JP6546437B2 - 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 drawing apparatus and method for predicting a drawing time.

  In recent years, with the high integration of LSI, the circuit line width of a semiconductor device has been further miniaturized. As a method of forming an exposure mask (also referred to as a reticle) for forming a circuit pattern on these semiconductor devices, an electron beam (EB: Electron Beam) drawing technology having excellent resolution is used.

  FIG. 9 is a conceptual diagram for explaining the operation of the variable-shaped electron beam writing apparatus. The variable-shaped electron beam writing apparatus operates as follows. In the first aperture 410, a rectangular opening 411 for forming the electron beam 330 is formed. Further, in the second aperture 420, a variable shaped opening 421 for forming the electron beam 330 which has passed through the opening 411 of the first aperture 410 into a desired rectangular shape is formed. The electron beam 330 emitted from the charged particle source 430 and having passed through the opening 411 of the first aperture 410 is deflected by the deflector and passes through a part of the variable shaped opening 421 of the second aperture 420 to be predetermined. The sample 340 mounted on a stage that moves continuously in one direction (for example, the X direction) is irradiated. That is, a rectangular shape capable of passing both the opening 411 of the first aperture 410 and the variable-shaped opening 421 of the second aperture 420 is a drawing area of the sample 340 mounted on a stage continuously moving in the X direction. It is drawn to. A method of creating an arbitrary shape by passing both the opening 411 of the first aperture 410 and the variable shaped opening 421 of the second aperture 420 is referred to as a variable forming method (VSB method).

  The drawing apparatus predicts a drawing time when drawing a chip pattern, and provides the user with the drawing time (for example, see Patent Document 1). In the case of predicting the drawing time, it is necessary to estimate the number of electron beam shots for forming the pattern to be drawn at a stage before the actual drawing process. Conventionally, the number of shots has been determined by dividing the pattern to be drawn into shot figures of sizes that can be shot using a fixed method. However, with the miniaturization of patterns, there has been a limit in performing highly accurate drawing only by dividing the method of division into shot figures by the same conventional method. Therefore, other division methods with different division positions are being considered. In the future, it is assumed that there will be a difference between the number of shots estimated in the stage before actual drawing processing and the number of shots in actual drawing processing when such another division method is used. Be done. As a result, when making a production plan when drawing a sample such as a mask, a predicted drawing time including an error is used, which causes a problem in creating an efficient production plan.

JP, 2013-171946, A

  As described above, in addition to the case where the method of dividing into shot figures is divided by the same conventional method, other dividing methods are being considered. As one of the other division | segmentation methods, the case where a division | segmentation position sets to the position different from the conventional method can be considered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a drawing apparatus and method capable of acquiring the number of shots with high accuracy even when another method having a division position different from that in the past is used when dividing into shot figures.

The charged particle beam drawing apparatus according to one aspect of the present invention is
A first storage unit storing drawing data in which pattern data of a figure pattern is defined;
A first shot number calculation unit that calculates a first number of shots of the figure pattern when the figure pattern is divided into a plurality of shot figures of sizes that can be shot by the charged particle beam from the end of the figure pattern;
Incremental shot number calculation unit that calculates the number of incremental shots of the figure pattern that is increased due to shifting from the end of the figure pattern to the inside of the figure pattern the division reference position that is the reference position when dividing the figure pattern When,
A second storage unit storing the number of incremental shots of the figure pattern;
The beam shot in the first small area using the first shot number and the incremental shot number for each first small area in the plurality of first small areas into which the drawing area of the sample is virtually divided A second shot number calculation unit that calculates a second shot number;
A drawing time prediction unit that predicts the drawing time using the second number of shots;
A drawing unit for drawing a figure pattern of which drawing time is predicted on a sample using a charged particle beam;
It is characterized by having.

In addition, the drawing unit draws the figure pattern in multiples,
Preferably, the second shot number calculation unit calculates the second shot number in consideration of the multiple drawing.

  Further, the second number of shots is the number of the plurality of small area layers in which the plurality of second small areas into which the drawing area is virtually divided are respectively arranged, and the second part of the plurality of second small areas. The division reference position of the figure pattern of the plurality of small area layers is shifted by the product of the number of drawing repetitions of the small area group and the number of first shots of the figure pattern arranged in the first small area It is preferable that the sum is calculated by the product of the number of small area layers, the number of drawing repetitions of the second small area group, and the number of incremental shots of the figure pattern arranged in the first small area.

  Further, in the case of shifting the division reference position of the figure pattern, it is preferable to shift the division reference position of the figure pattern from the end of the figure pattern to the inside of the figure pattern at a distance less than the maximum shot size.

The charged particle beam drawing method according to one aspect of the present invention is
A graphic pattern in a case where drawing data in which pattern data of a graphic pattern is defined is read out from the first storage device, and the graphic pattern is divided from the end of the graphic pattern into a plurality of shot graphics of a size that can be shot with a charged particle beam. Calculating a first number of shots;
Calculating the number of incremental shots of the figure pattern that is increased due to shifting from the end of the figure pattern to the inside of the figure pattern, the division reference position serving as the reference position when dividing the figure pattern;
Storing the number of incremental shots of the graphic pattern in a second storage device;
The beam shot in the first small area using the first shot number and the incremental shot number for each first small area in the plurality of first small areas into which the drawing area of the sample is virtually divided Calculating a second number of shots;
Predicting the drawing time using the second number of shots;
Drawing a figure pattern of which drawing time is predicted on a sample using a charged particle beam;
It is characterized by having.

  According to one aspect of the present invention, when dividing into shot figures, the number of shots can be obtained with high accuracy even if another method is used in which the dividing position is different from that in the related art. Therefore, the drawing time can be predicted with high accuracy.

