JP2013074207A - Charged particle beam lithography device and charged particle beam lithography method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged particle beam lithography device and a charged particle beam lithography method that can improve throughput.SOLUTION: A control computer 19 discriminates between a region of a drawing pattern requested to be precise and a region not to be precise, acquires the rate of the area of a pattern requested to be precisely drawn higher than a reference value to the area of the whole pattern from an input part 20, and determines a drawing condition according to whether the rate is equal to or larger than a predetermined value. When the rate is smaller than the predetermined value, a pattern requested to have drawing precision lower than the reference value is drawn with higher current density than a pattern requested to have drawing precision equal to or larger than the reference value. When the rate is equal to or larger than the predetermined value, all patterns are drawn with the same current density. The current density is varied by moving an adjustment aperture 101 with an opening part for transmitting an electron beam 54 in a perpendicular direction.

Description

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

  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. For manufacturing the mask, an electron beam drawing apparatus capable of drawing a fine pattern is used.

  Patent Document 1 discloses a variable shaping type electron beam drawing apparatus used in an electron beam lithography technique. The drawing data in such an apparatus is created by performing processing such as correction and graphic pattern division on design data (CAD data) such as a semiconductor integrated circuit designed using a CAD system.

  For example, 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 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. .

  When drawing in the sub-deflection area, a shot having a size and shape prepared according to the pattern figure is formed by the shaping deflector. Specifically, after the electron beam emitted from the electron gun is shaped into a rectangular shape by the first aperture, it is projected onto the second aperture by the shaping deflector to change the beam shape and dimensions. . Thereafter, as described above, the light is deflected by the sub-deflector and the main deflector and is irradiated onto the mask placed on the stage.

JP-A-9-293670

  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. Correspondingly, the shot size of the electron beam and the deflection width of the deflector in the electron beam drawing apparatus tend to be reduced. However, since reduction of the shot size and deflection width leads to longer drawing processing, it is an urgent task to improve the overall throughput.

  The present invention has been made in view of these points. That is, an object of the present invention is to provide a charged particle beam drawing apparatus and a charged particle beam drawing method capable of improving throughput.

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

A first aspect of the present invention is a charged particle beam drawing apparatus for drawing a pattern with a charged particle beam.
A control unit that obtains a ratio of the area of the pattern that requires drawing accuracy equal to or higher than a reference value to an area of the entire pattern, and determines a drawing condition depending on whether the ratio is equal to or greater than a predetermined value;
A diaphragm having an opening through which a charged particle beam is transmitted and movable in a vertical direction;
And an adjustment unit that receives a signal from the control unit and adjusts the position of the diaphragm.

According to a first aspect of the present invention, an aperture that shapes a charged particle beam into a predetermined shape;
A lens for illuminating the aperture with a charged particle beam;
A diaphragm is preferably disposed between the aperture and the lens.

A second aspect of the present invention is a charged particle beam drawing method for drawing a predetermined pattern with a charged particle beam.
Compare the ratio of the area of the pattern that requires drawing accuracy higher than the reference value to the area of the entire pattern with a predetermined value,
When the ratio is less than a predetermined value, a pattern that requires a drawing accuracy less than the reference value is drawn at a higher current density than a pattern that requires a drawing accuracy that is higher than the reference value,
When the ratio is equal to or greater than a predetermined value, all patterns are drawn with the same current density.

  In the second aspect of the present invention, it is preferable to change the current density by moving a diaphragm provided with an opening for transmitting the charged particle beam in the vertical direction.

In the second aspect of the present invention, drawing is performed by illuminating the aperture with a lens with a lens to form the charged particle beam into a predetermined shape,
The diaphragm is preferably disposed between the aperture and the lens.

  ADVANTAGE OF THE INVENTION According to this invention, the charged particle beam drawing apparatus and charged particle beam drawing method which can aim at the improvement of a throughput are provided.

It is a figure which shows the structure of the electron beam drawing apparatus by this Embodiment. It is explanatory drawing of the drawing method by an electron beam. It is a figure which shows a mode that an electron beam is made into a low current density by the aperture for current density adjustment. It is a figure which shows a mode that an electron beam is made into a high current density by the aperture for current density adjustment.

