in Implementation Example 1.

[0059] Fig.28 This is a diagram showing an example of a formula for a kernel defined as a continuous function in the first embodiment.

[0060] Fig.29This is a diagram for explaining a method of calculating the effective temperature in the first embodiment.

[0061] Fig.30 This is a diagram showing an example of the relationship between the line width CD and the temperature in the first embodiment.

[0062] Fig.31 This is a diagram showing an example of the relationship between the line width CD and the dose in the first embodiment.

[0063] Fig.32 This is a diagram showing an example of the structure of a drawing device in Embodiment 2.

[0064] Fig.33 This is a flowchart showing an example of the main process of the drawing method in the second embodiment. DETAILED DESCRIPTION

[0065] In the following embodiments, a configuration using an electron beam as an example of a charged particle beam will be described, but the charged particle beam is not limited to an electron beam, and may be a beam using charged particles such as an ion beam.

[0066] [Implementation Method 1]

[0067] Figure 1 1 is a conceptual diagram showing the structure of the drawing device in Embodiment 1. Figure 1 In the drawing apparatus 100, a drawing mechanism 150 and a control system circuit 160 are provided. The drawing apparatus 100 is an example of a multi-charged particle beam drawing apparatus and an example of a multi-charged particle beam exposure apparatus. The drawing mechanism 150 is provided with an electron lens barrel 102 (electron beam column) and a drawing chamber 103. An electron gun 201, an illumination lens 202, a forming 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 in the electron lens barrel 102. An XY stage 105 is arranged in the drawing chamber 103. On the XY stage 105, a sample 101 such as a mask that becomes a drawing target substrate during drawing (exposure) is arranged. The sample 101 includes an exposure mask when manufacturing a semiconductor device, or a semiconductor substrate (silicon wafer) for manufacturing a semiconductor device, etc. In addition, a resist is applied on the sample 101. The sample 101 includes, for example, a mask blank coated with a resist and not yet drawn. A reflection mirror 210 for measuring the position of the XY stage 105 is further arranged on the XY stage 105 .

[0068] The control system circuit 160 includes a control computer 110, a memory 112, a deflection control circuit 130, digital analog conversion (DAC) amplifier units 132 and 134, a lens control circuit 136, a stage control mechanism 138, a stage position measuring device 139, and storage devices 140, 142, and 144 such as a magnetic 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 measuring device 139, and the storage devices 140, 142, and 144 are connected to each other via a bus not shown. The deflection control circuit 130 is connected to the DAC amplifier units 132 and 134 and the blanking aperture array mechanism 204. The sub-deflector 209 is composed of electrodes of four or more poles, and is controlled by the deflection control circuit 130 via the respective DAC amplifiers 132 for each electrode. The main deflector 208 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 130 via a respective DAC amplifier 134. The stage position measuring device 139 receives reflected light from the reflection mirror 210 and measures the position of the XY stage 105 based on the principle of laser interferometry.

[0069] The control computer 110 includes a pattern density calculation unit 50, a dose calculation unit 52, a division unit 53, a dose representative value calculation unit 54, an acquisition unit 56, a kernel determination unit 57, an effective temperature calculation unit 58, a correction amount calculation unit 60, a correction unit 62, an irradiation time data generation unit 72, a data processing unit 74, a transmission control unit 79, and a drawing control unit 80. Each of the “units”, such as the pattern density calculation unit 50, the dose calculation unit 52, the division unit 53, the dose representative value calculation unit 54, the acquisition unit 56, the kernel determination unit 57, the effective temperature calculation unit 58, the correction amount calculation unit 60, the correction unit 62, the irradiation time data generation unit 72, the data processing unit 74, the transmission control unit 79, and the drawing control unit 80, has a processing circuit. The processing circuit includes, for example, a circuit, a computer, a processor, a circuit substrate, a quantum circuit, or a semiconductor device. Each of the “units” may use a common processing circuit (the same processing circuit) or may use different processing circuits (different processing circuits). The information input and output to the pattern density calculation unit 50, the dose calculation unit 52, the division unit 53, the dose representative value calculation unit 54, the acquisition unit 56, the kernel determination unit 57, the effective temperature calculation unit 58, the correction amount calculation unit 60, the correction unit 62, the irradiation time data generation unit 72, the data processing unit 74, the transmission control unit 79, and the drawing control unit 80, as well as the information in the calculation, are each stored in the memory 112.

[0070] The drawing operation of the drawing device 100 is controlled by the drawing control unit 80. In addition, the transmission control unit 79 controls the transmission process of the irradiation time data of each shot to the deflection control circuit 130.

[0071] In addition, chip data is input from outside 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 example, a graphic code, coordinates, and size are defined for each graphic. In addition, the drawing condition data includes information indicating the multiplicity and the stage speed.

[0072] In addition, the storage device 144 stores correlation data described later for calculating a modulation factor for correcting thermalization of the resist.

[0073] Here, in Figure 1 , the configuration required to explain Embodiment 1 is described. The drawing device 100 may generally include other necessary configurations.

[0074] Figure 2 : is a conceptual diagram showing the structure of the formed aperture array substrate in Embodiment 1. Figure 2 In the embodiment, holes (openings) 22 are formed in a matrix with p columns in the vertical direction (y direction) and q columns in the horizontal direction (x direction) (p, q ≥ 2) on the aperture array substrate 203 at a predetermined arrangement pitch. Figure 2 In the example, for example, 500 columns × 500 rows of holes 22 are formed in the horizontal and vertical directions (x, y directions). The number of holes 22 is not limited to this. Each hole 22 is formed by a rectangle of the same size and shape. Alternatively, it can also be a circle of the same diameter. Parts of the electron beam 200 pass through these multiple holes 22 respectively, thereby forming a multi-beam 20. In other words, the forming aperture array substrate 203 forms a multi-beam 20.

[0075] Figure 3 It is a cross-sectional view showing the structure of the blanking aperture array mechanism in the first embodiment.

[0076] Figure 4 FIG. 1 is a conceptual top view showing a portion of the structure within the membrane region of the blanking aperture array mechanism in Embodiment 1. Figure 3 and Figure 4 In the embodiment, the positional relationship between the control electrode 24, the counter electrode 26, the control circuit 41 and the pad 343 is consistent but not described. Figure 3 As shown, the blanking aperture array mechanism 204 is provided with a blanking aperture array substrate 31 using a semiconductor substrate made of silicon or the like on a support 33. In the film region 330 at the center of the blanking aperture array substrate 31, Figure 2The positions corresponding to the holes 22 of the shaped aperture array substrate 203 shown in the figure are openings for the passage of each beam of the multi-beam 20 (openings). Moreover, for each of the plurality of passage holes 25, a group of a control electrode 24 and an opposing electrode 26 (blanking device: blanking deflector) is respectively arranged at positions opposite to each other across the passage hole 25. In addition, a control circuit 41 (logic circuit; unit) for applying a deflection voltage to the control electrode 24 for each passage hole 25 is arranged inside the blanking aperture array substrate 31 near each passage hole 25. The opposing electrode 26 for each beam is connected to the ground.

[0077] In addition, if Figure 4 As shown, each control circuit 41 is connected to n-bit (e.g., 10-bit) parallel wiring for control signals. In addition to connecting n-bit parallel wiring for irradiation time control signals (data), each control circuit 41 is also connected to wiring for clock signals, load signals, emission signals, and power supplies. These wirings may also use part of the parallel wiring. For each beam constituting the multi-beam 20, a separate blanking mechanism 47 is formed by the control electrode 24, the opposing 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 a plurality of groups for each of the plurality of beams, and a plurality of shift registers for the plurality of beams in the same group are connected in series. Specifically, a plurality of control circuits 41 formed in an array in the membrane region 330 are grouped at a predetermined pitch, for example, in the same row or the same column. The control circuits 41 group in the same group are arranged such as Figure 4 Furthermore, the signals from the pads 343 arranged in each group are transmitted to the control circuit 41 in the group.

[0078] Figure 5 FIG. 1 is a diagram showing an example of a separate blanking mechanism according to Embodiment 1. Figure 5 In FIG. 4 , an amplifier 46 (an example of a switching circuit) is arranged in the control circuit 41. Figure 5In the example of the embodiment, as an example of the amplifier 46, a CMOS (Complementary MOS) inverter circuit is configured as a switch circuit. As a control signal, either an L (low) potential (e.g., ground potential) lower than a threshold voltage or an H (high) potential (e.g., 1.5 V) higher than a threshold voltage is applied 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 becomes a positive potential (Vdd), and the corresponding beam 20 is deflected by an electric field generated by a potential difference with the ground potential of the counter electrode 26, and is shielded by the limiting aperture substrate 206, thereby controlling the beam to be closed (OFF). On the other hand, when the H potential is applied to the input (IN) of the CMOS inverter circuit (active state), the output (OUT) of the CMOS inverter circuit becomes the ground potential, and the potential difference with the ground potential of the counter electrode 26 is eliminated, and the corresponding beam 20 is not deflected, so it passes through the limiting aperture substrate 206, thereby controlling the beam to be on. Blanking control is performed by this deflection.

[0079] Then, each individual blanking mechanism 47 controls the emission time of each beam individually using a counter circuit (not shown) according to the emission time control signal transmitted for each beam.

