JP6587887B2 - 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 for example, relates to a method for setting an irradiation amount of each pixel in multi-beam drawing and raster scan drawing.

  Lithography technology, which is responsible for the progress of miniaturization of semiconductor devices, is an extremely important process for generating a pattern among semiconductor manufacturing processes. In recent years, with the high integration of LSI, circuit line widths required for semiconductor devices have been reduced year by year. Here, the electron beam (electron beam) drawing technique has an essentially excellent resolution, and a mask pattern is drawn on a mask blank using an electron beam.

  For example, there is a drawing apparatus using a multi-beam. Compared with the case of drawing with one electron beam, the use of multi-beams enables irradiation with many beams at a time, so that the throughput can be significantly improved. In such a multi-beam type drawing apparatus, for example, an electron beam emitted from an electron gun is passed through a mask having a plurality of holes to form a multi-beam, and each of the unshielded beams is blanked. The image is reduced by the optical system, the mask image is reduced, deflected by the deflector, and irradiated to a desired position on the sample.

  Here, for example, since the variable shaped beam drawing apparatus can irradiate a beam having a specific shape at a desired position, the pattern edge position and the beam edge position can be drawn. On the other hand, in a multi-beam drawing apparatus in which the irradiation position of each beam cannot be freely controlled, the drawing target area is divided into a plurality of pixels and the drawing target pattern is converted into a pixel pattern (also referred to as a bit pattern). A pixel pattern is drawn. Therefore, it is difficult to make the pattern end correspond to the position of the beam end for all patterns. For this reason, in the multi-beam drawing apparatus, it is desired to adjust the irradiation amount of the beam that irradiates the pixel on which the pattern end is applied so that the pattern end is formed at a desired position. Here, as a method for determining the irradiation amount of each pixel, conventionally, as a first method, there is a method in which the beam irradiation amount is proportional to the pattern area density in the pixel. Similar to the first approach, for example, some pixels in the exposed area are exposed to 100 percent gray level, while others are not fully matched to the pattern area density. Only 50% of the gray level is exposed. A technique is disclosed in which the remaining pixels are exposed to a dose of 0 percent (see, for example, Patent Document 1). In addition, as a second method, there is a method of irradiating a beam with a dose of 100% if the center point of the pixel is in the pattern, and not irradiating the beam if not.

  Here, in the first method, if multiple drawing is not performed while shifting the position, it is possible to make the gradient of the beam profile at the pattern edge steep and to draw with high resolution. However, when performing multiple drawing while shifting the position, if the pattern is even a little on the pixel, the beam will be irradiated on that pixel, and the inclination of the beam profile will be reduced accordingly, and the resolution will be reduced. It will occur. Therefore, it becomes difficult to develop the resist so as to form a pattern with a highly accurate position and line width. In the second method, if the positions of the pixel boundary and the pattern edge do not match, the resolution position of the resist shifts, and it is difficult to increase the pattern edge accuracy in the first place.

JP 2010-123966 A

  Accordingly, an object of the present invention is to provide a charged particle beam drawing apparatus capable of drawing a highly accurate pattern while maintaining a high beam resolution in a drawing method for forming a pattern with a pixel pattern.

A charged particle beam drawing apparatus according to one embodiment of the present invention includes:
The number of shifts varies according to the number of shifts defined by the number of multiple drawing positions shifted in one of the x and y directions among multiple drawing positions in multiple drawing performed while shifting the position. An enlarged pattern creation unit that creates an enlarged pattern in which a graphic pattern to be drawn is enlarged along an inversely proportional shift amount ;
A reduced pattern creating unit that creates a reduced pattern obtained by reducing a figure pattern along the shift amount that is in proportion to the number of shifts and is inversely proportional to the number of shifts ;
An irradiation coefficient calculation unit that calculates an irradiation coefficient that modulates the irradiation amount of the charged particle beam irradiated to each of a plurality of small areas obtained by dividing the drawing area into a mesh shape using the enlarged pattern and the reduced pattern;
A drawing unit that draws a graphic pattern on a sample by a multiple drawing method performed while shifting the position using a charged particle beam of an irradiation amount obtained for each small region using an irradiation coefficient;
It is characterized by having.

  In addition, it is preferable that the irradiation coefficient calculation unit calculates the irradiation coefficient as 1 for each small area when the representative position of the small area falls within the reduced pattern.

  Further, it is preferable that the irradiation coefficient calculation unit calculates the irradiation coefficient as 0 for each small area when the representative position of the small area is located outside the enlarged pattern.

  Further, it is preferable that the irradiation coefficient calculation unit calculates the irradiation coefficient for each small area using the shift number when the representative position of the small area is located inside the enlarged pattern and outside the reduced pattern. .

The charged particle beam drawing method of one embodiment of the present invention includes:
The number of shifts varies according to the number of shifts defined by the number of multiple drawing positions shifted in one of the x and y directions among multiple drawing positions in multiple drawing performed while shifting the position. Creating an enlarged pattern in which a graphic pattern to be drawn is enlarged along an inversely proportional shift amount ;
A step of creating a reduced pattern obtained by reducing a graphic pattern along the shift amount inversely proportional to the shift, which changes according to the shift number;
A step of calculating an irradiation coefficient that modulates an irradiation amount of a charged particle beam irradiated to each of a plurality of small regions obtained by dividing a drawing region into a mesh shape using an enlarged pattern and a reduced pattern;
A step of drawing the graphic pattern on a sample by a multiple drawing method performed while shifting the position using a charged particle beam of an irradiation amount obtained for each small region using an irradiation coefficient;
It is characterized by having.

The charged particle beam drawing apparatus according to another aspect of the present invention includes:
In accordance with a value equal to or less than the number of shifts defined by the number of a plurality of drawing positions shifted in one of the x and y directions among a plurality of drawing positions in multiple drawing performed while shifting the position , An enlarged pattern creating unit that creates an enlarged pattern in which a graphic pattern to be drawn is enlarged along a shift amount that is inversely proportional to a value equal to or less than the shift number ;
A reduced pattern creating unit that creates a reduced pattern obtained by reducing a figure pattern along the shift amount that is in proportion to a value equal to or smaller than the number of shifts, and is inversely proportional to the value equal to or smaller than the number of shifts ;
An irradiation coefficient calculation unit that calculates an irradiation coefficient that modulates the irradiation amount of the charged particle beam irradiated to each of a plurality of small areas obtained by dividing the drawing area into a mesh shape using the enlarged pattern and the reduced pattern;
A drawing unit that draws a graphic pattern on a sample by a multiple drawing method performed while shifting the position using a charged particle beam of an irradiation amount obtained for each small region using an irradiation coefficient;
It is characterized by having.

A charged particle beam writing method according to another aspect of the present invention includes:
In accordance with a value equal to or less than the number of shifts defined by the number of a plurality of drawing positions shifted in one of the x and y directions among a plurality of drawing positions in multiple drawing performed while shifting the position , A step of creating an enlarged pattern in which a graphic pattern to be drawn is enlarged along a shift amount inversely proportional to a value equal to or less than the number of shifts ;
A step of creating a reduced pattern obtained by reducing a figure pattern along the shift amount inversely proportional to the value of the shift number or less, which changes according to the value of the shift number or less ,
A step of calculating an irradiation coefficient that modulates an irradiation amount of a charged particle beam irradiated to each of a plurality of small regions obtained by dividing a drawing region into a mesh shape using an enlarged pattern and a reduced pattern;
A step of drawing the graphic pattern on a sample by a multiple drawing method performed while shifting the position using a charged particle beam of an irradiation amount obtained for each small region using an irradiation coefficient;
It is characterized by having.

  According to one embodiment of the present invention, a highly accurate pattern can be drawn while maintaining a high beam resolution in a drawing method for forming a pattern using a pixel pattern.