FIG. 1 is a conceptual diagram showing a configuration of a drawing device in Embodiment 1. FIG. 5 is a conceptual diagram for describing each region in the first embodiment. FIG. 7 is a flowchart showing the main steps of the drawing method in Embodiment 1. FIG. 8 is a diagram for explaining an example of the number of shots when the rectangular pattern in Embodiment 1 is divided into shots with the division reference position variable. FIG. 8 is a diagram for describing an example of the number of shots when the right isosceles triangle pattern in the first embodiment is divided by making the division reference position variable. 5 is a diagram showing an example of a shot density map in Embodiment 1. FIG. FIG. 7 is a diagram showing an example of a figure allocation method according to the first embodiment. FIG. 7 is a conceptual diagram for illustrating another example of the relationship between the compartment area and the mesh area in the first embodiment. It is a conceptual diagram for demonstrating the operation | movement of a variable shaping | molding type 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 the electron beam, and may be a beam using charged particles such as an ion beam. Also, as an example of the charged particle beam apparatus, a variable-shaped writing apparatus will be described.

Embodiment 1
FIG. 1 is a conceptual diagram showing the 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 drawing apparatus of a variable molding type (VSB system). The drawing unit 150 includes an electron lens barrel 102 and a drawing chamber 103. In the electron lens barrel 102, an electron gun 201, an illumination lens 202, a first aperture 203, a projection lens 204, a deflector 205, a second aperture 206, an objective lens 207, a main deflector 208 and a sub deflector 209 are provided. It is arranged. An XY stage 105 is disposed in the drawing chamber 103. On the XY stage 105, a sample 101 such as a mask to be drawn is arranged at the time of drawing. The sample 101 includes an exposure mask for manufacturing a semiconductor device. The sample 101 also includes mask blanks on which a resist is applied and which has not been drawn yet.

  The control unit 160 includes control computers 110 and 120, a memory 112, a control circuit 130, and storage devices 140, 142, 146, and 148 such as magnetic disk devices. The control computers 110 and 120, the memory 112, the control circuit 130, and the storage devices 140, 142, 146, and 148 are connected to one another via a bus (not shown).

  In the control computer 110, a setting unit 50, a shot number calculation unit 52, an incremental shot number calculation unit 54, a shot density map creation unit 56, a determination unit 58, an SSSFL calculation unit 60, a shot number calculation unit 62, a drawing time prediction unit 64, a shot division unit 66, and an assignment unit 68 are arranged. Setting unit 50, shot number calculation unit 52, incremental shot number calculation unit 54, shot density map creation unit 56, determination unit 58, SSSFL calculation unit 60, shot number calculation unit 62, drawing time prediction unit 64, shot division unit 66, The functions such as the allocating unit 68 may be configured by hardware such as an electric circuit, or may be configured by software such as a program that executes these functions. Alternatively, it may be configured by a combination of hardware and software. Setting unit 50, shot number calculation unit 52, incremental shot number calculation unit 54, shot density map creation unit 56, determination unit 58, SSSFL calculation unit 60, shot number calculation unit 62, drawing time prediction unit 64, shot division unit 66, The information input to and output from the allocation unit 68 and the information being calculated are stored in the memory 112 each time.

  In the control computer 120, a shot data generation unit 40, an irradiation amount calculation unit 42, and a drawing processing unit 43 are disposed. The functions such as the shot data generation unit 40, the irradiation amount calculation unit 42, and the drawing processing unit 43 may be configured by hardware such as an electric circuit, or may be configured by software such as a program that executes these functions. Good. Alternatively, it may be configured by a combination of hardware and software. Information input to and output from the shot data generation unit 40, the irradiation amount calculation unit 42, and the drawing processing unit 43 and information under calculation are stored in a memory (not shown) each time.

  Here, FIG. 1 describes the configuration necessary to explain the first embodiment. The drawing apparatus 100 may generally have other necessary configurations. For example, although two-stage multi-stage deflectors of the main deflector 208 and the sub deflector 209 are used for position deflection, position deflection may be performed by three or more stages of multi-stage deflectors. .

  Drawing data in which data of a chip having a plurality of cells formed of at least one graphic pattern is defined is input from the outside of the drawing apparatus 100 and stored in the storage device 140 (first storage unit). In the chip data, pattern data of each figure pattern indicating the shape, arrangement coordinates, and size of each figure pattern is defined.

  FIG. 2 is a conceptual diagram for explaining each area in the first embodiment. In FIG. 2, the drawing area 10 of the sample 101 is virtually divided into a plurality of stripe areas 20 in a strip shape in the y direction, for example, with a deflectable width of the main deflector 208. Each stripe region 20 is virtually divided into a plurality of sub-fields (SF) 30 (small regions) in a mesh shape with the deflectable size of the sub deflector 209. Here, in order to draw a figure pattern by the drawing apparatus 100, it is necessary to divide each figure pattern defined in the chip data into a shot figure of a size that can be irradiated with one shot of a beam. Then, the shot figure 32 is drawn at each shot position in each SF 30.

  The drawing apparatus 100 advances the drawing processing for each stripe region 20 using the plurality of stages of deflectors. Here, as an example, two-stage deflectors such as a main deflector 208 and a sub deflector 209 are used. The drawing is advanced in the x direction with respect to the first stripe region 20 while the XY stage 105 moves continuously in the −x direction, for example. Then, after the drawing of the first stripe area 20 is finished, the drawing of the second stripe area 20 proceeds in the same or reverse direction. Thereafter, similarly, the drawing of the third and subsequent stripe areas 20 is advanced. Then, the main deflector 208 sequentially deflects the electron beam 200 to the reference position A of the SF 30 so as to follow the movement of the XY stage 105. For the reference position A, for example, the center position of the SF 30 is used. Alternatively, the position of the lower left corner of the SF 30 is also preferable. In addition, the sub-deflector 209 (second deflector) irradiates the shot beam (electron beam 200) shaped into the shot figure 32 to be irradiated into the SF 30 from the reference position A of each SF 30 to a desired position. Bias. Thus, the main deflector 208 and the sub deflector 209 have deflection areas of different sizes.

