JP5758325B2 - Charged particle beam drawing apparatus and charged particle beam drawing method - Google Patents

Description

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

  Lithography technology is an important technology responsible for the progress of miniaturization of semiconductor devices. In recent years, circuit line widths required for semiconductor devices have been reduced year by year. Therefore, a photomask having a highly accurate mask pattern is required in the lithography process of the semiconductor manufacturing process. An electron beam (charged particle beam) drawing apparatus having excellent resolution is used to create a photomask having such a high-accuracy mask pattern.

FIG. 5 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 411 for forming the electron beam 330 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 electron beam drawing described above, the influence of the so-called proximity effect, in which the pattern becomes thicker or thinner due to backscattered electrons, becomes a problem. One effective method for correcting the proximity effect is a dose correction method. This is a correction method for determining the irradiation amount for each position based on the size and density of the peripheral pattern of the beam irradiation position. This technique has already been put into practical use and is used for mask manufacturing (for example, see Patent Document 1).

Japanese Patent No. 3469422

  In the irradiation amount correction, the backscattering irradiation amount generated by the charged particle beam irradiated to the photomask being reflected by the mask and re-exposing the resist is calculated. This calculation is fast using a product sum (convolution) of a pattern density map that represents the pattern information in the layout with a mesh of several μm square, for example, and a Gaussian kernel that is often used instead of the backscattering distribution function. It has become. The accuracy of the correction calculation depends on the mesh size used in the pattern density map.

  In the conventional method, when the mesh size m / k (k is a natural number) is used instead of the mesh size m, the calculation amount necessary for the correction calculation increases in proportion to the cube of k. For this reason, if a smaller value is used for the mesh size used in the proximity correction calculation due to the demand for higher accuracy of the photomask, the proximity correction calculation may affect the drawing throughput due to the increased calculation amount. .

  An object of the present invention is to provide an apparatus and method capable of overcoming the above-described problems and suppressing the amount of calculation that increases when the mesh size used in correction calculation is reduced.

A charged particle beam drawing apparatus according to one embodiment of the present invention includes:
A charged particle beam drawing apparatus that irradiates a drawing region of a sample with a charged particle beam and draws a predetermined pattern on the drawing region,
A first kernel creation unit that calculates a value of a first kernel that is a value of a backscattering distribution function in a first mesh obtained by dividing a calculation region for calculating a dose for forming a predetermined pattern with a first mesh size. When,
A value of the second kernel that is an average value of the values of the first kernels of the plurality of first meshes belonging to the second mesh obtained by dividing the calculation region with the second mesh size that is an integer multiple of the first mesh size. A second kernel creation unit to calculate,
A difference kernel creation unit that calculates a difference kernel value that is a difference between the value of the first kernel and the value of the second kernel;
An area density calculating unit that calculates an area density of each first mesh to create a first area density map, calculates an area density of each second mesh, and creates a second area density map;
A dose density of each first mesh is calculated based on the first area density map and the second area density map to create a first dose density map, and the first area density map and the second area density are calculated. A dose density map creating unit for calculating a dose density of each second mesh based on the map and creating a second dose density map;
The first convolution calculation between the map value of the first dose density map and the difference kernel is performed in the first region, and the second convolution calculation of the map value of the second dose density map and the second kernel is performed. A convolution calculator that performs in a second region wider than the first region;
It is characterized by providing.

Furthermore, the charged particle beam drawing apparatus according to one embodiment of the present invention includes:
Based on the first convolution calculation result and the second convolution calculation result, a dose density calculation unit for creating a final dose density map, and a pattern is drawn in the drawing area based on the dose density. And a drawing unit.

  In addition, when the first convolution calculation unit performs the first convolution calculation, it is preferable to use a difference kernel corresponding to the position in the second mesh of the first mesh that is the convolution center.