1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 1. FIG. FIG. 3 is a conceptual diagram showing a configuration of a molded aperture array member in the first embodiment. FIG. 3 is a cross-sectional view showing a configuration of a blanking aperture array section in the first embodiment. FIG. 4 is a top conceptual view showing a part of the configuration in the membrane region of the blanking aperture array section in the first embodiment. 6 is a diagram for explaining a drawing order according to Embodiment 1. FIG. FIG. 4 is a flowchart showing main steps of the drawing method according to Embodiment 1. 5 is a diagram for explaining an enlarged graphic pattern creation method according to Embodiment 1. FIG. 6 is a diagram illustrating an example of a relationship between a shift number and a shift multiplicity according to Embodiment 1. FIG. 6 is a diagram illustrating an example of a pixel layer in the case of shift multiplicity N = 2 in Embodiment 1. FIG. 6 is a diagram illustrating an example of a pixel layer in the case of shift multiplicity N = 4 in Embodiment 1. FIG. 6 is a diagram illustrating an example of a pixel layer in the case of shift multiplicity N = 5 in Embodiment 1. FIG. 6 is a diagram for explaining a reduced graphic pattern creation method according to Embodiment 1. FIG. 3 is a diagram illustrating an example of an arrangement relationship between a pixel and a graphic pattern in Embodiment 1. FIG. 6 is a diagram illustrating an example of how to obtain an irradiation coefficient value according to Embodiment 1. FIG. 6 is a diagram for describing a signed distance calculation method according to Embodiment 1. FIG. FIG. 10 is a diagram for describing another calculation method of signed distance in the first embodiment. FIG. 10 is a diagram showing another example of how to obtain the value of the irradiation coefficient in the first embodiment. FIG. 10 is a diagram for explaining an example of a beam profile in the case where a graphic pattern in which the pixel boundary and the pattern end do not coincide with each other is shifted and multiple drawing is performed with multiplicity N = 2 in the first embodiment and the comparative example. FIG. 10 is a diagram for explaining another example of a beam profile in the case where a graphic pattern in which the pixel boundary and the pattern end do not coincide with each other is shifted and multiplexedly drawn with multiplicity N = 2 in the first embodiment and the comparative example. . FIG. 10 is a diagram showing an example of an incident dose profile for explaining the effect of the graphic end control of the rectangular pattern in the first embodiment. FIG. 6 is an enlarged view of a part of an example of an incident dose profile for explaining the effect of the graphic end control of the rectangular pattern in the first embodiment. FIG. 10 is a diagram showing an example of an incident dose profile for explaining the effect of the triangle pattern graphic end control according to the first embodiment. FIG. 6 is an enlarged view of a part of an example of an incident dose profile for explaining the effect of the triangle pattern graphic end control according to the first embodiment. FIG. 10 is a diagram showing an example of an incident dose profile for explaining the effect of figure end control of an arbitrary angle triangle pattern in the first embodiment. FIG. 6 is an enlarged view of a part of an example of an incident dose profile for explaining the effect of figure end control of an arbitrary angle triangle pattern in the first embodiment. It is a figure which shows another example of the incident dose profile for demonstrating the effect of the figure end control of the arbitrary angle | corner triangular pattern in Embodiment 1. FIG. FIG. 10 is an enlarged view of a part of another example of an incident dose profile for explaining the effect of figure edge control of an arbitrary angle triangle pattern in the first embodiment. 6 is a diagram illustrating an example of how to obtain the value of an irradiation coefficient in Embodiment 2. FIG. It is a figure which shows an example of the relationship between the shift number in Embodiment 2, and a shift multiplicity.

  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. In the following, a multi-beam drawing apparatus is described as an example of a charged particle beam drawing apparatus, but the present invention is not limited to this. For example, the present invention can be applied even to a raster scan type drawing apparatus. In other words, the technique of the first embodiment can be applied to a drawing method that forms a pattern by combining pixel patterns (bit patterns).

Embodiment 1 FIG.
FIG. 1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the first embodiment. In FIG. 1, the drawing apparatus 100 includes a drawing unit 150 and a control unit 160. The drawing apparatus 100 is an example of a multi charged particle beam drawing apparatus. The drawing unit 150 includes an electron column 102 and a drawing chamber 103. In the electron column 102, an electron gun 201, an illumination lens 202, a shaping aperture array member 203, a blanking aperture array section 204, a reduction lens 205, a limiting aperture member 206, an objective lens 207, and a deflector 208 are arranged. Yes. An XY stage 105 is disposed in the drawing chamber 103. On the XY stage 105, a sample 101 such as a mask blank which becomes a drawing target substrate at the time of drawing is arranged. The sample 101 includes an exposure mask for manufacturing a semiconductor device, or a semiconductor substrate (silicon wafer) on which the semiconductor device is manufactured. On the XY stage 105, a mirror 210 for measuring the position of the XY stage 105 is further arranged.

  The control unit 160 includes a control computer 110, a memory 112, a deflection control circuit 130, a stage position detector 139, and storage devices 140 and 142 such as a magnetic disk device. The control computer 110, the memory 112, the deflection control circuit 120, the stage position detector 139, and the storage devices 140 and 142 are connected to each other via a bus (not shown). In the storage device 140 (storage unit), drawing data in which pattern data of a plurality of graphic patterns is defined is input from the outside of the drawing device 100 and stored.

  In the control computer 110, the setting unit 50, the shift direction calculation unit 52, the shift amount calculation unit 54, the enlarged pattern creation unit 56, the reduction pattern creation unit 58, the determination unit 60, the irradiation coefficient calculation unit 62, and the k map creation unit 64. An irradiation amount calculation unit 66, an irradiation time calculation unit 68, a drawing control unit 70, a setting unit 71, and a dose map creation unit 72 are arranged. Setting unit 50, shift direction calculation unit 52, shift amount calculation unit 54, enlarged pattern creation unit 56, reduction pattern creation unit 58, determination unit 60, irradiation coefficient calculation unit 62, k map creation unit 64, dose calculation unit 66, Each function such as the irradiation time calculation unit 68, the drawing control unit 70, the setting unit 71, and the dose map creation unit 72 may be configured by hardware such as an electric circuit, or software such as a program for executing these functions. It may be constituted by. Alternatively, it may be configured by a combination of hardware and software. Setting unit 50, shift direction calculation unit 52, shift amount calculation unit 54, enlarged pattern creation unit 56, reduction pattern creation unit 58, determination unit 60, irradiation coefficient calculation unit 62, k map creation unit 64, dose calculation unit 66, Information input / output to / from the irradiation time calculation unit 68, the drawing control unit 70, the setting unit 71, and the dose map creation unit 72 and information being calculated are stored in the memory 112 each time.

  Here, FIG. 1 shows a configuration necessary for explaining the first embodiment. The drawing apparatus 100 may normally have other necessary configurations.

  FIG. 2 is a conceptual diagram showing the configuration of the molded aperture array member in the first embodiment. In FIG. 2A, the molded aperture array member 203 has vertical (y direction) m rows × horizontal (x direction) n rows (m, n ≧ 2) holes (openings) 22 at a predetermined arrangement pitch. It is formed in a matrix. In FIG. 2A, for example, 512 × 8 rows of holes 22 are formed. Each hole 22 is formed of a rectangle having the same size and shape. Alternatively, it may be a circle having the same outer diameter. Here, an example is shown in which eight holes 22 from A to H are formed in the x direction for each row in the y direction. When a part of the electron beam 200 passes through each of the plurality of holes 22, the multi-beam 20 is formed. Here, an example in which two or more holes 22 are arranged in both the vertical and horizontal directions (x and y directions) is shown, but the present invention is not limited to this. In addition, for example, one of the vertical and horizontal directions (x and y directions) may be a plurality of rows and the other may be only one row. Further, the arrangement of the holes 22 is not limited to the case where the vertical and horizontal directions are arranged in a grid pattern as shown in FIG. As shown in FIG. 2B, for example, the holes in the first row in the vertical direction (y direction) and the holes in the second row are shifted by a dimension a in the horizontal direction (x direction). Also good. Similarly, the holes in the second row in the vertical direction (y direction) and the holes in the third row may be arranged shifted by a dimension b in the horizontal direction (x direction).

FIG. 3 is a cross-sectional view showing the configuration of the blanking aperture array section in the first embodiment.
FIG. 4 is a top conceptual view showing a part of the configuration in the membrane region of the blanking aperture array section in the first embodiment. 3 and 4, the positional relationship among the control electrode 24, the counter electrode 26, and the control circuits 41 and 43 is not shown to be the same. In the blanking aperture array section 204, as shown in FIG. 3, a semiconductor substrate 31 made of silicon or the like is disposed on a support base 33. For example, the central portion of the substrate 31 is thinly cut from the back side and processed into a membrane region 30 (first region) having a thin film thickness h. The periphery surrounding the membrane region 30 is an outer peripheral region 32 (second region) having a thick film thickness H. The upper surface of the membrane region 30 and the upper surface of the outer peripheral region 32 are formed to have the same height position or substantially the height position. The substrate 31 is held on the support base 33 on the back surface of the outer peripheral region 32. The central part of the support base 33 is open, and the position of the membrane region 30 is located in the open area of the support base 33.

  In the membrane region 30, passage holes 25 (openings) for passing the beams of the multi-beams are opened at positions corresponding to the holes 22 of the shaping aperture array member 203 shown in FIG. 2. As shown in FIGS. 3 and 4, on the membrane region 30, a set of blanking deflection control electrodes 24 and counter electrodes 26 sandwiching the passage holes 25 in the vicinity of the passage holes 25 ( (Blanker: Blanking deflector) is arranged. A control circuit 41 (logic circuit) that applies a deflection voltage to the control electrode 24 for each passage hole 25 is disposed in the vicinity of each passage hole 25 on the membrane region 30. The counter electrode 26 for each beam is grounded.