  The drawing apparatus 100 according to the first embodiment predicts the drawing time taken when drawing a chip as pre-processing before executing the drawing process. In order to predict the drawing time, when the electron beam 200 is deflected by the sub deflector 209 to each shot position in the SF where the number of shots of the electron beam 200, the irradiation time required for one shot, and the pattern are arranged. The sum (shot cycle time) of the settling time (settling time) of an amplifier (not shown) for the sub deflector 209 is required. In addition, the time required for moving the beam between SFs (deflection time), and the time required for moving between the stripe regions are required. In the first embodiment, in particular, the number of shots of the electron beam 200 is calculated with high accuracy.

  FIG. 3 is a flow chart showing main steps of the drawing method in the first embodiment. In FIG. 3, the drawing method in Embodiment 1 includes a parameter setting step (S102), a shot number calculation step (S104), an incremental shot number calculation step (S106), and a shot density map generation step (S108). A series of processes including a determination process (S110), an increment non-shot number calculation process (S112), a drawing time prediction process (S118), and a drawing process (S120) are performed.

  Alternatively, the drawing method in the first embodiment includes a parameter setting step (S102), a shot number calculation step (S104), an incremental shot number calculation step (S106), a shot density map generation step (S108), and a determination step A series of processes including (S110), SSSFL number calculation process (S114), incremental shot number calculation process (S116), drawing time prediction process (S118), and drawing process (S120) are performed.

  That is, some steps differ between the case where the shot shift determined in the determination step (S110) is not performed and the case where the shot shift is performed.

  FIG. 4 is a diagram for explaining an example of the number of shots when the rectangular pattern in the first embodiment is divided by changing the dividing reference position. In the example of FIG. 4, a rectangular pattern is shown as an example of the figure pattern. In the first embodiment, at the time of performing multiple drawing, the division reference position which is the reference position in the case of dividing the figure pattern into shots is made variable. In other words, multiple drawing is performed in which paths in which shot shift is not performed and paths in which shot shift are performed are mixed. By mixing the path in which the shot shift is not performed and the path in which the shot shift is performed, it is possible to average the boundary shift error between the shot figures and improve the connection accuracy between the shot figures.

  In the first embodiment, although the case where the number of shots is calculated on the premise of multiple drawing is described below, the present invention is not limited to this. The following method can be applied to the calculation of the number of shots at the time of shot shift even when multiple drawing is not performed.

For example, as shown in FIG. 4A, the first pass shows the case where the end of the rectangular pattern is used as a division reference position, and the end is divided into a plurality of shot figures of a size that can be shot with the electron beam 200 from the end. ing. In other words, in the example of FIG. 4A, the case where shot shift is not performed is shown. In the example of FIG. 4 (a), the left lower end of the rectangular pattern as a dividing reference position O _1, is performed shots divided into x and y directions. In the x direction, two divisions are performed with the preset maximum shot size, and a division is performed in which the remaining area smaller than twice the maximum shot size is divided into halves. In the y direction, three divisions are performed with the preset maximum shot size, and divisions in which the remaining area smaller than twice the maximum shot size is divided into halves are shown. As a result, the rectangular pattern is divided into twenty shot figures by the shot division.

Next, for example, as shown in FIG. 4B, in the second pass, as shown in FIG. 4B, the rectangular pattern has only a quarter of the maximum shot size in the x direction from the end of the rectangular pattern and a quarter of the maximum shot size in the The case where the position shifted from the end to the inside of the rectangular pattern is used as the division reference position. The case of dividing into a plurality of shot figures of sizes that can be shot by the electron beam 200 from the divided reference position shifted in the x and y directions by 1/4 from the end portion is shown. In other words, in the example of FIG. 4B, the case where shot shift is performed in the x and y directions by 1⁄4 of the maximum shot size from the end portion is shown. In the example of FIG. 4 (b), from the lower left end of the rectangular pattern by a 1/4 of the maximum shot size x, a position shifted in the y-direction as divided reference position O _2, carried out shots divided into x and y directions ing. In the x direction, two divisions with the preset maximum shot size and the third division size shown in FIG. 4A (1/2 the size of the remaining area in the division in FIG. 4A) And the remaining area and the left end area generated by the shot shift. In the y direction, three divisions with the preset maximum shot size and the third division size shown in FIG. 4A (1/2 of the remaining area in the division in FIG. 4A) It shows the case where it is divided into four divided areas formed by division in size), and the remaining area and the lower end area generated by the shot shift. As a result, the rectangular pattern is divided into 30 shot figures by the shot division. That is, the number of incremental shots is 10 as compared with the case without shot shift (in the case of FIG. 4A).

  Note that four divided areas are formed in the x direction by two divisions with a preset maximum shot size and divisions in which the remaining area smaller than twice the maximum shot size is halved. It may be divided into the left end region generated by the shot shift. Similarly, five divided areas formed by three divisions with a preset maximum shot size in the y direction and divisions in which the remaining area smaller than twice the maximum shot size is divided into halves And the lower end region generated by the shot shift.

Next, for example, as shown in FIG. 4C, for the third pass, as shown in FIG. 4C, the rectangular pattern has a half of the maximum shot size in the x direction from the end of the rectangular pattern and a quarter of the maximum shot size in the y The case where the position shifted from the end to the inside of the rectangular pattern is used as the division reference position. The figure shows the case of dividing into a plurality of shot figures of sizes that can be shot by the electron beam 200 from the division reference position shifted by 1/2 in the x direction and 1/4 in the y direction from the end. In other words, in the example of FIG. 4C, the case of performing a 1/2 shot shift of the maximum shot size in the x direction from the end and a 1/4 shot shift of the maximum shot size in the y direction is shown. In the example of FIG. 4C, the division reference position O ₃ is a position shifted by 1/2 of the maximum shot size in the x direction from the lower left end of the rectangular pattern and 1⁄4 of the maximum shot size in the y direction. Shot division is performed in the direction and y direction. In the x direction, two divisions with the preset maximum shot size and the third division size shown in FIG. 4A (1/2 the size of the remaining area in the division in FIG. 4A) And the remaining area and the left end area generated by the shot shift. In the y direction, three divisions with the preset maximum shot size and the third division size shown in FIG. 4A (1/2 of the remaining area in the division in FIG. 4A) It shows the case where it is divided into four divided areas formed by division in size), and the remaining area and the lower end area generated by the shot shift. As a result, the rectangular pattern is divided into 30 shot figures by the shot division. That is, the number of incremental shots is 10 as compared with the case without shot shift (in the case of FIG. 4A).