[0080] Next, a specific example of the operation of the drawing mechanism 150 is described. The electron beam 200 emitted from the electron gun 201 (emitting source) illuminates the entire forming aperture array substrate 203 approximately vertically through the illumination lens 202. A plurality of rectangular holes 22 (openings) are formed on the forming aperture array substrate 203, and the electron beam 200 illuminates the area including all the plurality of holes 22. Each portion of the electron beam 200 irradiated to the position of the plurality of holes 22 passes through the plurality of holes 22 of the forming aperture array substrate 203, thereby forming, for example, a rectangular multi-beam (multiple electron beams) 20. Such a multi-beam 20 passes through the respective corresponding blankers (first deflector: individual blanking mechanism 47) of the blanking aperture array mechanism 204. The blanker performs blanking control on the beam that passes through individually during the set drawing time (irradiation time) so that the beam becomes an on state.

[0081] The multi-beam 20 that has passed through the blanking aperture array mechanism 204 is reduced by the reduction lens 205 and moves toward the center hole formed in the limiting aperture substrate 206. Here, the electron beam deflected by the blanker of the blanking aperture array mechanism 204 is located away from the hole in the center of the limiting aperture substrate 206 and is shielded by the limiting aperture substrate 206. On the other hand, the electron beam that is not deflected by the blanker of the blanking aperture array mechanism 204 is as shown in FIG. Figure 1 As shown, the multi-beam 20 that has passed through the hole in the center of the limiting aperture substrate 206. In this way, the limiting aperture substrate 206 shields each beam that has been deflected to the beam OFF state by the individual blanking mechanism 47. And, each beam that is emitted once is formed by using the beam that has passed through the limiting aperture substrate 206 from beam on to beam off. The multi-beam 20 that has passed through the limiting aperture substrate 206 is focused by the objective lens 207 to become a pattern image of a desired reduction ratio. The multi-beam 20 that has passed through the limiting aperture substrate 206 is deflected in the same direction as a whole by the main deflector 208 and the auxiliary deflector 209, and irradiates the respective irradiation positions on the sample 101 of each beam. In addition, for example, when the XY stage 105 is continuously moved, 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 for tracking control. The multiple beams 20 irradiated at one time are ideally arranged at a pitch obtained by multiplying the arrangement pitch of the multiple holes 22 of the aperture array substrate 203 by the above-mentioned desired reduction ratio.

[0082] Figure 6 1 is a conceptual diagram for explaining an example of a drawing operation in Implementation Example 1. Figure 6 As shown, for example, the drawing area 30 of the sample 101 is virtually divided into a plurality of rectangular stripe areas 32 with a predetermined width in the y direction. First, the XY stage 105 is moved and adjusted so that the irradiation area 34 that can be irradiated by the emission of the multi-beam 20 is located at the left end or the left side of the first stripe area 32, and the drawing begins. When drawing the first stripe area 32, the XY stage 105 is moved in the -x direction, for example, and the drawing is relatively performed in the x direction. The XY stage 105 is continuously moved at a constant speed, for example. After the drawing of the first stripe area 32 is completed, the stage position is moved in the -y direction, and this time, the XY stage 105 is moved in the x direction, for example, and the drawing is performed in the -x direction in the same manner. Repeat this action to draw each stripe area 32 in sequence. By alternately changing the direction for drawing, the drawing time can be shortened. However, it is not limited to the case where the drawing is performed while changing the direction alternately, and when drawing each stripe area 32, the drawing can also be performed in the same direction. When the XY stage 105 is moved at a constant speed, the continuous moving speed of each stripe may be different. In one emission, the multi-beam formed by the holes 22 of the aperture array substrate 203 forms a plurality of emission patterns with a maximum number equal to the number of holes 22.

[0083] Figure 7 FIG. 1 is a diagram showing an example of a multi-beam irradiation area and a drawing target pixel in Embodiment 1. Figure 7In the embodiment, the stripe area 32 is divided into a plurality of grid areas in a grid shape, for example, according to 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) of the depicted object. The size of the pixel 36 of the depicted object is not limited to the beam size, and can also be composed of any size regardless of the beam size. For example, it can also be composed of a size of 1 / a (a is an integer greater than 1) of the beam size. Figure 7 In the example, the depiction area 30 of the sample 101 is divided into a plurality of stripe areas 32, for example, in the y direction with a width dimension substantially the same as the dimension of the irradiation area 34 (beam array area) that can be irradiated by a single irradiation of the multi-beam 20. The dimension of the rectangular irradiation area 34 in the x direction can be defined by 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 by the number of beams in the y direction × the spacing between beams in the y direction. Figure 7 In the example, for example, the illustration of a multi-beam of 500 columns × 500 rows is omitted and represented as a multi-beam of 8 columns × 8 rows. Furthermore, within the irradiation area 34, a plurality of pixels 28 (beam drawing positions) that can be irradiated by a single emission of the multi-beam 20 are shown. The spacing between adjacent pixels 28 on the sample surface d becomes the spacing between each beam of the multi-beam 20. A sub-irradiation area 29 (pitch unit) is formed by a rectangular area surrounded by the beam spacing size in the x and y directions. Each sub-irradiation area 29 includes a pixel 28. In Figure 7 In the example shown in FIG. 2 , for example, the pixel at the upper left corner of each sub-irradiation region 29 becomes the pixel 28 at the drawing position of the beam. Each sub-irradiation region 29 is composed of, for example, 10×10 pixels. Figure 7 In the example of FIG. 1 , each sub-irradiation region 29 of 10×10 pixels is abbreviated to 4×4 pixels.

[0084] Figure 8 FIG. 1 is a diagram for explaining an example of a multi-beam imaging operation in Embodiment 1. Figure 8 In the example of FIG. 1 , 10 different beams are used to depict the sub-irradiation areas 29 on the surface of the sample 101. Figure 8 In the example shown, a drawing action is shown in which the XY stage 105 continuously moves at a speed of, for example, a distance L equal to 25 beam pitches while drawing an area of ​​1 / 10 (one-tenth of the number of beam roots used in irradiation) within each sub-irradiation area 29. Figure 8 In the depiction operation shown in the example, for example, while the XY stage 105 moves a distance L corresponding to 25 beam pitches, the irradiation position (pixel 36) is sequentially shifted by the sub-deflector 209 with an emission cycle time t trk-cycleThe multi-beam 20 is emitted 10 times, thereby depicting (exposing) 10 different pixels in the same sub-irradiation area 29. During the period of depicting (exposing) 10 pixels, the multi-beam 20 is deflected as a whole by the main deflector 208 so that the relative position of the irradiation area 34 and the sample 101 will not be offset due to the movement of the XY stage 105, so that the irradiation area 34 follows the movement of the XY stage 105. In other words, tracking control is performed. Therefore, the distance L deflected by the main deflector 208 in each tracking control becomes the tracking distance.

[0085] When a tracking cycle ends, the tracking is reset and returns to the last tracking start position. In addition, since the depiction of the first pixel row from the top of each sub-irradiation area 29 is completed, after the tracking is reset, in the next tracking cycle, the sub-deflector 209 is first deflected to align (offset) the depiction position of the beam to depict the pixel column of each sub-irradiation area 29 that has not yet been depicted, such as the second row from the top. In this way, each time the tracking is reset, the pixel column to be depicted next is changed. During the 10 tracking controls, each pixel 36 in each sub-irradiation area 29 is depicted one by one. In the depiction of the stripe area 32, this action is repeated, so that Figure 6 As shown in FIG. 1 , the position of the irradiation region 34 is sequentially moved to the irradiation regions 34 a to 34 o, and the stripe region 32 is drawn.

[0086] exist Figure 8 In the example of FIG. 1 , the sub-irradiation region 29 on the sample surface located at the lower right corner of the irradiation region 34 with a width of W is located at a position moved by a distance L in the left direction from the lower right corner of the irradiation region 34 in the second tracking control. Therefore, the sub-irradiation region 29 located at the lower right corner of the irradiation region 34 in the first tracking control is depicted by another beam located at a position away from the lower right corner of the irradiation region 34 in the left direction by a distance L in the second tracking control. Here, the sub-irradiation region 29 is depicted by a beam that has moved, for example, 25 beams away from the beam at the lower right corner in the -x direction.

[0087] For example, in the drawing process in which the multiplicity per stage path is set to 2, each pixel 36 in each sub-irradiation area 29 can be drawn twice by performing tracking control 20 times.

[0088] Fig. 9 1 is a diagram showing an example of the relationship between the temperature distribution and the temperature caused by irradiating a region corresponding to one beam pitch with one beam in a comparative example of the first embodiment. Fig. 9 In the figure, the vertical axis represents temperature and the horizontal axis represents temperature distribution. Fig. 9As shown in the figure, the temperature distribution caused by irradiation with one beam is wide in the footing region. Therefore, the influence is applied to a wide range. However, as the influence on the footing region, the temperature of one beam is as small as 0.01°C or less at most.