  Further, as shown in FIG. 4, each control circuit 41 is connected to, for example, a 10-bit parallel wiring for a control signal. Each control circuit 41 is connected to a clock signal line and a power supply line in addition to, for example, a 10-bit parallel line for a control signal. As the clock signal line and the power supply wiring, a part of the parallel wiring may be used. An individual blanking mechanism 47 including the control electrode 24, the counter electrode 26, and the control circuit 41 is configured for each beam constituting the multi-beam. In the example of FIG. 3, the control electrode 24, the counter electrode 26, and the control circuit 41 are arranged in the membrane region 30 where the substrate 31 is thin. However, the present invention is not limited to this.

  The electron beam 20 passing through each passage hole 25 is deflected by a voltage applied to the two electrodes 24 and 26 that form a pair independently. Blanking is controlled by such deflection. In other words, the set of the control electrode 24 and the counter electrode 26 respectively blanks and deflects the corresponding beam among the multi-beams that have passed through the plurality of holes 22 (openings) of the shaping aperture array member 203.

  Next, the operation of the drawing unit 150 in the drawing apparatus 100 will be described. The electron beam 200 emitted from the electron gun 201 (emission part) illuminates the entire shaped aperture array member 203 almost vertically by the illumination lens 202. A plurality of rectangular holes (openings) are formed in the molded aperture array member 203, and the electron beam 200 illuminates a region including all of the plurality of holes. Each part of the electron beam 200 irradiated to the positions of the plurality of holes passes through the plurality of holes of the shaping aperture array member 203, thereby, for example, a plurality of rectangular electron beams (multi-beams) 20a to 20e. Is formed. The multi-beams 20a to 20e pass through the corresponding blankers (first deflector: individual blanking mechanism) of the blanking aperture array unit 204, respectively. Each of these blankers deflects the electron beam 20 that individually passes (performs blanking deflection).

  The multi-beams 20 a to 20 e that have passed through the blanking aperture array unit 204 are reduced by the reduction lens 205 and travel toward the central hole formed in the limiting aperture member 206. Here, the electron beam 20 deflected by the blanker of the blanking aperture array unit 204 is displaced from the central hole of the limiting aperture member 206 and is blocked by the limiting aperture member 206. On the other hand, the electron beam 20 that has not been deflected by the blanker of the blanking aperture array unit 204 passes through the central hole of the limiting aperture member 206 as shown in FIG. Blanking control is performed by ON / OFF of the individual blanking mechanism, and ON / OFF of the beam is controlled. As described above, the limiting aperture member 206 blocks each beam deflected so as to be in the beam OFF state by the individual blanking mechanism. For each beam, one shot beam is formed by the beam that has passed through the limiting aperture member 206 formed from when the beam is turned on until when the beam is turned off. The multi-beam 20 that has passed through the limiting aperture member 206 is focused by the objective lens 207 to form a pattern image with a desired reduction ratio, and each beam that has passed through the limiting aperture member 206 (the entire multi-beam 20) is deflected by the deflector 208. The beams are deflected collectively in the same direction, and irradiated to the respective irradiation positions on the sample 101 of each beam. For example, when the XY stage 105 is continuously moving, the beam irradiation position is controlled by the deflector 208 so as to follow (track) the movement of the XY stage 105. The position of the XY stage 105 is measured by irradiating a laser from the stage position detector 139 toward the mirror 210 on the XY stage 105 and using the reflected light. The multi-beams 20 irradiated at a time are ideally arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of holes of the shaping aperture array member 203 by the desired reduction ratio. The drawing apparatus 100 draws the multi-beam 20 that becomes a shot beam while following the movement of the XY stage 105 during each tracking operation by the drawing control unit 70 by the drawing control unit 70 by moving the beam deflection position by the deflector 208. A drawing operation of irradiating along the sequence is performed. When drawing a desired pattern, a beam required according to the pattern is controlled to be turned on by blanking control.

  FIG. 5 is a diagram for explaining the drawing order in the first embodiment. The drawing area 31 (or the chip area to be drawn) of the sample 101 is divided into striped areas 35 on a strip with a predetermined width. Each stripe region 35 is virtually divided into a plurality of mesh pixel regions 36 (pixels). The size of the pixel region 36 (pixel) is preferably, for example, a beam size or a size smaller than that. For example, a size of about 10 nm is preferable. The pixel area 36 (pixel) is an irradiation unit area per one beam of the multi-beam.

  When the sample 101 is drawn with the multi-beam 20, the irradiation region 34 is irradiated by one irradiation with the multi-beam 20. As described above, while following the movement of the XY stage 105 during the tracking operation, the entire multi-beam 20 that becomes a shot beam is irradiated in sequence one pixel at a time by moving the beam deflection position by the deflector 208. Go. Then, which pixel of the multi-beam is irradiated to which pixel on the sample 101 is determined by the drawing sequence. Using the beam pitch between the beams adjacent to each other in the x and y directions of the multi-beam, the beam pitch between the beams adjacent to each other in the x and y directions on the surface of the sample 101 (x direction) × beam pitch (y direction). The region is composed of an n × n pixel region (sub-pitch region). For example, when the XY stage 105 moves in the −x direction by the beam pitch (x direction) in one tracking operation, the irradiation position is shifted by one beam in the x direction or the y direction (or oblique direction). Pixels are drawn. The other n pixels in the same n × n pixel region are similarly drawn by a beam different from the beam described above in the next tracking operation. In this way, by drawing n pixels by different beams in n tracking operations, all the pixels in one n × n pixel area are drawn. The same operation is performed at the same time for other n × n pixel areas in the multi-beam irradiation area, and drawing is performed in the same manner. With this operation, all the pixels in the irradiation region 34 can be drawn. By repeating these operations, the entire corresponding stripe region 35 can be drawn. The drawing apparatus 100 can draw a desired pattern by a combination of pixel patterns (bit patterns) formed by irradiating a necessary pixel with a beam having a necessary irradiation amount.

  FIG. 6 is a flowchart showing main steps of the drawing method according to the first embodiment. 6, the drawing method according to the first embodiment includes a graphic pattern setting step (S102), a shift direction calculation step (S104), a shift amount calculation step (S106), an enlarged pattern creation step (S108), and a reduction. A pattern creation step (S110), a path setting step (S111), a determination step (S112), an irradiation coefficient calculation step (S113), an irradiation coefficient map creation step (S114), and a dose map creation step (S120). A series of steps of an irradiation amount calculation step (S130), an irradiation time map creation step (S132), and a drawing step (S134) are performed.

  As the graphic pattern setting step (S102), the setting unit 50 reads the drawing data from the storage device 140 and sets one of a plurality of graphic patterns defined in the drawing data.

  As the shift direction calculation step (S104), the shift direction calculation unit 52 calculates the shift direction of each vertex of the graphic pattern for shifting the graphic pattern in, for example, an enlargement direction. Here, as an example, the direction for enlarging is calculated, but the direction for reducing may be calculated.

  FIG. 7 is a diagram for explaining an enlarged graphic pattern creation method according to the first embodiment. An enlarged graphic pattern 42 shown in FIG. 7 is an enlarged example of a triangular graphic pattern 40 having vertices 1, 2, and 3. In FIG. 7, side s1, side s2, and side s3 are sides of the enlarged pattern 42. The side s1 is parallel to the side passing through the vertices 1 and 2 and passes through the point p1, and s2 is the side parallel to the side passing through the vertices 2 and 3 and passes through the point p2, and the side passing through the s3 vertex 3 and 1 Are arranged on a straight line passing through the point p3 in parallel. The arrows extending from the vertices 1, 2 and 3 in the figure indicate the arrangement directions from the vertex 1 to the point p1, from the vertex 2 to the point p2, and from the vertex 3 to the point 3, respectively. The shift direction calculation unit 52 calculates the difference in coordinates between the vertices 1 and 2 and determines the arrangement direction from the vertex 1 to the point p1 based on the magnitude of the absolute value of the obtained difference and the sign. Specifically, first, the coordinate v1 of the vertex 1 is v1 = (x1, y1), the coordinate v2 of the vertex 2 is v2 = (x2, y2), and dx = x2-x1 and dy = y2-y1 are calculated. To do. Next, the absolute values | dx | and | dy | of the obtained dx and dy are compared. If the value of | dx | is small, the direction of the sign of dx along the x-axis can be reduced. For example, the direction of the sign of dy along the y axis is determined as the arrangement direction from the vertex 1 to the point p1. In FIG. 7, | dy | is smaller than | dx | for the side v1v2, and the sign of dy is negative. Therefore, p1 is arranged in the -y direction from vertex 1

  Similarly, the shift direction calculation unit 52 calculates the difference in coordinates between the vertices 2 and 3, and obtains the arrangement direction from the vertex 2 to the point p2 based on the magnitude of the absolute value of the obtained difference and the sign. Specifically, assuming that the coordinate v3 of the vertex 3 is v3 = (x3, y3), first, dx = x3-x2 and dy = y3-y2 are calculated. Next, the absolute values | dx | and | dy | of the obtained dx and dy are compared. If the value of | dx | is small, the direction of the sign of dx along the x-axis can be reduced. For example, the direction of the sign of dy along the y axis is determined as the arrangement direction from the vertex 2 to the point p2. In FIG. 7, | dx | is smaller than | dy | for the sides passing through the vertices 2 and 3, and the sign of dx is positive. Therefore, p2 is arranged in the + x direction from the vertex 2.