  Note that four divided areas are formed in the x direction by two divisions with a preset maximum shot size and divisions in which the remaining area smaller than twice the maximum shot size is halved. It may be divided into the left end region generated by the shot shift. Similarly, five divided areas formed by three divisions with a preset maximum shot size in the y direction and divisions in which the remaining area smaller than twice the maximum shot size is divided into halves And the lower end region generated by the shot shift.

Next, for example, as shown in FIG. 4D, the fourth pass has a rectangular pattern that is 3⁄4 of the maximum shot size in the x direction and 1⁄4 of the maximum shot size in the y direction from the end of the rectangular pattern. The case where the position shifted from the end to the inside of the rectangular pattern is used as the division reference position. The figure shows the case of dividing into a plurality of shot figures of sizes that can be shot by the electron beam 200 from the division reference position shifted from the end by 3/4 in the x direction and 1/4 in the y direction. In other words, in the example of FIG. 4D, the case of performing 1⁄4 shot shift of the maximum shot size in the y direction and 3⁄4 of the maximum shot size in the x direction from the end is shown. In the example of FIG. 4D, the division reference position O ₄ is a position shifted by 3⁄4 of the maximum shot size in the x direction from the lower left end of the rectangular pattern and 1⁄4 of the maximum shot size in the y direction. Shot division is performed in the direction and y direction. In the x direction, four divided areas are formed by two divisions with a preset maximum shot size and divisions in which the remaining area smaller than twice the maximum shot size is halved, and the shot It shows the case where it is divided into the left end region generated by the shift. In the y direction, three divisions with the preset maximum shot size and the third division size shown in FIG. 4A (1/2 of the remaining area in the division in FIG. 4A) It shows the case where it is divided into four divided areas formed by division in size), and the remaining area and the lower end area generated by the shot shift. As a result, the rectangular pattern is divided into 30 shot figures by the shot division. That is, the number of incremental shots is 10 as compared with the case without shot shift (in the case of FIG. 4A).

  Note that five divided areas are formed in the y direction by three divisions with a preset maximum shot size and divisions in which the remaining area smaller than twice the maximum shot size is halved. It may be divided into the lower end region generated by the shot shift.

As described above, when the division reference position is shifted to the inside of the figure pattern with a size smaller than the maximum shot size (shot shift), the number of incremental shots to be increased can be made the same regardless of the shift amount. . In general, the rectangular pattern can be defined as follows when the number of divisions in the x and y directions (the number of shot figures after division) without shot shift is n and m, respectively.
(1) When n> 1 and m> 1, the number of incremental shots is n + m + 1.
(2) When n> 1 and m = 1, the number of incremental shots is one.
(3) In the case of n = 1 and m> 1, the number of incremental shots is one.
(4) When n = 1 and m = 1, the number of incremental shots is zero.

  FIG. 5 is a diagram for explaining an example of the number of shots in the case of dividing the right isosceles triangle pattern according to the first embodiment into shots while making the dividing reference position variable. In the example of FIG. 5, a right triangle pattern is shown as an example of the figure pattern.

For example, as shown in FIG. 5A, in the first pass, the end of the right-angled isosceles triangle pattern is divided into a plurality of shot figures of a size that can be shot by the electron beam 200 from the end. The case is shown. In other words, in the example of FIG. 5A, the case where shot shift is not performed is shown. In the example of FIG. 4A, shot division is performed in the x direction and the y direction with the lower left end (right angle position) of the rectangular pattern as the division reference position O ₁ ′. In the x direction, a case is shown in which the base is divided into three divided areas of the maximum shot size by two divisions with the preset maximum shot size. In the y direction, the case of dividing into three divided areas of the maximum shot size by two divisions with the preset maximum shot size is shown. As a result, three rectangular patterns and three right isosceles triangle patterns are divided into a total of six shot figures by the shot division.

Next, for example, as shown in FIG. 5 (b), the second pass is 0 in the x direction from the end of the rectangular isosceles triangle pattern and 1⁄4 of the maximum shot size in the y direction. The case where the position shifted from the end to the inside of the right-angled isosceles triangle pattern is used as the division reference position. The figure shows the case of dividing into a plurality of shot figures of sizes that can be shot by the electron beam 200 from the division reference position shifted in the x and y directions by (0,1 / 4) from the end. In other words, in the example of FIG. 5B, the case where the shot shift is performed in the y direction by 1⁄4 of the maximum shot size from the end portion is shown. In the example of FIG. 5 (b), as the divided reference position O ₂ to a position obtained by 1/4 shifted in the y-direction of the maximum shot size from the lower left end of the right-angled isosceles triangle pattern, the shot segmentation in the x and y directions Is going. In the x direction, the base is divided into three divided areas of the maximum shot size and the remaining one divided area at the base by three divisions with a preset maximum shot size. In the y direction, the left side is divided into two divided areas of the maximum shot size, the remaining one divided area, and the lower end area generated by the shot shift by the division twice with the preset maximum shot size. As a result, by the shot division, six rectangular patterns and a right-angled isosceles triangle pattern are divided into four, ie, a total of ten shot figures. That is, the number of incremental shots is four as compared with the case without shot shift (in the case of FIG. 5A).