[0089] Fig.10 : is a diagram showing an example of the relationship between the temperature distribution and the temperature caused by the simultaneous irradiation of multiple beams in Embodiment 1. Fig.10 In the figure, the vertical axis represents temperature and the horizontal axis represents temperature distribution. The temperature rise of one beam is less than 0.01°C at most, but when 500×500=250,000 beams are irradiated simultaneously, Fig.10 As shown, the temperature rise of each beam overlaps in the footing region. As a result, for example, when 500×500=250,000 beams are irradiated simultaneously, the temperature rise in the footing region is significant.

[0090] The technology for predicting and correcting the heating effect in a single beam drawing based on a single beam is well known, but there is no precedent for correcting the heating effect in a multi-beam drawing method where, for example, 250,000 beams are simultaneously emitted multiple times in each stage path. It is not realistic to calculate the heat generated by each of the 250,000 beams in the same way as a single beam in terms of the amount of calculation.

[0091] In case of multi-beam, since the current density J is much smaller than that of a single beam such as the VSB method, the temperature rises slowly. Moreover, the temperature distribution of one emission spreads by tens of μm during this period. Therefore, even if the emission data and dose data within the stripe are divided and calculated centrally to a certain extent, sufficient accuracy can be obtained. In addition, as mentioned above, in multi-beam drawing, since a raster scanning method is used, the position is determined by time. Therefore, if the dose data and the drawing speed (stage speed or tracking cycle time) are determined, the rising temperature is determined. Compared with the drawing of the VSB method which requires both position and time, simple corrections can be made.

[0092] Therefore, in the first embodiment, the dose information of the stripe region 32 is distributed as certain Nx×Ny pixel information including the grid of interest for which the temperature is to be calculated. For the grid of interest, the temperature of each beam irradiation divided into multiple times is calculated. Then, its statistical value (e.g., average value) is used as the effective temperature for correction. The following is a specific description.

[0093] Fig.11 1 is a flowchart showing an example of the main steps of the drawing method in Embodiment 1. Fig.11In the drawing method in embodiment 1, a series of steps are implemented, including a pattern density calculation step (S102), a dose calculation step (S104), a processing grid segmentation step (S106), a dose representative value calculation step (S108), a stage speed and beam array size input step (S109), a kernel determination step (S110), an effective temperature calculation step (S112), a correction amount calculation step (S114), a correction step (S118), an irradiation time data generation step (S120), a data processing step (S122), and a drawing step (S124).

[0094] First, for each stripe region 32 , drawing data is read from the storage device 140 .

[0095] As a 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 in the target stripe region 32. The pattern density calculation unit 50 creates a pattern density map for each stripe region 32 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.

[0096] As a dose calculation process (S104), the dose calculation unit 52 calculates the dose (irradiation amount) for each pixel 36 to irradiate the pixel 36. The dose can be calculated, for example, as a value obtained by multiplying a preset base irradiation amount Dbase by the proximity effect correction irradiation coefficient Dp and the pattern density ρ. In this way, the dose is preferably calculated in proportion to the area density of the pattern calculated for each pixel 36. For the proximity effect correction irradiation coefficient Dp, the drawing area (here, for example, the stripe area 32) is virtually divided into a plurality of proximity grid areas (grid areas for proximity effect correction calculation) in a grid-like manner of a prescribed size. The size of the proximity grid area is preferably set to about 1 / 10 of the influence range of the proximity effect, for example, about 1 μm. In addition, the drawing data is read out from the storage device 140, and for each proximity grid area, the pattern area density ρ' of the pattern arranged in the proximity grid area is calculated.

[0097] Next, a proximity effect correction irradiation coefficient Dp for correcting the proximity effect is calculated for each adjacent grid area. Here, the size of the grid area for calculating the proximity effect correction irradiation coefficient Dp does not need to be the same as the size of the grid area 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 the method used in the previous single-beam drawing method.

[0098] Then, the dose calculation unit 52 uses the calculated dose of each pixel 36 to create a dose map (1) for each stripe area 32. The dose of each pixel 36 is defined as each element of the dose map (1). In the above example, the dose is calculated as an absolute value obtained by multiplying the reference irradiation amount Dbase, but it is not limited to this. It is also possible to assume that the reference irradiation amount Dbase is 1 and calculate the dose as a relative value relative to the reference irradiation amount Dbase. In other words, it is also possible to calculate the dose as a coefficient value obtained by multiplying the proximity effect correction irradiation coefficient Dp and the pattern density ρ. The produced dose map (1) is stored in the storage device 144.

[0099] As a processing grid division step (S106), the division unit 53 (division processing circuit) divides the drawing area of ​​the sample 101 into a plurality of processing grids 39 (grid areas) in the drawing advancing direction and in a direction linearly independent of the drawing advancing direction. In other words, the division unit 53 (division processing circuit) divides each of the plurality of stripe areas obtained by dividing the drawing area of ​​the sample in the y direction by the size of the beam array area of ​​the multi-charged particle beam on the sample surface in the y direction into a plurality of grid areas in the x direction (second direction) parallel to the y direction and the moving direction (-x direction) of the stage along each stripe area. Specifically, the division unit 53 (division processing circuit) divides each stripe area 32 into a plurality of processing grids (grid areas) in the y direction (first direction) by a size of 1 / Ny of the size W of the beam array area and in the x direction (second direction) orthogonal to the y direction by a size of 1 / Nx of the size W of the beam array area (Nx, Ny are both integers greater than 2).

[0100] Fig.12 : is a diagram showing an example of a processing grid in Embodiment 1. As described above, the drawing area 30 of the sample 101 is divided into a plurality of stripe areas 32, for example, in the y direction, with a size W of the irradiation area 34 (beam array area) of the multi-beam 20 on the surface of the sample 101. Furthermore, each stripe area 32 is divided into a plurality of processing grids (grid areas) 39 with a size of 1 / Ny (Ny is an integer greater than 2) of the size W of the irradiation area 34 (beam array area) in the y direction, and with a size of 1 / Nx (Nx is an integer greater than 2) of the size W of the irradiation area 34 (beam array area) in the x direction. The size sx in the x direction and the size sy in the y direction of each processing grid 39 are composed of sizes larger than the sub-irradiation area 29 of the beam spacing size. In Fig.12 In the example of FIG. 1 , the size sx in the x direction and the size sy in the y direction of each processing grid 39 are expressed as the same size s.

[0101] In Embodiment 1, the size s of the processing grid 39 is preferably set to, for example, the tracking distance L. The tracking distance L is k times (k is a natural number) the inter-beam spacing size on the surface of the sample 101. In the above example, the tracking distance L is set to, for example, 25 times the inter-beam spacing size. Therefore, the size s of the processing grid 39 is preferably set to, for example, a size of 25 beam spacing amounts. Therefore, the size s of the processing grid 39 is a size larger than the inter-beam spacing size on the surface of the sample 101. Moreover, the processing grid 39 is an area that is large enough relative to the pixel 36 that becomes the unit area of ​​each beam irradiated.

[0102] As a dose representative value calculation step (S108), the dose representative value calculation unit 54 (dose statistical value calculation circuit) calculates representative values ​​of the doses of the beams irradiating the processing grids 39 as dose representative values ​​D for each of the plurality of processing grids 39 (grid areas), wherein the plurality of processing grids 39 (grid areas) are obtained by dividing the drawing area of ​​the sample 101 irradiated by the plurality of beams 20 in the drawing progress direction and in a direction linearly independent of the drawing progress direction. In other words, the dose representative value calculation unit 54 (dose statistical value calculation circuit) calculates representative values ​​of the plurality of doses of the plurality of beams irradiating the processing grid 39 as dose representative values ​​D for each of the divided processing grids 39. The processing grid 39 includes a plurality of sub-irradiation areas 29. As described above, each sub-irradiation area 29 is irradiated with a plurality of different beams. In the above example, for example, irradiation is performed with 10 different beams each separated by 25 beam pitches in the x direction, and a plurality of pixels 36 are included in the processing grid 39. Here, a representative value (dose representative value Dij) of the dose defined for all pixels 36 within the processing grid 39 is calculated. As a representative value, for example, an average value, a maximum value, a minimum value, or a central value can be cited. Here, as the dose representative value Dij, for example, an average dose as an average value is calculated. The dose representative value calculation unit 54 uses the calculated dose representative value Dij of each processing grid 39 to create a dose representative value map. The dose of each processing grid 39 is defined as each element of the dose representative value map. i indicates the index in the x direction of the processing grid 39. j indicates the index in the y direction of the processing grid 39. The created dose representative value map is stored in the storage device 144.

[0103] In the first embodiment, the effective temperature in each processing grid 39 is calculated as described in the effective temperature calculation step (S112) to be described later. First, the effective temperature will be described.

[0104] A calculation process is performed of the temperature rise provided to the grid area of ​​interest, which is one of the plurality of processing grids 39, by the heat generated by beam irradiation of each processing grid 39 within the processing area corresponding to the beam array area. This calculation process is performed by convolution processing using a dose representative value of each processing grid 39 and a heat diffusion function representing heat diffusion formed by the processing grid 39.

[0105] The above-mentioned calculation process is repeated while shifting the position of the processing area corresponding to the beam array area in the x direction on the stripe area, and the representative values ​​of the multiple temperature rises obtained by performing the repeated process multiple times until the processing grid 39 is located at the position from one end to the other end of the processing area in the x direction are calculated as the effective temperature of the grid area of ​​interest. Specifically, for each processing grid 39, the effective temperature is calculated using the dose statistics Dij of each processing grid 39 and the heat diffusion function PSF representing the heat diffusion formed by each grid. The heat diffusion function PSF can be defined by the following formula (1) as a general heat diffusion equation.

