JP5871557B2 - 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, and more particularly to a method for correcting a pattern dimension variation due to forward scattering of electrons in electron beam drawing.

  Lithography technology, which is responsible for the progress of miniaturization of semiconductor devices, is an extremely important process for generating a pattern among semiconductor manufacturing processes. In recent years, with the high integration of LSI, circuit line widths required for semiconductor devices have been reduced year by year. In order to form a desired circuit pattern on these semiconductor devices, a highly accurate original pattern (also referred to as a reticle or a mask) is required. Here, the electron beam (electron beam) drawing technique has an essentially excellent resolution, and is used for producing a high-precision original pattern.

FIG. 10 is a conceptual diagram for explaining the operation of a conventional variable shaping type electron beam drawing apparatus.
The variable shaped electron beam (EB) drawing apparatus operates as follows. In the first aperture 410, a rectangular opening for forming the electron beam 330, for example, a rectangular opening 411 is formed. Further, the second aperture 420 is formed with a variable shaping opening 421 for shaping the electron beam 330 having passed through the opening 411 of the first aperture 410 into a desired rectangular shape. The electron beam 330 irradiated from the charged particle source 430 and passed through the opening 411 of the first aperture 410 is deflected by the deflector, passes through a part of the variable shaping opening 421 of the second aperture 420, and passes through a predetermined range. The sample 340 mounted on a stage that continuously moves in one direction (for example, the X direction) is irradiated. That is, the drawing area of the sample 340 mounted on the stage in which the rectangular shape that can pass through both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is continuously moved in the X direction. Drawn on. A method of creating an arbitrary shape by passing both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is referred to as a variable shaping method (VSB method).

  In the above-described electron beam drawing, line width uniformity within a sample surface, for example, a mask surface with higher accuracy is required. Here, in such electron beam drawing, when a circuit pattern is drawn by irradiating a resist-coated mask with an electron beam, the electron beam passes through the resist layer and reaches the layer below it, and then reappears on the resist layer again. A phenomenon called a proximity effect due to incident backscattering occurs. Thereby, at the time of drawing, the dimension fluctuation | variation which will be drawn in the dimension shifted | deviated from the desired dimension will arise. On the other hand, even when development or etching after drawing is performed, a dimensional variation called a loading effect due to the density of the circuit pattern occurs.

Here, there is a proximity effect correction coefficient η with which the proximity effect correction matches well for each reference dose D _base . Therefore, there is disclosed a method for calculating a dose that is corrected in accordance with the dimensional variation due to the loading effect while changing the set of the reference dose D _base and the proximity effect correction coefficient η to maintain the proximity effect correction (for example, , See Patent Document 1).

JP 2007-150243 A

  However, it has been found that, with the recent miniaturization of patterns, as the size of the drawn pattern becomes smaller, an error occurs in the conventional dose calculation model.

  FIG. 11 is a diagram for explaining an example of a conventional dose model. In the conventional dose model, as shown in FIG. 11, by setting 1/2 of the dose D to a threshold dose Dth that is a resist resolution threshold, the pattern 300 has a position D / 2 in the beam profile. It was drawn with the dimension L.

  FIG. 12 is a diagram for explaining an example of dimensions when a pattern having a small dimension is drawn using a conventional dose model. When a pattern having a small line width dimension is drawn with the dose set in the conventional dose model, when the pattern becomes smaller than a certain size, the dose with the maximum dose D ′ set as shown in FIG. D does not reach. Therefore, even if the pattern 302 having a dimension determined by D ″ is planned, the actually obtained dimension is a pattern 304 with a threshold dose Dth smaller than that.

  Here, in order to calculate all the irradiation amounts including such deviations from the beginning, it is necessary to calculate all the drawing areas in units of smaller areas, so that the processing time is very long. Therefore, for example, it is conceivable that a correction amount is calculated in advance before drawing and defined as additional information in layout data input to the drawing apparatus. However, such a method has a problem that it cannot be used when a parameter used for correction calculation needs to be changed. For this reason, it is desirable to perform correction calculation more easily in the drawing apparatus. However, conventionally, a sufficient technique for solving such a problem has not been established.

  Accordingly, an object of the present invention is to provide an apparatus and a method that can overcome the above-described problems and can correct a dimensional variation of a pattern having a smaller size together with other dimensional variation factors.

A charged particle beam drawing apparatus according to one embodiment of the present invention includes:
Proximity effect correction irradiation coefficient that corrects dimensional fluctuation caused by proximity effect using forward scattering correction irradiation coefficient that corrects dimensional fluctuation caused by forward scattering of charged particles depending on pattern dimension in correction direction for each graphic pattern Proximity effect correction irradiation coefficient calculation unit to calculate,
A dose calculation unit that calculates a dose using the proximity effect correction irradiation coefficient and the forward scattering correction irradiation coefficient;
A drawing unit that draws the graphic pattern on the sample using a charged particle beam based on the irradiation amount;
It is provided with.

Further, using a function dependent on the forward scattering correction irradiation coefficient, further comprising a fog correction irradiation coefficient calculation unit for calculating a fog correction irradiation coefficient for correcting the dimensional variation caused by the fog,
It is preferable that the dose calculation unit further calculates the dose using the fog correction irradiation coefficient.

Further, a dimensional variation calculation unit that calculates the dimensional variation due to the loading effect;
A coefficient indicating the relationship between the pattern dimension and the charged particle beam dose using the pattern dimension and the proximity effect density, and the tolerance for calculating the tolerance varying depending on the pattern dimension and the proximity effect density An arithmetic unit;
Further comprising
It is preferable that the dose calculation unit further calculates the dose using the tolerance and the dimensional variation due to the loading effect.

Also, a coefficient indicating the relationship between the pattern dimension and the irradiation amount of the charged particle beam using the pattern dimension and the proximity effect density, and a first tolerance that varies depending on the pattern dimension and the proximity effect density. A first tolerance calculation unit for calculating
A coefficient indicating the relationship between the pattern size and the charged particle beam dose using the proximity effect density, and does not vary depending on the pattern size at the same proximity effect density, but varies depending on the proximity effect density. A second tolerance calculation unit for calculating a second tolerance;
Further comprising
It is preferable that the dose calculation unit further calculates the dose using the first tolerance, the second tolerance, and the dimensional variation caused by the loading effect.

The charged particle beam drawing method of one embodiment of the present invention includes:
Proximity effect correction irradiation coefficient that corrects dimensional fluctuation caused by proximity effect using forward scattering correction irradiation coefficient that corrects dimensional fluctuation caused by forward scattering of charged particles depending on pattern dimension in correction direction for each graphic pattern A process of calculating;
A step of calculating an irradiation amount using the proximity effect correction irradiation coefficient and the forward scattering correction irradiation coefficient;
Drawing the figure pattern on the sample using a charged particle beam based on the irradiation amount;
It is provided with.

  According to one aspect of the present invention, it is possible to correct a dimensional variation caused by a pattern having a smaller size, along with other variation factors such as a proximity effect. As a result, highly accurate drawing can be performed.

1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 1. FIG. FIG. 3 is a conceptual diagram for explaining how to correct the dose in the first embodiment. FIG. 3 is a diagram illustrating an example of a plurality of figures constituting a pattern in the first embodiment. 6 is a diagram illustrating an example of a format of drawing data for each graphic in the first embodiment. FIG. FIG. 4 is a flowchart showing main steps of the drawing method according to Embodiment 1. 4 is a graph showing an example of correlation data between a pattern dimension CD and an irradiation amount D in the first embodiment. It is a figure which shows another example of the some figure which comprises the pattern in Embodiment 1. FIG. 6 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 2. FIG. FIG. 10 is a flowchart showing main steps of a drawing method according to Embodiment 2. It is a conceptual diagram for demonstrating operation | movement of the conventional variable shaping type | mold electron beam drawing apparatus. It is a figure for demonstrating an example of the conventional irradiation amount model. It is a figure for demonstrating an example of the dimension at the time of drawing the pattern which cannot be said to be sufficiently larger than the electron forward scattering radius with the conventional irradiation amount model.

  Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and a beam using charged particles such as an ion beam may be used. Further, a variable shaping type drawing apparatus will be described as an example of the charged particle beam apparatus. Further, in the equations described below, x is a vector indicating the position.

Embodiment 1 FIG.
FIG. 1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the first embodiment. In FIG. 1, the drawing apparatus 100 includes a drawing unit 150 and a control unit 160. The drawing apparatus 100 is an example of a charged particle beam drawing apparatus. In particular, it is an example of a variable shaping type (VSB type) drawing apparatus. The drawing unit 150 includes an electron column 102 and a drawing chamber 103. In the electron column 102, there are an electron gun 201, an illumination lens 202, a blanking deflector 212, a blanking aperture 214, a first shaping aperture 203, a projection lens 204, a deflector 205, a second shaping aperture 206, an objective. A lens 207 and a deflector 208 are arranged. An XY stage 105 that can move at least in the XY direction is disposed in the drawing chamber 103. On the XY stage 105, a sample 101 to be drawn is arranged. The sample 101 includes an exposure mask and a silicon wafer for manufacturing a semiconductor device. Masks include mask blanks.

  The control unit 160 includes control computers 110 and 120, memories 111 and 121, a deflection control circuit 130, a digital-analog converter (DAC) amplifier 132, and storage devices 140, 142, 144, and 146 such as a magnetic disk device. Yes. The control computers 110 and 120, the memories 111 and 121, the deflection control circuit 130, and the storage devices 140, 142, 144, and 146 are connected to each other via a bus (not shown). The deflection control circuit 130 is connected to the blanking deflector 212 via the DAC amplifier 132.

In the control computer 110, an area density ρ calculation unit 41, a dimensional variation ΔCD calculation unit 40, a function ρ _p1 / 2α calculation unit 44, and a function ρ _pL / 2α calculation unit 46 are arranged. Each function such as the area density ρ calculation unit 41, the ΔCD calculation unit 40, the ρ _p1 / 2α calculation unit 44, and the function ρ _pL / 2α calculation unit 46 may be configured by software such as a program. Alternatively, it may be configured by hardware such as an electronic circuit. Alternatively, a combination thereof may be used. The input data necessary for the control computer 110 or the calculated result is stored in the memory 111 each time.

  In the control computer 120, a proximity effect correction irradiation coefficient Dp (x) calculation unit 50, a proximity effect correction irradiation coefficient Dp ′ (x) calculation unit 51, a fog correction irradiation coefficient Df (x) calculation unit 52, a dose density ρ. '(X) calculation unit 53, tolerance DL (U, L) calculation unit 54, irradiation dose D (x) calculation unit 56, irradiation time (t) calculation unit 58, shot data generation unit 60, and drawing control unit 62 Is arranged. Proximity effect correction irradiation coefficient Dp (x) calculation unit 50, proximity effect correction irradiation coefficient Dp ′ (x) calculation unit 51, fog correction irradiation coefficient Df (x) calculation unit 52, dose density ρ ′ (x) calculation unit 53 Each function such as a tolerance DL (U, L) calculation unit 54, an irradiation dose D (x) calculation unit 56, an irradiation time (t) calculation unit 58, a shot data generation unit 60, and a drawing control unit 62 is a program. It may be configured by software. Alternatively, it may be configured by hardware such as an electronic circuit. Alternatively, a combination thereof may be used. The input data necessary for the control computer 120 or the calculated result is stored in the memory 121 each time.

  In the storage device 140, for each figure, drawing data based on each figure data in which a figure code, coordinates of a reference position, a figure size in the x direction, a figure size in the y direction, and a line width dimension w of the figure in the correction direction are defined. Is input from the outside and stored. For example, when the pattern after the OPC process is fractured and the pattern is decomposed into a plurality of figures, the line width of the figure in the correction direction described above for each figure constituting the pattern obtained by connecting the plurality of figures A dimension w is defined as attribute information. When a plurality of figures come into contact with each other in the correction direction, the line width dimension in the correction direction of the whole connected figure is defined.

  In addition, a plurality of discrete tolerances DL (U, L) are input from the outside as parameters and stored in the storage device 144. The tolerance DL (U, L) is defined as a coefficient indicating the relationship between the pattern dimension CD and the electron beam irradiation amount D depending on the pattern dimension CD and the proximity effect density U. In other words, the tolerance DL (U, L) is a value that varies as the pattern dimension CD changes even if the proximity effect density U is the same. Conversely, the tolerance DL (U, L) is a value that varies as the proximity effect density U changes even if the pattern size CD is the same. Here, the pattern dimension CD and the proximity effect density U are made variable, and the tolerance DL (U, L) under a plurality of discrete conditions is obtained in advance by experiments or the like.

  Here, FIG. 1 shows a configuration necessary for explaining the first embodiment. The drawing apparatus 100 may normally have other necessary configurations. For example, although the objective deflection is performed using the one-stage deflector 208 here, two or more stages of deflectors may be used. For example, a main and sub two-stage main deflector and sub deflector may be used. Alternatively, a three-stage first objective deflector, second objective deflector, and third objective deflector may be used. Further, the deflection control circuit 130 is connected to the deflector 205 and the deflector 208 via respective DAC amplifiers (not shown).

FIG. 2 is a conceptual diagram for explaining how to correct the dose in the first embodiment. As described above, it has been found that with the recent miniaturization of patterns, as the size of a drawn pattern becomes smaller, an error occurs in the conventional dose calculation model. Specifically, the conventional dose model is established when the dimension of the drawn pattern is sufficiently larger than the influence radius σ _ps of the forward scattering of electrons. For this reason, when the dimension of the drawn pattern is reduced to a dimension that cannot be said to be sufficiently large with respect to the influence radius σ _ps of the forward scattering of electrons, a deviation from the conventional irradiation model occurs. For an electron forward scattering influence radius σ _ps of 20 to 30 nm, for example, if the line width dimension of the pattern is 150 nm, the conventional irradiation dose model is established without being affected by forward scattering. However, for example, when the line width dimension of the pattern is reduced to about 50 nm or less, a dimensional error occurs in the conventional dose model due to the influence of forward scattering.

  When the pattern size is such that it is affected by such forward scattering, the maximum dose D ′ does not reach the set dose D as indicated by the dose profile 30 in FIG. Therefore, even if the irradiation dose accumulated at the edge position of the pattern 10 is planned when irradiation is performed by the conventional method, the actually obtained dimension is the pattern 12 having a smaller threshold irradiation dose Dth. . Therefore, in the first embodiment, the irradiation amount accumulated at the edge position of the pattern 10 when the irradiation is performed by the conventional method is defined as the product of the forward scattering correction irradiation coefficient α (L (x)) and the irradiation amount D. In other words, αD obtained by multiplying the dose D is defined by α as the contribution ratio of forward scattering. Then, as shown in FIG. 2B, the correction is made so that αD becomes the threshold dose Dth. In other words, by multiplying each value of the dose profile 30 by 1 / (2α) and converting it to the dose profile 32, it is possible to match the conventional dose model. Therefore, in the first embodiment, in calculating the irradiation amount, the forward scattering correction irradiation coefficient α (L (x)) is calculated by obtaining the forward scattering correction irradiation coefficient α (L (x)) for each figure. To perform subsequent correction calculations. With this method, the amount of calculation processing can be greatly reduced compared to the case where all correction amounts are calculated from the beginning.

  FIG. 3 is a diagram showing an example of a plurality of figures constituting the pattern in the first embodiment. FIG. 3 shows an example of a so-called L-shaped pattern that extends as the pattern 20 changes in line width on the way. The pattern 20 is divided into a plurality of figures 22 a, b, c,... By fracturing processing before data is input to the drawing apparatus 100. Here, an important size in each figure is not the longitudinal direction (line direction) of the pattern 20 but the line width dimension orthogonal to the pattern 20. Therefore, it is the line width dimension in the direction orthogonal to the longitudinal direction (line direction) of the pattern 20 that needs to correct the dimension variation. However, in the conventional drawing data, only the figure code, coordinates, x direction size, and y direction size of each divided figure are defined, and the line width dimension in the direction to be corrected (correction direction) is not defined. . Therefore, it is difficult to specify the correction direction as it is. Therefore, in the first embodiment, in addition to the graphic code, coordinates, x-direction size, and y-direction size of the graphic, a line width dimension L in the correction direction is defined in the pattern data of each graphic of the drawing data. Configured. In the example of FIG. 3, for example, a line width dimension L1 is defined in addition to the coordinates (x1, y1) and the size (Lx1, Ly1) for the divided figure 22a. The same applies to the other figures 22b, c,. Even when the extending direction of the pattern 20 is changed in the middle, the line width dimension in the direction orthogonal to the longitudinal direction (line direction) of the pattern 20 after the change may be defined in the pattern data of the figure. In the example of FIG. 3, for example, a line width dimension L17 is defined in addition to the coordinates (x17, y17) and the size (Lx17, Ly17) for the divided figure 22n. When a plurality of figures come into contact with each other in the correction direction, the line width dimension in the correction direction of the whole connected figure is defined. In the first embodiment, the forward scattering correction irradiation coefficient α (L (x)) is obtained using the line width dimension L in the correction direction. By using the line width dimension L as a parameter, the forward scattering correction irradiation coefficient α (L (x)) can be easily obtained. Further, even when the drawing condition is changed in the drawing apparatus 100, α (L (x)) can be obtained using the line width dimension L as a parameter. Therefore, it is possible to avoid the problem that the correction amount cannot be used when the drawing condition is changed, such as when the correction amount is calculated before the drawing and defined as attribute information in the input data.

  FIG. 4 is a diagram showing an example of the format of drawing data for each graphic in the first embodiment. In FIG. 4, the drawing data input to the drawing apparatus 100 is defined with a header, a figure code (k-code), an arrangement coordinate (x, y), and a figure dimension (L1, L2) for each figure. A line width dimension L in the correction direction is further defined as attribute information.

FIG. 5 is a flowchart showing main steps of the drawing method according to the first embodiment. 5, the drawing method according to the first embodiment includes an area density ρ calculating step (S100), a dimensional variation ΔCD calculating step (S102), and a function ρ _p1 / 2α (L (x)) calculating step (S108). A proximity effect correction irradiation coefficient Dp ′ (x) calculation step (S112), a dose density ρ ′ (x) calculation step (S115), a fog correction irradiation coefficient Df (x) calculation step (S116), a function ρ _pL / 2α (L (x)) calculation step (S118), proximity effect correction irradiation coefficient Dp (x) calculation step (S120), tolerance DL (U, L) calculation step (S122), irradiation dose A series of steps of a D (x) calculation step (S124) and a drawing step (S126) are performed. In the first embodiment, the dimensional fluctuation caused by forward scattering, the dimensional fluctuation caused by the proximity effect, the dimensional fluctuation caused by the fogging, and the dimensional fluctuation caused by the loading effect are all corrected. This is not a limitation. For example, an irradiation amount obtained by correcting the dimensional variation due to forward scattering and the dimensional variation due to the proximity effect may be obtained. Thereby, the dimensional variation caused by forward scattering and the dimensional variation caused by the proximity effect can be corrected. In other words, the dose that corrects the dimensional variation due to forward scattering and one or more of the dimensional variations due to the proximity effect, fogging, or loading effect may be obtained. First, the control computer 110 reads drawing data from the storage device 140. Then, the following calculation is performed.

As the area density ρ calculating step (S100), the area density ρ calculating unit 41 virtually divides the drawing area of the sample 101 into a plurality of mesh areas of a predetermined size, and determines the area density occupied by the graphic pattern for each mesh area. Calculate. The area density ρ calculation unit 41 calculates the area density ρ _{L (x)} for each mesh region having a size of, for example, 1/10 of the influence radius of the loading effect. The mesh size for calculating the area density ρ _{L (x)} is preferably about 100 to 500 μm, for example.

In the dimension variation amount ΔCD calculation step (S102), the ΔCD calculation unit 40 calculates the dimension variation amount ΔCD (x) due to the loading effect for each graphic pattern defined in the drawing data. The ΔCD calculation unit 40 is an example of a dimensional variation amount calculation unit. The dimensional variation amount ΔCD (x) is expressed by the following equation (5) using the distribution function g _{L (x)} , area density ρ _{L (x)} , loading effect correction coefficient γ, and position-dependent dimensional variation amount P (x) Defined in 1). As the distribution function g _{L (x)} , for example, a Gaussian distribution function or the like is preferably used. The area density ρ _{L (x)} may be a value calculated for each mesh region having a size of, for example, 1/10 of the radius of influence of the loading effect. The calculated ΔCD (x) is temporarily stored in the storage device 142.

In the ρ _p1 / 2α (L (x)) calculation step (S108), the ρ _p1 / 2α calculation unit 44 calculates an area density for correcting the dimensional variation due to the proximity effect for fogging effect correction. In this step, the area density is calculated by assigning a weight of 1 / 2α (L (x)) to the pattern area for each figure. In the embodiment, this weighted area density is expressed as ρ / 2α (L (x)) for the sake of convenience using the unweighted area density ρ. The calculated function ρ _p1 / 2α (L (x)) is temporarily stored in the storage device 142.

α (L (x)) is a coefficient depending on the pattern dimension L (x). α (L (x)) is defined by the following equation (2) using the pattern dimension L (x) and the normalized distribution function g _ps (x). The distribution function g _ps (x) is defined by the following equation (3) using the forward scattering influence radius σ _ps . The area density ρ _p1 may be a value calculated for each mesh region having a mesh size Δ _p1 larger than the original mesh size for proximity effect correction for fogging effect correction. For example, it may mesh size delta _p1 is calculated for each mesh region of 5 to 10 [mu] m.

  Then, α (L (x)) is obtained when the coordinate of the end of the graphic pattern is x. In other words, for example, when the center position of the dimension L of the graphic pattern is the center of the distribution function, α (L (x)) is obtained when x = L / 2. Thereby, the forward scattering correction irradiation coefficient which becomes a contribution ratio of forward scattering is obtained.

In the proximity effect correction irradiation coefficient Dp ′ (x) calculation step (S112), the Dp ′ (x) calculation unit 51 uses ρ _p1 / 2α (L (x)) to use the proximity effect for the fog correction calculation. The proximity effect correction irradiation coefficient Dp ′ (x) for correcting the dimensional variation due to the is calculated. Dp ′ (x) is defined by the following equation (4) using ρ _p1 / 2α (L (x)), distribution function g _p (x), and proximity effect correction coefficient η.

As the distribution function g _p (x), for example, a Gaussian distribution function or the like is preferably used. In addition, ρ _p1 / 2α (L (x)) of the second term in the formula (4) can shorten the calculation processing time by using the already obtained function ρ _p1 / 2α (L (x)). Here, reduces the number of calculations because it a size larger than the mesh size delta _pL of mesh size delta _p1 is inherent proximity correction for head correction calculation can be shortened processing time. As described above, Dp ′ (x) for fog correction calculation that can correct the dimensional variation due to the proximity effect while correcting the dimensional variation due to the forward scattering can be acquired.

As the irradiation density ρ ′ (x) calculation step (S115), the irradiation density ρ ′ (x) calculation unit 53 calculates the irradiation density ρ ′ (x). The dose density ρ ′ (x) is a function that depends on the forward scattering correction irradiation coefficient α (L (x)). ρ ′ (x) is the proximity effect correction irradiation coefficient Dp ′ (x) for the fog correction calculation, ρ _p1 / 2α (L (x)), the proximity effect mesh size Δ _p1 for the fog correction calculation, and the fog effect correction with a mesh size delta _f of use is defined by the following equation (5). Mesh size delta _f, it is preferable effect size of the radius of example 1/10 of the fogging effect. For example, about 100 to 500 μm is preferable. Here, ρ ′ (x) is named as the dose density, but this is a name for convenience and other names may be used. The function ρ ′ (x) may be simply used.

In the fog correction irradiation coefficient Df (x) calculation step (S116), the Df (x) calculation unit 52 has a dose density ρ ′ (x) that is a function dependent on the forward scattering correction irradiation coefficient α (L (x)). Is used to calculate the fog correction irradiation coefficient Df (x) for correcting the dimensional variation caused by the fog. The Df (x) calculation unit 52 is an example of a fog correction irradiation coefficient calculation unit. Df (x) is defined by the following formula (6) using the distribution function g _f (x), the dose density ρ ′ (x), the fog correction coefficient θ, and the proximity effect correction coefficient η.

For example, a Gaussian distribution function or the like is preferably used as the distribution function g _f (x). In addition, for the second term ρ ′ (x) in the equation (6), the calculation processing time can be shortened by using the already obtained function ρ ′ (x). As described above, it is possible to acquire Df (x) that can correct the dimensional variation due to the proximity effect and further the fog while correcting the dimensional variation due to the forward scattering.

In the function ρ _pL / 2α (L (x)) calculation step (S118), the ρ _pL / 2α calculation unit 46 calculates the area density for correcting the dimensional variation caused by the original proximity effect that is not for the fogging effect correction. calculate. In this step, the area density is calculated by assigning a weight of 1 / 2α (L (x)) to the pattern area for each figure. The calculated function ρ _pL / 2α (L (x)) is temporarily stored in the storage device 142.

For α (L (x)), the above-described equations (2) and (3) may be used. The area density ρ _pL may be a value calculated for each mesh region having a mesh size Δ _pL of 1/10 of the original influence radius of the proximity effect. For example, it may be calculated for each mesh region having a mesh size _ΔpL of about 1 μm. The ρ _pL / 2α calculation unit 46 is arranged in the control computer 110 in FIG. 1, but may be arranged in the control computer 120.

In the proximity effect correction irradiation coefficient Dp (x) calculation step (S120), the Dp (x) calculation unit 50 corrects dimensional variations caused by the original proximity effect using ρ _pL / 2α (L (x)). The proximity effect corrected irradiation coefficient Dp (x) is calculated. The Dp (x) calculation unit 50 is an example of a proximity effect correction irradiation coefficient calculation unit. Dp (x) is defined by the following formula (7) using ρ _pL / 2α (L (x)), distribution function g _p (x), and proximity effect correction coefficient η.

As the distribution function g _p (x), for example, a Gaussian distribution function or the like is preferably used. In addition, ρ _pL / 2α (L (x)) of the second term in the equation (7) can shorten the calculation processing time by using the already obtained function ρ _pL / 2α (L (x)). As described above, it is possible to obtain Dp (x) that can correct the dimensional variation due to the proximity effect while correcting the dimensional variation due to the forward scattering.

  In the tolerance DL (U, L) calculation step (S122), the DL (U, L) calculation unit 54 uses the pattern dimension L and the proximity effect density U to calculate the pattern dimension L and the electron beam irradiation amount D. A tolerance DL (U, L) that varies depending on the pattern dimension L and the proximity effect density U is calculated. The DL (U, L) calculation unit 54 is an example of a tolerance calculation unit.

  FIG. 6 is a graph showing an example of correlation data between the pattern dimension CD and the dose D in the first embodiment. The vertical axis represents the pattern dimension CD, and the horizontal axis represents the dose D in logarithm. Here, for example, the proximity effect density U (x) = 0 (0%), 0.5 (50%), and 1 (100%) are obtained by experiments. Since the proximity effect density U (x) = 0 actually means that there is no pattern, it can be approximated by drawing one line pattern for measurement in a state where there is nothing around. . On the other hand, the proximity effect density U (x) = 1 is a pattern in the entire mesh including the periphery, and the dimension cannot be measured. Therefore, the measurement line pattern is set to 1 for example in a state where the periphery is completely filled with the pattern. Can be approximated by drawing one. Here, the proximity effect density U (x) to be set is not limited to 0%, 50%, and 100%. For example, it is also preferable to use any one of 10% or less, 50%, and 90% or more. Moreover, you may measure by not only three types but another number. For example, four or more types may be measured. The tolerance DL (U, L) indicates, for example, the slope of the graph. Until the pattern dimension L is large enough not to be influenced by forward scattering, the tolerance DL (U, L) is constant with respect to the proximity effect density U (x) regardless of the pattern dimension L. be able to. However, when the pattern dimension L becomes smaller than the level affected by the forward scattering, the pattern dimension L changes depending on the pattern dimension L even if the proximity effect density U (x) is constant. Therefore, in the first embodiment, a plurality of discrete tolerances DL (U, L) that vary depending on the pattern dimension L and the proximity effect density U are obtained in advance by experiments or the like using the evaluation pattern. It is stored in the storage device 144.

Then, the DL (U, L) calculation unit 54 can obtain continuous DL (U, L) by reading and fitting a plurality of discrete DL (U, L) data from the storage device 144. The proximity effect density U (x) is defined as a value obtained by convolving and integrating the distribution function g _p (x) with a pattern area density ρ _p (x) in the proximity effect mesh within the range of the proximity effect influence range σ _p or more. Is done. The proximity effect mesh preferably has a size of, for example, about 1/10 of the above-described proximity effect influence radius σ _p , for example, a size of about 1 μm.

In the irradiation amount D (x) calculation step (S124), the D (x) calculation unit 56 uses the proximity effect correction irradiation coefficient Dp (x) and the forward scattering correction irradiation coefficient α (L (x)) to perform the irradiation amount. D (x) is calculated. The D (x) calculation unit 56 is an example of an irradiation amount calculation unit. In the first embodiment, the irradiation dose D (x) is further calculated using the fog correction irradiation coefficient Df (x). In the first embodiment, the dose D (x) is further calculated using the tolerance DL (U, L) and the dimensional variation amount ΔCD caused by the loading effect. The irradiation dose D (x) is expressed as follows using the reference irradiation dose D _base , Dp (x), α (L (x)), Df (x), DL (U, L), and ΔCD (x). It is defined by equation (8).

  By calculating the dose from the equation (8), it is possible to correct the dimensional variation caused by the proximity effect, the fogging, and the loading effect while correcting the dimensional variation caused by the forward scattering. When correcting the dimensional variation due to the proximity effect while correcting the dimensional variation due to the forward scattering without correcting the dimensional variation due to the fogging and the loading effect, Df (x), DL ( U, L) and ΔCD (x) need not be used. When correcting the dimensional variation due to the proximity effect and the fog while correcting the dimensional variation due to the forward scattering without correcting the dimensional variation due to the loading effect, DL (U, L), and If ΔCD (x) is not used. Df (x) is used when correcting the dimensional variation due to the proximity effect and the loading effect while correcting the dimensional variation due to the forward scattering without correcting the dimensional variation due to the fog. If there is no. In this way, the formula may be adjusted appropriately according to the content to be corrected. In either case, dimensional variations due to forward scattering can be corrected. The calculated dose D (x) is stored in the storage device 146. At this time, it is preferable that the irradiation amount D (x) is stored as data converted into the irradiation time t by the irradiation time calculation unit 58. The irradiation time t can be obtained by dividing the irradiation amount D (x) by the current density J.

  On the other hand, in parallel with the process of calculating the dose, the shot data generation unit 58 receives drawing data from the storage device 140, performs a plurality of stages of data conversion processing, and generates apparatus-specific shot data. The shot data generation unit 58 converts a plurality of figure patterns defined in the drawing data into shot figures of a size that can be irradiated with one electron beam 200 (size that can be formed), and the irradiation position and shot of each shot figure Shot data in which a figure type, a shot figure size, and the like are defined is generated. Such shot data is stored in the storage device 146.

  As the drawing step (S122), under the control of the drawing control unit 62, the deflection control circuit 130 first reads the irradiation amount D (x) data from the storage device 146, and is defined for each shot figure for each shot figure. The electron beam 200 is irradiated for the irradiation amount (irradiation time), and when the irradiation time t elapses, a deflection amount for deflecting the electron beam 200 to be shielded is calculated. Then, the deflection voltage having such a deflection amount is applied to the corresponding blanking deflector 212 via the DAC amplifier 132. Further, the deflection control circuit 130 calculates a deflection amount for deflecting the electron beam 200 to a defined drawing position along the shot data. Similarly, a deflection amount for forming a graphic of the graphic type and size defined for each shot graphic is calculated. Then, a deflection voltage of each deflection amount is applied to the corresponding deflectors 205 and 208 via a DAC amplifier (not shown). Then, under the control of the drawing control unit 62, the drawing unit 150 draws the graphic pattern on the sample 101 using the electron beam 200 based on the obtained dose D (x). Specifically, the following operation is performed.

  When the electron beam 200 emitted from the electron gun 201 (emission unit) passes through the blanking deflector 212, it is controlled by the blanking deflector 212 so as to pass through the blanking aperture 214 in the beam ON state. In the beam OFF state, the entire beam is deflected so as to be shielded by the blanking aperture 214. The electron beam 200 that has passed through the blanking aperture 214 until the beam is turned off after the beam is turned off becomes one shot of the electron beam. The blanking deflector 212 controls the direction of the passing electron beam 200 to alternately generate a beam ON state and a beam OFF state. For example, the voltage may be applied to the blanking deflector 212 when the beam is OFF, without applying a voltage when the beam is ON. The irradiation amount per shot of the electron beam 200 irradiated on the sample 101 is adjusted at the irradiation time t of each shot.

  As described above, the electron beam 200 of each shot generated by passing through the blanking deflector 212 and the blanking aperture 214 illuminates the entire first shaping aperture 203 having a rectangular hole, for example, a rectangular hole, by the illumination lens 202. To do. Here, the electron beam 200 is first formed into a rectangle, for example, a rectangle. Then, the electron beam 200 of the first aperture image that has passed through the first shaping aperture 203 is projected onto the second shaping aperture 206 by the projection lens 204. The deflector 205 controls the deflection of the first aperture image on the second shaping aperture 206 and can change the beam shape and dimensions (variable shaping is performed). Such variable shaping is performed for each shot, and is usually shaped into different beam shapes and dimensions for each shot. The electron beam 200 of the second aperture image that has passed through the second shaping aperture 206 is focused by the objective lens 207, deflected by the deflector 208, and placed on the XY stage 105 that moves continuously. 101 is irradiated to a desired position. Since the XY stage 105 is moving, the deflector 208 deflects the electron beam 200 so as to follow the movement of the XY stage 105.

  As described above, according to the first embodiment, it is possible to correct dimensional variation caused by forward scattering of charged particles, along with other variation factors such as proximity effect. As a result, even if the dimension of the pattern to be drawn is a dimension that cannot be said to be sufficiently large with respect to the radius of influence of the forward scattering of electrons, highly accurate drawing can be performed.

  FIG. 7 is a diagram showing another example of a plurality of figures constituting the pattern in the first embodiment. As described above, the important size in each figure is not the longitudinal direction (line direction) of the pattern 20 but the line width dimension orthogonal thereto. Therefore, it is the line width dimension in the direction orthogonal to the longitudinal direction (line direction) of the pattern 20 that needs to correct the dimensional variation due to the process related to mask manufacturing. However, in the conventional drawing data, only the figure code, coordinates, x-direction size, and y-direction size of each divided figure are defined, but the direction to be corrected (correction direction) is not defined. For this reason, it is difficult to specify the correction direction itself as it is. If the correction direction itself can be specified, the line width dimension L in the correction direction can be obtained from the figure code, the x direction size, and the y direction size. Therefore, in addition to the graphic code, coordinates, x-direction size, and y-direction size of the graphic, the correction direction may be further defined in the pattern data of each graphic of the drawing data. In the example described above, the coordinates (x1, y1), the size (Lx1, Ly1), and the line width dimension L1 are defined for the figure 22a obtained by dividing the pattern 20, but in FIG. 7, the coordinates (x1, y1) are defined. , Size (Lx1, Ly1), and correction direction Y are defined. Similarly, the same applies to the other figures 22b, c,. Even when the extending direction of the pattern 20 is changed in the middle, the direction orthogonal to the longitudinal direction (line direction) of the changed pattern 20 may be defined in the pattern data of the figure as the correction direction. In the example of FIG. 7, for example, the correction direction X is defined in addition to the coordinates (x17, y17) and the size (Lx17, Ly17) for the divided figure 22n.

  Then, the α (L (x)) calculation unit 42 first calculates the pattern dimension L in the correction direction from the correction direction. Thereafter, calculation may be performed in the same manner as described above.

Embodiment 2. FIG.
In the first embodiment, an example in which the irradiation amount is calculated using a parameter different from the correction of the proximity effect for the correction of the loading effect is shown. In the second embodiment, a case where a set of a reference irradiation amount D _base and a proximity effect correction coefficient η that corrects a dimensional variation due to a loading effect while maintaining proximity effect correction for each position of the substrate will be described. To do. The contents other than the points specifically described below are the same as those in the first embodiment.

FIG. 8 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the second embodiment. In FIG. 8, a reference irradiation amount D _base (ΔCD) calculation unit 70, a proximity effect correction coefficient η (ΔCD) calculation unit 72, and a tolerance DL (U) calculation unit 74 are further added to the control computer 120. Except for this, it is the same as FIG. The reference dose D _base (ΔCD) calculation unit 70, the proximity effect correction coefficient η (ΔCD) calculation unit 72, and the tolerance DL (U) calculation unit 74 are similar to other functions in the control computer 120, such as software. It may be constituted by. Alternatively, it may be configured by hardware such as an electronic circuit. Alternatively, a combination thereof may be used. The input data necessary for the control computer 120 or the calculated result is stored in the memory 121 each time.

FIG. 9 is a flowchart showing main steps of the drawing method according to the second embodiment. In FIG. 9, in the drawing method according to the second embodiment, after the ΔCD calculation step (S102), the reference dose D _base (ΔCD) calculation step (S104) and the proximity effect correction coefficient η (ΔCD) calculation step (S106). And a point where a tolerance DL (U) calculation step (S123) is added after a tolerance DL (U, L) calculation step (S122), a proximity effect correction irradiation coefficient Dp ′ (x) calculation step The proximity correction irradiation coefficient Dp ′ (x) calculation step (S115) is added instead of (S112), and the fog correction irradiation coefficient Df (x) is replaced with the fog correction irradiation coefficient Df (x) calculation step (S116). ) A point where a calculation step (S117) is added, a point where a proximity effect correction irradiation coefficient Dp (x) calculation step (S121) is added instead of the proximity effect correction irradiation coefficient Dp (x) calculation step (S120), Beauty, except that dose D (x) calculation step instead (S125) is added in the dose D (x) calculation step (S124), it is similar to FIG.

  Similar to the first embodiment, the storage device 144 stores a plurality of discrete tolerances DL (U, L) as parameters from the outside. In the second embodiment, in addition, a plurality of discrete tolerances DL (U) are input as parameters from the outside and stored. The tolerance DL (U) is defined as a coefficient indicating the relationship between the pattern dimension CD and the electron beam dose D depending on the proximity effect density U. In other words, the tolerance DL (U) is a value that does not vary even if the pattern dimension CD changes if the proximity effect density U is the same. For example, correlation data between the pattern dimension CD and the dose D is experimentally obtained by using an evaluation pattern having a size that is large enough that the pattern dimension L is not affected by forward scattering. For example, the proximity effect density U (x) = 0 (0%), 0.5 (50%), and 1 (100%) are obtained by experiments. And tolerance DL (U) shows the inclination of the graph of the correlation data of pattern dimension CD and dose D, for example. Thereby, it is possible to obtain a plurality of discrete tolerances DL (U) depending on the proximity effect density U without depending on the pattern dimension CD. A plurality of discrete tolerances DL (U) are stored in the storage device 144.

The storage device 144 further stores correlation data between the dimensional variation amount ΔCD caused by the loading effect and the reference irradiation amount D _base that can simultaneously correct the dimensional variation amount ΔCD while maintaining the proximity effect correction. Similarly, correlation data between the dimensional variation amount ΔCD caused by the loading effect and the proximity effect correction coefficient η capable of simultaneously correcting the dimensional variation amount ΔCD while maintaining the proximity effect correction is stored. Here, there is a proximity effect correction coefficient η with which the proximity effect correction matches well for each reference dose D _base .

Therefore, a set of the reference dose D _base and the proximity effect correction coefficient η is determined for each ΔCD. Prior to drawing, the dimensional variation amount ΔCD is made variable in advance, and such correlation data is obtained in advance by experiments for each dimensional variation amount ΔCD. As described above, the storage device 144 stores the data of the reference irradiation amount D _base (ΔCD) depending on the dimensional variation amount ΔCD caused by the loading effect, and the proximity effect correction coefficient η (ΔCD similarly dependent on the dimensional variation amount ΔCD. ) Data is stored.

  In the second embodiment, the contents of each process from the area density ρ calculating step (S100) to the ΔCD calculating step (S102) are the same as those in the first embodiment.

In the reference dose D _base (ΔCD) calculation step (S104), the D _base (ΔCD) calculation unit 70 reads ΔCD (x) from the storage device 144 and uses ΔCD (x) to obtain the reference dose D _base ( ΔCD) is calculated.

  In the proximity effect correction coefficient η (ΔCD) calculation step (S106), the η (ΔCD) calculation unit 72 reads ΔCD (x) from the storage device 144 and uses ΔCD (x) to calculate the proximity effect correction coefficient η (ΔCD ) Is calculated.

As described above, a set of the reference irradiation amount D _base (ΔCD) and the proximity effect correction coefficient η (ΔCD) that can simultaneously correct the dimensional variation ΔCD while maintaining the proximity effect correction can be acquired. The content of the ρ _p1 / 2α (L (x)) calculation step (S108) is the same as that in the first embodiment.

In the proximity effect correction irradiation coefficient Dp ′ (x) calculation step (S114), the Dp ′ (x) calculation unit 51 uses ρ _p1 / 2α (L (x)) to use the proximity effect for the fog correction calculation. The proximity effect correction irradiation coefficient Dp ′ (x) for correcting the dimensional variation due to the is calculated. Dp ′ (x) is defined by the following equation (9) instead of equation (4) using the proximity effect correction coefficient η (ΔCD (x)) instead of η.

  As described above, Dp ′ (x) for fog correction calculation that can correct the dimensional variation due to the proximity effect while correcting the dimensional variation due to the forward scattering can be acquired. At the same time, the loading effect is corrected. However, with regard to the correction of the loading effect, an error caused by forward scattering remains as it is, so that the amount is corrected later.

As the irradiation density ρ ′ (x) calculation step (S115), the irradiation density ρ ′ (x) calculation unit 53 calculates the irradiation density ρ ′ (x). Here, when obtaining the dose density ρ ′ (x), in the second embodiment, the above-described equation (5) is corrected using the reference dose D _base (ΔCD) and the reference dose D _base . The dose density ρ ′ (x) in the second embodiment is defined by the following equation (10) instead of equation (5).

In the fog correction irradiation coefficient Df (x) calculation step (S117), the Df (x) calculation unit 52 has a dose density ρ ′ (x) that is a function depending on the forward scattering correction irradiation coefficient α (L (x)). Is used to calculate the fog correction irradiation coefficient Df (x) for correcting the dimensional variation caused by the fog. The Df (x) calculation unit 52 is an example of a fog correction irradiation coefficient calculation unit. Df (x) is defined by the following equation (11) using the distribution function g _f (x), the dose density ρ ′ (x), the fog correction coefficient θ, and the proximity effect correction coefficient η. Here, ρ ′ (x) is defined by the equation (10).

  As described above, it is possible to acquire Df (x) that can correct the dimensional variation due to the proximity effect and further the fog while correcting the dimensional variation due to the forward scattering. At the same time, the loading effect is corrected. However, with regard to the correction of the loading effect, an error caused by forward scattering remains as it is, so that the amount is corrected later.

  In the tolerance DL (U, L) calculation step (S122), the tolerance DL (U, L) (first tolerance) is calculated. The contents of the tolerance DL (U, L) calculation step (S122) are the same as those in the first embodiment. The DL (U, L) calculation unit 54 is an example of a first tolerance calculation unit. In the second embodiment, as described above, the tolerance DL (U) calculation step (S123) is further performed.

  In the tolerance DL (U) calculation step (S123), the DL (U) calculation unit 74 uses the proximity effect density U (x) and is a coefficient indicating the relationship between the pattern dimension L and the electron beam dose D. In the same proximity effect density U (x), the tolerance DL (U) (second tolerance) which does not change depending on the pattern dimension L and changes depending on the proximity effect density U (x). Calculate. The DL (U) calculation unit 54 is an example of a second tolerance calculation unit. The DL (U) calculation unit 74 can obtain continuous DL (U) by reading a plurality of discrete DL (U) data from the storage device 144 and fitting them.

In the irradiation amount D (x) calculation step (S125), the irradiation amount D (x) calculation unit 56 includes a proximity effect correction irradiation coefficient Dp (x), a forward scattering correction irradiation coefficient α (L (x)), and a tolerance DL. The dose D (x) is calculated using (U, L), the tolerance DL (U), and the dimensional variation ΔCD (x) caused by the loading effect. The irradiation dose D (x) is calculated using the reference irradiation dose D _base (ΔCD), Dp (x), Df (x), DL (U, L), DL (U), and ΔCD (x) as follows: It is defined by equation (12).

By calculating the dose from the equation (12), it is possible to correct the dimensional variation caused by the proximity effect, the fogging, and the loading effect while correcting the dimensional variation caused by the forward scattering. Df (x) is used when correcting the dimensional variation due to the proximity effect and the loading effect while correcting the dimensional variation due to the forward scattering without correcting the dimensional variation due to the fog. If there is no. In this way, the formula may be adjusted appropriately according to the content to be corrected. In the second embodiment, the loading effect is corrected by D _base (ΔCD) and η (ΔCD). However, since the error due to forward scattering remains as it is, the corresponding amount is corrected by a term using DL (U, L), DL (U), and ΔCD (x).

As described above, according to the second embodiment, even when D _base (ΔCD) and η (ΔCD) depending on ΔCD are used, it is caused by forward scattering of electrons together with other fluctuation factors such as a proximity effect. It is possible to correct the dimensional variation. As a result, even if the dimension of the pattern to be drawn is a dimension that cannot be said to be sufficiently large with respect to the radius of influence of the forward scattering of electrons, highly accurate drawing can be performed.

The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In the first embodiment described above, the ΔCD calculation step (S100) is arranged next to the ρ calculation step (S100), but the present invention is not limited to this. The ΔCD calculation step (S100) may be performed anywhere as long as the irradiation amount D (x) calculation step (S124) is started. Similarly, the DL (U, L) calculation step (S122) may be performed anywhere as long as the dose D (x) calculation step (S124) is started. In the second embodiment, either the D _base (ΔCD) calculating step (S104) or the η (ΔCD) calculating step (S106) may be performed first. Alternatively, parallel processing may be performed. The ΔCD calculation step (S100) is performed anywhere before the start of the D _base (ΔCD) calculation step (S104) and the η (ΔCD) calculation step (S106). good. Further, either the DL (U, L) calculation step (S122) or the DL (U) calculation step (S123) may be performed first. Alternatively, parallel processing may be performed. The DL (U, L) calculation step (S122) and the DL (U) calculation step (S123) may be performed anywhere as long as the dose D (x) calculation step (S125) is started. Further, it is preferable that the forward scattering correction irradiation coefficient α (L (x)) is calculated according to the definitions of the equations (2) and (3) in each equation every time the equations used are calculated.

  In addition, although descriptions are omitted for parts and the like that are not directly required for the description of the present invention, such as a device configuration and a control method, a required device configuration and a control method can be appropriately selected and used. For example, although the description of the control unit configuration for controlling the drawing apparatus 100 is omitted, it goes without saying that the required control unit configuration is appropriately selected and used.

  In addition, all charged particle beam writing apparatuses and methods that include elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

10, 12, 20 pattern 22 figure 30, 32 dose profile 40 ΔCD calculation unit 41 ρ calculation unit 44 function ρ _p1 / 2α calculation unit 46 function ρ _pL / 2α calculation unit 50 Dp (x) calculation unit 51 Dp ′ (x ) Calculation unit 52 Df (x) calculation unit 53 ρ ′ (x) calculation unit 54 DL (U, L) calculation unit 56 D (x) calculation unit 58 Irradiation time calculation unit 60 Shot data generation unit 62 Drawing control unit 70 D _base (ΔCD) calculation unit 72 η (ΔCD) calculation unit 74 DL (U) calculation unit 100 Drawing apparatus 101 Sample 102 Electron barrel 103 Drawing chamber 105 XY stage 110, 120 Control computer 111, 121 Memory 130 Deflection control circuit 132 DAC
140, 142, 144, 146 Storage device 150 Drawing unit 160 Control unit 200 Electron beam 201 Electron gun 202 Illumination lens 203 First shaping aperture 204 Projection lens 205 Deflector 206 Second shaping aperture 207 Objective lens 208 Main deflector 209 Sub deflector 212 Blanking deflector 214 Blanking aperture 330 Electron beam 340 Sample 410 First aperture 411 Opening 420 Second aperture 421 Variable shaped opening 430 Charged particle source

Claims (5)

Proximity effect correction irradiation coefficient that corrects dimensional fluctuation caused by proximity effect using forward scattering correction irradiation coefficient that corrects dimensional fluctuation caused by forward scattering of charged particles depending on pattern dimension in correction direction for each graphic pattern Proximity effect correction irradiation coefficient calculation unit to calculate,
A dose calculation unit that calculates a dose using the proximity effect correction irradiation coefficient and the forward scattering correction irradiation coefficient;
A drawing unit that draws the graphic pattern on the sample using a charged particle beam based on the irradiation amount;
A charged particle beam drawing apparatus comprising: Using a function dependent on the forward scattering correction irradiation coefficient, further comprising a fog correction irradiation coefficient calculation unit for calculating a fog correction irradiation coefficient for correcting dimensional variation due to fog,
The charged particle beam drawing apparatus according to claim 1, wherein the irradiation amount calculation unit further calculates the irradiation amount using the fog correction irradiation coefficient. A dimensional variation calculation unit for calculating the dimensional variation due to the loading effect;
Using the pattern dimension and proximity effect density, a coefficient indicating the relationship between the pattern dimension and the charged particle beam irradiation amount, and calculating a tolerance that varies depending on the pattern dimension and the proximity effect density A tolerance calculation unit to
Further comprising
The charged particle beam drawing apparatus according to claim 1, wherein the irradiation amount calculation unit further calculates the irradiation amount using the tolerance and a dimensional variation amount resulting from a loading effect. Using the pattern size and the proximity effect density, a first tolerance that is a coefficient indicating the relationship between the pattern size and the irradiation amount of the charged particle beam depending on the pattern size and the proximity effect density is calculated. A first tolerance calculation unit;
A coefficient indicating the relationship between the pattern size and the irradiation amount of the charged particle beam using the proximity effect density, and does not change depending on the pattern size at the same proximity effect density and depends on the proximity effect density. A second tolerance calculation unit for calculating a second tolerance that changes in accordance with
Further comprising
The said irradiation amount calculation part further calculates the said irradiation amount using the said 1st tolerance, the said 2nd tolerance, and the dimension variation | change_quantity resulting from a loading effect, It is characterized by the above-mentioned. 3. The charged particle beam drawing apparatus according to 2. Proximity effect correction irradiation coefficient that corrects dimensional fluctuation caused by proximity effect using forward scattering correction irradiation coefficient that corrects dimensional fluctuation caused by forward scattering of charged particles depending on pattern dimension in correction direction for each graphic pattern A process of calculating;
Calculating a dose using the proximity effect corrected irradiation coefficient and the forward scattering corrected irradiation coefficient;
Drawing the figure pattern on the sample using a charged particle beam based on the irradiation amount;
A charged particle beam drawing method comprising:

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