The charged particle beam drawing method of one embodiment of the present invention includes:
A charged particle beam writing method for irradiating a drawing region of a sample with a charged particle beam and drawing a predetermined pattern on the drawing region,
Calculating a value of a first kernel that is a value of a backscattering distribution function in a first mesh obtained by dividing a calculation region for calculating an irradiation dose for forming a predetermined pattern by a first mesh size;
The value of the second kernel is calculated from the average value of the values of the first kernels of a plurality of first meshes belonging to the second mesh obtained by dividing the calculation area with the second mesh size that is an integer multiple of the first mesh size. And
A difference kernel value that is a difference between the first kernel value and the second kernel value is calculated;
Calculate the area density of each first mesh to create a first area density map, calculate the area density of each second mesh to create a second area density map,
A dose density of each first mesh is calculated based on the first area density map and the second area density map to create a first dose density map, and the first area density map and the second area density are calculated. Calculating a dose density of each of the second meshes based on the map to create a second dose density map;
A first convolution calculation of the map value of the first dose density map and the difference kernel is performed in the first region, and a second convolution calculation of the map value of the second dose density map and the second kernel is performed. Is performed in a second region wider than the first region.

Furthermore, the charged particle beam drawing method of one embodiment of the present invention includes:
Create a final dose density map based on the first convolution calculation result and the second convolution calculation result described above,
It is desirable to draw the predetermined pattern in the drawing area based on the final dose map.

  In the charged particle beam writing method of one embodiment of the present invention, the first convolution calculation may be performed using the difference kernel corresponding to the position in the second mesh of the first mesh that is the convolution center. desirable.

According to one aspect of the present invention, the calculation with a small mesh (first mesh) is performed in a region having only a small area around the center, so that the amount of calculation is reduced as compared with the conventional case.
In one aspect of the present invention, a calculation with a large mesh (second mesh) is added, but the amount of calculation increased by this is not large, so a decrease in the amount of calculation with a small mesh contributes to the overall calculation. Time is shortened.

  As described above, according to one embodiment of the present invention, the same accuracy as the conventional one can be calculated in a shorter time.

1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 1. FIG. 3 is a flowchart showing main steps of the drawing method according to Embodiment 1. 6 is a diagram showing an example of a difference kernel in the first embodiment. FIG. 5 is a diagram showing an example of an area density map in the first embodiment. FIG. It is a conceptual diagram for demonstrating operation | movement of the conventional variable shaping type | mold electron beam drawing apparatus.

  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.

(Embodiment 1)
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 (blanker) 212, a blanking aperture 214, a first shaping aperture 203, a projection lens 204, a deflector 205, and a second shaping aperture. 206, an objective 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 a control computer 110, a memory 111, a deflection control circuit 120, a DAC (digital / analog converter) amplifier unit 130 (deflection amplifier), and storage devices 140 and 142 such as a magnetic disk device. The control computer 110, the memory 112, the deflection control circuit 120, and the storage devices 140 and 142 are connected to each other via a bus (not shown). A DAC amplifier unit 130 is connected to the deflection control circuit 120. The DAC amplifier unit 130 is connected to the blanking deflector 212.

  A digital signal for blanking control is output from the deflection control circuit 120 to the DAC amplifier unit 130. The DAC amplifier unit 130 converts the digital signal into an analog signal, amplifies it, and applies it to the blanking deflector 212 as a deflection voltage. The electron beam 200 is deflected by such a deflection voltage, and a beam of each shot is formed.

  Further, in the control computer 110, a kernel creation unit 60, a kernel creation unit 61, a difference kernel creation unit 62, an area density calculation unit 63, an area density calculation unit 64, a setting unit 65, a uy calculation unit 66, and a Py calculation unit 67. , U calculation unit 68, addition unit 69, dn calculation unit 70, determination unit 71, ρn calculation unit 72, Dn calculation unit 73, D calculation unit 74, irradiation time calculation unit 75, and drawing unit 76 are arranged. Kernel creation unit 60, kernel creation unit 61, difference kernel creation unit 62, area density calculation unit 63, area density calculation unit 64, setting unit 65, convolution calculation unit uy calculation unit 66, Py calculation unit 67, u calculation unit 68, the addition unit 69, the dn calculation unit 70, the determination unit 71, the ρn calculation unit 72, the Pn calculation unit 73, the D calculation unit 74, the irradiation time calculation unit 75, and the drawing unit 76 are configured by software such as a program. May be. 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 112 each time. Similarly, the deflection control circuit 120 may be configured by a computer that is operated by software such as a program, or may be configured by hardware such as an electronic circuit. Alternatively, a combination thereof may be used.