Next, for example, as shown in FIG. 5C, the third pass is a right-angled isosceles triangle by 1⁄2 in the x direction from the end of the right-angled isosceles triangle pattern and 1⁄2 of the maximum shot size in the y direction. The case where the position shifted from the end of the pattern to the inside of the rectangular isosceles triangle pattern is used as the division reference position. The figure shows the case of dividing into a plurality of shot figures of sizes that can be shot by the electron beam 200 from the division reference position shifted in the x and y directions by (1/2, 1/2) from the end. In other words, in the example of FIG. 5C, the case where shot shift is performed in the x and y directions by 1⁄2 of the maximum shot size from the end portion is shown. In the example of FIG. 5C, a position shifted in the x and y directions by 1/2 of the maximum shot size from the lower left end of the right-angled isosceles triangle pattern is taken as the divided reference position O ₃ and shot in the x and y directions It is divided. In the x direction, division is performed twice at a preset maximum shot size into two divided areas of the maximum shot size at the base, one remaining divided area, and a left end area generated by the shot shift. In the y direction, the left side is divided into two divided areas of the maximum shot size, the remaining one divided area, and the lower end area generated by the shot shift by the division twice with the preset maximum shot size. As a result, by the shot division, six rectangular patterns and a right-angled isosceles triangle pattern are divided into four, ie, a total of ten shot figures. That is, the number of incremental shots is four as compared with the case without shot shift (in the case of FIG. 5A).

Next, for example, as shown in FIG. 5D, the fourth pass is a right-angled isosceles triangle from the end of the right-angled isosceles triangle pattern by 1/2 in the x direction and 3/4 of the maximum shot size in the y direction. The case where the position shifted from the end of the pattern to the inside of the rectangular isosceles triangle pattern is used as the division reference position. The figure shows the case of dividing into a plurality of shot figures of sizes that can be shot by the electron beam 200 from the division reference position shifted in the x and y directions by (1/2, 3/4) from the end. In other words, in the example of FIG. 5D, the case where shot shift is performed in the x and y directions by 1⁄2 of the maximum shot size from the end portion is shown. In the example of FIG. 5C, a divided reference position O is a position shifted in the y direction by 3/4 of the maximum shot size in the x direction by 1/2 of the maximum shot size from the lower left end of the right-angled isosceles triangle pattern. _{As 4} , the shot division is performed in the x direction and the y direction. In the x direction, division is performed twice at a preset maximum shot size into two divided areas of the maximum shot size at the base, one remaining divided area, and a left end area generated by the shot shift. In the y direction, the left side is divided into two divided areas of the maximum shot size, the remaining one divided area, and the lower end area generated by the shot shift by the division twice with the preset maximum shot size. As a result, by the shot division, six rectangular patterns and a right-angled isosceles triangle pattern are divided into four, ie, a total of ten shot figures. That is, the number of incremental shots is four as compared with the case without shot shift (in the case of FIG. 5A).

As described above, when the division reference position is shifted to the inside of the figure pattern with a size smaller than the maximum shot size (shot shift), the number of incremental shots to be increased can be made the same regardless of the shift amount. . In general, if the number of divisions in the x and y directions without shot shift (the number of shot figures after division) is n, the number of incremental shots can be defined as follows: .
(1) In the case of n> 1, the number of incremental shots is n + 1.
(2) In the case of n = 1, the number of incremental shots is zero.

  As described above, when the division reference position is shot shifted to the inside of the figure pattern with a size smaller than the maximum shot size, the number of incremental shots to be increased can be made the same regardless of the shift amount. In other words, the number of incremental shots can be made the same regardless of how the shot figure is cut. Therefore, in the first embodiment, when the division reference position of the figure pattern is shifted, the division reference position of the figure pattern is shifted from the end of the figure pattern to the inside of the figure pattern at a distance less than the maximum shot size.

  Moreover, in the example mentioned above, although the case where the shift amount of each path | path mutually differs was shown, it does not restrict to this. Among the plurality of paths, at least one path may be different from the other. Also, there may be a path with the same shot shift amount.

  In the parameter setting step (S102), the setting unit 50 sets each parameter in the case of performing multiple drawing. For example, drawing processing (1) which repeatedly draws while shifting the position by stripe area 20 units, SF 30 of one column in the width (short side) direction of stripe area 20 in stripe area 20 is set as SF group (SFGR) Multiple drawing is performed combining drawing processing (2) for drawing repeatedly without shifting the position in units of SF groups. At that time, as the parameters, the number of drawing times (number of SF layers) of drawing process (1) and the number of times drawing (SF group repetition number) of drawing process (2) are set. In addition, when using the shot shift function, it is set which shift amount the shift reference position should be shifted by which drawing processing. For example, it is preferable to set for each pass of drawing processing (1) for creating an SF layer for each pass.

  In the shot number calculation step (S104), first, the shot division unit 66 reads corresponding drawing data from the storage device 140 for each stripe region 20 or each frame region obtained by virtually dividing the chip region into strips, for example. Each figure pattern is divided into a plurality of shot figures of sizes that can be shot by the electron beam 200 from the end of the figure pattern for each pattern. The division method is, as described above, with the lower left end of the figure pattern as the division reference position, for example, division at the maximum shot size in the x direction, and the remainder is smaller than twice the maximum shot size Divide into halves. Similarly, for example, division is performed in the y direction at the maximum shot size, and when the remainder is smaller than twice the maximum shot size, the remainder is divided in half.

  Then, the shot number calculation unit 52 (first shot number calculation unit) divides the figure pattern into a plurality of shot figures of sizes that can be shot by the electron beam from the edge of the figure pattern (the number of shots of the figure pattern ( Calculate the first shot number). For example, the number of shots (first number of shots) is calculated by counting the number of shot figures divided for each figure pattern. The calculated number of shots of the figure pattern is stored in the storage device 142 (second storage unit).

  In the incremental shot number calculation step (S106), the incremental shot number calculation unit 54 is caused to shift the division reference position serving as the reference position when dividing the figure pattern from the end of the figure pattern to the inside of the figure pattern. Calculate the number of incremental shots of the graphic pattern to be increased. The incremental shot number is calculated for each figure pattern. As described above, if the figure type and the division number n, m in the x, y directions are determined, the incremental shot number can be calculated. If the size of the figure pattern is known, the division number n, m is determined. Therefore, the number of incremental shots can be calculated according to the type and size of the figure pattern. The calculated incremental shot number of the graphic pattern is stored in the storage device 142 (second storage unit).

