JP5547113B2 - Charged particle beam drawing apparatus and charged particle beam drawing method - Google Patents

Description

  The present invention relates to a charged particle beam drawing apparatus and a charged particle beam drawing method.

  In recent years, the circuit line width required for a semiconductor element has become increasingly narrower as the large scale integrated circuit (LSI) is highly integrated and has a large capacity. The semiconductor element uses an original pattern pattern (a mask or a reticle, which will be collectively referred to as a mask hereinafter) on which a circuit pattern is formed, and the circuit is exposed and transferred onto a wafer by a reduction projection exposure apparatus called a stepper. Manufactured by forming. An electron beam lithography apparatus is used to manufacture a mask for transferring such a fine circuit pattern onto a wafer.

  The electron beam lithography system has an essentially excellent resolution because the electron beam used is a charged particle beam, and can secure a large depth of focus, so that it is possible to suppress dimensional fluctuations even on high steps. Have advantages. Patent Document 1 discloses a method for manufacturing a semiconductor integrated circuit device using an electron beam drawing apparatus.

  In pattern miniaturization, it is important to improve the edge roughness of the pattern. Conventionally, increasing the electron beam irradiation amount by increasing the resist thickness or using a low-sensitivity resist has been effective in improving edge roughness. However, on the other hand, the resist tends to become thinner as the pattern becomes finer. In addition, since the increase in irradiation dose decreases the throughput, there is a problem with such a conventional method.

  Therefore, Non-Patent Document 1 discloses a technique for improving edge roughness by optimizing etching parameters. However, Non-Patent Document 1 does not specifically disclose how much improvement is effective.

  Non-Patent Document 2 describes that a new process called a resist smoothing process is provided after development. However, the introduction of such a new process may lead to an increase in mask defects and an increase in dimensional variation due to the process.

JP-A-11-312634

T. T. et al. Imoto et al., Toppan Printing, “Study of etching process for LER and resolution”, Proc. of SPIE, 7748, 77480D-1 to 77480D-10. S. Kobayashi et al., Tokyo Electron Kyushu Co., Ltd., Tokyo Electron Co., Ltd., “LWR reduction by novel lithography and etch technologies”, Proc. of SPIE, Volume 7639, pp. 76314-1 to 743914-7

  The present invention has been made in view of the above problems. That is, an object of the present invention is to provide a charged particle beam drawing apparatus and a charged particle beam drawing method that do not require thickening of a resist and that can improve roughness by minimizing a decrease in throughput. There is.

  Other objects and advantages of the present invention will become apparent from the following description.

According to a first aspect of the present invention, there is provided an input unit for inputting a relationship between a pattern area density, a charged particle beam irradiation amount, and a pattern roughness;
From the area density of the pattern in the predetermined region and the irradiation amount of the charged particle beam, using the above relationship, a determination unit that determines whether the roughness of the pattern is equal to or less than an allowable value,
When the determination unit determines that the roughness exceeds the allowable value, the calculation unit calculates a resizing amount that reduces the area density of the pattern, and
For the resized pattern based on the resize amount calculated by the calculation unit, the area density of the pattern and the irradiation amount of the charged particle beam in the above region are obtained, and the roughness of the pattern is less than the allowable value by the determination unit. It is related with the charged particle beam drawing apparatus characterized by determining whether or not.

  In the first aspect of the present invention, the dose is preferably obtained using a proximity effect correction coefficient.

In the second aspect of the present invention, the relationship between the area density of the pattern, the irradiation amount of the charged particle beam, and the roughness of the pattern is obtained.
From the area density of the pattern in the predetermined region and the irradiation amount of the charged particle beam, it is determined whether the roughness of the pattern is equal to or less than an allowable value using the above relationship,
If the roughness is below the allowable value, draw a pattern with this dose,
If the roughness exceeds the allowable value, calculate the resize amount to reduce the area density of the pattern, and for the resized pattern based on this resize amount, the area density of this pattern in the above region and the irradiation amount of the charged particle beam And repeating the process of determining whether or not the roughness of this pattern is below the allowable value using the above relationship until the roughness is below the allowable value, then the area density of the pattern that is below the allowable value and The present invention relates to a charged particle beam drawing method characterized by drawing with a combination of irradiation doses.

  In the second aspect of the present invention, the dose is preferably obtained using a proximity effect correction coefficient.