[0106]

Formula 1

[0107] (1)

[0108] The function representing the surface temperature of the quartz glass substrate obtained by equation (1) can be used. Here, λ represents the thermal diffusivity of the temperature-diffusing substance. An example of the solution of the above equation will be described later as an explanation of equation (3-1).

[0109] Using the dose representative value Dij and the heat spread function PSF, for example, the following processing is performed: a convolution process of calculating the temperature rise provided to the grid area of ​​interest by the heat generated by beam irradiation to each processing grid 39 in the processing area, which is a rectangular area of ​​the same size as the beam array area composed of Nx×Ny processing grids 39, is simultaneously performed on the stripe area 32 of the object by shifting the rectangular area in the x direction by the size s of the processing grid 39 until the grid area of ​​interest is included in the rectangular area. This process is performed N times until the grid area of ​​interest is located at one end of the rectangular area in the x direction and at the other end. Then, a statistical value of the result of the N-times convolution process is calculated as the effective temperature T(k, l).

[0110] Fig.13 is a diagram for explaining the calculation method of the effective temperature in Embodiment 1. The effective temperature T(k, l) can be obtained by Fig.13The formula (2) shown in FIG. 3 is defined. In the stripe region 32, M processing grids 39 are arranged in the x direction and N processing grids 39 in the y direction. In the formula (2), the processing grid 39 in the y direction and the kth column in the x direction among the multiple processing grids 39 in the stripe region 32 is represented as the grid region of interest.

[0111] In the formula (2), i represents the index in the x direction in the dose statistical value map. The index in the x direction of the processing grid 39 at the left end of the stripe region 32 is defined as i=0.

[0112] j represents the index in the y direction in the dose statistics map. The y direction index j=0 is defined as the lowest processing grid 39 in the stripe region 32 .

[0113] N represents the number of grids in the longitudinal direction (y direction) of the input dose map used for effective temperature calculation.

[0114] M represents the number of grid cells in the lateral direction (x direction) of the input dose map used for the effective temperature calculation.

[0115] (k, l) represents the index (reference number) of the processing grid (focus grid area) for calculating the effective temperature T in the (M×N) processing grids.

[0116] Dij represents the dose representative value assigned to the processing grid 39 of index (k, l) in the dose representative value map. (μC / cm^2)

[0117] m represents the number of the beam irradiation from l-N+1 to l-th performed before the beam array area (N×N, where Nx=Ny=N) passes through the grid of interest (k, l). When the processing grid size s is set to the tracking distance L, m is consistent with the number of the tracking reset from l-N+1 to l-th performed before the beam array area passes through the grid of interest (k, l). When m=l-N+1, the grid of interest is located at the right end of the (N×N) beam array area. When m=l, the grid of interest is located at the left end.

[0118] n represents the beam irradiation numbers from 0th to mth. When the processing grid size s is set to the tracking distance L, n coincides with the tracking reset numbers from 0th to mth.

[0119] Since the tracking reset has not been performed in the first tracking control (tracking cycle), the tracking reset number is 0. Since the tracking reset is performed once in the second tracking control, the tracking reset number is 1.

[0120] PSF(n, m, ki, lj) represents the heat spread function.

[0121] Fig.14This is a diagram for explaining a part of the calculation formula of the effective temperature in the first embodiment. Fig.14 In the formula (2), the portion surrounded by the dotted line represents the calculation part of the convolution processing. In the calculation part of the convolution processing of the formula (2), the convolution processing is performed to calculate the temperature rise provided to the grid area of ​​interest indexed (k, l) by the heat generated by the beam irradiation of each grid area in the rectangular area 35 having the same size as the beam array area composed of N×N processing grids 39. A rectangular area 35 is used, the left end of which is the nth column of the processing grid 39 and the right end is the n+N-1th column of the processing grid 39. Therefore, in the rectangular area 35, N×N processing grids 39 corresponding to the nth column to the n+N-1th column in the x direction and the 0th row to the N-1th row in the y direction are arranged.

[0122] Fig.15 This is a diagram for explaining an example of a calculation formula for the heat diffusion function in Embodiment 1. The heat diffusion function PSF(n, m, ki, lj) is given by Fig.15 The equation (3-1) shown in FIG. 3 can be obtained by solving the above heat conduction equation under the initial condition that the volume obtained by multiplying the grid size by Rg is uniformly heated by beam irradiation on the substrate surface, and under the boundary conditions that the XY direction is infinite and the Z direction is the substrate depth direction and semi-infinite.

[0123] Symbols repeated in equation (2) in the heat spread function PSF(n, m, ki, lj) represent the same symbols as those in equation (2). Fig.15 The heat diffusion function PSF (n, m, ki, lj) shown in FIG. 1 defines a case where the XY stage 105 moves at a constant speed in the opposite direction (-x direction) to the drawing direction, for example, the x direction. Fig.15 As shown, the heat spread function PSF(n, m, ki, lj) is defined using the tracking cycle time obtained from the velocity v of the XY stage 105.

[0124] In formula (3-1), Rg represents the flying distance of a 50 kV electron beam in quartz. For example, flying distance Rg = (0.046 / ρ)E 1.75 .

[0125] ρ represents the density of the substrate (quartz) (eg, 2.2 g / cm^3).

[0126] σn,m represents a function determined by the number of tracking resets (mn) performed from the nth to the mth. Function σn,m is defined in formula (3-3).

[0127] Function A is defined in formula (3-2).

[0128] In formula (3-2), V represents the acceleration voltage of the electron beam.

[0129] Cp represents the specific heat of the substrate (quartz) (eg, 0.77 J / g / K).

[0130] In formula (3-3), λ represents the thermal diffusivity of the substrate (quartz) (for example, 0.0081 cm^2 / sec).

[0131] (mn) indicates the number of tracking resets performed from the nth to the mth.

[0132] t trk-cycle Indicates the tracking cycle time. Tracking cycle time t trk-cycle Expressed by formula (3-4).

[0133] v stage Indicates the stage speed.

[0134] In a multi-beam profiling device, it is usually optimized to have a stage velocity v within the stage path. stage = (constant), the transmission (in the previous example, 10 transmissions) ends during the tracking period. The tracking distance L (= W / N) is followed by the stage speed, so the tracking cycle time t trk-cycle It can be defined by equation (3-4).

[0135] Fig.16 is a diagram for explaining another part of the calculation formula for the effective temperature in the first embodiment. Fig.14 The convolution process described in the above is performed while shifting the rectangular area 35 from the left end of the stripe area 32 (n=0) in the x direction by the size s of the processing grid 39 until the grid area of ​​interest with index (k, l) is included in the rectangular area 35 (n=m). Fig.16 The calculation part surrounded by the dashed line of equation (2) shown in FIG. Fig.16 In the example of FIG. 1 , the rectangular area 35 is moved to a state where the grid area of ​​interest with index (k, l) is located at the right end of the rectangular area 35. In this state, the left end of the rectangular area 35 is located at the k-N+1th column, and the right end is located at the kth column.

[0136] Fig.17 This is a diagram for explaining another part of the calculation formula of the effective temperature in the first embodiment.

[0137] Fig.18 This is a diagram for explaining another part of the calculation formula of the effective temperature in the first embodiment. Fig.18 Specifically, it is expressed as Fig.17 The calculation part of the processing.

[0138] like Fig.17 As shown, Fig.16 The process shown in FIG. 1 is performed N times until the grid area of ​​interest becomes the right end of one end of the rectangular area 35 in the x direction and becomes the left end of the other end. Fig.18 As shown in formula (4), from n = 0 to n = m = k-N + 1 Fig.16 The process shown, from n = 0 to n = m = k-N + 2 Fig.16 The process shown, from n = 0 to n = m = k-N + 3 Fig.16 The process shown, ..., from n = 0 to n = m = k Fig.16 The processing shown in FIG. 1 is performed N times, and their total is calculated. The rectangular area 35 is configured with N processing grids 39 in the x direction, so in order to focus on the grid area from the right end to the left end of the rectangular area 35, it is processed N times. This processing is performed by Fig.17 The calculation part surrounded by the dotted line of the equation (2) shown in FIG. Then, the statistical value of the result of N times of convolution processing is calculated as the effective temperature T(k, l). Such processing is performed by Fig.18 The calculation part surrounded by the dashed line of the equation (2) shown in FIG. 2 shows that the average value obtained by dividing the sum of N convolution processes by N is calculated as the effective temperature T(k, l).

[0139] In addition, the number of divisions of the rectangular area and the number of calculation processing times may not necessarily be the same. That is, it may be divided into N pieces and the number of calculation processing times may be set to be smaller than N (downsampling). In addition, it may be divided into N pieces and allocated to a number of grids larger than N (upsampling).

[0140] The effective temperature T(k, l) is not limited to the average value, but may be the maximum value, minimum value, or central value of the results of N-times convolution processing. More preferably, the central value is better. More preferably, the average value is better.