  Similarly, the shift direction calculation unit 52 calculates the difference in coordinates between the vertices 3 and 1, and obtains the arrangement direction from the vertex 3 to the point p3 based on the magnitude of the absolute value of the obtained difference and the sign. Specifically, first, the coordinates v3 of the vertex 3 is set to v3 = (x3, y3), and dx = x3-x2 and dy = y3-y2 are calculated first. Next, the absolute values | dx | and | dy | of the obtained dx and dy are compared. If the value of | dx | is small, the direction of the sign of dx along the x-axis can be reduced. For example, the direction of the sign of dy along the y axis is determined as the arrangement direction from the vertex 3 to the point p3. In FIG. 7, | dy | is smaller than | dx | for the sides passing through the vertices 3 and 1, and the sign of dy is positive. Therefore, p3 is arranged in the + y direction from the vertex 3.

As the shift amount calculation step (S106), the shift amount calculation unit 54 calculates the shift amount s when the graphic pattern 40 is enlarged to the enlarged graphic pattern 42. Specifically, the shift amount s is defined by the following equation (1) using the grid width w of the pixel 36 and the shift number m.
(1) s = w / (2 · m)

  Here, the shift number m is defined by the number of a plurality of drawing positions shifted in one of the x direction and the y direction among a plurality of drawing positions in multiple drawing performed while shifting the position. The shift number m is obtained according to the multiplicity (shift multiplicity) performed while shifting the position of multiple drawing set as the drawing processing condition of the drawing data to be drawn on the sample 101.

  FIG. 8 is a diagram showing an example of the relationship between the number of shifts and the shift multiplicity in the first embodiment. Here, the irradiation region 34 that can be irradiated by multi-beam one-time irradiation is shown as a grid. FIG. 8A shows an example of two rendering positions in multiple rendering with a virtual reference grid and a shift multiplicity N = 2. In the example of FIG. 8A, the irradiation region 34 (grid) around the pixel 37a is irradiated for the first drawing. Then, for the second drawing, the irradiation region 34 (grid) around the pixel 37b is irradiated. Accordingly, in the example of FIG. 8A, the multiplicity (shift multiplicity) N = 2 in the multiple drawing performed while shifting the position. In this case, in the example of FIG. 8A, since there are two drawing positions in which the pixel 37a and the pixel 37b are shifted in the x direction, the shift number m in the x direction is 2. Since there are two drawing positions shifted in the y direction between the pixel 37a and the pixel 37b, the shift number m in the y direction is 2. Therefore, since the number of the plurality of drawing positions shifted in the x and y directions is two, the shift number m is 2.

  In the example of FIG. 8B, the irradiation region 34 (grid) centering on the pixel 37a is irradiated for the first drawing. Then, for the second drawing, the irradiation region 34 (grid) around the pixel 37b is irradiated. Then, for the third drawing, the irradiation region 34 (grid) around the pixel 37c is irradiated. For the fourth drawing, the irradiation region 34 (grid) centering on the pixel 37d is irradiated. Therefore, in the example of FIG. 8B, the multiplicity (shift multiplicity) N = 4 in the multiple drawing performed while shifting the position. In this case, in the example of FIG. 8B, since there are two drawing positions shifted in the x direction between the pixel 37a and the pixel 37b, the shift number m in the x direction is 2. Since there are two drawing positions (or the pixel 37b and the pixel 37d) shifted in the y direction between the pixel 37a and the pixel 37c, the shift number m in the y direction is 2. Therefore, since the number of the plurality of drawing positions shifted in the x and y directions is two, the shift number m is 2.

  In the example of FIG. 8C, similarly, irradiation areas 34 (grids) each centering on five pixels are irradiated. Therefore, in the example of FIG. 8C, the multiplicity (shift multiplicity) N = 5 in the multiple drawing performed while shifting the position. In such a case, in the example of FIG. 8C, since there are five drawing positions shifted in the x direction, the shift number m in the x direction is 5. Since there are five drawing positions shifted in the y direction, the shift number m in the y direction is 5. Therefore, since the number of a plurality of drawing positions shifted in the x and y directions is five, the shift number m is 5.

  In the example of FIG. 8D, similarly, irradiation regions 34 (grids) each centering eight pixels are irradiated. Accordingly, in the example of FIG. 8D, the multiplicity (shift multiplicity) N = 8 in the multiple drawing performed while shifting the position. In such a case, in the example of FIG. 8D, since there are four drawing positions shifted in the x direction, the shift number m in the x direction is 4. Since there are four drawing positions shifted in the y direction, the shift number m in the y direction is 4. Therefore, since the number of drawing positions shifted in the x and y directions is four, the shift number m is 4.

  In the example of FIG. 8E, similarly, the irradiation areas 34 (grids) each centering on nine pixels are irradiated. Accordingly, in the example of FIG. 8E, the multiplicity (shift multiplicity) N = 9 in the multiple drawing performed while shifting the position. In this case, in the example of FIG. 8E, there are three drawing positions shifted in the x direction, so the shift number m in the x direction is 3. Since there are three drawing positions shifted in the y direction, the shift number m in the y direction is 3. Therefore, since the number of drawing positions shifted in both the x and y directions is 3, the shift number m is 3.

  In the example of FIG. 8F, similarly, irradiation regions 34 (grids) each centering on ten pixels are irradiated. Therefore, in the example of FIG. 8F, the multiplicity (shift multiplicity) N = 10 in the multiple drawing performed while shifting the position. In such a case, in the example of FIG. 8F, there are ten drawing positions shifted in the x direction, so the shift number m in the x direction is 10. Since there are ten drawing positions shifted in the y direction, the shift number m in the y direction is 10. Therefore, since the number of the plurality of drawing positions shifted in the x and y directions is 10, the shift number m is 10.

  In the example of FIG. 8G, similarly, irradiation regions 34 (grids) each centering 16 pixels are irradiated. Accordingly, in the example of FIG. 8G, the multiplicity (shift multiplicity) N = 16 in the multiple drawing performed while shifting the position. In such a case, in the example of FIG. 8G, since there are four drawing positions shifted in the x direction, the shift number m in the x direction is 4. Since there are four drawing positions shifted in the y direction, the shift number m in the y direction is 4. Therefore, since the number of drawing positions shifted in the x and y directions is four, the shift number m is 4. In the example of FIG. 8H, the multiplicity (shift multiplicity) N = 4 in the multiple drawing performed while shifting the position. In such a case, in the example of FIG. 8H, there are four drawing positions shifted in the x direction, so the shift number m in the x direction is 4. Since there are four drawing positions shifted in the y direction, the shift number m in the y direction is 4. Therefore, since the number of drawing positions shifted in the x and y directions is four, the shift number m is 4.

  FIG. 9 is a diagram illustrating an example of a pixel layer when the shift multiplicity N = 2 in the first embodiment. In the example of FIG. 9, after the first drawing, the second drawing is performed by shifting the position by 1/2 pixel in the x direction and the y direction, and the multiple drawing with the shift multiplicity N = 2 is performed. Shows the case.

  FIG. 10 is a diagram illustrating an example of a pixel layer when the shift multiplicity N = 4 in the first embodiment. In the example of FIG. 10, after the first drawing, the second drawing is performed by shifting the position in the x direction and the y direction by ½ pixel. Similarly, every ½ pixel in the x direction. The third drawing is performed by shifting the positions in the x and y directions. Similarly, the fourth drawing is performed by shifting the positions in the x direction and the y direction by ½ pixel respectively. A case of performing multiple drawing is shown.

  FIG. 11 is a diagram illustrating an example of a pixel layer when the shift multiplicity N = 5 in the first embodiment. In the example of FIG. 11, after the first drawing, the second drawing is performed with the position shifted by 2/5 pixels in the x direction and 1/5 pixel in the y direction. Similarly, 2 in the x direction. / 5 pixels and 1/5 pixel in the y direction, and the third drawing is performed with the position shifted. Similarly, 3/5 pixel in the -x direction and 1/5 pixel in the y direction are shifted to 4 respectively. Similarly, the drawing is performed for the second time. Similarly, the drawing is performed for the fifth time by shifting the position by 2/5 pixels in the x direction and 1/5 pixel in the y direction. Show.

  As an enlarged pattern creating step (S108), the enlarged pattern creating unit 56 creates an enlarged pattern 42 obtained by enlarging the graphic pattern 40 to be drawn according to the shift number m. Specifically, the enlargement pattern creation unit 56 enlarges a straight line (a straight line extending each side) passing through two vertices at both ends of each side of the graphic pattern along the calculated shift direction and shift amount. The enlarged pattern 42 is created by moving (shifting) to and creating a figure surrounded by the plurality of straight lines.