  In addition, drawing data is input from the outside and stored in the storage device 140.

  Here, FIG. 1 shows a configuration necessary for explaining the first embodiment. The drawing apparatus 100 may normally have other necessary configurations. For example, each DAC amplifier unit for the deflector 205 and the deflector 208 may be provided.

FIG. 2 is a flowchart showing main steps of the drawing method according to the first embodiment. In FIG. 2, the drawing method according to the first embodiment includes a kernel f (J, j) creation step (S101), a kernel F (J) creation step (S102), and a kernel δf (J, j) creation step (S103). ), An area density map ρ (I, i) creation step (S104), an area density map Ρ (I) creation step (S105), an iteration count n setting step (S106), and a parameter uy (I) calculation step and (S107), a parameter Ρy _n (I) calculation step (S108), the parameter _u n (I, i) and the calculation step (S109), and the addition step (S110), and dn calculation step (S 111), determination step (S112), ρ _n (I, i) calculation step (S113), P _n (I) calculation step (S114), dose D calculation step (S115), irradiation time calculation step (S116), drawing Carrying out the extent (S117) refers to a series of steps.

In the kernel f (J, j) creation step (S101), the kernel creation unit 60 uses the first mesh obtained by dividing the calculation area for calculating the dose for forming a predetermined pattern in the drawing area of the sample. The value of the kernel f (J, j) that is the value of the backscattering distribution function is calculated. f (J, j) is a standardized Gaussian function g (x) whose standard deviation value is the spread σ of electron backscattering, and the mesh size of the first mesh set in the setting unit 65 (first The ratio k between the mesh size) m ₁ and the first mesh size m ₁ and the mesh size (second mesh size) m _{2 of} the second mesh to which the plurality of first meshes belong is larger than the first mesh. And
f (J, j) = g (m ₁ × k × J + m ₁ × (j−s))
k = 2s + 1 (s is an integer of 1 or more)
−s ≦ j ≦ s
Is defined. The second mesh size m ₂ is set in the setting unit 65 from the set m ₁ and k. When creating the kernel f (J, j), the range of the J value to be used is J = 0 as the center of the kernel, and the product of the second mesh size m ₂ and | J | A range corresponding to about 3 times is used. For example, J ₂ = floor (3σ / m ₂ ) and −J ₂ ≦ J ≦ J ₂ is used for the range of J values. As the values of σ, m ₁ , m ₂ , and k, values recorded in advance in the storage device 140 or the memory 112 may be used.

なお、Ｓ１０２で、カーネルＦ（Ｊ）作成時に用いられるＪの値の範囲は、Ｓ１０１でカーネルｆ（Ｊ，ｊ）作成時に用いたＪの値の範囲とする。 In the kernel F (J) creation step (S102), the kernel creation unit 61 creates a kernel F (J). F (J) is an average value of the kernel f (J, j) in the second mesh, and is obtained from Expression (1).

Note that the range of the J value used when creating the kernel F (J) in S102 is the range of the J value used when creating the kernel f (J, j) in S101.

式（４）でｍｏｄは剰余を表す。 In the kernel δf (i ₁ , J, j) creation step (S103), the difference kernel creation unit 62 creates a kernel δf (i ₁ , J, j). The difference kernel δf is defined by the following equation (2).

In the equation (4), mod represents a remainder.

The range of the value of i ₁ used in the kernel δf (i ₁ , J, j) in S103 is 0 to k−1. As the range of the value of J, a range in which the value of m ₂ × | J | corresponds to about 1 to 2 times σ is used. For example, when the range of the value of J is a range in which the value of m ₂ × | J | is σ, J ₁ = floor (σ / m ₂ ) and −J ₁ ≦ J ≦ J _{1 is set} to the value of J Use for range. j is determined for a range from 0 to k-1. The value of J ₁ is able to reduce the calculation amount of correction calculated smaller than J _2.