  According to the first aspect of the present invention, there is provided a charged particle beam drawing apparatus that does not require thickening of a resist and that can improve the roughness while minimizing a decrease in throughput.

  According to the second aspect of the present invention, there is provided a charged particle beam writing method that does not require thickening of a resist and that can improve the roughness while minimizing a decrease in throughput.

It is an example of the result of having measured the relationship between the irradiation amount of an electron beam, and line edge roughness, changing the area density of a line pattern. It is a figure explaining an example of the method of deriving the relationship of FIG. It is a block diagram of the electron beam drawing apparatus in this Embodiment. It is explanatory drawing of the drawing method by an electron beam. It is a figure explaining the drawing data correction | amendment part of this Embodiment.

  FIG. 1 is an example of a result of measuring the relationship between the electron beam irradiation amount and line edge roughness (LER) by changing the area density of the line pattern. In the figure, 0%, 25%, 50%, 75%, and 100% indicate local area densities of the line pattern, respectively. These can be, for example, the pattern area density in a rectangular region having a side of about several tens of μm.

  For example, as shown in FIG. 2, the pattern area density is approximately 0% line pattern, 25% line pattern, 50% line pattern, 75% line pattern, and 100% line pattern. Arrange a set of patterns. Then, each pattern is drawn on the mask by changing the value D of the electron beam irradiation amount D (10 conditions from D1 to D10). Next, the edge roughness of the drawn pattern is evaluated. For example, with respect to a line and space pattern, fine irregularities on both edges are measured with a dimension SEM to calculate edge roughness. Next, when the graph is drawn with the irradiation amount on the horizontal axis and the edge roughness on the vertical axis, the same result as in FIG. 1 is obtained.

  As can be seen from FIG. 1, the edge roughness increases as the pattern area density increases and the electron beam irradiation amount decreases. Here, if the allowable value of edge roughness is 3.7, for example, a pattern exceeding the allowable value can be specified by the area density and the dose. That is, if the area density and the irradiation dose are known, it is possible to grasp in advance the location where the edge roughness increases on the mask using the relationship shown in FIG.

  Therefore, in the present embodiment, a portion where the edge roughness is expected to increase is resized so as to reduce the area density of the pattern, and the electron beam irradiation amount at the portion is increased. As described above, the higher the area density of the pattern and the lower the electron beam irradiation amount, the larger the edge roughness. Therefore, the edge roughness can be reduced by performing the resizing process and the irradiation amount adjustment. it can. In addition, since the change in the finished dimension due to the reduction in the area density is suppressed by the increase in the irradiation amount, a pattern having the same finished dimension as before the resizing can be obtained. Furthermore, since the irradiation amount is increased only at the resized portion, the overall throughput is not significantly reduced.

  For example, in FIG. 1, in the pattern with an area density of 97.5% indicated by the symbol x, the edge roughness exceeds the allowable value when the irradiation amount is low. Therefore, this pattern is resized to an area density of 90%, and the irradiation amount is increased. Then, as shown in FIG. 1, the edge roughness can be within an allowable value. According to the inventor's study, it has been confirmed that the increase in the dose accompanying the pattern resizing does not have a large effect on the resist heating. However, when recalculating the actual dose, It is preferable to pay attention to this point.

  On the other hand, in FIG. 1, the pattern whose edge roughness is originally equal to or less than the allowable value does not need to be resized, and may be drawn with the area density and the irradiation amount as they are.

  By doing in this way, edge roughness can be improved only in the part which needs improvement of edge roughness among the whole patterns. According to this method, since it is not necessary to increase the thickness of the resist, it does not go against pattern miniaturization. Further, as described above, the increase in the irradiation amount is performed only on the resized pattern, so that the throughput is not greatly reduced.

  FIG. 3 is a configuration diagram of the electron beam drawing apparatus according to the present embodiment.

  As shown in FIG. 3, a stage 3 on which a mask 2 as a sample is placed is provided in a sample chamber 1 of the electron beam drawing apparatus. The mask 2 is formed by forming a chromium (Cr) film as a light shielding film on a mask substrate such as quartz, and further forming a resist film thereon. A molybdenum silicon (MoSi) film or the like may be used instead of the chromium film. The resist film can be a film formed using a chemically amplified resist.

  In this embodiment mode, writing is performed on the resist film with an electron beam. The stage 3 is driven in the X direction and the Y direction by the stage drive circuit 4. The moving position of the stage 3 is measured by a position circuit 5 using a laser length meter or the like.