  As a reduction pattern creation step (S110), the reduction pattern creation unit 58 creates a reduction pattern obtained by reducing the figure pattern 40 in accordance with the shift number m.

  FIG. 12 is a diagram for explaining a reduced graphic pattern creation method according to the first embodiment. The reduced graphic pattern 44 shown in the figure is an example of reducing the triangular graphic pattern 40 having the same vertices 1, 2, and 3 as in FIG. In FIG. 7, side t1, side t2, and side t3 are sides of the enlarged pattern 44. Side t1 is on a straight line passing through point q1 in parallel with the side passing through vertices 1 and 2, t2 is on a straight line passing through point q2 in parallel with the side passing through vertices 2 and 3, and side passing through side t3 vertices 3 and 1 Are arranged on a straight line passing through the point q3 in parallel. The arrows extending from the vertices 1, 2 and 3 in the figure indicate the arrangement directions from the vertex 1 to the point q1, from the vertex 2 to the point q2, and from the vertex 3 to the point q3, respectively. The arrangement method from the vertex 1 to the point q1 is opposite to the arrangement direction from the vertex 1 to the point p1 obtained in the description of FIG. Accordingly, in the case of FIG. 12, q1 is arranged in the + y direction from the vertex 1.

  Similarly, the arrangement direction from the vertex 2 to the point q2 is opposite to the arrangement direction from the vertex 2 to the point p2 obtained in the description of FIG. Therefore, in the case of FIG. 12, q2 is arranged in the −x direction from the vertex 2.

  Similarly, the arrangement direction from the vertex 3 to the point q3 is the opposite direction to the arrangement direction from the vertex 3 to the point p3 obtained in the description with reference to FIG. Therefore, in the case of FIG. 12, q3 is arranged in the −y direction from the vertex 3.

  Also, the shift amount s has already been calculated by the equation (1). Therefore, the reduced pattern creation unit 58 extends a straight line (extending each side) between the two vertices at both ends of each side of the graphic pattern along the calculated shift direction (direction opposite to the enlargement direction) and the calculated shift amount. The reduced pattern 44 is created by moving (shifting) the line in the direction of reduction and creating a figure surrounded by the plurality of lines.

  Then, returning to the graphic pattern setting step (S102), the graphic pattern setting step (S102) to the reduced pattern creating step (S110) are repeated for all the graphic patterns defined in the drawing data. Note that these loop processes are preferably performed in units of stripe regions 35. Thus, an enlarged pattern and a reduced pattern are created for each graphic pattern.

  As the path setting step (S111), the setting unit 71 sets a path for multiple drawing performed while shifting the position. For example, in the case of multiplicity (shift multiplicity) N = 2 in multiplex drawing performed while shifting the position, the first drawing process is set as pass 1, and the second drawing process with shifted position is set as pass 2. Should be set. At that time, the setting unit 71 creates a pixel layer for pass 2 whose position is shifted. The shift amount may be shifted by 1/2 pixel, for example, as described above.

  As a determination step (S112), the determination unit 60 uses the pixel layer of the path for each pixel 36 and the representative position (for example, the center) of the pixel 36 is outside the enlarged pattern 42 of any graphic pattern ( Or on the line), in the reduced pattern 44 of the graphic pattern (or on the line), or elsewhere (between the reduced pattern 44 of the graphic pattern and the enlarged pattern 42). judge.

  FIG. 13 is a diagram illustrating an example of an arrangement relationship between a pixel and a graphic pattern in the first embodiment. In FIG. 13, the pixel at the representative position 39a is determined to be located outside the enlarged pattern 42 of the graphic pattern. The pixel at the representative position 39b is determined that the representative position 39b is located within the reduced pattern 44 of the graphic pattern. The pixel at the representative position 39c determines that the representative position 39c is located between the reduced pattern 44 and the enlarged pattern 42 of the graphic pattern.

  In the irradiation coefficient calculation step (S113), the irradiation coefficient calculation unit 62 uses the enlarged pattern 42 and the reduced pattern 44 to irradiate each of the plurality of pixels 36 (small areas) in which the drawing area is divided into a mesh shape. An irradiation coefficient k for modulating the irradiation amount of the electron beam is calculated. Here, the irradiation coefficient calculation unit 62 calculates the irradiation coefficient k as 1 for each pixel 36 when the representative position (for example, the center) of the pixel 36 falls within the reduced pattern 44. Further, the irradiation coefficient calculation unit 62 calculates the irradiation coefficient k to 0 for each pixel 36 when the representative position of the pixel 36 is located outside the enlarged pattern 42. In addition, for each pixel 36, the irradiation coefficient calculation unit 62 calculates the irradiation coefficient k using the function f when the representative position of the pixel 36 is located between the enlarged pattern 42 and the reduced pattern 44 (k = f). Specifically, for each pixel 36, the irradiation coefficient calculation unit 62 performs irradiation using the shift number m when the representative position of the pixel 36 is located inside the enlarged pattern 42 and outside the reduced pattern 44. The coefficient k is calculated.

  FIG. 14 is a diagram illustrating an example of how to obtain the value of the irradiation coefficient in the first embodiment. As shown in FIG. 14A, the function f is defined using a signed distance L (LX or LY) from the target pixel to the side using the original graphic pattern 40 and a shift number m. When the signed distance L of the pixel 36 is (m−1) / (2m) or less, it is defined by the function f = 0. When the signed distance L of the pixel 36 is (m + 1) / (2m) or more, it is defined by the function f = 1. When the signed distance L of the pixel 36 is larger than (m−1) / (2m) and smaller than (m + 1) / (2m), it is defined by the function f = (mL− (m−1) / 2). The The relationship between the shift number m and the shift multiplicity described above is as shown in FIG. Further, the value of the function f changes according to the signed distance L of the pixel 36 as shown in FIG. When the signed distance L of the pixel 36 is (m−1) / (2m) to (m + 1) / (2m), the value of the function f increases in a linear proportion.

FIG. 15 is a diagram for explaining a signed distance calculation method according to the first embodiment. As shown in FIG. 15, the distance from the coordinate (x, y) of the representative position (for example, the center) of the target pixel 36 to the side of the graphic pattern 40 is calculated including the sign. In the example of FIG. 15, for example, a case of a triangular graphic pattern 40 is shown. The coordinates of the three vertices of the graphic pattern 40 are v1, v2, and v3. It is assumed that the coordinates v1 = (v1x, v1y), the coordinates v2 = (v2x, v2y), and the coordinates v3 = (v3x, v3y). The equation of the straight line L12 passing through the vertices v1 and v2 can be defined by the following equation (2). Note that dx = v2x−v1x and dy = v2y−v1y.
(2) dx (y−v1y) = dy (y−v1x)

Also, using the equation (2), the equation FL12 (x, y) of the straight line L12 passing through the vertices v1 and v2 is rewritten as the following equation (3).
(3) FL12 (x, y) = dy (y−v1x) −dx (y−v1y)

  When the representative position (x, y) of the target pixel 36 is substituted into Expression (3), if the sign of FL12 (x, y) is negative, the representative position (x, y) is the vertex v1, It means the outside of the side passing through v2 (the outside of the graphic pattern 40). Conversely, if the sign of FL12 (x, y) is positive, the representative position (x, y) means the inside of the side passing through the vertices v1 and v2 of the graphic pattern 40 (inside the graphic pattern 40). Therefore, the same calculation is performed for each side, and if all are positive, the representative position (x, y) is inside the graphic pattern 40.

Here, if the signed distance L from the representative position (x, y) of the target pixel 36 to the straight line L12 along the x and y axes is a signed distance LY along the y axis, the expression (4-1) ). If it is a signed distance LX along the x-axis, it is defined by equation (4-2).
(4-1) LY (x, y) = y−v1y− (dy / dx) (x−v1x)
(4-2) LX (x, y) = x−v1x− (dx / dy) (y−v1y)

FIG. 16 is a diagram for explaining another calculation method of the signed distance in the first embodiment. As shown in FIG. 16A, the signed distance LY along the y-axis with respect to a certain straight line from the representative position (x, y) of the target pixel 36 is calculated using the following equation (3): 5-1). Further, as shown in FIG. 16B, a signed distance LY along the x-axis with respect to a certain straight line from the representative position (x, y) of the target pixel 36 is expressed by the following equation (3). It can be defined by equation (5-2).
(5-1) LY (x, y) = FL12 (x, y) / dx
(5-2) LX (x, y) = FL12 (x, y) / dy

  In the calculation of the function f, the signed distance L is the smaller of the absolute values of LX and LY.