[0141] The position of the grid region of interest is changed, and the effective temperature T(i, j) is obtained for each position (i, j) of the processing grid 39 .

[0142] As described above, instead of calculating the temperature rise for each shot and each beam, the dose representative value Dij of the processing grid 39 is used to calculate the effective temperature T(i, j) per unit of the processing grid 39. The effective temperature T(i, j) can be calculated for each processing grid 39, which is much larger than the pixel 36, which is the unit area irradiated by the beam of each shot. Therefore, the amount of calculation can be greatly reduced.

[0143] Although the effective temperature T may be calculated each time by the above method, in the first embodiment, the calculation method of the effective temperature T is further improved.

[0144] Fig.19 FIG. 1 is a diagram for explaining an example of a virtual model of effective temperature in Embodiment 1. Fig.19 In the case of point irradiation of 1μC charge at position coordinates (0, 0) by multi-beam mapping, the effective temperature observed at any position (x, y) (the average temperature during the period when the BAA region passes through the (x, y) region) is calculated to obtain the kernel. Fig.19 In the graph below the position coordinate (0,0), the vertical axis represents the charge amount and the horizontal axis represents the time t. In addition, in the graph below an arbitrary position (x, y), the vertical axis represents the temperature and the horizontal axis represents the time t.

[0145] like Fig.19 As shown in the graph below the position coordinate (0, 0), it is assumed that the beam array area of ​​size Lx in the x direction moves continuously and linearly at the stage speed Vstage, and the charge is continuously and linearly irradiated. Furthermore, it is assumed that the irradiation starts at the right end of the beam array area and ends at the left end. Under these two assumptions, the effective temperature at any position (x, y) is approximately calculated. Fig.19 The graph under the position coordinate (0, 0) shows the state of sequential irradiation at the time when the beam array area passes. As shown in the graph under an arbitrary position (x, y), the temperature rise occurs at the time (t = Lx / Vstage) when the beam array area is point-irradiated at the position coordinate (0, 0) and before and after. The effective temperature represents the average temperature at the time when the beam array area passes.

[0146] Fig. 20 : is a diagram for explaining an example of the kernel derivation process in Implementation Example 1. In the stripe region 32, M processing grids 39 are arranged along the x direction, and Ny processing grids 39 are arranged along the y direction. If the middle position in the y direction in the stripe region 32 is set to j=0, the processing grids 39 from -Ny / 2 to +Ny / 2 are arranged in the y direction in the stripe region 32. In addition, if the position of the central part in the x direction in the stripe region 32 is set to i=0, the processing grids 39 from -∞ to M are arranged in the x direction in the stripe region 32. In formula (5), the coordinate processing grid 39 in the 1st row in the y direction and the kth column in the x direction among the multiple processing grids 39 in the stripe region 32 is represented as the grid area of ​​interest.

[0147] In addition, Fig. 20 In the figure, the size sx of the processing grid 39 in the x direction is the value obtained by dividing the beam array size Lx in the x direction by the number of grids Nx in the beam array in the x direction. In addition, the size sy of the processing grid 39 in the y direction is the value obtained by dividing the beam array size Ly in the y direction by the number of grids Ny in the y direction in the beam array.

[0148] Here, it is assumed that the processing grid points at positions i = 0 and j = 0 are irradiated with a charge of 1 μC. At this time, if the dose representative value Dij of the processing grid at position (0, 0) is set as the average value per unit area, then Dij = 1 / (sxsy), and the dose representative values ​​of the processing grids other than i = 0 and j = 0 are set to zero. In this case, the effective temperature T(k, l) is defined as the kernel T(k, l). The kernel T(k, l) can be expressed as Fig. 20 As described above, since the index setting method is changed, the integration range on the right side of equation (5) is changed from the integration range on the right side of equation (2).

[0149] Here, it is assumed that Nx and Ny are infinite. In other words, it is assumed that the size of the processing grid is infinitely small.

[0150] Fig.21 It is a diagram showing another example of the kernel derivation process in Implementation Method 1. By making the sizes sx and sy of the processing grid infinitesimal, equation (5) can be transformed as shown in equation (6-1). Among them, function C is shown in equation (6-2). Function E is shown in equation (6-3). Here, the thermal diffusion function PSF is represented by the above equations (3-1) to (3-3). The tracking cycle time ttrkcycle can be defined by dividing the value of the processing grid size sx in the x direction by the stage speed Vstage. In addition, the processing grid size sx is the value obtained by dividing the x-direction size Lx of the beam array area by the number of grids Nx in the x direction within the beam array area. In other words, this means that a virtual tracking distance Lx / Nx is defined. Therefore, the function σn,m of equation (3-3) can be transformed into equation (6-4).

[0151] Fig. 22 : is a diagram showing another example of the kernel derivation process in Embodiment 1. As described above, it is assumed that the number of grids Nx and Ny in the processing area overlapping the beam array area is infinite. In other words, it is assumed that the size of the processing grid 39 is infinitesimal.

[0152] And, in Fig. 22 In the figure, the value obtained by dividing the reference number i representing the grid area in the beam travel direction (x direction) within the processing area of ​​the same size as the beam array area by the number Nx of grid areas in the beam travel direction within the processing area overlapping with the beam array area, and multiplying it by the size Lx of the beam array area in the beam travel direction, and the value transformed by taking Nx to the limit of infinity, is defined as the integral variable ω.

[0153] In addition, Fig. 22In the figure, the value obtained by dividing the reference number j representing the grid area in the y direction within the processing area of ​​the same size as the beam array area by the number Ny of grid areas in the y direction within the processing area overlapping with the beam array area is multiplied by the size Ly of the beam array area in the y direction, and the value transformed by taking Ny to the limit of infinity is defined as the integral variable ξ.

[0154] In addition, Fig. 22 In the figure, the value obtained by dividing the beam irradiation number m, m = k-Nx+1, k-Nx, ... k, by the number of grid areas Nx, which is performed Nx times in sequence before the processing area consisting of the size of Nx×Ny passes through the focus grid of coordinates (k, l), is multiplied by the size Lx of the beam array area in the beam travel direction (x direction), and the value transformed by taking Nx as the limit of infinity is defined as the integral variable u.

[0155] In addition, Fig. 22 In the equation, the value obtained by dividing the beam irradiation number n for the mth, m-1th, m-2th, ... in sequence by the number of grid areas Nx is multiplied by the size Lx of the beam array area in the beam travel direction (x direction), and the value transformed by taking Nx to the limit of infinity is defined as the integral variable v.

[0156] Therefore, the convolution processing part of the right-hand side term of equation (6-1) which defines the kernel K(k, l) and which sums Lx / Nx from i=n to n+Nx-1 can be defined as the term component representing the integration operation of integrating from v to v+Lx with the integral variable ω as shown in equation (7-1).

[0157] In addition, the convolution processing part of the right-hand side term of equation (6-1) which defines the kernel K(k, l) and which sums Ly / Ny from j=-Ly / 2 to +Ly / 2 can be defined as a term component representing the integration operation of integrating from -Ly / 2 to +Ly / 2 with the integral variable ξ as shown in equation (7-2).

[0158] In addition, the convolution processing part of the right-hand side term of equation (6-1) which defines the kernel K(k, l) and which sums Lx / Nx from n=-∞ to m can be defined as a term component representing the integration operation of integrating from -∞ to u with the integral variable v as shown in equation (7-3).

[0159] In addition, the convolution processing part of the right-hand side term of equation (6-1) which defines the kernel K(k, l) and which sums Lx / Nx from m=k-Nx+1 to k can be defined as a term component representing the integration operation of integrating from x-Lx to x with the integral variable u as shown in equation (7-4).

[0160] In addition, the term components integrated with the integral variables ω and ξ are integral operations that represent the accumulation of the temperature rise contributed by the heat generated by the irradiated beam at a certain position (ω, ξ) in the beam array region to the position (x, y) when the beam array region is located at a certain position v. Therefore, the integral range of ω and ξ is within the beam array region, ω is v to v+Lx, and ξ is -Ly / 2 to +Ly / 2.

[0161] The term component integrated with the integral variable v is: the temperature rise accumulated by the above integration operation is further integrated when the temperature rise contributed to the position (x, y) with respect to the beam array region at each position from infinity to position u. Therefore, the integration range of v is from -∞ to u.

[0162] The term component integrated with the integral variable u is an integration operation that further integrates the temperature rise accumulated by the above integration operation from when one end of the beam array area is at position (x, y) to when the other end is at position (x, y). Therefore, the integration range of u is from x-Lx to x.

[0163] Therefore, the kernel K(k, l) can be defined by an integral expression using the integral variable ω, the integral variable ξ, the integral variable u, and the integral variable v. Specifically, the kernel K(k, l) can be defined by a term component representing an integral operation of integrating the integral variable ω, a term component representing an integral operation of integrating the integral variable ξ, a term component representing an integral operation of integrating the integral variable v, a term component representing an integral operation of integrating the integral variable u, a function A / (πσ u，v 2 )erf(Rg / σ u，v )e^(-((x-ω) 2 +(y-ξ) 2 ) / σ u，v ) is defined by equation (8-1) which is obtained by multiplying the Dirac delta function δ(ω,ξ).