  An electron beam optical system 10 is installed above the sample chamber 1. The optical system 10 includes an electron gun 6, various lenses 7, 8, 9, 11, 12, a blanking deflector 13, a shaping deflector 14, a beam scanning main deflector 15, and a beam scanning sub deflector. 16 and two beam shaping apertures 17, 18 and the like.

  FIG. 4 is an explanatory diagram of a drawing method using an electron beam. As shown in this figure, the pattern 51 drawn on the mask 2 is divided into strip-shaped frame regions 52. Drawing with the electron beam 54 is performed for each frame region 52 while the stage 3 continuously moves in one direction (for example, the X direction). The frame area 52 is further divided into sub-deflection areas 53, and the electron beam 54 draws only necessary portions in the sub-deflection areas 53. The frame area 52 is a strip-shaped drawing area determined by the deflection width of the main deflector 15, and the sub-deflection area 53 is a unit drawing area determined by the deflection width of the sub-deflector 16.

  Positioning of the reference position of the sub deflection area is performed by the main deflector 15, and drawing in the sub deflection area 53 is controlled by the sub deflector 16. That is, the main deflector 15 positions the electron beam 54 in a predetermined sub-deflection region 53, and the sub-deflector 16 determines the drawing position in the sub-deflection region 53. Further, the shape and size of the electron beam 54 are determined by the shaping deflector 14 and the beam shaping apertures 17 and 18. Then, the sub-deflection area 53 is drawn while continuously moving the stage 3 in one direction. When drawing of one sub-deflection area 53 is completed, the next sub-deflection area 53 is drawn. When drawing of all the sub-deflection areas 53 in the frame area 52 is completed, the stage 3 is stepped in a direction orthogonal to the direction in which the stage 3 is continuously moved (for example, the Y direction). Thereafter, the same processing is repeated, and the frame area 52 is sequentially drawn.

  The sub-deflection region is a region where the electron beam 54 is scanned by the sub-deflector 16 at a speed higher than that of the main deflection region, and is generally a minimum drawing unit. When the inside of the sub deflection region is drawn, a shot having a size and shape prepared according to the pattern figure is formed by the shaping deflector 14. Specifically, the electron beam 54 emitted from the electron gun 6 is shaped into a rectangular shape by the first aperture 17, and then projected onto the second aperture 18 by the shaping deflector 14. Change the dimensions. Thereafter, as described above, the electron beam 54 is deflected by the sub-deflector 16 and the main deflector 15 and is applied to the mask 2 placed on the stage 3.

  CAD data created by a designer (user) is converted into design intermediate data in a hierarchical format such as OASIS. The design intermediate data stores design pattern data created for each layer and formed on each mask. Here, generally, the electron beam drawing apparatus is not configured to directly read OASIS data. That is, unique format data is used for each manufacturer of the electron beam drawing apparatus. For this reason, the OASIS data is converted into format data unique to each electron beam drawing apparatus for each layer and then input to the apparatus.

  In FIG. 3, reference numeral 20 denotes an input unit, which is a part where format data is input to the electron beam drawing apparatus through a magnetic disk as a storage medium. Since the figure included in the design pattern is a basic figure of a rectangle or a triangle, for example, the coordinates (x, y) at the reference position of the figure, the length of the side, a rectangle, a triangle, etc. Information such as a graphic code serving as an identifier for discriminating between graphic types, and graphic data defining the shape, size, position, etc. of each pattern graphic is stored.

  Furthermore, a set of figures existing in a range of about several tens of μm is generally called a cluster or a cell, and data is hierarchized using this. In the cluster or cell, arrangement coordinates and repeated descriptions are also defined when various figures are arranged independently or repeatedly at a certain interval. The cluster or cell data is further arranged in a strip-shaped region called a frame or stripe having a width of several hundreds μm and a length of about 100 mm corresponding to the total length of the photomask in the X direction or Y direction. .

  The graphic pattern division processing is performed in units of the maximum shot size defined by the size of the electron beam, and the coordinate position, size, and irradiation time of each divided shot are also set. Then, drawing data is created so that a shot is formed according to the shape and size of the graphic pattern to be drawn. The drawing data is divided into strip-shaped frames (main deflection areas) and further divided into sub-deflection areas. That is, the drawing data of the entire chip has a data hierarchical structure including a plurality of strip-shaped frame data according to the size of the main deflection area and a plurality of sub deflection area units smaller than the main deflection area in the frame. .