  As described above, the shot size of the electron beam and the deflection width of the deflector are small in the electron beam drawing apparatus. Such reduction in shot size and deflection width leads to longer drawing processing and lowers throughput. By the way, the pattern drawn on the mask does not necessarily require high drawing accuracy for all of the patterns. That is, although a part of the drawing pattern is required to have high resolution, a lower resolution is often sufficient for the other part. However, in the conventional drawing method, the overall drawing conditions are determined in accordance with the drawing conditions of some patterns that require high resolution. This means that drawing is performed with excessive accuracy for a pattern that does not require high drawing accuracy.

Therefore, in the present embodiment, the area (S _H ) of a pattern that requires a drawing accuracy higher than the reference value is obtained, and the ratio (S _H / S) of this area to the area (S) of the entire drawing pattern is obtained. calculate. The overall throughput is improved by changing the drawing condition depending on whether this ratio is equal to or greater than a predetermined value.

The main factor that determines the drawing speed in the electron beam drawing apparatus is the current density of the electron beam. The higher the current density, the shorter the time for exposing the photosensitive agent, so that the drawing speed increases. However, as the current density increases, beam resolution degradation (beam blur) due to the Coulomb effect increases. For this reason, it is necessary to determine the current density in consideration of the required drawing accuracy. In the present embodiment, when the ratio ( _SH / S) is equal to or greater than a predetermined value, drawing is performed at a low current density because high drawing accuracy is required for most of the drawing patterns. On the other hand, when the ratio (S _H / S) is less than a predetermined value, a pattern requiring high drawing accuracy and a pattern not required are mixed, so that a low current density is used for the former. Draw with a high current density for the latter. That is, the current density is switched according to the pattern drawing accuracy.

  FIG. 1 is an example of an electron beam drawing apparatus according to this embodiment.

  As shown in FIG. 1, a stage 3 on which a sample 2 is installed is provided in a sample chamber 1 of the electron beam drawing apparatus. In the sample 2, for example, a chromium film and a resist are formed in this order on a glass substrate or a quartz substrate. In this embodiment mode, writing is performed on the resist 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 31 is installed above the sample chamber 1. The electron beam optical system 31 includes an electron gun 6, illumination lenses 7 and 8, projection lenses 9 and 10, a reduction lens 11, an objective lens 12, a blanking deflector 13, a shaping deflector 14, and a main deflection for beam scanning. 15, a beam scanning sub-deflector 16, a current density adjusting aperture 101, and two beam forming first and second apertures 17 and 18.

  FIG. 2 is an explanatory diagram of a drawing method using an electron beam. As shown in this figure, the pattern 51 drawn on the sample 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 region 53 is performed by the main deflector 15, and drawing in the sub deflection region 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, the first aperture 17 for beam shaping, and the second aperture 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 53 is a region where the electron beam 54 is scanned and drawn 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 53 is drawn, shots having dimensions and shapes prepared according to the pattern figures are 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 sample 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. 1, reference numeral 20 denotes an input unit, which is a part where format data is input to an 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 description when various figures are arranged alone or repeatedly at a certain interval are also defined. The cluster data or cell data is further arranged in a strip-shaped region called a frame or stripe having a width of several hundred μm and a length of about 100 mm corresponding to the total length of the mask in the X 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, among the drawing patterns of the sample 2, the area (S _H ) of the pattern that requires drawing accuracy equal to or higher than the reference value is obtained. Then, the ratio ( _SH / S) of this area to the entire area (S) of the drawing pattern is obtained and input to the control computer 19 through the input unit 20. The control computer 19 is a “control unit” in the present invention, and controls the operation of the current density adjusting aperture driving circuit 100 as an adjusting unit, as will be described later.

Control computer 19, the ratio of _{((S H / S);} . The following, also referred to as high-resolution ratio) is equal to or a predetermined value r ₀ or more. For example, the predetermined value r _{0 as} a reference for determination is determined as follows.

Assuming that the high resolution rate is r, when 0 <r <r ₀ , the drawing time t is expressed by Equation (1). In Expression (1), _{t f} is r = rendering time when the 1 (total writing time). T ₀ is an offset time, for example, a stage moving time, a settling time, and an electron beam drift correction time.

In addition, when r ₀ ≦ r <1, the drawing time t is expressed by Expression (2).

From Expressions (1) and (2), the drawing time reduction rate Δt / t _f by drawing with a combination of a low current density and a high current density is expressed by Expression (3). However, k = (t ₀ / t _f ), which indicates the ratio of the offset time to the total drawing time. Usually, k = 0.1 to 0.2.

For example, in the case of a mask for the wafer 32 nm generation, the total writing time by the conventional writing method is about t _f = 20 hours. If this is to be shortened by about 10%, the relationship of equation (4) is established.

From the expressions (3) and (4), the predetermined value r ₀ is expressed by the expression (5).

According to the above example, by the predetermined value r ₀ and 0.9, in the pattern of r <r _0, so that the total writing time can be shortened by 10% or more.

For example, the predetermined value r ₀ = 0.7. When the ratio (S _H / S) of the area (S _H ) of the pattern that requires a drawing accuracy equal to or higher than the reference value to the area (S) of the entire drawing pattern is 0.7 or more, the control computer 19 It is determined that high drawing accuracy is required for most of the patterns, and the drawing condition is set to a low current density. In this case, the drawing time t is expressed by Expression (6). However, D ₀ is the sensitivity of the resist to be drawn.

On the other hand, when the ratio (S _H / S) is less than 0.7, the control computer 19 determines that a pattern that requires high drawing accuracy and a pattern that does not need to be mixed, and the pattern The current density is switched according to the drawing accuracy. That is, when drawing the former, the drawing condition is set to a low current density, and when drawing the latter, the drawing condition is set to a high current density. The drawing time t in this case is expressed by Expression (7). However, _JH is a high current density and _JL is a low current density.

  The current density of the electron beam 54 is switched by the current density adjusting aperture 101 of FIG. The current density adjusting aperture 101 is a “diaphragm” in the present invention, and is movable along the optical path of the electron beam 54 and includes an opening through which the electron beam 54 is transmitted.

  FIGS. 3 and 4 are diagrams showing how the current density of the electron beam 54 is changed using the current density adjusting aperture 101.

  As shown in FIGS. 3 and 4, the electron beam 54 emitted from the electron gun 6 is irradiated to the first aperture 17 for beam shaping by the illumination lenses 7 and 8. At this time, the current density adjusting aperture 101 is disposed between the illumination lens 8 and the first aperture 17 for beam shaping. The current density adjusting aperture 101 has an opening 102 through which the electron beam 54 is transmitted. Although not shown, the current density adjusting aperture 101 is configured to be movable up and down along the beam axis 200 of the electron beam 54.

  By arranging the current density adjusting aperture 101 as described above and moving it up and down, the current density of the electron beam 54 can be changed. Note that the current density of the electron beam 54 can be changed by changing the relative distance between the first aperture 17 and the second aperture 18 for beam shaping shown in FIG. 1 without providing the current density adjusting aperture 101. Is also possible. However, in the case of this method, the amount of blur of the electron beam 54 varies between the portion formed by the first aperture 17 and the portion formed by the second aperture 18, so that the current density adjusting aperture 101 Is preferred.

  3 and 4 are different in the position of the current density adjusting aperture 101. According to FIG. 3, the electron beam 54 can have a low current density. On the other hand, according to FIG. 4, the electron beam 54 can have a higher current density than that of FIG.

As described above, the input unit 20 shown in FIG. 1 includes a drawing data that has been converted into format data unique to the electron beam drawing apparatus and a pattern that requires drawing accuracy equal to or higher than a reference value among drawing patterns. The ratio (S _H / S) of the area (S _H ) to the area (S) of the entire drawing pattern is input.

  The drawing data read from the input unit 20 by the control computer 19 is first divided into a portion requiring drawing accuracy and another portion. Each of the frames is temporarily stored in the pattern memory 21 for each frame area 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, the drawing graphic data, etc. is sent 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, blanking data based on the data is created by the pattern data decoder 22 and sent 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 beam optical system 31 to control the shape and size of the electron beam 54.

  In the pattern data decoder 22, desired beam shape data is created based on the drawing data and 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.

  The drawing data decoder 23 generates positioning data for the sub deflection region 53 based on the drawing data, and this data is sent to the main deflector driver 26. Next, 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 position in the sub deflection region 53.

  Further, the drawing data decoder 23 generates a control signal for scanning the sub deflector 16 based on the drawing data. After the control signal is sent to the sub deflector driver 27, a predetermined sub deflection signal is applied from the sub deflector driver 27 to the sub deflector 16. Drawing in the sub deflection region 53 is performed by repeatedly irradiating the electron beam 54 after the settling time has elapsed.

  The control computer 19 is also connected to the deflection control unit 30. The deflection control unit 30 operates the blanking circuit 24, the beam shaper driver 25, the main deflector driver 26, and the sub deflector driver 27 based on information from the control computer 19 and information from the settling time determination unit 29. To control.

The control computer 19 occupies the area (S) of the entire drawing pattern in the information input from the input unit 20, that is, the area (S _H ) of the pattern that requires a drawing accuracy equal to or higher than the reference value among the drawing patterns. For the ratio (S _H / S), it is determined whether or not this ratio is equal to or greater than a predetermined value r ₀ .

For example, when the predetermined value r ₀ = 0.7, if the ratio (S _H / S) is 0.7 or more, the control computer 19 sets the drawing condition for the sample 2 to a low current density. Then, the current density adjusting aperture 101 is adjusted to a position where the electron beam 54 has a low current density through the current density adjusting aperture driving circuit 100. For example, the current density adjusting aperture 101 is positioned as shown in FIG.

On the other hand, if the ratio (S _H / S) is less than 0.7, the control computer 19 sets the drawing conditions for the sample 2 to two conditions of a low current density and a high current density, thereby improving the pattern drawing accuracy. In response, a signal is sent to the current density adjusting aperture driving circuit 100 so that the position of the current density adjusting aperture 101 is switched. When the aperture driving circuit 100 for adjusting the current density draws a pattern that requires a drawing accuracy of a reference value or higher, the current density adjusting aperture 101 is placed at a position where the electron beam 54 has a low current density (for example, FIG. 3). In the case of drawing a pattern whose required drawing accuracy is less than the reference value, the current density adjusting aperture 101 is placed at a position where the electron beam 54 has a high current density (for example, the position shown in FIG. 4). To do.

  Next, an electron beam writing method according to the present embodiment will be described with reference to FIGS.

  First, the sample 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.

  The current density adjusting aperture driving circuit 100 adjusts the position of the current density adjusting aperture 101 in accordance with a command from the control computer 19.

Of the drawing patterns, the ratio (S _H / S) of the area (S _H ) of the pattern that requires drawing accuracy equal to or higher than the reference value to the area (S) of the entire drawing pattern is compared with a predetermined value r ₀ , When the value is equal to or greater than the predetermined value r ₀ , the control computer 19 adjusts the current density adjusting aperture 101 to a position where the electron beam 54 has a low current density through the current density adjusting aperture driving circuit 100. In this case, the position of the current density adjusting aperture 101 is not changed until all drawing on the sample 2 is completed. Note that the relationship between the value of the current density and the position of the current density adjusting aperture 101 is known in advance. Thereby, the effort at the time of adjustment can be suppressed to the minimum.

On the other hand, when the ratio (S _H / S) is less than the predetermined value r ₀ , the control computer 19 causes the current density adjusting aperture 101 to change the position of the current density adjusting aperture 101 in accordance with the pattern drawing accuracy. A signal is sent to the drive circuit 100.

  For example, when drawing a pattern that requires drawing accuracy that is equal to or higher than a reference value for the first time, the control computer 19 sends a signal to the current density adjusting aperture driving circuit 100 so that the current density adjusting aperture 101 is lowered by the electron beam 54. The position should be the current density. Also in this case, the relationship between the value of the current density and the position of the current density adjusting aperture 101 is known in advance. In addition, a current density suitable for a pattern that requires a drawing accuracy equal to or higher than a reference value and a current density suitable for a pattern having no problem with a drawing accuracy less than the reference value are determined in advance.

  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 sample 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 sample 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 sample 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 sample 2. The sub deflector 16 positions the drawing position in the sub deflection region 53.

  Drawing with the electron beam 54 on the sample 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.

Of the drawing patterns, the ratio (S _H / S) of the area (S _H ) of the pattern that requires drawing accuracy equal to or higher than the reference value to the area (S) of the entire drawing pattern is less than the predetermined value r ₀ In the middle of drawing, the control computer 19 sends a signal to the aperture driving circuit 100 for adjusting the current density. Then, the position of the current density adjusting aperture 101 is adjusted so as to obtain a current density corresponding to the pattern drawing accuracy.

  For example, as described above, when drawing a pattern that requires drawing accuracy equal to or higher than the reference value first, the current density adjusting aperture 101 is adjusted to the position of the low current density. Thereafter, the position of the current density adjusting aperture 101 is changed when drawing a pattern whose required drawing accuracy is less than the reference value. Specifically, a signal is sent from the control computer 19 to the current density adjusting aperture driving circuit 100, and the current density adjusting aperture 101 is changed to a position where the electron beam 54 has a high current density.

In the present embodiment, the low current density can be, for example, a current density of 30 A / cm ² , and the high current density can be, for example, a current density of 200 A / cm ² . Note that the change in current density is not limited to two steps, and may be three or more steps.

After drawing all the frame regions 52 of the sample 2 as described above, the mask is replaced with a new mask, and drawing by the same method as above is repeated. At this time, when the type of the drawing pattern (for example, line pattern or hole pattern) or the generation of the drawing pattern changes with the replacement of the mask, new information from the input unit 20, that is, the drawing pattern Then, the ratio (S _H / S) of the area (S _H ) of the pattern that requires a drawing accuracy higher than the reference value to the area (S) of the whole drawing pattern is input to the control computer 19.

Control computer 19 discriminates the area otherwise the pattern area drawn precision is required, a new drawing condition above-mentioned ratio of _(S H _/ S) is equal to or a predetermined value r ₀ or more Set. Then, the position of the current density adjusting aperture 101 is adjusted through the current density adjusting aperture driving circuit 100.

As described above, in the present embodiment, the area (S _H ) of a pattern that requires a drawing accuracy higher than a reference value is obtained, and the ratio of this area to the area (S) of the entire drawing pattern (S _H) / S). Since the electron beam current density is changed depending on whether this ratio is equal to or greater than a predetermined value, the throughput of the entire drawing process can be improved. For example, when the predetermined value is 0.9, in the case of a mask for a wafer 32 nm generation used as a leading edge mask, the total drawing time by the conventional drawing method can be shortened by 10% or more depending on the pattern.

  Further, in this embodiment, since the current density is determined in relation to the required drawing accuracy, even if the beam resolution is lowered by increasing the current density, the drawing accuracy is problematic. There will be no decline. In other words, it is possible to efficiently draw a pattern including a pattern that requires high drawing accuracy.

  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.

  In this embodiment, two illumination lenses are provided, but the present invention is not limited to this. By providing two illumination lenses, the current density can be adjusted with the lenses. However, in the present embodiment, this can be performed by the current density adjusting aperture, so that only one illumination lens may be used.

DESCRIPTION OF SYMBOLS 1 Sample chamber 2 Sample 3 Stage 4 Stage drive circuit 5 Position circuit 6 Electron gun 7, 8 Illumination lens 9, 10 Projection lens 11 Reduction lens 12 Objective lens 13 Blanking deflector 14 Molding deflector 15 Main deflector 16 Sub deflection Device 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 deflector Area deflection amount calculation unit 29 Settling time determination unit 30 Deflection control unit 31 Electron beam optical system 51 Pattern to be drawn 52 Frame region 53 Sub deflection region 54 Electron beam 100 Current density adjustment aperture drive circuit 101 Current density adjustment aperture 10 2 Aperture 200 Beam axis

Claims (5)

In a charged particle beam drawing apparatus that draws a pattern with a charged particle beam,
A control unit that obtains a ratio of the area of the pattern that requires drawing accuracy equal to or higher than a reference value to an area of the entire pattern, and determines a drawing condition depending on whether the ratio is equal to or greater than a predetermined value;
A diaphragm having an opening through which the charged particle beam is transmitted and movable in a vertical direction;
A charged particle beam drawing apparatus comprising: an adjustment unit that receives a signal from the control unit and adjusts the position of the diaphragm. An aperture for shaping the charged particle beam into a predetermined shape;
A lens for illuminating the aperture with the charged particle beam;
The charged particle beam drawing apparatus according to claim 1, wherein the diaphragm is disposed between the aperture and the lens. In a charged particle beam drawing method for drawing a predetermined pattern with a charged particle beam,
Compare the ratio of the area of the pattern that requires drawing accuracy higher than the reference value to the area of the entire pattern with a predetermined value,
When the ratio is less than a predetermined value, a pattern that requires drawing accuracy less than the reference value is drawn at a higher current density than a pattern that requires drawing accuracy that is greater than the reference value,
When the ratio is equal to or greater than a predetermined value, all the patterns are drawn with the same current density.   The charged particle beam drawing method according to claim 3, wherein the current density is changed by moving a diaphragm having an opening for transmitting the charged particle beam in a vertical direction. The drawing is performed by illuminating the charged particle beam with a lens on an aperture, thereby shaping the charged particle beam into a predetermined shape,
5. The charged particle beam writing method according to claim 3, wherein the diaphragm is disposed between the aperture and the lens.

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