[0164] In addition, the Dirac delta function δ(ω, ξ) is a function that satisfies equations (8-2) and (8-3). In addition, the function σ u，v Defined by formula (8-4).

[0165] In addition, by making the sizes of the processing grid sx and sy infinitesimal, the differential form of the error function can be defined by formula (8-5).

[0166] Fig.23This is a diagram for explaining the kernel in Embodiment 1. The kernel K(x, y) represents the average temperature (effective temperature) at any position during the beam array region passage when (x, y) = (0, 0) is continuously irradiated with a charge of 1 μC during the beam array region passage. Fig.23 The lower right figure of shows the case where a charge of 1 μC is continuously irradiated during the passage of the beam array area. The vertical axis represents the charge amount and the horizontal axis represents the time. In this case, Fig.23 As shown in the figure above, even behind the charge irradiation point at coordinate (0, 0), a non-zero effective temperature appears at x>-Lx. This is because the heat generated by irradiation at the right end of the beam array area is as follows Fig.23 As shown in the lower left figure of , it contributes as a heating effect when the inner side of the beam array area is irradiated. That is, the kernel depends on the size Lx of the beam array area.

[0167] Fig.24 : is a diagram showing an example of the relationship between the stage speed and the kernel in Implementation Example 1. Fig.24 In the example of FIG. 1 , an example of four kernels with different stage speeds Vstage of vstage=v1 to v4 is shown, on the basis of a constant x-direction dimension Lx of the beam array. Fig.24 As shown, the core has an asymmetric temperature distribution with different heights and shapes for each stage speed. Fig.24 As can be seen from the example, as the stage speed increases, the temperature in the center of the temperature distribution becomes higher.

[0168] Fig.25 FIG. 1 is a diagram showing an example of the relationship between the moving direction dimension of the beam array and the kernel in Embodiment 1. Fig.25 In the example of FIG. 1 , an example of three kernels with different x-direction dimensions Lx of beam arrays Lx=Lx1 to Lx3 is shown, based on a constant stage speed. Fig.25 As shown, the core has a temperature distribution with different heights and shapes for each x-dimension Lx of the beam array. Fig.25 As can be seen from the example, the smaller the x-direction dimension Lx of the beam array is, the higher the temperature in the center of the temperature distribution is.

[0169] Fig.26 FIG. 2 is another diagram showing another example of the relationship between the moving direction dimension of the beam array and the kernel in Embodiment 1. Fig.26 In the Fig.25 An example of temperature distribution of the three beam arrays with dimension Lx in the x direction. The vertical axis represents temperature. The horizontal axis represents the position in the x direction. Fig.26 As shown in the example of FIG. 1 , the shapes of the rise and fall of the temperature distribution of the core are different depending on the size Lx of the beam array area.

[0170] Therefore, in the first embodiment, a plurality of kernels corresponding to the stage speed and the beam array size Lx are prepared in advance.

[0171] Fig. 27 FIG. 1 is a diagram showing an example of a kernel defined as a table in Implementation Example 1. Fig. 27 In the kernel K(x, y) is defined as the value of each position in a range larger than the beam array area. This is because there is an effect of residual heat after the beam array passes. For example, when the beam array area size Lx is set to a range of about 100 μm (maximum value) to 10 μm (minimum value), it is preferable to calculate the kernel in the range of about ±300 μm in the x and y directions, respectively.

[0172] exist Fig. 27 In the example of , the stage speed Vstage, the x-direction (opposite to the stage travel direction) dimension Lx of the beam array, the position (x, y), and the kernel value K(x, y) at each position are associated and defined as a table. With respect to the value of the kernel K(x, y) at each position, it is assumed that the beam array region continuously moves at a constant speed while irradiating a point charge of 1 μC to the center position of the kernel, and that the irradiation of the point charge starts at one end of the beam array region and ends at the other end. Under these two assumptions, the value of the kernel K(x, y) at each position represents a representative value of the temperature during the period when the beam array region passes through the position.

[0173] In addition, reference is made to the stage speed and the size of the beam array area actually used, and when there are no matching values, linear interpolation values ​​using the previous and next values ​​may be used.

[0174] Fig.28 : is a diagram showing an example of a formula for a kernel defined as a continuous function in Implementation 1. Fig.28 In the example, equation (9) shows an example of a function obtained by approximating five kernels with different stage speeds based on the addition of five Gaussian functions that are anisotropic in the x and y directions. In addition, a coefficient Ai is prepared in advance for each stage speed, and the coefficients Ai, σxi, σyi after linear interpolation are used for the speeds between the stage speeds defined in the table. And, for example, for each beam array area size Lx, it is sufficient to prepare an equation for a kernel defined as a continuous function. Alternatively, it is also preferable to prepare a function obtained by approximating multiple kernels with different stage speeds and beam array area sizes Lx.

[0175] As described above, in Embodiment 1, a plurality of kernels are prepared in advance depending on the stage speed and the beam array area size Lx. The plurality of kernels are stored in the storage device 144 .

[0176] As a stage speed and beam array size input process (S109), the acquisition unit 56 acquires the stage speed Vstage and the beam array size Lx in this drawing process. Specifically, the stage speed Vstage and the beam array size Lx set when setting the drawing conditions not shown in the figure are acquired. The setting of the drawing conditions is performed by a manual input operation of the user. Alternatively, it is preferable that a plurality of drawing condition parameters including the stage speed Vstage and the beam array size Lx are pre-set on an input screen not shown in the figure so that a plurality of conditions can be selected respectively, and the user selects each drawing condition parameter from the set plurality of conditions. The beam array size Lx changes when, for example, the number of beams in the beam array that can be irradiated by the drawing device 100 is limited and used. Specifically, there can be cited a case where only the beam array in the central part of the beam array where the influence of aberration is small is used. As a result, the number of beams is reduced, so although the drawing time becomes longer, the accuracy of the drawing position can be improved.

[0177] In the kernel determination step ( S110 ), the kernel determination unit 57 determines a corresponding kernel from among a plurality of kernels based on the acquired (input) stage speed Vstage and beam array size Lx.

[0178] As the effective temperature calculation step (S112), the effective temperature calculation unit 58 calculates the representative value of the temperature rise provided to each of the plurality of processing grids 39 by the heat caused by the beam irradiation, as the effective temperature T(k, l) of each of the plurality of processing grids 39, by convolution processing of the kernel determined by the speed of the stage 105 on which the sample 101 is placed and the size of the beam array region on the surface of the sample 101 of the multi-beam 20 in the drawing progress direction and the representative value of the dose. In other words, the effective temperature calculation unit 58 inputs the speed Vstage of the stage 105 and the size Lx of the beam array region in the x direction, and calculates the representative value of the temperature rise provided to the grid region of interest (k, l) as one of the plurality of processing grids 39 by the heat caused by the beam irradiation in the processing region having the same size as the beam array region overlapping the beam array region on the surface of the sample 101, as the effective temperature T of the target grid region (k, l). The calculated effective temperature is output to and stored in the memory 112 or the storage device 142. Specifically, the operation is performed as follows.

[0179] Fig.29 1 is a diagram for explaining the method of calculating the effective temperature in the first embodiment. Fig.29As shown, the effective temperature calculation unit 58 performs convolution processing on the dose distribution of the dose representative value Dij and the kernel K (xk, yl). (xk, yl) represents the position within the kernel. Thus, the effective temperature T (k, l) of the grid of interest can be calculated. The effective temperature T (k, l) of the grid of interest can be defined by the formula (10) representing the convolution processing. In the convolution processing, while shifting the center of the kernel within the dose distribution, the sum of the element products of the elements with the same position is calculated. The sum of the element products of the kernel center position at the coordinate (k, l) becomes the effective temperature T (k, l).

[0180] Here, in the above example, the case where the stage 105 moves at a constant speed is described, but it is not limited to this. Even in the case where the stage 105 moves at a variable speed, the above calculation formula (10) can be applied. In this case, the stage speed distribution is stored in the storage device 144. The effective temperature calculation unit 58 obtains the stage speed at the position where the core center is located, and selects the core corresponding to the stage speed at the position where the core center is located. Thus, the effective temperature using the above core can be calculated even in the case of variable speed movement.

[0181] As a correction amount calculation step (S114), the correction amount calculation unit 60 calculates the dose of the plurality of beams in the multi-beam 20 for irradiating the grid area of ​​interest, which is one of the plurality of grid areas, using the effective temperature in each of the plurality of grid areas. For example, first, the correction amount calculation unit 60 calculates the modulation rate α(x) of the dose depending on the effective temperature T.

[0182] Fig.30 FIG. 1 is a diagram showing an example of the relationship between line width CD and temperature in Embodiment 1. Fig.30 In the figure, the vertical axis represents the line width CD (Critical Dimension) and the horizontal axis represents the temperature. Fig.30 As shown, it can be seen that as the temperature of the resist increases, the deviation of the line width CD also increases. The CD change ΔCD / ΔT [nm / K] caused by the heating effect has a linear relationship. This value varies depending on the type of resist and the type of substrate, so it is obtained by conducting experiments. Therefore, an approximate formula for approximating the CD change ΔCD per unit temperature ΔT is obtained in advance. The relevant data (1) is input from the outside and stored in the storage device 144.