FIG. 3 is a diagram illustrating an example of a difference kernel in the first embodiment. FIG. 3A shows the difference kernel when i ₁ = 0 (formula (2)), FIG. 3B shows i ₁ = 1, and FIG. 3C shows i ₁ = −1. At this time, σ = 10 μm, m ₁ = 0.05σ, k = 3 (m ₂ = 0.15σ), the left vertical axis indicates the value of the difference kernel, the lower horizontal axis indicates the value of J, For the two J values, the difference kernel values of the first meshes are shown in the order of j = 0, j = 1, and j = 2 from the left side.

In the area density map ρ (I, i) creation step (S104), the area density calculation unit 63 reads the drawing data from the storage device 140 for each frame region, and sets each mesh size to the first mesh size m _1. The pattern area density ρ (I, i) in the mesh region at the position is calculated. The coordinates (I, i) here are set for each frame region.

FIG. 4 is a diagram showing an example of the pattern area density ρ (I, i) in the first embodiment. In FIG. 4A, each mesh obtained by dividing the calculation region into a grid mesh of the second mesh size m ₂ indicated by a thick solid line is further converted into a grid mesh of the first mesh size m ₁ indicated by a dotted line. The state of division was shown. A thin solid line indicates a pattern. FIG. 4 shows a case where the second mesh size m ₂ is three times the first mesh size m ₁ . FIG. 4B shows a pattern area density ρ () corresponding to the pattern area included in the mesh (I, i) whose mesh size is the first mesh size m ₁ for the calculation region divided into meshes as shown in FIG. I, i).

The region for creating the area density map ρ (I, i) changes depending on how many correction calculations are performed. When the correction calculation is obtained up to the order of Nmax, the area density map ρ (I, i) is performed for each of the areas where the four sides of the area for creating the dose map are expanded by m ₂ × (J ₂ +1) × Nmax.

In the area density map Ρ (I) creation step (S105), the area density calculation unit 64 calculates an average value P (I) of the pattern area density ρ (I, i) in the mesh I at the mesh width m1. . For an area where the pattern area density ρ (I, i) is not created, an area density map with a mesh size m ₂ is created using layout data.

The region for creating the area density map Ρ (I) changes depending on how many correction calculations are performed. When the correction calculation is calculated up to the order of Nmax, the area density map ρ (I, i) is performed for each of the areas obtained by extending the four sides of the area for creating the dose map by m ₂ × (J1 + 1) × Nmax.

FIG. 4C is a diagram illustrating an example of the average value P (I) of the pattern density ρ (I, i) in the mesh I in the embodiment. The value in the mesh having the mesh size m ₂ indicated by the solid line in FIG. 4C is the mesh having the mesh size m ₁ indicated by the dotted line in the mesh having the mesh size m ₂ indicated by the solid line in FIG. It is calculated from the value of

  In the repeat count n setting step (S106), the setting unit 65 sets the repeat count (n) when performing the dose calculation. Here, the first n = 0 is set. Thereafter, for each frame and for each mesh region in each frame, an irradiation amount used for the mesh region is obtained.

  In steps S107 to S109, convolution calculation is performed using the kernel value created in S102 and S103 and the map value of the area density map created in S104 and S105.

式（６）中のＪｙは次式（８）で定義される。

式（６）で、Ｕｙｎ（Ｉ，ｉ）を求めるＩの範囲は、計算次数ｎに応じて変わる。求めるＩの範囲は、照射量密度マップを作成する領域の四辺をＪ_２×（Ｎｍａｘ−ｎ）拡張した領域である。Ｊについての加算は、―Ｊ_２≦Ｊ≦Ｊ_２を範囲として行う。 In the parameter uy (I) calculation step (S107), the uy calculation unit 66 calculates the parameter uy (I). The parameter uy _n (I) is defined by equations (5), (6), and (7).

Jy in the formula (6) is defined by the following formula (8).