  In the present embodiment, an allowable value of line edge roughness (LER: Line Edge Roughness) and a calibration table are also input to the input unit 20. Instead of this line edge roughness, line width roughness (LWR: Line Width Roughness) can also be used. The line edge roughness (LER) is calculated by measuring the fine irregularities on both edges individually, whereas the line width roughness (LWR) is calculated by interlocking the fine irregularities on both edges. Measured as "local dimensional fluctuation". The “roughness” of the present invention may be either line edge roughness (LER) or line width roughness (LWR).

  The allowable value is appropriately determined according to the specifications of the mask. For example, according to 2010 ITRS (International Technology Roadmap for Semiconductors: International Semiconductor Technology Roadmap), EUVL (Extreme Ultra Violet Lithology) mask roughness (LWR: Line 2020) Meters) and is expected to be 3.7 nm (nanometers) in 2012.

  The calibration table is obtained using the correlation map of the pattern area density, the electron beam irradiation amount, and the line edge roughness as described with reference to FIG.

  For example, as shown in FIG. 2, the pattern area density is approximately 0% line pattern, 25% line pattern, 50% line pattern, 75% line pattern, and 100% line pattern. Arrange a set of patterns. Then, the value of the electron beam irradiation amount D is changed (10 conditions from D1 to D10), and drawing is performed on the mask. Next, the edge roughness of the drawn pattern is evaluated. For example, for one line in a line-and-space pattern, after measuring the fine irregularities of both edges with a dimension SEM, the Peak to Peak value is obtained at each edge and averaged to obtain edge roughness. Next, after plotting measurement points with the irradiation amount on the horizontal axis and the edge roughness on the vertical axis, fitting is performed using an appropriate function, and a graph similar to FIG. 1 is drawn. In addition, these functions are interpolated to obtain different area density graphs.

  From the graph obtained as described above, a calibration table of the pattern area density and the irradiation amount necessary for setting the line edge roughness exceeding the allowable value below the allowable value is created.

  In the present embodiment, it is not always necessary to use a calibration table, and it is sufficient that the relationship between the pattern area density, the electron beam irradiation amount, and the edge roughness of the pattern is shown.

  In FIG. 3, the drawing data read from the input unit 20 by the control computer 19 is temporarily stored in the pattern memory 21 for each frame region 52. The pattern data for each frame area 52 stored in the pattern memory 21, that is, the frame information composed of the drawing position and drawing graphic data, etc. is sent to the drawing data correction unit 31 together with the line edge roughness tolerance and the calibration table. It is done.

  FIG. 5 is a diagram illustrating the drawing data correction unit 31 in FIG.

  In the electron beam drawing apparatus, it is necessary to perform correction processing for changing the beam irradiation amount so that the pattern size after drawing becomes the same as the size of the design data. This process is performed for factors that cause pattern dimension fluctuations such as proximity effect, fogging effect, and loading effect.

  In the present embodiment, as shown in FIG. 5, the correction process is performed on the pattern data sent from the pattern memory 21. Specifically, the pattern area density calculation unit 31a divides the entire drawing area on the mask into a mesh shape with a predetermined grid size, and obtains the area density of the pattern for each obtained small area. Then, the irradiation amount calculation unit 31b calculates the irradiation amount of the electron beam for each small region using the proximity effect correction coefficient. More preferably, in addition to the proximity effect correction coefficient, the dose is calculated using correction coefficients for the fogging effect and the loading effect.

  Next, the LER determination unit 31c determines whether or not the line edge roughness is equal to or less than an allowable value using the calibration table described above with respect to the obtained irradiation amount and the area density of the pattern in each small region. . When the edge roughness of the pattern is less than or equal to the allowable value, this irradiation amount is sent to the pattern data decoder 22 and the drawing data decoder 23. On the other hand, when it is determined that the line edge roughness exceeds the allowable value, the resizing amount calculation unit 31d calculates a resizing amount for reducing the area density of the pattern. This calculation is performed using the calibration table.