[0183] Fig.31 FIG. 1 is a diagram showing an example of the relationship between the line width CD and the dose in Embodiment 1. Fig.31 In the figure, the vertical axis represents the line width CD and the horizontal axis represents the dose. Fig.31 In the example, the horizontal axis is expressed in logarithmic terms. Fig.31As 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 between the CD change and the dose ΔCD / ΔD depending on each type of resist substrate and each pattern density. In addition, an approximate formula for approximating the CD change per unit dose ΔCD is obtained in advance. The related data (2) is input from the outside and stored in the storage device 144.

[0184] The correction amount calculation unit 60 reads the relevant data (1) and (2) from the storage device 144, and calculates the dose change amount ΔD per unit temperature ΔT that depends on the pattern density as the modulation rate α(x) of the dose that depends on the effective temperature T. The modulation rate α(x) that depends on the pattern density ρ is defined by the following equation (11).

[0185] (11) α(x)=(ΔCD / ΔT) / (ΔCD / ΔD) ρ =(ΔD / ΔT) ρ

[0186] The correction amount calculation unit 60 calculates a value obtained by multiplying the effective temperature T(i, j) by the modulation rate α(x) as the correction amount.

[0187] As a correction step (S118), the correction unit 62 (an example of a dose correction circuit) uses the effective temperature T(i, j) to correct the dose of the multiple beams irradiating each grid area of ​​interest. The corrected dose D'(x) can be calculated by the following formula (12). x represents the index of the pixel 36. (i, j) represents the index of the processing grid. In addition, the pattern density ρ can use the pattern density of the pixel 36 as the target.

[0188] (12) D'(x)=D(x)-T(i,j)·α(x)

[0189] Then, the correction unit 62 generates a dose map (2) for each stripe region 32 using the calculated corrected dose D'(x) of each pixel 36. 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 of the temperature rise amount can be returned to the designed size. The prepared dose map (2) is stored in the storage device 144.

[0190] As an irradiation time data generation step (S120), the irradiation time data generation unit 72 calculates the irradiation time t of the electron beam for causing the corrected dose D'(x) calculated for the pixel 36 to be incident. 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 (a coefficient value of the dose) relative to the reference irradiation amount Dbase calculated by assuming the reference irradiation amount Dbase to be 1, the dose statistical value Dij of each processing grid 39 is also calculated as a relative value relative to the reference irradiation amount Dbase. Therefore, the effective temperature T(i, j) of each processing grid 39 is also calculated as a relative value relative to the reference irradiation amount 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 amount Dbase by the current density J.

[0191] 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 grayscale levels, where the maximum irradiation time Ttr is set to, for example, 1023 grayscale levels (10 bits). The grayscaled irradiation time data is stored in the storage device 142.

[0192] As a data processing step ( S122 ), the data processing unit 74 rearranges the irradiation time data in the emission order according to the drawing sequence, and rearranges the data in the data transfer order taking into account the arrangement order of the shift registers of each group.

[0193] As a drawing process (S124), under the control of the drawing control unit 80, the transmission control unit 79 transmits the irradiation time data to the deflection control circuit 130 in the transmission order. The deflection control circuit 130 outputs the blanking control signal to the blanking aperture array mechanism 204 in the transmission order, and outputs the deflection control signal to the DAC amplifier units 132 and 134 in the transmission order. Then, the drawing mechanism 150 draws a pattern on the sample 101 using the multi-beam 20 of the dose D'(x) respectively corrected by the effective temperature T(i, j). In other words, the drawing mechanism 150 draws a pattern on the sample 101 using the correction amount calculated using the effective temperature obtained by the above-mentioned effective temperature calculation method.

[0194] In the above example, the case where the stripe regions 32 for which the calculation of the dose D′(x) is completed are sequentially drawn is described. For example, during the drawing process of a certain stripe region 32, the calculation of the dose D′(x) of the previous stripe region 32 or the previous two stripe regions 32 of the stripe region 32 being drawn is performed in parallel. In other words, the case where the calculation of the dose D′(x) is performed simultaneously with the drawing process is described. However, this is not limited to this. The calculation of the effective temperature T(i, j) and / or the dose D′(x) may also be performed as a pre-processing before starting the drawing process.

[0195] As described above, according to Embodiment 1, in multi-beam drawing, the influence of temperature rise of each shot and each beam is not accumulated, and resist heating can be corrected. In addition, by preparing a plurality of cores in advance, the amount of calculation processing in drawing processing can be greatly reduced.

[0196] [Implementation Method 2]

[0197] In the first embodiment, a structure for correcting resist thermalization by dose modulation based on the effective temperature obtained by using the kernel is described. The method for correcting resist thermalization is not limited to this. In the second embodiment, a structure for correcting by adjusting the size of the drawn graphic pattern itself based on the effective temperature obtained by using the kernel is described. Hereinafter, the contents other than the points specifically described may be the same as those in the first embodiment.

[0198] Fig.32 FIG. 2 is a diagram showing an example of the structure of a drawing device in Embodiment 2. Fig.32 Except that the correction unit 63 is provided instead of the correction unit 62, the same Figure 1 same.

[0199] exist Fig.32In the embodiment, each of the “parts” such as the pattern density calculation part 50, the dose calculation part 52, the division part 53, the dose representative value calculation part 54, the acquisition part 56, the kernel determination part 57, the effective temperature calculation part 58, the correction amount calculation part 60, the correction part 63, the irradiation time data generation part 72, the data processing part 74, the transmission control part 79, and the drawing control part 80 has a processing circuit. The processing circuit includes, for example, a circuit, a computer, a processor, a circuit substrate, a quantum circuit, or a semiconductor device. Each of the “parts” may use a common processing circuit (the same processing circuit) or may use a different processing circuit (a different processing circuit). Information input and output to the pattern density calculation part 50, the dose calculation part 52, the division part 53, the dose representative value calculation part 54, the acquisition part 56, the kernel determination part 57, the effective temperature calculation part 58, the correction amount calculation part 60, the correction part 63, the irradiation time data generation part 72, the data processing part 74, the transmission control part 79, and the drawing control part 80 and information in operation are stored in the memory 112 at any time.

[0200] Fig.33 1 is a flowchart showing an example of the main steps of the drawing method in Embodiment 2. Fig.33 The present invention is similar to the present invention except that the correction amount calculation step (S115) and the correction step (S117) are performed instead of the correction amount calculation step (S114) and the correction step (S118). Fig.11 same.

[0201] The contents of each step from the pattern density calculation step ( S102 ) to the effective temperature calculation step ( S112 ) are the same as those in the first embodiment.

[0202] As a correction amount calculation step (S115), the correction amount calculation unit 60 uses the effective temperature in each of the plurality of grid areas to calculate a correction amount for correcting the pattern data of the graphics drawn in the grid area of ​​interest, which is one of the plurality of grid areas, in the multi-beam 20. Specifically, the operation is performed as follows. The correction amount calculation unit 60 uses the relationship between the effective temperature T(i, j) and the dimensional change (ΔCD / ΔT) of the drawn pattern to calculate the correction amount. Further, the correction amount calculation unit 60 refers to the correlation data (1) stored in the storage device 144, which approximates the CD change ΔCD per unit temperature ΔT. And, the value obtained by multiplying T(i, j) of each grid area of ​​interest and (ΔCD / ΔT) is calculated as the correction amount.

[0203] As a correction step (S117), the correction unit 63 (an example of a size adjustment processing circuit) uses the correction amount calculated using the relationship between the effective temperature T (i, j) and the size change amount (ΔCD / ΔT) of the drawn pattern to adjust the size of the graphic pattern drawn in the processing grid for each processing grid. The corrected pattern size L'(x) can be obtained by the following formula (13). x represents the index of the pixel 36. (i, j) represents the index of the processing grid. In addition, the pattern density ρ can use the initial pattern density of the pixel 36 as the object.

[0204] (13) L'(x)=L(x)-T(i,j)·(ΔCD / ΔT)

[0205] The size L(y) in the y direction is similarly resized. Then, the data of each graphic pattern after the resizing is stored in the storage device 144 .

[0206] As the irradiation time data generating step ( S120 ), the pattern density calculating unit 50 uses the size-adjusted graphic pattern data to calculate the pattern density ρ (area density of the pattern) for each pixel 36 in the target stripe region 32 . Then, a pattern density map is created.

[0207] In the dose calculation step ( S104 ), the dose calculation unit 52 uses the newly created pattern density map to calculate the dose D′(x) (irradiation amount) for irradiating the pixel 36 for each pixel 36 . Then, the dose map is newly created.

[0208] The irradiation time data generating unit 72 calculates the irradiation time t of the electron beam for causing the calculated size-adjusted dose D′(x) to be incident on the pixel 36 for each pixel 36. The irradiation time t can be calculated by dividing the dose D′(x) by the current density J.

[0209] 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 grayscale levels, where the maximum irradiation time Ttr is set to, for example, 1023 grayscale levels (10 bits). The grayscaled irradiation time data is stored in the storage device 142.

[0210] The contents of the data processing step ( S122 ) and the drawing step ( S124 ) are the same as those of Embodiment 1. In the drawing step ( S124 ), the drawing mechanism 150 draws the size-adjusted pattern on the sample 101 using the multi-beam 20 .