In Expression (6), the range of I for obtaining Uyn (I, i) varies depending on the calculation order n. The range of I to be obtained is an area obtained by extending four sides of the area for creating the dose density map by J ₂ × (Nmax−n). The addition for J is performed in the range of −J ₂ ≦ J ≦ J ₂ .

In Expression (7), the range of I for obtaining δuyn (I, i) varies depending on the calculation order n. The range of I to be obtained is an area obtained by extending four sides of the area for creating the dose density map by J ₁ × (Nmax−n). The addition for J is performed in the range of −J ₁ ≦ J ≦ J ₁ .

In Expression (5), the range of I for obtaining uyn (I, i) varies depending on the calculation order n. The range of I to be obtained is a region obtained by extending four sides of the region for creating the dose density map by J ₂ × (Nmax−n). When calculating the value of Equation (5), there is no value of δyn (I, i) depending on the value of I. In that case, the value of δuny (I, i) is treated as 0.

式（９）でＰｙｎ（Ｉ）を求めるＩの値の範囲は、計算次数ｎに応じて変わる。求めるＩの範囲は、照射量密度マップを作成する領域の四辺をＪ_１×（Ｎｍａｘ―ｎ）拡張した領域である。 In the parameter Ρy _n (I) calculation step (S108), the Py calculation unit 67 calculates the parameter Py (I). The parameter Py (I) is an average value of uy (I, i) in the mesh I and is defined by the following equation (9).

The range of the value of I for obtaining Pyn (I) in equation (9) varies depending on the calculation order n. The range of I to be obtained is an area obtained by extending four sides of the area for creating the dose density map by J ₁ × (Nmax−n).

式（１２）中のＪｘは式（１３）で定義される。

式（１１）で、Ｕｘ_ｎ（Ｉ）を求めるＩの範囲は、計算次数ｎに応じて変わる。求めるＩの範囲は、照射量密度マップを作成する領域の四辺をＪ_２×（Ｎｍａｘ−ｎ）拡張した領域である。Ｊについての加算は、―Ｊ_２≦Ｊ≦Ｊ_２を範囲として行う。 Parameter _u n (I, i) in the calculation step (S109), u calculation unit 68 calculates the parameter _u n (I, i). u _n (I, i) is defined by equations (10), (11), and (12).

Jx in the equation (12) is defined by the equation (13).

In Expression (11), the range of I for obtaining Ux _n (I) varies depending on the calculation order n. The range of I to be obtained is an area obtained by extending four sides of the area for creating the dose density map by J ₂ × (Nmax−n). The addition for J is performed in the range of −J ₂ ≦ J ≦ J ₂ .

In Expression (12), the range of I for obtaining δux _n (I, i) varies depending on the calculation order n. The range of I to be obtained is an area obtained by extending four sides of the area for creating the dose density map by J ₁ × (Nmax−n). The addition for j is performed in the range of −J ₁ ≦ J ≦ J ₁ .

In Expression (10), the range of I for obtaining un (I, i) varies depending on the calculation order n. The range of I to be obtained is a region obtained by extending four sides of the region for creating the dose density map by J ₂ × (Nmax−n). When calculating the value of Equation (10), there is no value of δx _n (I, i) depending on the value of I. In that case, the value of δun (I, i) is treated as 0.

  In the adding step (S110), the adding unit 69 adds 1 to n.

判定工程（Ｓ１１２）において、判定部７１は、計算次数が所定のＮｍａｘに達したかどうかを判定する。計算次数が所定のＮｍａｘに達している場合には、照射量計算工程（Ｓ１１５）へと進む。計算次数がまだ所定のＮｍａｘに達していない場合には、ρｎ（Ｉ，ｉ）計算工程（Ｓ１１３）に進む。 In the dn calculation step (S111), the dn calculation unit (irradiation dose density map creation unit) 70 calculates dn, and an nth-order dose density map is created. dn is defined by the following equations (14) and (15).

In the determination step (S112), the determination unit 71 determines whether or not the calculation order has reached a predetermined Nmax. If the calculated order has reached a predetermined Nmax, the process proceeds to the dose calculation step (S115). If the calculation order has not yet reached the predetermined Nmax, the process proceeds to the ρn (I, i) calculation step (S113).