  In the shot density map creating step (S108), the shot density map creating unit 56 sets the drawing area 10 (or chip area) of the sample 101 for each mesh area in a plurality of mesh areas (first small areas) virtually divided. Create a shot density map that defines the number of SFs, the number of shots, and the number of incremental shots. The created shot density map is stored in the storage unit 144.

  FIG. 6 is a diagram showing an example of a shot density map in the first embodiment. FIG. 6A shows an example of a shot density map in the entire drawing area 10 (or chip area). Each mesh area 12 which comprises a shot density map shows the area | region of several adjacent SF30. It consists of a × b SFs 30. In the example of FIG. 6B, it is configured by 4 × 4 16 SFs 30. The mesh area 12 is preferably adjusted to (1 / k) times (k is a natural number) times the compartment (CPM) area obtained by dividing the stripe area 20 toward the long side. For example, it is preferable that the CPM region is configured by 4 × 4 16 SFs 30. Once the drawing time in the CPM area is determined, the stage speed in the CPM area can be calculated and set.

  In the example of FIG. 6, an example of the shot density map in the entire drawing area 10 (or chip area) is shown, but first, a shot density map of 20 stripe areas (or frame units of chips) is created, and then Preferably, shot density maps of 20 units of stripe areas (or frame units of chips) are merged to create shot density maps of the entire drawing area 10 (or chip area).

  First, for each figure pattern, the assignment unit 68 assigns the figure pattern to the mesh area 12 at a position to which the reference position (for example, the lower left end) of the figure pattern belongs. Then, the shot density map creation unit 56 reads out the number of shots of the figure pattern allocated to the mesh area 12 from the storage device 142 for each mesh area 12, and is allocated to the mesh area 12 for each mesh area 12. Sum the number of shots of the figure pattern. Similarly, the incremental shot number of the figure pattern allocated to the mesh area 12 is read out from the storage unit 142, and the incremental shot number of the figure pattern allocated to the mesh area 12 is summed up for each mesh area 12. Then, in accordance with the format shown in the example of FIG. 6C, the number of SFs, the number of shots, and the number of incremental shots are defined for each mesh area 12. For example, a storage capacity of 24 bytes is allocated to each mesh area 12. Then, 4 bytes are defined as the SF number, 8 bytes as the total shot number of the rectangular shot figure, 8 bytes as the total shot number of the triangular shot figure, and the total incremental shot number is defined using the remaining 4 bytes. As a result, when performing the shot shift, it is possible to eliminate the need to separately create a shot density map each time the division position is shifted. For example, it is possible to eliminate the need to create a shot density map separately for each SF layer. Creating separate shot density maps requires a significant increase in storage device capacity. However, in the first embodiment, since the incremental shot number can be defined for each figure pattern regardless of the shift amount, the shot density map for one drawing area 10 (or one chip area) (or one SF layer) can be used. it can. Therefore, it is possible to eliminate the need for a significant capacity increase of the storage device. Furthermore, since the shot number calculation is not performed for each shift amount of the shot shift, the calculation time can be significantly reduced.

  FIG. 7 is a diagram showing an example of a figure allocation method according to the first embodiment. In the example described above, the figure pattern is allocated to the mesh area 12 at the position to which the reference position (for example, the lower left end) of the figure pattern belongs for each figure pattern, but the present invention is not limited thereto. As shown in FIG. 7, it is also preferable to assign the figure pattern to the SF 30 of the position to which the reference position 34 (for example, the lower left end) of the shot figure belongs for each shot figure 33. Then, the number of shots of the figure pattern assigned to the plurality of SFs 30 corresponding to the mesh area 12 may be totaled for each mesh area 12. However, since there is no corresponding shot figure for the incremental shot number, the incremental shot number of the figure pattern may be allocated to the mesh area 12 of the position to which the reference position (for example, the lower left end) of the figure pattern belongs.

  FIG. 8 is a conceptual diagram for explaining another example of the relationship between the compartment area and the mesh area in the first embodiment. In the example of FIG. 6A, the mesh area 12 is aligned with the compartment (CPM) area obtained by dividing the stripe area 20 toward the long side, but the present invention is not limited to this. As shown in FIG. 8, it is preferable that the size of the CPM region 14 is configured by a plurality of mesh regions 12. In the example of FIG. 8, for example, the case where the CPM region 14 is configured by the 2 × 2 mesh region 12 is shown.

  In the determination step (S110), the determination unit 58 determines whether to use the shot shift function when drawing the sample 101 this time. Specifically, it is determined that the shot shift function is to be used if it is set in which drawing process the shift reference position is to be shifted by what shift amount. If not set, it is determined that the shot shift function is not used. If the shot shift function is not used, the process proceeds to the step for calculating the number of shots without increment (S112). If the shot shift function is to be used, the process proceeds to the SSSFL number calculation step (S114).

  When the shot number calculation unit 62 (an example of the second shot number calculation unit) does not use the shot shift function as the shot number calculation step without increment (S112), each shot mesh area 12 (or CPM area) of the shot density map The number of shots (second number of shots) of the beam shot in the mesh area 12 (or CPM area) is calculated using the defined number of shots. Here, the number of shots in consideration of multiple drawing is calculated. Specifically, when the shot number calculation unit 62 does not use the shot shift function, the number of SF layers (the number of SFLs), the number of repetitions of the SF group (the number of SFGRs), and the number of shots defined in the mesh area 12 The product is calculated as the number of shots in consideration of multiple drawing.

  In the SSSFL number calculation step (S114), the SSSFL calculation unit 60 reads the set parameter and calculates the number of SF layers to be shot-shifted (the number of SSSFLs). As described above, when performing multiple drawing, shot shift is not performed in all the passes of drawing processing (1). Therefore, here, the number of SF layers (number of SSSFLs) to be shot-shifted is calculated among the number of times of drawing (number of SF layers) of the drawing process (1).

When the shot number calculation unit 62 (an example of the second shot number calculation unit) uses the shot shift function as the incremental shot number calculation step (S116), each shot mesh area 12 (or CPM area) of the shot density map is used. The number of shots of the beam shot in the mesh area 12 (or CPM area) (first small area) using the defined number of shots (first number of shots) and the number of incremental shots (second number Calculate the number of shots). Here, the number of shots in consideration of multiple drawing is calculated. Specifically, the number (the number of SFLs) of the plurality of SF layers (small area layers) in which the plurality of SFs 30 (second small areas) in which the drawing area 10 (or chip area) is virtually divided is arranged The drawing repetition number (SFGR number) of a part of the SF group (second small area group) of the SFs 30 (second small area) and the graphic disposed in the mesh area 12 (first small area) The product of the number of shots of the pattern (the number of first shots), the number of SF layers to which the division reference position of the figure pattern is shifted among the plurality of SF layers (the number of SSSFLs), the number of SFGRs, and the mesh area 12 The sum of the product of the graphic pattern to be arranged and the number of incremental shots is calculated. The number of shots in the mesh area 12 when using the shot shift function is specifically defined by the following equation (1).
(1) Number of shots = number of SFLs / number of SFGRs / number of shots
+ Number of SSSFLs, number of SFGRs, number of incremental shots

In the drawing time prediction step (S118), the drawing time prediction unit 64 predicts the drawing time using the calculated number of shots (the second number of shots). Specifically, for example, the drawing time prediction unit 64 calculates the shot cycle time (one irradiation time and one for the sub-deflector 209) in the calculated number of shots Ntotal (the second number of shots) for each mesh region 12. The time (shot cycle total time Ts) taken for the shot of the mesh area 12 is calculated by multiplying the sum of settling times of a digital-to-analog conversion (DAC) amplifier (not shown). The total shot number Ntotal is the sum of the irradiation time t 'of the shot of each beam and the settling time (settling time) ts of a not-shown DAC amplifier that applies a deflection voltage to the sub deflector 209. It can be calculated (predicted) by the following equation (2) as a multiplied value. The irradiation time t ′ may be variable for each shot by correction such as proximity effect, but here, it may be approximated by the maximum irradiation time in one shot. The settling time ts may be a constant value.
(2) Ts = (t '+ ts) Ntotal

  Further, for example, the drawing time prediction unit 64 has a value obtained by multiplying the number of SFs by the deflection time (the settling time of the not-shown DAC amplifier for the main deflector 208) for moving between the SFs 30 for each mesh region 12 ( Calculate the product). Also, for example, the total of the moving time taken when moving between the stripe regions 20 is calculated.

  Then, for example, the drawing area is calculated by calculating the sum of the product of the time taken for shots in each mesh area 12 and the deflection time and the number of SFs required for moving between the SFs 30 and the movement time between the stripe areas 20. Predict the drawing time for the entire 10 The predicted drawing time is stored in the storage unit 146.

  The drawing time prediction unit 64 may predict the drawing time for each stripe area. In such a case, for example, the sum of the time taken for the shot of each mesh area 12 and the deflection time taken for moving between SFs 30 of each mesh area 12 may be calculated for each stripe area. In the first embodiment, since the drawing time is predicted using the number of shots (the second number of shots) in consideration of the number of incremental shots, a highly accurate drawing time can be predicted.

  Then, after such drawing time prediction is performed, the drawing process is actually advanced for the chip defined in the drawing data.

  In the drawing step (S120), the drawing unit 150 draws a figure pattern of which drawing time is predicted on the sample 101 using the electron beam 200. Specifically, it operates as follows.

  First, as a shot data generation process, the shot data generation unit 40 reads chip data from the storage device 140, performs data conversion processing of a plurality of stages, and generates shot data unique to the apparatus. As described above, in order to draw a graphic pattern by the drawing apparatus 100, it is necessary to divide each graphic pattern defined in the drawing data into a size that can be irradiated with one shot of a beam. Therefore, the shot data generation unit 40 generates shot figures by dividing each figure pattern into a size that can be irradiated with one shot of a beam in order to actually draw. Then, shot data is generated for each shot figure. In the shot data, for example, graphic data such as graphic type, graphic size, and irradiation position are defined. The generated shot data is stored in the storage device 148. Shot data is generated for each pass of drawing processing (1) in multiple drawing. The same shot data may be repeatedly used for the drawing process (2) in which the position is not shifted.

  On the other hand, as the irradiation amount calculation step, the irradiation amount calculation unit 42 calculates the irradiation amount for each mesh area of a predetermined size. The dose can be calculated using a value obtained by multiplying the reference dose Dbase by a correction coefficient. As the correction coefficient, for example, it is preferable to use a fogging effect correction irradiation coefficient Df (ρ) for correcting fogging effect. The fogging effect correction irradiation coefficient Df ()) is a function depending on the pattern density ρ of the fogging mesh. Since the influence radius of the fogging effect is several mm, it is preferable to set the size of the fogging mesh to about 1/10 of the radius of influence, for example, 1 mm, in order to perform the correction operation. In addition, it is preferable that the irradiation amount be corrected with a correction coefficient for proximity effect correction, a correction coefficient for loading correction, or the like. Also in these corrections, the pattern density in the mesh area for each calculation is used. The pattern density calculated in each layer described above may be used also for these pattern densities. Then, the dose computing unit 42 creates a dose map in which each computed dose is defined for each region. As described above, in the first embodiment, the pattern density ρ can be obtained with high accuracy even with respect to the pattern density 行 う at the time of performing the dose correction, so it is possible to calculate the dose corrected more accurately. . The generated dose map is stored in the storage device 148.

  Then, the drawing processing unit 43 outputs a control signal to the control circuit 130 so as to perform drawing processing. The control circuit 130 inputs the shot data and the irradiation amount map from the storage unit 146, and controls the drawing unit 150 according to the control signal from the drawing processing unit 43. The drawing unit 150 controls the electron beam 200 with the main deflector 208 and the sub deflector A plurality of figure patterns in the chip 44 are drawn on the sample 101 while performing multistage deflection with the multistage deflector of the unit 209. Specifically, it operates as follows.

  The electron beam 200 emitted from the electron gun 201 (emission unit) illuminates the entire first aperture 203 having a rectangular, for example, 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 aperture 203 is projected onto the second aperture 206 by the projection lens 204. The first aperture image on the second aperture 206 is deflection-controlled by the deflector 205 so that the beam shape and size can be changed (variablely shaped). Then, the electron beam 200 of the second aperture image that has passed through the second aperture 206 is focused by the objective lens 207, deflected by the main deflector 208 and the sub deflector 209, and continuously moved. It irradiates to the desired position of the sample 101 arrange | positioned at. FIG. 1 shows the case where multistage deflection of two stages of main and sub stages is used for position deflection. In such a case, the main deflector 208 deflects the electron beam 200 of the corresponding shot while following the stage movement to the reference position A of the SF 30, and the sub deflector 209 deflects the beam of the corresponding shot over each irradiation position in the SF 30. It suffices to deflect. Further, the drawing process (2) is repeated by the number of repetitions for each SF group for one column in the direction of the short side of the stripe region 20. Further, the drawing process (1) is repeated for the SF layer while sequentially shifting the position for each SF group. This allows multiple drawing to proceed.

  As described above, according to the first embodiment, when dividing into shot figures, it is possible to acquire the number of shots with high accuracy even when another method having a dividing position different from the conventional one is used. Therefore, the drawing time can be predicted with high accuracy.

  The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In the example described above, it is assumed that the case of performing shot shift and the case of not performing shot shift in multiple drawing are mixed, but the present invention is not limited to this. Even when drawing a sample in a single drawing process without performing multiple drawing, when the division reference position is shifted from the end of the figure pattern to the inside, the above-described method is applied to the calculation of the number of shots. it can.

  In addition, although descriptions are omitted for parts that are not directly necessary for the description of the present invention, such as the device configuration and control method, the required device configuration and 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 necessary control unit configuration is appropriately selected and used.

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

10 drawing area 12 mesh area 14 CPM area 20 stripe area 30 SF
32, 33 shot figure 34 reference position 40 shot data generation unit 42 irradiation amount calculation unit 43 drawing processing unit 50 setting unit 52 shot number calculation unit 54 incremental shot number calculation unit 56 shot density map generation unit 58 determination unit 60 SSSFL calculation unit 62 Shot number calculation unit 64 Drawing time prediction unit 66 Shot division unit 68 Allocation unit 100 Drawing device 101, 340 Sample 102 Electronic lens barrel 103 Drawing room 105 XY stage 110, 120 Control computer 112 Memory 130 Control circuit 140, 142, 146, 148 Storage device 150 Drawing unit 160 Control unit 200 Electron beam 201 Electron gun 202 Illumination lens 203, 410 First aperture 204 Projection lens 205 Deflector 206, 420 Second aperture 207 Objective lens 208 Main deflector 209 Secondary deflector 330 Electron line 411 aperture 421 variable shaped aperture 430 charged particle source

Claims (5)

A first storage unit storing drawing data in which pattern data of a figure pattern is defined;
A first shot number calculation unit that calculates a first number of shots of the figure pattern when the figure pattern is divided from the end of the figure pattern into a plurality of shot figures of sizes that can be shot with a charged particle beam;
An increment for calculating the number of incremental shots of the figure pattern, which increases due to shifting from the end of the figure pattern to the inside of the figure pattern, which is the reference position when dividing the figure pattern. A shot number calculation unit,
A second storage unit storing the number of incremental shots of the graphic pattern;
The sample drawing area is shot in the first small area using the first shot number and the incremental shot number for each first small area in the plurality of first small areas into which the sample division area is virtually divided. A second shot number calculator for calculating a second shot number of the beam;
A drawing time prediction unit that predicts drawing time using the second number of shots;
A drawing unit for drawing the figure pattern of which drawing time is predicted on a sample using a charged particle beam;
A charged particle beam drawing apparatus comprising: The drawing unit performs multiple drawing of the figure pattern,
The charged particle beam drawing apparatus according to claim 1, wherein the second shot number calculation unit calculates the second shot number in consideration of multiple drawing.   The second shot number may be the number of a plurality of small area layers in which the plurality of second small areas into which the drawing area is virtually divided may be respectively disposed, and a part of the plurality of second small areas. A product of the number of drawing repetitions of two small area groups and the first shot number of the figure pattern arranged in the first small area, and the division reference position of the figure pattern of the plurality of small area layers is Calculated by the sum of the number of small area layers to be shifted, the product of the number of drawing repetitions of the second small area group, and the number of incremental shots of the figure pattern arranged in the first small area. The charged particle beam drawing apparatus according to claim 2, characterized in that   When shifting the division reference position of the figure pattern, the division reference position of the figure pattern is shifted from the end of the figure pattern to the inside of the figure pattern at a distance less than the maximum shot size. The charged particle beam drawing apparatus in any one of 1-3. The drawing data in which pattern data of a figure pattern is defined is read out from the first storage device, and the figure pattern is divided from the end of the figure pattern into a plurality of shot figures which can be shot by charged particle beams. Calculating a first number of shots of the figure pattern;
Calculating an incremental number of shots of the figure pattern which is increased due to shifting from the end of the figure pattern to the inside of the figure pattern, which is a reference position when dividing the figure pattern; When,
Storing the incremental shot number of the graphic pattern in a second storage device;
The sample drawing area is shot in the first small area using the first shot number and the incremental shot number for each first small area in the plurality of first small areas into which the sample division area is virtually divided. Calculating a second number of shots of the beam;
Predicting a drawing time using the second number of shots;
Drawing the figure pattern of which drawing time is predicted on a sample using a charged particle beam;
A charged particle beam drawing method comprising:

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