[0211] As described above, according to Embodiment 2, in multi-beam drawing, the influence of temperature rise of each shot and each beam is not accumulated, and resist thermalization can be corrected by the resizing process. In addition, by preparing a plurality of cores in advance, the amount of calculation processing in the drawing process can be greatly reduced.

[0212] The embodiments have been described above with reference to specific examples, but the present invention is not limited to these specific examples.

[0213] In addition, it is also possible to cause a computer to execute the functions of the processes described in Embodiments 1 and 2. Furthermore, a program for causing a computer to execute the functions of the processes may be stored in a non-transitory, tangible, readable recording medium such as a magnetic disk device, for example.

[0214] In addition, the description of the device structure, control method, and other parts that are not directly necessary for the description of the present invention is omitted, but the necessary device structure and control method can be appropriately selected and used. For example, the description of the control unit structure for controlling the rendering device 100 is omitted, but of course the necessary control unit structure can be appropriately selected and used.

[0215] In addition, the effective temperature calculation method of all multi-charged particle beam delineation areas, the multi-charged particle beam delineation device, the multi-charged particle beam delineation method and the program (or a readable recording medium that non-temporarily records the program) that have the elements of the present invention and can be appropriately modified by those skilled in the art are included in the scope of the present invention.

[0216] Industrial Applicability

[0217] The invention relates to a method for calculating the effective temperature of a multi-charged particle beam drawing area, a multi-charged particle beam drawing device, a multi-charged particle beam drawing method and a program (or a readable recording medium that non-temporarily records the program), which can be used, for example, in a method for correcting the heating of a resist generated during multi-beam drawing.

[0218] Description of Reference Numerals

[0219] 20 Multi-beam

[0220] 22 holes

[0221] 24 Control electrode

[0222] 25 through hole

[0223] 26 Counter electrode

[0224] 28, 36 pixels

[0225] 29 sub-irradiation area

[0226] 30 Drawing area

[0227] 32 Stripe Area

[0228] 34 Irradiation area

[0229] 35 Rectangular area

[0230] 39 Processing Grid

[0231] 41 Control circuit

[0232] 46 Amplifier

[0233] 47 Single blanking mechanism

[0234] 50 Pattern density calculation unit

[0235] 52 Dose calculation unit

[0236] 53 Division

[0237] 54 Dose representative value calculation unit

[0238] 56 Acquisition

[0239] 57 Kernel Decision Department

[0240] 58 Effective temperature calculation unit

[0241] 60 Correction amount calculation unit

[0242] 62, 63 Revision

[0243] 72. Irradiation time data generation unit

[0244] 74 Data Processing Department

[0245] 79 Transmission Control Unit

[0246] 80 Drawing control unit

[0247] 100 Drawing Device

[0248] 101 Sample

[0249] 102 Electronic tube

[0250] 103 Drawing Room

[0251] 105 XY stage

[0252] 110 Control Computer

[0253] 112 Memory

[0254] 130 Deflection control circuit

[0255] 132, 134DAC amplifier unit

[0256] 136 Lens control circuit

[0257] 138 Stage control mechanism

[0258] 139 Stage position detector

[0259] 140, 142, 144 storage device

[0260] 150 Depicting Organization

[0261] 160 Control system circuit

[0262] 200 Electron beam

[0263] 201 Electron Gun

[0264] 202 Lighting lens

[0265] 203 Forming aperture array substrate

[0266] 204 Blanking Aperture Array Mechanism

[0267] 205 Zooming Lens

[0268] 206 Restricted Aperture Substrate

[0269] 207 Objective

[0270] 208 Main deflector

[0271] 209 Auxiliary deflector

[0272] 210 Reflector

[0273] 330 membrane area

[0274] 343 pad

Claims

1. A method for calculating the effective temperature of a region delineated by a multi-charged particle beam, It is characterized in that For each of a plurality of grid areas formed by dividing a drawing area of ​​a sample irradiated by a multi-charged particle beam in a drawing progress direction and in a direction linearly independent of the drawing progress direction, a representative value of the dose of the beam irradiating the grid area is calculated as a representative dose value, By performing convolution processing on a kernel determined by the speed of a stage on which the sample is placed and the size of the beam array area on the surface of the sample of the multi-charged particle beam in the depicted direction of travel and the dose representative value, representative values ​​of the temperature rise imparted to each of the plurality of grid areas by the heat caused by beam irradiation are calculated and output as respective effective temperatures of the plurality of grid areas.

2. The method for calculating the effective temperature of a region delineated by a multi-charged particle beam according to claim 1, It is characterized in that The kernel is defined as the value of each position within a specified range, Assuming that the beam array area moves continuously at a constant speed while irradiating a point charge at the center position of the core, and assuming that the irradiation of the point charge starts at one end of the beam array area and ends at the other end, under these two assumptions, the value at each position of the core represents a representative value of the temperature of the beam array area during the period when the beam array area passes through this position.

3. The method for calculating the effective temperature of a region delineated by a multi-charged particle beam according to claim 1, It is characterized in that The kernel is defined by an integral formula using an integral variable ω, an integral variable ξ, an integral variable u, and an integral variable v, The integral variable ω is obtained by multiplying a value obtained by dividing a reference number i representing a grid area in the beam traveling direction within a processing area of ​​the same size as the beam array area by the number Nx of grid areas in the beam traveling direction within the processing area overlapping with the beam array area by the size Lx of the beam array area in the beam traveling direction, and transforming the value by taking Nx as an infinite limit. The integral variable ξ is obtained by multiplying a value obtained by dividing a reference number j representing a grid area in the first direction within the processing area of ​​the same size as the beam array area by the number Ny of grid areas in the first direction within the processing area overlapping with the beam array area by the size Ly of the beam array area in the first direction, and transforming Ny to an infinite limit. The integral variable u is obtained by multiplying the value obtained by dividing the beam irradiation number m of m=k-Nx+1, k-Nx, ... k, which is performed Nx times in sequence before the processing area composed of the size of Nx×Ny passes through the grid of interest of the coordinates (k, l) by the number of grid areas Nx by the size Lx of the beam array area in the beam travel direction, and transforming it by taking the limit of Nx as infinity, The integral variable v is the value obtained by dividing the beam irradiation number n performed in sequence such as the mth, m-1th, m-2th, ... by the number of grid areas Nx and multiplying it by the size Lx of the beam array area in the direction of beam travel, and is obtained by transforming Nx to the limit of infinity.

4. A multi-charged particle beam drawing method, comprising drawing a pattern on the sample using a correction amount calculated using the effective temperature obtained by the effective temperature calculation method according to claim 1, It is characterized in that calculating a correction amount for correcting doses of a plurality of beams of the multi-charged particle beam that irradiate a grid area of ​​interest that is one of the plurality of grid areas or pattern data of a graphic drawn within the grid area of ​​interest using the effective temperature in each of the plurality of grid areas, A pattern is drawn on the sample using the correction amount.

5. A recording medium which is a readable recording medium which non-temporarily records a program for causing a computer to execute the following functions: A function of calculating, for each of a plurality of grid areas formed by dividing a drawing area of ​​a sample irradiated by a multi-charged particle beam in a drawing progress direction and a direction linearly independent of the drawing progress direction, a representative value of the dose of the beam irradiating within the grid area as a representative dose value; and By performing convolution processing on a kernel determined by the speed of a stage on which the sample is placed and the size of a beam array area depicting the direction of travel on the surface of the sample of a multi-charged particle beam, and the dose representative value, representative values ​​of the temperature rise imparted to each of the plurality of grid areas by the heat caused by beam irradiation are calculated as a function of the effective temperature of each of the plurality of grid areas.

6. A recording medium which is a readable recording medium which non-temporarily records a program for causing a computer to execute the following functions: The functions described in claim 5, A function of calculating a correction amount for correcting doses of a plurality of beams of the multi-charged particle beams for irradiating the grid area of ​​interest, which is one of the plurality of grid areas, or pattern data of a figure drawn within the grid area of ​​interest, using the effective temperature in each of the plurality of grid areas; as well as A function of drawing a pattern on the sample using the correction amount.

7. A multi-charged particle beam delineation device, It is characterized in that have: a dose representative value calculation circuit for calculating, for each of a plurality of grid areas formed by dividing a drawing area of ​​a sample irradiated by a multi-charged particle beam in a drawing progress direction and in a direction linearly independent of the drawing progress direction, a representative value of the dose of the beam irradiating the grid area as a dose representative value; an effective temperature calculation circuit for calculating, by convolution processing of a kernel determined by a speed of a stage on which the sample is placed and a size of a beam array region on a surface of the sample in the depicted traveling direction of the multi-charged particle beam and the dose representative value, a representative value of a temperature rise given to each of the plurality of grid regions by heat caused by beam irradiation as an effective temperature of each of the plurality of grid regions; a correction amount calculation circuit that calculates a correction amount for correcting doses of a plurality of beams of the multi-charged particle beam that irradiate a grid area of ​​interest that is one of the plurality of grid areas or pattern data of a graphic drawn within the grid area of ​​interest, using the effective temperature in each of the plurality of grid areas; as well as The drawing means draws a pattern on the sample using the calculated correction amount.

Images