FIG. 17 is a diagram showing another example of how to obtain the value of the irradiation coefficient in the first embodiment. In FIG. 17, it is assumed that the representative position (for example, the center) of the pixel 36 is outside the reduced pattern 44 and inside the enlarged pattern 42. The point that is 1 if the representative position (for example, the center) of the pixel 36 is inside the reduced pattern 44 and 0 if it is outside the enlarged pattern 42 is the same as described above. In this case, as shown in FIG. 17A, the value of the equation FL12 (x, y) of the straight line L12 that is the side of the reduced pattern 44 at the representative position (x, y) of the pixel 36 (FL reduction (x, y, y)) is negative. On the other hand, as shown in FIG. 17B, the value of the equation FL12 (x, y) of the straight line L12 that is the side of the enlarged pattern 42 at the representative position (x, y) of the pixel 36 (FL expansion (x, y)). )) Is positive. When the representative position of the pixel 36 is located between the enlarged pattern 42 and the reduced pattern 44, the irradiation coefficient k is defined by the function f. In such a case, the function f can be defined by the following equation (6).
(6) k = f = m · (FL expansion (x, y) −FL contraction (x, y)) / max. (| Dx |, | dy |)

  Note that dx and dy are obtained for the enlarged pattern 42 and the reduced pattern 44, respectively. And max. (| Dx |, | dy |) means the largest value among the absolute value of dx and the absolute value of dy of the enlarged pattern 42 and the reduced pattern 44, respectively.

  As an irradiation coefficient map creation step (S114), the k map creation unit 64 creates an irradiation coefficient k map in the pass for each pass. The irradiation coefficient k map is preferably created for each stripe region 35. The created irradiation coefficient map is stored in the storage device 142.

  As a dose map creation step (S120), the dose map creation unit 72 calculates a dose amount of each pixel for each pass and creates a dose map. Specifically, it operates as follows. The dose map creation unit 72 reads the drawing data from the storage device 140 and arranges the drawing area of the sample 101 or the chip area to be drawn in each mesh area of a plurality of mesh areas virtually divided into mesh shapes. The area density ρ of the pattern to be calculated is calculated. The mesh area when calculating the area density ρ does not need to coincide with the pixel. The mesh region is preferably about 1/10 of the influence radius of the proximity effect, for example, about 1 μm. For the calculation of the fogging effect and loading effect, the size should be larger. On the other hand, since the pixel size is, for example, a beam size (on the order of several tens of nm), the mesh region is usually larger than the pixel. Using the area density ρ, a correction irradiation coefficient Dp for correcting a dimensional variation for a phenomenon causing a dimensional variation such as a proximity effect, a fogging effect, and a loading effect by the dose is calculated. In addition, for each multiple drawing pass performed while shifting the position, the area density ρ ′ occupied by the pattern in each pixel in the pixel layer of the pass is calculated. For each pixel 36, for each pixel 36, for example, a dose amount D obtained by multiplying the reference irradiation amount Dbase by the corrected irradiation coefficient Dp (x, y), the area density ρ ′ (x, y), and 1 / multiplicity N. Calculate (x, y). The coordinates (x, y) here indicate the position of the pixel. As the corrected irradiation coefficient Dp, the value of the mesh area where the pixel 36 is located may be used. Here, as an example, the dose is set to 1 / multiplicity N for each pass, but the present invention is not limited to this. The dose ratio may be variable for each pass. Then, for each pass, a dose map is created with the calculated dose amount D (x, y) of each pixel as a map value. The dose map is preferably created for each stripe region 35. The created dose map is stored in the storage device 142.

  The dose map creation step (S120) may be performed in parallel with the steps from the graphic pattern setting step (S102) to the irradiation coefficient map creation step (S114).

  As the dose calculation step (S130), the dose calculation unit 66 reads the dose map and the irradiation coefficient map for the path from the storage device 142 for each pass, and uses the irradiation coefficient k for each pixel 36. The dose D at is calculated. Specifically, the dose D in the pass may be calculated by multiplying the dose in the pass by the irradiation coefficient k.

  In the irradiation time map creation step (S132), the irradiation time calculation unit 68 calculates the irradiation time t of each pixel for each pass by dividing the dose D of each pixel by the current density J for each pass. Then, for each pass, an irradiation time map is created with the calculated irradiation time t of each pixel as a map value. The irradiation time map is preferably created for each stripe region 35. The created irradiation time map is stored in the storage device 142. Further, the irradiation time calculation unit 68 converts the obtained irradiation time into, for example, 10-bit irradiation time data with irradiation time resolution. Irradiation time data (shot data) is stored in the storage device 142.

  If there are still paths that have not yet been created, the process returns to the path setting process (S111), and each process from the path setting process (S111) to the irradiation time map creating process (S132) until all the paths are completed. repeat. Note that these loop processes are preferably performed in units of stripe regions 35. Thus, an irradiation time map is created for each pass.

  In the drawing step (S134), the deflection control circuit 130 reads the irradiation time data from the storage device 142 under the control of the drawing control unit 70, and outputs the irradiation time data to the control circuit 41 for each beam for each shot. To do. Then, for each pass, the drawing unit 150 draws a graphic pattern on the sample 101 by a multiple drawing method performed while shifting the position using an electron beam with an irradiation amount obtained for each pixel using the irradiation coefficient k. Specifically, the drawing unit 150 draws a pattern on the sample 101 using the multi-beam 20 including the corresponding beam of the calculated irradiation time t for each pass. The drawing order is advanced in accordance with a drawing sequence controlled by the drawing control unit 70. Each path may be switched for each stripe area, or each path may be switched for each shot. Drawing time can be shortened by switching each pass for each shot.

  FIG. 18 is a diagram for explaining an example of a beam profile in the case where a graphic pattern in which the pixel boundary and the pattern end do not coincide with each other is shifted and multiplexedly drawn with multiplicity N = 2 in the first embodiment and the comparative example. It is. In FIG. 18A, the pixel layer of the first layer (L = 1) (first pass), the pixel layer of the second layer (L = 2) (second pass), and the graphic pattern 48a are superimposed. Is shown. In the example of FIG. 18A, a graphic pattern in which the boundary of the pixel 36 and the pattern end do not coincide is shown. In the example of FIG. 18A, the second pass is drawn by shifting the position in the x and y directions by 1/2 pixel from the position of the pixel layer in the first pass. FIG. 18B shows a cross section of the graphic pattern 48a. In FIG. 18C, as Comparative Example 1, an example of a beam profile in the case where the first pass drawing and the second pass drawing are performed by a method in which the beam irradiation amount is simply proportional to the pattern area density in the pixel. Is shown. In FIG. 18D, as a comparative example 2, the first pass is a method in which a beam with a dose of 100% is irradiated if the center point of the pixel is within the pattern, and if not, the beam is not irradiated. 2 shows an example of a beam profile in the case of performing drawing and drawing in the second pass. FIG. 18E shows an example of a beam profile when the first pass drawing and the second pass drawing are performed by the method of the first embodiment. In Comparative Example 1, irradiation is performed if a graphic pattern overlaps even within a pixel. For this reason, the inclination of the beam profile is reduced accordingly, and the resolution is lowered. Therefore, it becomes difficult to develop the resist so as to form a pattern with a highly accurate position and line width. On the other hand, in both Comparative Example 2 and Embodiment 1, the inclination of the beam profile is not reduced, and a decrease in resolution can be suppressed.

  FIG. 19 is a diagram for explaining another example of the beam profile in the case where the graphic pattern in which the pixel boundary and the pattern end do not coincide with each other and the multiple drawing is performed with the multiplicity N = 2 in the first embodiment and the comparative example. FIG. In FIG. 19A, the pixel layer of the first layer (L = 1) (first pass), the pixel layer of the second layer (L = 2) (second pass), and the graphic pattern 48b are superimposed. Is shown. In the example of FIG. 19A, a graphic pattern 48b is shown in which the left end side of the graphic pattern 48a is made to coincide with the boundary of the 1/4 pixel reduced pixel 36 and the right end side of the graphic pattern 48a is reduced by 1/2 pixel. In the example of FIG. 19A, the second pass drawing is performed by shifting the position in the x and y directions by 1/2 pixel from the position of the pixel layer of the first pass. FIG. 19B shows a cross section of the graphic pattern 48b. In FIG. 19C, as Comparative Example 1, an example of a beam profile in the case where the first pass drawing and the second pass drawing are performed by a method in which the beam irradiation amount is simply proportional to the pattern area density in the pixel. Is shown. In FIG. 19D, as Comparative Example 2, the first pass is a method in which a beam with a dose of 100% is irradiated if the center point of the pixel is within the pattern, and if not, the beam is not irradiated. 2 shows an example of a beam profile in the case of performing drawing and drawing in the second pass. FIG. 19 (e) shows an example of a beam profile when the first pass drawing and the second pass drawing are performed by the method of the first embodiment. In Comparative Example 2, if the position of the pixel boundary and the pattern edge do not match as in the second pass, the resolution position of the resist shifts, and it is difficult to increase the pattern edge accuracy in the first place. On the other hand, in both Comparative Example 1 and Embodiment 1, the resolution position of the resist can be matched with the position of the pattern edge.