  The pattern data is resized based on the resize amount calculated by the resize amount calculation unit 31d. And the area density and irradiation amount for every small area | region are calculated | required with respect to the pattern data after resizing. Thereafter, in the LER determination unit 31c, it is determined again whether or not the line edge roughness of the resized pattern is equal to or less than the allowable value. It is sent to the decoder 23. On the other hand, if the allowable value is exceeded, the process of performing the resizing process in the resizing amount calculation unit 31d is repeated. Such a process is repeated until the line edge roughness is equal to or less than the allowable value, and then drawing is performed with a combination of the area density and the irradiation amount of the pattern that is equal to or less than the allowable value.

  The pattern area density and dose data determined as described above are sent from the drawing data correction unit 31 to the pattern data decoder 22 and the drawing data decoder 23 which are data analysis units.

  Information from the pattern data decoder 22 is sent to a blanking circuit 24 and a beam shaper driver 25. Specifically, the pattern data decoder 22 creates blanking data based on the data and sends it to the blanking circuit 24. Desired beam size data is also created and sent to the beam shaper driver 25. Then, a predetermined deflection signal is applied from the beam shaper driver 25 to the shaping deflector 14 of the electron optical system 10 to control the size of the electron beam 54.

  Information from the pattern data decoder 22 is sent to the sub deflection region deflection amount calculation unit 28. The sub deflection region deflection amount calculation unit 28 calculates the deflection amount (movement distance) of the electron beam for each shot in the sub deflection region 53 from the beam shape data created by the pattern data decoder 22. The calculated information is sent to the settling time determination unit 29, and the settling time corresponding to the movement distance by the sub deflection is determined.

  The settling time determined by the settling time determination unit 29 is sent to the deflection control unit 30, and then the deflection control unit 30 measures the blanking circuit 24, the beam shaper driver 25, the main pattern while timing the pattern drawing. It is appropriately sent to either the deflector driver 26 or the sub deflector driver 27.

  On the other hand, the output of the drawing data decoder 23 is sent to the main deflector driver 26 and the sub deflector driver 27. Then, a predetermined deflection signal is applied from the main deflector driver 26 to the main deflector 15, and the electron beam 54 is deflected and scanned to a predetermined main deflection position. Further, a predetermined sub deflection signal is applied from the sub deflector driver 27 to the sub deflector 16, and drawing in the sub deflection area 53 is performed. This drawing process is performed as follows.

  In FIG. 3, first, the mask 2 is placed on the stage 3 in the sample chamber 1. Next, the position of the stage 3 is detected by the position circuit 5, and the stage 3 is moved to a position where drawing can be performed by the stage drive circuit 4 based on a signal from the control computer 19.

  Next, an electron beam 54 is emitted from the electron gun 6. The emitted electron beam 54 is collected by the illumination lens 7. Then, the blanking deflector 13 performs an operation for irradiating the mask 2 with the electron beam 54.

  The electron beam 54 incident on the first aperture 17 passes through the opening of the first aperture 17 and is then deflected by the shaping deflector 14 controlled by the beam shaper driver 25. And it passes through the opening part provided in the 2nd aperture 18, and becomes a beam shape which has a desired shape and a dimension. This beam shape is a drawing unit of the electron beam 54 applied to the mask 2.

  The electron beam 54 is shaped into a beam shape and then reduced by the reduction lens 11. The irradiation position of the electron beam 54 on the mask 2 is controlled by the main deflector 15 controlled by the main deflector driver 26 and the sub deflector 16 controlled by the sub deflector driver 27. The main deflector 15 positions the electron beam 54 in the sub deflection region 53 on the mask 2 (shown in FIG. 4). The sub deflector 16 positions the drawing position in the sub deflection region 53.

  Drawing with the electron beam 54 on the mask 2 is performed by scanning the electron beam 54 while moving the stage 3 in one direction. Specifically, the pattern is drawn in each sub deflection region 53 while moving the stage 3 in one direction. After all the sub-deflection areas 53 in one frame area 52 have been drawn, the stage 3 is moved to a new frame area 52 and drawn similarly.

  In the present embodiment, line edge roughness can be determined in real time simultaneously with drawing. However, this determination may be performed in an offline state where drawing is not performed. When performed off-line, there is an advantage that it is not necessary to determine whether or not the edge roughness is equal to or less than an allowable value and to reduce the drawing time due to the resizing process.

  According to the present embodiment, while performing drawing (or in an offline state), the line edge roughness is allowed by using the calibration table for the electron beam irradiation amount and the pattern area density in each small region. It is determined whether or not it is less than or equal to the value. When the edge roughness of the pattern is less than the allowable value, drawing is performed using this irradiation amount. On the other hand, when it is determined that the line edge roughness exceeds the allowable value, a resize amount for reducing the area density of the pattern is calculated. Next, with respect to the resized pattern data based on the resize amount, the area density and the irradiation amount for each small region are obtained, and whether or not the line edge roughness of the resized pattern is below the allowable value again. A determination is made.

  The resize amount is calculated using a calibration table. Thereafter, the recalculation of the irradiation amount is performed on the pattern data resized based on the resize amount. The irradiation amount after resizing becomes larger than the irradiation amount before resizing. Such resize processing and dose recalculation are repeated until the edge roughness is determined to be less than or equal to the allowable value. Then, drawing is performed with a combination of the area density and the irradiation amount of the pattern determined to be equal to or less than the allowable value.

  According to this embodiment, the edge roughness can be improved without increasing the thickness of the resist. Further, the increase in the irradiation amount is performed only for the resized pattern, so that the throughput is not greatly reduced. Further, since the change in the finished dimension due to the reduction in the area density of the pattern is suppressed by the increase in the irradiation amount, a pattern having the same finished dimension as before the resizing can be obtained. Furthermore, according to the present embodiment, a mask can be manufactured without changing the conventional process. In particular, for a pattern whose edge roughness is less than or equal to an allowable value, neither the drawing conditions nor the process conditions need to be changed. Therefore, there is no need to worry about a decrease in mask quality such as an increase in defects.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, although the electron beam is used in the above embodiment, the present invention is not limited to this, and the present invention can also be applied to the case where another charged particle beam such as an ion beam is used.

DESCRIPTION OF SYMBOLS 1 Sample chamber 2 Mask 3 Stage 4 Stage drive circuit 5 Position circuit 6 Electron gun 7, 8, 9, 11, 12 Various lenses 10 Optical system 13 Blanking deflector 14 Molding deflector 15 Main deflector 16 Sub deflector 17 First aperture 18 Second aperture 19 Control computer 20 Input unit 21 Pattern memory 22 Pattern data decoder 23 Drawing data decoder 24 Blanking circuit 25 Beam shaper driver 26 Main deflector driver 27 Sub deflector driver 28 Sub deflection area deflection Amount calculation unit 29 Settling time determination unit 30 Deflection control unit 31 Drawing data correction unit 31a Pattern area density calculation unit 31b Irradiation amount calculation unit 31c LER determination unit 31d Resize amount calculation unit 51 Pattern to be drawn 52 Frame region 53 Sub deflection region 54 Electron beam

Claims (4)

An input unit for inputting the relationship between the area density of the pattern, the irradiation amount of the charged particle beam, and the roughness of the pattern;
A determination unit that determines whether or not the roughness of the pattern is equal to or less than an allowable value from the area density of the pattern in a predetermined region and the irradiation amount of the charged particle beam, using the relationship described above;
A calculation unit for calculating a resizing amount for reducing the area density of the pattern when the determination unit determines that the roughness exceeds the allowable value;
For the resized pattern based on the resize amount calculated by the calculation unit, the area density of the pattern and the irradiation amount of the charged particle beam in the region are obtained, and the roughness of the pattern is less than the allowable value by the determination unit. A charged particle beam drawing apparatus for determining whether or not there is a charged particle beam.   The charged particle beam drawing apparatus according to claim 1, wherein the irradiation amount is obtained using a proximity effect correction coefficient. Obtain the relationship between the pattern area density, the charged particle beam dose, and the roughness of the pattern,
From the area density of the pattern in a predetermined region and the irradiation amount of the charged particle beam, it is determined whether or not the roughness of the pattern is an allowable value or less using the above relationship,
When the roughness is less than or equal to the allowable value, the pattern is drawn according to the irradiation amount,
When the roughness exceeds the allowable value, a resize amount for reducing the area density of the pattern is calculated, and for the resized pattern based on the resize amount, the area density of the pattern in the region and the charged particle beam A pattern in which the irradiation amount is obtained, and the process of determining whether the roughness of the pattern is equal to or less than the allowable value using the relationship is repeated until the roughness is equal to or less than the allowable value, and then the pattern is equal to or less than the allowable value. A charged particle beam writing method, wherein writing is performed with a combination of the area density and the irradiation amount. The charged particle beam drawing method according to claim 3, wherein the irradiation amount is obtained using a proximity effect correction coefficient.

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