ρｎ（Ｉ，ｉ）を求めるＩの範囲は、計算次数ｎに応じて変わる。求めるＩの範囲は、照射量マップを作成する領域の四辺をＪ_２×（Ｎｍａｘ―ｎ＋１）拡張した領域である。 In the ρn (I, i) calculation step (S113), the ρn calculation unit 72 calculates ρn (I, i) that is the area density map value of the first mesh. ρn (I, i) is defined by the product of ρ ₀ (I, i) and dn (I, i) as in equation (16).

The range of I for obtaining ρn (I, i) varies depending on the calculation order n. The range of I to be obtained is an area obtained by extending four sides of the area for creating the dose map by J ₂ × (Nmax−n + 1).

Ｐｎ（Ｉ，ｉ）を求めるＩの範囲は、計算次数ｎに応じて変わる。求めるＩの範囲は、照射量マップを作成する領域の四辺をＪ_２×（Ｎ_ｍａｘ−ｎ＋１）拡張した領域である。 In the P _n (I) calculation step (S114), the Pn calculation unit 73 calculates P _n (I, i) that is the area density map value of the second mesh. P _n (I) is an average value of ρn (I, i) in the mesh I, and is defined by the following equation (17).

The range of I for obtaining Pn (I, i) varies depending on the calculation order n. The range of I to be obtained is an area obtained by extending four sides of the area for creating the dose map by J ₂ × (N _max −n + 1).

  After S114, the process returns to S107. By repeating S107 to S114, the calculation accuracy can be improved.

照射時間計算工程（Ｓ１１６）において、照射時間演算部７５は、各ショットにおける電子ビーム２００の照射時間Ｔを計算する。照射時間Ｔは照射量密度ＤにＤ_{ｂａｓｅｄｏｓｅ}を掛けたものを電流密度Ｊで除することで求めることができる。算出された照射時間は偏向制御回路１２０に出力される。 In the dose calculation step (S115), the D calculation unit (dose density calculation unit) 74 calculates the dose density D (I, i) of the corresponding mesh by using the obtained d1, d2,. To do. The dose density D (I, i) is defined by the following equation (18).

In the irradiation time calculation step (S116), the irradiation time calculator 75 calculates the irradiation time T of the electron beam 200 in each shot. The irradiation time T can be obtained by dividing the dose density D multiplied by D _basis by the current density J. The calculated irradiation time is output to the deflection control circuit 120.

  In the drawing process (S117), the drawing unit 76 draws a desired pattern in the corresponding mesh region with the irradiation amount obtained for each mesh. Specifically, it operates as follows. The deflection control circuit 120 outputs a digital signal for controlling the irradiation time for each shot to the DAC amplifier unit 130. The DAC amplifier unit 130 converts the digital signal into an analog signal, amplifies it, and applies it to the blanking deflector 212 as a deflection voltage.

  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 with the irradiation time T of each shot.

  The electron beam 200 of each shot generated by passing through the blanking deflector 212 and the blanking aperture 214 as described above illuminates the entire first shaping aperture 203 having a rectangular hole by the illumination lens 202. Here, the electron beam 200 is first shaped into 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. The desired position is irradiated. As described above, a plurality of shots of the electron beam 200 are sequentially deflected onto the sample 101 serving as the substrate by each deflector.

  The calculation process in each frame 20 described above is sequentially performed in real time as the drawing process progresses.

  As described above, according to the first embodiment, it is possible to perform the dose calculation using two different mesh sizes. Thereby, the calculation amount itself can be suppressed and the calculation time can be shortened. As a result, the drawing time can be shortened and the throughput of the apparatus can be improved.

  As mentioned above, although the example of the specific aspect of this invention was demonstrated by Embodiment 1 of this invention, this invention is not limited to the said embodiment.

60 Kernel Creation Unit 61 Kernel Creation Unit 62 Difference Kernel Creation Unit 63 Area Density Calculation Unit 64 Area Density Calculation Unit 65 Setting Unit 66 Uy Calculation Unit 67 Py Calculation Unit 68 u Calculation Unit 69 Addition Unit 70 dn Calculation Unit 71 Determination Unit 72 ρn Calculation unit 73 Dn calculation unit 74 D calculation unit 75 Irradiation time calculation unit 76 Drawing unit 100 Drawing device 101 Sample 102 Electron barrel 103 Drawing room 105 XY stage 110 Control computer 112 Memory 120 Deflection control circuit 130 DAC amplifier unit 140 Storage device 142 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 Deflector 212 Blanking deflector 214 Blanking area Perch 330 Electron beam 340 Sample 410 First aperture 411 Opening 420 Second aperture 421 Variable shaping opening 430 Charged particle source

Claims (6)

A charged particle beam drawing apparatus that irradiates a drawing region of a sample with a charged particle beam and draws a predetermined pattern on the drawing region,
First kernel creation for calculating a value of a first kernel that is a value of a backscattering distribution function in a first mesh obtained by dividing a calculation region for calculating an irradiation dose for forming the predetermined pattern by a first mesh size And
A second kernel that is an average value of the values of the first kernels of a plurality of the first meshes belonging to a second mesh obtained by dividing the calculation region by a second mesh size that is an integral multiple of the first mesh size. A second kernel creation unit for calculating the value of
A difference kernel creation unit for calculating a difference kernel value that is a difference between the value of the first kernel and the value of the second kernel;
Calculating an area density of each first mesh to create a first area density map; calculating an area density of each second mesh to create a second area density map; and
Based on the first area density map and the second area density map, a dose density of each of the first meshes is calculated to create a first dose density map, and the first area density map and the A dose density map creating unit that calculates a dose density of each of the second meshes based on a second area density map and creates a second dose density map;
A first convolution calculation of the map value of the first dose density map and the difference kernel is performed in a first region, and a second value of the map value of the second dose density map and the second kernel is calculated. A convolution calculation unit that performs a convolution calculation in a second region wider than the first region;
A charged particle beam drawing apparatus comprising: A dose density calculation unit for creating a final dose density map based on the first convolution calculation result and the second convolution calculation result;
A drawing unit for drawing the pattern in the drawing region based on the dose density;
The charged particle beam drawing apparatus according to claim 1, further comprising:   The said convolution calculation part uses the said difference kernel according to the position in the 2nd mesh of the 1st mesh which is a convolution center, when performing the said 1st convolution calculation. The charged particle beam drawing apparatus described in 1. A charged particle beam drawing method for irradiating a drawing region of a sample with a charged particle beam and drawing a predetermined pattern on the drawing region,
Calculating a value of a first kernel which is a value of a backscattering distribution function in a first mesh obtained by dividing a calculation region for calculating an irradiation dose for forming the predetermined pattern by a first mesh size;
From the average value of the values of the first kernels of a plurality of the first meshes belonging to the second mesh obtained by dividing the calculation region with a second mesh size that is an integer multiple of the first mesh size, Calculate the value,
Calculating a difference kernel value which is a difference between the value of the first kernel and the value of the second kernel;
Calculating the area density of each of the first meshes to create a first area density map, calculating the area density of each of the second meshes to create a second area density map,
Based on the first area density map and the second area density map, a dose density of each of the first meshes is calculated to create a first dose density map, and the first area density map and the Calculating a dose density of each of the second meshes based on a second area density map to create a second dose density map;
A first convolution calculation of the map value of the first dose density map and the difference kernel is performed in a first region, and a second value of the map value of the second dose density map and the second kernel is calculated. The charged particle beam drawing method, wherein the convolution calculation is performed in a second region wider than the first region. further,
Based on the first convolution calculation result and the second convolution calculation result, create a final dose density map,
The charged particle beam drawing method according to claim 4, wherein the predetermined pattern is drawn in the drawing region based on the final dose density map.   6. The charged particle beam according to claim 4, wherein the first convolution calculation is performed using the difference kernel corresponding to a position in the second mesh of the first mesh which is a convolution center. Drawing method.

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