  As described above, according to the first embodiment, both weak points of Comparative Examples 1 and 2 can be overcome.

  FIG. 20 is a diagram showing an example of an incident dose profile for explaining the effect of the graphic end control of the rectangular pattern in the first embodiment. In FIG. 20, the horizontal axis indicates the position, and the vertical axis indicates the dose. FIG. 20 shows a case where two rectangular patterns whose positions are shifted are drawn. The rectangular pattern shown on the left shows a graph in which incident dose profiles drawn by shifting the position of the end 10 times by 1 nm are overlaid. The rectangular pattern shown on the right shows a graph in which incident dose profiles drawn by shifting the position of the end portion 10 times by 0.1 nm are superimposed.

  FIG. 21 is an enlarged view of a part of an example of the incident dose profile for explaining the effect of the rectangular pattern graphic end control in the first embodiment. FIG. 21A shows the result of enlarging the A portion of the incident dose profile of the rectangular pattern shown on the left in FIG. FIG. 21B shows a result of enlarging the B portion of the incident dose profile of the rectangular pattern shown on the right side of FIG. According to the first embodiment, as shown in FIG. 21A, not only the 1 nm figure end position can be controlled as shown in FIG. 21A, but also the 0.1 nm figure end position can be controlled as shown in FIG. .

  FIG. 22 is a diagram showing an example of an incident dose profile for explaining the effect of the pattern end control of the triangular pattern in the first embodiment. In FIG. 22, the horizontal axis indicates the position, and the vertical axis indicates the dose. FIG. 22 shows a case where two triangular patterns whose positions are shifted are drawn. The triangle pattern shown on the left shows a graph in which incident dose profiles drawn by shifting the position of the end of the oblique line by shifting the position in the x direction by 5 nm each by 1 nm are superimposed. The triangle pattern shown on the right shows a graph in which incident dose profiles drawn by shifting the position of the end of the diagonal line by shifting the position in the x direction by 0.1 nm five times are overlapped.

  FIG. 23 is an enlarged view of a part of an example of an incident dose profile for explaining the effect of the shape end control of the triangular pattern in the first embodiment. FIG. 23A shows a result of enlarging the C portion of the incident dose profile of the triangular pattern shown on the left in FIG. FIG. 23B shows a result of enlarging the D portion of the incident dose profile of the triangular pattern shown on the right side of FIG. According to the first embodiment, not only the 1 nm figure end position can be controlled for the triangular pattern as shown in FIG. 23A, but also the 0.1 nm figure end position can be controlled as shown in FIG. 23B. .

  FIG. 24 is a diagram showing an example of an incident dose profile for explaining the effect of the graphic end control of the arbitrary angle triangular pattern in the first embodiment. In FIG. 24, the horizontal axis indicates the position, and the vertical axis indicates the dose. FIG. 24 shows a case where two arbitrary angled triangular patterns (30 ° in this case) with different positions are drawn. The arbitrary angle triangle pattern shown on the left shows a graph in which incident dose profiles drawn by shifting the position of the end of the oblique line by shifting the position in the x direction by 5 nm each by 1 nm are superimposed. The arbitrary angle triangular pattern shown on the right shows a graph in which incident dose profiles drawn by shifting the position of the end portion of the oblique line by shifting the position in the x direction by 0.1 nm five times are overlapped.

  FIG. 25 is an enlarged view of a part of an example of the incident dose profile for explaining the effect of the figure end control of the arbitrary angle triangle pattern in the first embodiment. FIG. 25A shows a result of enlarging the E portion of the incident dose profile of the arbitrary angle triangular pattern shown on the left in FIG. FIG. 25B shows a result of enlarging the F portion of the incident dose profile of the arbitrary angle triangular pattern shown on the right side of FIG. According to the first embodiment, as shown in FIG. 25 (a), as for an arbitrary angle triangle pattern of 30 °, as shown in FIG. 25 (a), the shape edge position of 0.1 nm is controlled as shown in FIG. 25 (b). You can also control the position.

  FIG. 26 is a diagram showing another example of the incident dose profile for explaining the effect of the graphic end control of the arbitrary angle triangular pattern in the first embodiment. In FIG. 26, the horizontal axis indicates the position, and the vertical axis indicates the dose. FIG. 26 shows a case where two arbitrary angle triangular patterns (15 ° in this case) with different positions are drawn. The arbitrary angle triangle pattern shown on the left shows a graph in which incident dose profiles drawn by shifting the position of the end of the oblique line by shifting the position in the x direction by 5 nm each by 1 nm are superimposed. The arbitrary angle triangular pattern shown on the right shows a graph in which incident dose profiles drawn by shifting the position of the end portion of the oblique line by shifting the position in the x direction by 0.1 nm five times are overlapped.

  FIG. 27 is an enlarged view of a part of another example of the incident dose profile for explaining the effect of the figure end control of the arbitrary angle triangle pattern in the first embodiment. FIG. 27A shows a result of enlarging the G portion of the incident dose profile of the arbitrary angle triangular pattern shown on the left in FIG. FIG. 27B shows a result of enlarging the H portion of the incident dose profile of the arbitrary angle triangular pattern shown on the right side of FIG. According to the first embodiment, as shown in FIG. 27 (a), for a 15 ° arbitrary angle triangle pattern, the shape edge position of 1 nm is controlled as well as the shape edge position of 0.1 nm as shown in FIG. 27 (b). You can also control the position.

Embodiment 2. FIG.
In the first embodiment, the case where the function f (= irradiation coefficient k) is calculated using the shift number m as it is is described, but the present invention is not limited to this. In the second embodiment, a case in which other values including the shift number m are used will be described. The configuration of the drawing apparatus 100 is the same as that shown in FIG. The configuration of the drawing method is the same as in FIG. Hereinafter, the contents other than those specifically described are the same as those of the first embodiment. The contents of the graphic pattern setting step (S102) and the shift direction calculation step (S104) are the same as those in the first embodiment.

  FIG. 28 is a diagram illustrating an example of how to obtain the value of the irradiation coefficient in the second embodiment. As in the case described with reference to FIG. 14C, when the shift number m is used as it is, the value of the function f is the signed distance L of the pixel 36 as shown in the graph A ′ of FIG. It changes according to. Here, when the shift number m takes a large value, the slope of the graph A ′ becomes steep. In such a case, even if the signed distance L changes slightly, the value of the function f (irradiation coefficient k) changes greatly. Therefore, in the second embodiment, as shown in the graph B ′, the slope is configured to be gentler (smaller) than the graph A ′. Therefore, in the second embodiment, a value M equal to or less than the shift number is defined without using the shift number m as it is. A value M equal to or less than the shift number is defined by 1 ≦ M ≦ m. Thus, the value M equal to or less than the shift number is equal to or less than the shift number m and a value equal to or greater than 1 is used.

As the shift amount calculation step (S106), the shift amount calculation unit 54 calculates the shift amount s when the graphic pattern 40 is enlarged to the enlarged graphic pattern 42. Specifically, the shift amount s is defined by the following equation (7) using the grid width w of the pixel 36 and a value M equal to or less than the shift number.
(7) s = w / (2 · M)

  As an enlarged pattern creating step (S108), the enlarged pattern creating unit 56 creates an enlarged pattern 42 obtained by enlarging the graphic pattern 40 to be drawn according to the value M equal to or less than the number of shifts. The specific contents are the same as in the first embodiment. Here, the shift amount s obtained by Expression (7) is used.

  As a reduction pattern creation step (S110), the reduction pattern creation unit 58 creates a reduction pattern obtained by reducing the figure pattern 40 according to the value M equal to or less than the number of shifts. The specific contents are the same as in the first embodiment. Here, the shift amount s obtained by Expression (7) is used.

  The contents of the path setting step (S111) and the determination step (S112) are the same as those in the first embodiment.

  In the irradiation coefficient calculation step (S113), the irradiation coefficient calculation unit 62 uses the enlarged pattern 42 and the reduced pattern 44 to irradiate each of the plurality of pixels 36 (small areas) in which the drawing area is divided into a mesh shape. An irradiation coefficient k for modulating the irradiation amount of the electron beam is calculated. The irradiation coefficient calculation unit 62 calculates the irradiation coefficient k as 1 for each pixel 36 when the representative position (for example, the center) of the pixel 36 falls within the reduced pattern 44. Further, the irradiation coefficient calculation unit 62 calculates the irradiation coefficient k to 0 for each pixel 36 when the representative position of the pixel 36 is located outside the enlarged pattern 42. In addition, for each pixel 36, the irradiation coefficient calculation unit 62 calculates the irradiation coefficient k using the function f when the representative position of the pixel 36 is located between the enlarged pattern 42 and the reduced pattern 44 (k = f). This is the same as in the first embodiment. Specifically, for each pixel 36, the irradiation coefficient calculation unit 62 sets a value M equal to or less than the shift number when the representative position of the pixel 36 is located inside the enlarged pattern 42 and outside the reduced pattern 44. To calculate the irradiation coefficient k. However, the calculation of the function f is shown in FIG. The relationship between the shift multiplicity and the shift number m at that time is shown in FIG. As shown in FIG. 28A, the function f is defined using a signed distance L (LX or LY) from the target pixel to the side using the original graphic pattern 40 and a value M equal to or less than the shift number. Is done. When the signed distance L of the pixel 36 is (M−1) / (2M) or less, the function is defined by f = 0. When the signed distance L of the pixel 36 is equal to or greater than (M + 1) / (2M), the function is defined as f = 1. When the signed distance L of the pixel 36 is larger than (M−1) / (2M) and smaller than (M + 1) / (2M), it is defined by the function f = (ML− (M−1) / 2). The When the signed distance L of the pixel 36 is (M−1) / (2M) to (M + 1) / (2M), the value of the function f increases linearly as shown in FIG. The following steps are the same as those in the first embodiment.

  As described above, by changing the shift number m from the shift number m to a value M equal to or less than the shift number, even when the shift number m takes a large value, it is possible to suppress the steepness of the graph. Therefore, a rapid change in irradiation amount can be suppressed. Since the signed distance L changes for each pass, the function f (irradiation coefficient k) changes for each pass. As a result, the possibility of adjustment with beams of a plurality of paths is greater than that of adjustment with individual beams in one path, so that averaging can be performed. Therefore, the drawing accuracy can be improved.

  Here, in the example of FIG. 8, when the number of drawing positions shifted in both the x and y directions has the same value, that is, the shift number m is uniquely determined, the relationship between the shift number and the shift multiplicity An example is shown, but the present invention is not limited to this.

  FIG. 29 is a diagram illustrating an example of the relationship between the number of shifts and the shift multiplicity according to the second embodiment. FIG. 29 shows an example of four rendering positions in multiple rendering with a virtual reference grid and a shift multiplicity N = 4. In the example of FIG. 29, since there are four drawing positions shifted in the x direction, the shift number m in the x direction is 4. Since there are two drawing positions shifted in the y direction, the shift number m in the y direction is 2. Therefore, the number of drawing positions shifted in the x and y directions is different. In the second embodiment, in such a case, the shift number m is defined as a small number. In the example of FIG. 29, the number of shifts in the y direction is used. Therefore, in the second embodiment, the value M equal to or smaller than the shift number is a value equal to or smaller than the shift number m defined by such a small number.

  The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, when the case where the number of drawing positions shifted in the x and y directions shown in FIG. 29 is different is applied to the first embodiment, the number of drawing positions shifted in the x and y directions is small. The shift number m may be defined by the number. In the example of FIG. 29, the shift number in the y direction may be used.

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

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

20 Multi-beam 22 Hole 24, 44 Control electrode 25, 45 Passing hole 26, 46 Counter electrode 31 Drawing area 34 Irradiation area 35 Stripe area 36, 37 Pixel 39 Representative position 40 Graphic pattern 41 Control circuit 42 Enlargement pattern 44 Reduction pattern 47 Individual Blanking mechanism 48 Graphic pattern 50 Setting unit 52 Shift direction calculation unit 54 Shift amount calculation unit 56 Enlarged pattern creation unit 58 Reduction pattern creation unit 60 Determination unit 62 Irradiation coefficient calculation unit 64 k map creation unit 66 Irradiation amount calculation unit 68 Irradiation time Calculation unit 70 Drawing control unit 71 Setting unit 72 Dose map creation unit 100 Drawing device 101 Sample 102 Electron barrel 103 Drawing room 105 XY stage 110 Control computer 112 Memory 130 Deflection control circuit 139 Stage position detectors 140 and 142 Storage device 150 Drawing Part 160 Control unit 200 electron beam 201 electron gun 202 illumination lens 203 shaping aperture array member 204 blanking aperture array 205 reduction lens 206 limiting aperture member 207 objective lens 208 deflector 210 mirrors

Claims (10)

The number of shifts varies according to the number of shifts defined by the number of multiple drawing positions shifted in one of the x and y directions among multiple drawing positions in multiple drawing performed while shifting the position. An enlarged pattern creation unit that creates an enlarged pattern in which a graphic pattern to be drawn is enlarged along an inversely proportional shift amount ;
A reduced pattern creating unit that creates a reduced pattern obtained by reducing the figure pattern along the shift amount inversely proportional to the shift number, which changes according to the shift number ;
An irradiation coefficient calculation unit that calculates an irradiation coefficient that modulates an irradiation amount of a charged particle beam irradiated to each of a plurality of small areas in which a drawing area is divided into meshes using the enlarged pattern and the reduced pattern; ,
A drawing unit that draws the graphic pattern on the sample by a multiple drawing method that is performed while shifting the position using a charged particle beam of an irradiation amount obtained for each small region using the irradiation coefficient;
A charged particle beam drawing apparatus comprising:   2. The charged particle beam drawing apparatus according to claim 1, wherein the irradiation coefficient calculation unit calculates the irradiation coefficient as 1 for each small area when a representative position of the small area falls within the reduced pattern. .   3. The charge according to claim 1, wherein the irradiation coefficient calculation unit calculates the irradiation coefficient as 0 for each small area when a representative position of the small area is located outside the enlarged pattern. Particle beam drawing device.   The irradiation coefficient calculation unit calculates the irradiation coefficient for each small area when the representative position of the small area is located inside the enlarged pattern and outside the reduced pattern. The charged particle beam drawing apparatus according to any one of claims 1 to 3. The number of shifts varies according to the number of shifts defined by the number of multiple drawing positions shifted in one of the x and y directions among multiple drawing positions in multiple drawing performed while shifting the position. Creating an enlarged pattern in which a graphic pattern to be drawn is enlarged along an inversely proportional shift amount ;
Creating a reduced pattern by reducing the figure pattern along the shift amount inversely proportional to the shift number, which changes according to the shift number ;
A step of calculating an irradiation coefficient that modulates an irradiation amount of a charged particle beam irradiated to each of a plurality of small regions obtained by dividing the drawing region into a mesh using the enlarged pattern and the reduced pattern;
Drawing the figure pattern on the sample by a multiple drawing method performed while shifting the position using a charged particle beam of an irradiation amount obtained for each small region using the irradiation coefficient;
A charged particle beam writing method comprising: In accordance with a value equal to or less than the number of shifts defined by the number of a plurality of drawing positions shifted in one of the x and y directions among a plurality of drawing positions in multiple drawing performed while shifting the position , An enlarged pattern creating unit that creates an enlarged pattern in which a graphic pattern to be drawn is enlarged along a shift amount that is inversely proportional to a value equal to or less than the shift number ;
A reduced pattern creation unit that creates a reduced pattern obtained by reducing the figure pattern along the shift amount that is inversely proportional to the value that is less than or equal to the number of shifts , depending on the value that is less than or equal to the number of shifts ;
An irradiation coefficient calculation unit that calculates an irradiation coefficient that modulates an irradiation amount of a charged particle beam irradiated to each of a plurality of small areas in which a drawing area is divided into meshes using the enlarged pattern and the reduced pattern; ,
A drawing unit that draws the graphic pattern on the sample by a multiple drawing method that is performed while shifting the position using a charged particle beam of an irradiation amount obtained for each small region using the irradiation coefficient;
A charged particle beam drawing apparatus comprising:   The irradiation coefficient calculation unit, for each small area, when the representative position of the small area is located inside the enlarged pattern and outside the reduced pattern, the irradiation coefficient is calculated using a value equal to or less than the shift number. The charged particle beam drawing apparatus according to claim 6, wherein: When the number of drawing positions shifted in the x direction is different from the number of drawing positions shifted in the y direction, the shift number is defined as a small number,
The charged particle beam drawing apparatus according to claim 6 or 7, wherein a value equal to or smaller than the shift number defined by the small number is used.   The charged particle beam drawing apparatus according to claim 6, wherein a value equal to or greater than 1 is used as the value equal to or less than the shift number. In accordance with a value equal to or less than the number of shifts defined by the number of a plurality of drawing positions shifted in one of the x and y directions among a plurality of drawing positions in multiple drawing performed while shifting the position , A step of creating an enlarged pattern in which a graphic pattern to be drawn is enlarged along a shift amount inversely proportional to a value equal to or less than the number of shifts ;
Creating a reduced pattern by reducing the figure pattern along the shift amount inversely proportional to the value less than the shift number, which changes according to the value less than the shift number;
A step of calculating an irradiation coefficient that modulates an irradiation amount of a charged particle beam irradiated to each of a plurality of small regions obtained by dividing the drawing region into a mesh using the enlarged pattern and the reduced pattern;
Drawing the figure pattern on the sample by a multiple drawing method performed while shifting the position using a charged particle beam of an irradiation amount obtained for each small region using the irradiation coefficient;
A charged particle beam writing method comprising: