Beam writing method and beam writing device

Abstract

The present invention provides a beam writing method that efficiently performs edge enhancement processing and that suppresses an increase in computation time. In this method, a graphic of writing data is reduced to generate a reduced graphic inside, and each graphic is rasterized to calculate first and second area densities for each pixel. In a region outside the reduced graphic, the irradiation amount is obtained on the basis of the first area density and a positive first coefficient. In an overlapping region of two graphics, the irradiation amount is calculated by combining a value based on the first area density and a value based on the second area density and a negative second coefficient, and writing is performed on the basis of the calculated irradiation amount.

Description

Beam lithography method and beam lithography apparatus

[0001] The present invention relates to a beam lithography method and a beam lithography apparatus for drawing patterns on a substrate using a beam.

[0002] With the increasing integration of LSIs, the circuit line widths required for semiconductor devices are becoming smaller year by year. To form desired circuit patterns on semiconductor devices, a method is employed in which a high-precision original pattern formed on silica is reduced and transferred onto a wafer using a reduction projection exposure system. For the production of high-precision original patterns, so-called electron beam lithography technology is used, in which a resist is exposed using an electron beam writing system to form the pattern.

[0003] The electron beam lithography system performs rasterization to calculate the coverage rate (area density) of the input shape for each pixel, which is divided into sections of a predetermined size, and controls the irradiation amount for each beam.

[0004] Furthermore, in electron beam lithography systems, edge enhancement processing is performed to improve resolution and reduce edge position errors by increasing the irradiation amount in the edge regions of the pattern and decreasing the irradiation amount inside the edge regions. In edge enhancement processing, for example, as shown in Figure 15, the edges of pattern 300 are moved inward by a predetermined bias amount to generate a reduced pattern 302. Then, the edge region 304 of pattern 300 excluding the reduced pattern 302 is determined.

[0005] Next, rasterization is performed on both the reduced pattern 302 and the edge region 304 to calculate the pattern area density for each pixel. For the reduced pattern 302, the irradiation amount is determined for each pixel by multiplying the pattern area density by the reference irradiation amount. For the edge region 304, the irradiation amount is determined by multiplying the pattern area density for each pixel by the reference irradiation amount and a predetermined coefficient of 1 or more. This enables edge enhancement processing with a larger irradiation amount in the edge region 304 compared to the reduced pattern 302.

[0006] However, when rasterizing both the reduced pattern 302 and the edge region 304 in this way, it is necessary to retain and process vertex information that defines the shapes of the reduced pattern 302 and the edge region 304. Since the edge region 304 has vertices on both its outer and inner edges, the amount of vertex information data is large, leading to an increase in the computation time required for edge enhancement.

[0007] JP 2019-176049 JP 2020-21919 JP 2017-5189 JP 2019-176047 JP 5-267142 US patent publication No. 2010 / 0058279 JP 4-239381 Patent 6026949 JP 7-85293 JP 6-274308 JP 6-274149

[0008] The object of this invention is to provide a beam lithography method and beam lithography apparatus that can efficiently perform edge enhancement processing.

[0009] A beam drawing method according to one aspect of the present invention is a beam drawing method for drawing a pattern on a substrate using a beam, comprising the steps of: reducing a figure defined in drawing data and generating a reduced figure inside the figure; rasterizing the figure and calculating a first area density for each pixel; rasterizing the reduced figure and calculating a second area density for each pixel; calculating a beam irradiation amount for the region of the figure outside the reduced figure based on the first area density and a predetermined positive first coefficient; calculating a beam irradiation amount for the overlapping region where the figure and the reduced figure overlap by summing a value based on the first area density and the first coefficient and a value based on the second area density and a predetermined negative second coefficient; and drawing the pattern on the substrate using the beam based on the calculated beam irradiation amount.

[0010] A beam lithography apparatus according to one aspect of the present invention is a beam lithography apparatus for drawing a pattern on a substrate using a beam, comprising: a reduced-figure generation unit that reduces a figure defined in drawing data and generates a reduced figure inside the figure; an irradiation amount calculation unit that rasterizes the figure and calculates a first area density for each pixel, rasterizes the reduced figure and calculates a second area density for each pixel, calculates a beam irradiation amount for the region of the figure outside the reduced figure based on the first area density and a predetermined positive first coefficient, and calculates a beam irradiation amount by summing a value based on the first area density and the first coefficient and a value based on the second area density and a predetermined negative second coefficient for the overlapping region where the figure and the reduced figure overlap; and a drawing unit that draws the pattern on the substrate using the beam based on the calculated beam irradiation amount.

[0011] According to the present invention, edge enhancement processing can be performed efficiently, and the increase in computation time can be suppressed.

[0012] This is a schematic diagram of a charged particle multibeam lithography apparatus according to an embodiment of the present invention. This is a plan view of a molded aperture array substrate. This is a flowchart explaining the lithography method. This is a diagram showing an example of generating a reduced figure. This is a diagram showing the irradiation amount distribution by superimposing the original figure pattern and the reduced figure. This is a diagram showing an example of a combination of edge enhancement processing and X / Y bias processing. This is a diagram showing an example of a combination of edge enhancement processing and X / Y bias processing. This is a diagram showing an example of a combination of edge enhancement processing and X / Y bias processing. This is a diagram showing an example of a cubic Bézier curve. This is a diagram showing an example of a cubic Bézier curve. This is a diagram showing the bias amount of the curve edge. This is a diagram showing the curve edge after movement. This is a diagram showing the reduced figure and edge region after the curve edge has been moved. This is a diagram showing the control points of the Bézier curve after the curve edge has been moved. This is a diagram showing an example of generating a reduced pattern.

[0013] Embodiments of the present invention will be described below with reference to the drawings. In the embodiments, an electron beam will be described as an example of a beam. However, the beam is not limited to an electron beam, but may also be other charged particle beams such as ion beams or light such as lasers.

[0014] Figure 1 is a schematic diagram of a drawing apparatus 100 according to an embodiment. As shown in Figure 1, the drawing apparatus 100 comprises a drawing unit 150 and a control unit 160. The drawing apparatus 100 is an example of a charged particle multibeam lithography apparatus. The drawing unit 150 comprises an electron-optical lens barrel 102 and a drawing chamber 103. Inside the electron-optical lens barrel 102 are an electron source 201, an illumination lens 202, a molded aperture array substrate 203, a blanking aperture array substrate 204, a reduction lens 205, a limiting aperture member 206, an objective lens 207, and a deflector 208.

[0015] An XY stage 105 is placed inside the drawing chamber 103. The substrate 101 to be drawn is placed on the XY stage 105. The substrate 101 is, for example, a mask blank or a semiconductor substrate (silicon wafer). A mirror 210 for position measurement is also placed on the XY stage 105.

[0016] The control unit 160 includes a control computer 110, a deflection control circuit 130, a stage position detector 139, and memory units 140 and 142. The memory unit 140 receives and stores drawing data from an external source. The drawing data defines information for multiple graphic patterns that describe the semiconductor circuit patterns to be formed on the substrate 101.

[0017] The control computer 110 includes a bias amount acquisition unit 111, a reduced figure generation unit 112, an irradiation amount calculation unit 113, an irradiation time control data generation unit 114, a drawing control unit 115, and a bias processing unit 116. Each part of the control computer 110 may be composed of hardware such as electrical circuits, or it may be composed of software such as programs that execute these functions. Alternatively, it may be composed of a combination of hardware and software. If it is composed of software, a program that realizes at least some of the functions of the control computer 110 is stored in a storage unit 142 (recording medium) such as a CD-ROM. The control computer 110 is a computer with a CPU, and the CPU reads and executes the program. The storage unit 142 is not limited to removable ones such as magnetic disks or optical disks, but may also be a fixed recording medium such as a hard disk drive or memory.

[0018] The stage position detector 139 irradiates the mirror 210 with a laser and receives the reflected light, detecting the position of the XY stage 105 using the principle of laser interferometry.

[0019] Figure 2 is a conceptual diagram showing the configuration of the molded aperture array substrate 203. As shown in Figure 2, the molded aperture array substrate 203 has a plurality of apertures 203a formed along the vertical (y-direction) and horizontal (x-direction) at a predetermined arrangement pitch. Preferably, each aperture 203a is formed as a rectangle or circle of the same dimensions and shape. A portion of the electron beam 200 passes through each of these plurality of apertures 203a to form multibeams 20a to 20e.

[0020] The blanking aperture array substrate 204 has through holes formed in it to match the positions of each aperture 203a of the molded aperture array substrate 203. A blanker, consisting of a pair of electrodes, is placed in each through hole. By, for example, grounding one of the two electrodes of the blanker to maintain ground potential and switching the other electrode to ground potential or a potential other than ground potential, the deflection of the beam passing through the through hole is switched on and off, thereby controlling blanking. If the blanker does not deflect the beam, the beam is on. If the blanker deflects the beam, the beam is off. In this way, multiple blankers perform blanking deflection of their respective beams from among the multiple beams that have passed through the multiple apertures 203a of the molded aperture array substrate 203.

[0021] The electron beam 200 emitted from the electron source 201 (emitting section) illuminates the entire molded aperture array substrate 203 by the illumination lens 202. The electron beam 200 illuminates the region that includes all the apertures 203a. As the electron beam 200 passes through multiple apertures 203a of the molded aperture array substrate 203, a multi-beam 20a to 20e containing multiple individual beams is formed. The overall shape of the beam array of the multi-beams 20a to 20e is, for example, rectangular.

[0022] The individual beams constituting the multi-beam 20 pass through their respective blankers in the blanking aperture array substrate 204. The blankers blank-blind the individual beams that are to be turned off. The blankers do not blank-blind the individual beams that are to be turned on. The multi-beams 20a to 20e that have passed through the blanking aperture array substrate 204 are reduced in size by the reduction lens 205 and proceed toward the central opening formed in the limiting aperture member 206.

[0023] Here, individual beams controlled to the beam-off state are deflected by the blanker and follow a trajectory that passes outside the opening of the limiting aperture member 206, and are therefore shielded by the limiting aperture member 206. On the other hand, individual beams controlled to the beam-on state are not deflected by the blanker and pass through the opening of the limiting aperture member 206. In this way, blanking control is performed by turning the blanker's deflection on / off, and the off / on state of the individual beams is controlled. The blanking aperture array substrate 204 functions as an irradiation time control unit that controls the irradiation time of each beam in the multi-beam system.

[0024] The limiting aperture member 206 allows individual beams that have been deflected by the blanker of the blanking aperture array substrate 204 to be in a beam-on state to pass through, and shields individual beams that have been deflected by the blanker of the blanking aperture array substrate 204 to be in a beam-off state. Then, a multi-beam for one shot is formed by the beams that have passed through the limiting aperture member 206 from the time the beam is turned on until it is turned off.

[0025] The multi-beams that have passed through the limiting aperture member 206 are focused by the objective lens 207, forming a pattern image with a desired reduction ratio on the substrate 101. Each beam (the entire multi-beam) that has passed through the limiting aperture member 206 is deflected together in the same direction by the deflector 208 and irradiated to a desired position on the substrate 101.

[0026] When the XY stage 105 is moving continuously, the deflector 208 controls the beam irradiation position so that it follows the movement of the XY stage 105, at least while the beam is irradiating the substrate 101. The multi-beams irradiated at once will ideally be aligned at a pitch obtained by multiplying the array pitch of the multiple apertures 203a of the molded aperture array substrate 203 by the desired reduction ratio described above.

[0027] The pattern drawing method with edge enhancement processing according to this embodiment will be explained with reference to the flowchart shown in Figure 3.

[0028] In the bias amount acquisition process (step S1), the bias amount acquisition unit 111 reads drawing data from the storage unit 140 and acquires the bias amount of the edges of the graphic pattern defined in the drawing data. The bias amount corresponds to the width of the edge region that is subject to edge enhancement processing.

[0029] In the reduced shape generation process (step S2), the reduced shape generation unit 112 reduces the shape pattern defined in the drawing data by a bias amount and generates a reduced shape inside the original shape pattern.

[0030] For example, as shown in Figure 4, the reduced shape generation unit 112 performs a negative bias process on the original shape pattern F0 to generate a reduced shape F2. The area inside the original shape pattern F0 and outside the reduced shape F2 becomes the edge region F1. In this process, the reduced shape F2 is generated, but the shape of the edge region F1 is not generated. Therefore, the vertex information of the original shape pattern F0 and the vertex information of the reduced shape F2 are retained.

[0031] For example, in this embodiment, the vertex information of four points in the original geometric pattern F0 and the vertex information of four points in the scaled-down geometric figure F2, for a total of eight points, are stored.

[0032] In contrast, when generating an edge region F1 and storing the vertex information of the edge region F1 and the vertex information of the scaled-down figure F2, a total of eight vertex information points are required for the edge region F1: four vertices on the outer perimeter and four vertices on the inner perimeter. That is, the vertex information points for eight points of the edge region F1 and the vertex information points for four points of the scaled-down figure F2, for a total of twelve vertex information points, are stored.

[0033] As in the present embodiment, by not generating a graphic in the edge region F1 and holding the vertex information of the original graphic pattern F0 and the vertex information of the reduced graphic F2, the data amount of the vertex information can be reduced.

[0034] In the irradiation dose calculation step (step S3), an irradiation dose calculation unit 113 virtually divides the drawing region of a substrate 101 into a plurality of rectangular mesh regions (divided regions). The size of each mesh region is, for example, approximately the same size as one beam, and each mesh region serves as a pixel (unit irradiation region). The irradiation dose calculation unit 113 calculates a pattern area density (coverage) ρ of each pixel for each of the original graphic pattern and the reduced graphic.

[0035] For each pixel, the irradiation dose calculation unit 113 calculates the pattern area density ρ obtained from the original graphic pattern １ (first area density) by multiplying it by a reference irradiation dose D ０ and a coefficient α (first coefficient) to obtain an irradiation dose α·ρ １ ·D ０ The irradiation dose calculation unit 113 also, for each pixel, multiplies the pattern area density ρ obtained from the reduced graphic ２ (second area density) by a reference irradiation dose D ０ and a coefficient β (second coefficient) to obtain an irradiation dose β·ρ ２ ·D ０ The coefficient α is a value of 1 or more, and the coefficient β is a negative value. The coefficients α and β are set in advance and defined in the drawing data.

[0036] The reduced graphic overlaps the original graphic pattern. For a pixel in an overlapping region where the reduced graphic exists, the irradiation dose calculation unit 113 adds β·ρ １ ·D ０ , which is an irradiation dose with a negative value, to the irradiation dose α·ρ ２ ·D ０ to obtain the irradiation dose of the pixel.

[0037] For example, as shown in FIG. 5, the coefficient α corresponding to the original graphic pattern F0 is 1.4, and the coefficient β corresponding to the reduced graphic F2 is −0.4. By superimposing a negative irradiation dose on the portion of the reduced graphic F2, 100% of the reference irradiation dose D ０ is obtained, and for the edge region F1, the reference irradiation dose D０ This results in 140% of the original value, enabling edge enhancement processing.

[0038] In the irradiation time control data generation process (step S4), the irradiation time control data generation unit 114 calculates the irradiation time for each beam by dividing the calculated irradiation amount by the current amount of each of the multiple beams constituting the multibeam, rearranges the irradiation time data in the order of shots according to the drawing sequence, and generates irradiation time control data.

[0039] In the data transfer process (step S5), the drawing control unit 115 outputs irradiation time control data to the deflection control circuit 130. The deflection control circuit 130 outputs the irradiation time control data to each blanker of the blanking aperture array substrate 204.

[0040] In the drawing process (step S6), the drawing control unit 115 controls the drawing unit 150 to perform the drawing process on the substrate 101. Each blanker of the blanking aperture array substrate 204 switches the beam on / off based on the irradiation time control data to provide a desired exposure amount for each pixel.

[0041] In this embodiment, since no shapes are generated in the edge region, and the vertex information of the original shape pattern and the vertex information of the scaled-down shape are retained, the amount of vertex information data is reduced, and edge enhancement processing can be performed efficiently.

[0042] Edge enhancement processing and X / Y bias processing of shapes may be combined. X / Y bias processing is a process that reduces (or enlarges) a shape by different amounts in the X direction and the Y direction which is perpendicular to the X direction.

[0043] For example, the bias processing unit 116 first applies a predetermined amount of bias processing to the graphic pattern F10 in the X and Y directions, as shown in Figure 6, to generate a biased graphic F10'. Next, by performing the above edge enhancement processing on the biased graphic F10', a larger illumination amount can be set for the edge region F11 than for the reduced graphic F12, which is a scaled-down version of the biased graphic F10'. In this way, for example, if the graphic becomes larger due to setting a larger illumination amount for the edge region F11, by pre-calculating F10 as a scaled-down biased graphic F10', the size of the graphic pattern after drawing can be set to the size of the graphic pattern F10.

[0044] In the example shown in Figure 6, performing edge enhancement processing after X / Y bias processing makes the width of the edge region F11 uniform around the entire circumference.

[0045] Conversely to the above, as shown in Figure 7, a reduced figure F22 may be generated first from the figure pattern F20, and then a predetermined amount of bias processing may be applied to the figure pattern F20 and the reduced figure F22 in the X and Y directions to generate a biased figure F20' and a biased reduced figure F22'. The area inside the biased figure F20' and outside the biased reduced figure F22' becomes the edge region F21. A positive irradiation amount is assigned to the biased figure F20' and a negative irradiation amount is assigned to the biased reduced figure F22', and the negative irradiation amount is added to the positive irradiation amount for the biased reduced figure F22'.

[0046] As shown in Figure 8, a scaled-down figure F22 may be generated first from the figure pattern F20, and then a predetermined amount of bias processing may be applied only to the scaled-down figure F22 in the X and Y directions to generate a biased scaled-down figure F22'. The area inside the figure pattern F20 and outside the biased scaled-down figure F22' becomes the edge region F21. In this example, the width of the edge region F21 will not be uniform, but the emphasis width can be changed depending on the location of the figure.

[0047] When the shape to be drawn on the substrate 101 includes a curve, the curve may be represented by a cubic Bézier curve, and the position information of the control points of the cubic Bézier curve may be defined in the drawing data. As shown in Figure 9, the cubic Bézier curve is represented by four control points P. ０ ~P３ Of these, starting point P ０ and endpoint P ３ The two control points (endpoints) are located on the curve.

[0048] Furthermore, a cubic Bézier curve is a parametric curve, and as shown in Figure 10, the curve (x(t), y(t)) is represented by the parameter t (0 ≤ t ≤ 1).

[0049] The bias amount acquisition unit 111 reads drawing data from the storage unit 140 and acquires the bias amount of the curved edge of the geometric pattern defined in the drawing data. The bias amount acquisition unit 111 acquires the bias amount at multiple points (points corresponding to multiple parameter values) on the Bézier curve that represents the curved edge. The bias amount to be acquired is Bézier curve B １ Among the multiple (n+1) control points that represent the starting point P, the endpoint (starting point P) ０ and endpoint P ｎ The amount of bias in ) is T ０ , T ｍ (m is an integer greater than or equal to 2) and one or more intermediate points (t = t １ ~t ｍ－１ The amount of bias in ) is T １ ~T ｍ－１ This includes the bias amount, which can be a vector quantity at each parameter value or a constant quantity in the normal direction. The bias amount may also be calculated as a function dependent on the curvature of the curve.

[0050] For example, as shown in Figure 11, starting point P ０ (t=0) and endpoint P ３ Bias amount T at (t=1) ０ , T ２ And, Bézier curve B １ The middle part (t = t １ The amount of bias in ) is T １ The bias amount is obtained. The bias amount may be input to the control computer 110 from an external device, or it may be obtained by interpolating with a monotonic function from the parameters of the preceding and succeeding curves.

[0051] The reduced shape generation unit 112 performs a process to shift the curve edges defined in the drawing data by a bias amount. That is, the reduced shape generation unit 112 generates a Bézier curve B that represents the curve edges of the pattern defined in the drawing data. １Bézier curve B obtained by shifting the bias amount ２ Control point Q that represents ０ ~Q ｎ Calculate (Bézier curve B) ２ (See Figure 12 for details.)

[0052] The reduced figure generation unit 112 generates the original Bézier curve B １ Endpoint (starting point P) ０ and endpoint P ｎ ) bias amount T ０ , T ｍ Point Q moved by (m is an integer greater than or equal to 2) ０ Q ｎ We will find point Q. ０ Q ｎ B is the Bézier curve after bias treatment. ２ This becomes the starting and ending point. For example, as shown in Figure 11, point P ０ (t=0) is the bias amount T ０ Moved point Q ０ And point P ３ The bias amount T ２ Moved point Q ３ To find out.

[0053] The reduced figure generation unit 112 generates the original Bézier curve B １ The parameter t is given the bias amount in the middle part. １ ~t ｍ－１ The point corresponding to the bias amount T １ ~T ｍ－１ The moved point and Bézier curve B ２ Parameter t １ ~t ｍ－１ Control points Q other than the endpoints such that the norm of the positional difference with the corresponding point becomes small. １ ~Q ｎ－１ The following is calculated. For example, the reduced figure generation unit 112 uses the least squares method to find the Q that minimizes D in the following equation (1). ｉ = (x ｉ , y ｉ ) Find the control points Q other than the endpoints. １ ~Q ｎ－１ Calculate the original Bézier curve B. １ The parameter t is given the bias amount in the middle part. １ ~t ｍ－１the corresponding point is moved by the bias amount T １ to T ｍ－１ and the point obtained after movement, and the parameter t of the Bezier curve B ２ t １ to t ｍ－１ the control points Q are determined by the least square method such that the sum of squared differences of positions between the point corresponding to １ to Q ｎ－１ and the moved point is minimized.

[0054]

[0055] For example, the above processing is applied to the example shown in FIG. 11, and points Q １ , Q ２ are calculated. A Bezier curve B represented by control points Q ０ to Q ３ accurately represents a curve obtained by moving the original Bezier curve B ２ by the bias amount from the original Bezier curve B １ with high accuracy.

[0056] Instead of formula (1), Q that minimizes D in the following formula (2) ｉ = (x ｉ , y ｉ ) is obtained, and control points Q other than the end points １ to Q ｎ－１ may be calculated.

[0057]

[0058] By using the above method, a curved edge obtained by moving the curved edge of a figure by a desired bias amount can be obtained. A straight edge of a figure can be moved by the bias amount using a known method. This makes it possible to move the edge surrounding the figure by the bias amount. For example, as shown in FIG. 13, a reduced figure 402 obtained by reducing the original figure pattern 400 is obtained. The hatched area obtained by removing the reduced figure 402 from the figure pattern 400 serves as an edge area 404.

[0059] When generating an edge region 404 and holding control point information for the edge region 404, information on outer peripheral control points and inner peripheral control points is required for the edge region 404. However, by not generating a graphic for the edge region 404 and holding the control point information of the original graphic pattern 400 and the control point information of the reduced graphic 402, the data amount of the control point information can be reduced.

[0060] Edge enhancement processing can be realized by performing the aforementioned irradiation amount calculation step (step S3) for the graphic pattern 400 and the reduced graphic 402.

[0061] The reduced graphic generation unit 112 is configured such that control point Q ０ and control point Q １ a straight line connecting the two is parallel to the straight line connecting control point P ０ and control point P １ and the straight line connecting control point Q ｎ－１ and control point Q ｎ is parallel to the straight line connecting control point P ｎ－１ and control point P ｎ , and control points Q １ to Q ｎ－１ may be calculated. This enables the angle of the connecting portion of the curve to be maintained.

[0062] In this case, the reduced graphic generation unit 112 obtains a, b, Q that minimize D in the following formula (3) ｉ =(x ｉ , y ｉ ), and calculates control points Q １ to Q ｎ－１ .

[0063]

[0064] For example, applying the above processing to the example shown in FIG. 11 gives points Q １ , Q ２ calculated as shown in FIG. 14. The straight line connecting control point Q ０ and control point Q １ is parallel to the straight line connecting control point P ０ and control point P １ , and the straight line connecting control point Q ２ and control point Q ３ is parallel to the straight line connecting control point P ２ and control point P ３The line connecting the two points is parallel, and the angle of the curved connection point is maintained.

[0065] Instead of equation (3), find the values ​​of a, b, and Q such that D in equation (4) is minimized. ｉ = (x ｉ , y ｉ ) Find the control point Q １ ~Q ｎ－１ You may calculate this.

[0066]

[0067] Control point Q ０ and control point Q １ The straight line connecting these points is the control point P. ０ and control point P １ The line connecting the two points does not need to be parallel; it may be slightly inclined. Control point Q ｎ－１ and control point Q ｎ The straight line connecting these points is the control point P. ｎ－１ and control point P ｎ The line connecting the two points does not have to be parallel; it may be slightly inclined. That is, control point Q ０ and control point Q １ The straight line connecting these points is the control point P. ０ and control point P １ The line connecting the two points is approximately parallel, and control point Q ｎ－１ and control point Q ｎ The straight line connecting these points is the control point P. ｎ－１ and control point P ｎ Control point Q should be approximately parallel to the line connecting the two points. １ ~Q ｎ－１ You may calculate this.

[0068] The curves of the geometric patterns may also be defined using parametric curves other than cubic Bézier curves, such as B-spline curves. Furthermore, the degree of the parametric curve is not limited to 3.

[0069] In the above embodiment, a coefficient α of 1 or more is assigned to the original geometric pattern, a negative coefficient β is assigned to the reduced geometric pattern, and for pixels where the reduced geometric pattern exists, the irradiation dose is α・ρ. １ ・D ０ The negative irradiation dose is β・ρ ２ ・D ０We have described a configuration in which the irradiation amount of the pixel is determined by adding the values, but a positive coefficient β' is assigned to the reduced shape, and for pixels in which the reduced shape exists, the irradiation amount α・ρ １ ・D ０ From irradiation dose β'・ρ ２ ・D ０ The illumination amount for the pixel may be determined by subtracting the value of

[0070] In the above embodiment, a configuration was described in which a reduced shape is generated from the original shape pattern and the illumination amount per pixel is calculated for both the original shape pattern and the reduced shape. However, edge enhancement processing can also be achieved by first determining the illumination amount per pixel for the original shape pattern, and then reducing the illumination amount of the reduced pixel group, which is obtained by reducing the pixel group corresponding to the original shape pattern, by a predetermined amount.

[0071] In the above embodiment, an example was described in which a reduced figure is generated internally by the control computer 110 and the negative irradiation amount of the reduced figure is added to the irradiation amount of the pattern before bias processing. However, the generation of the reduced figure and the assignment of the negative irradiation amount to the reduced figure may be performed by an external device, and drawing data including information on the original figure before reduction, information on the reduced figure, positive first irradiation amount information assigned to the original figure, and negative second irradiation amount information assigned to the reduced figure may be prepared and input to the control computer 110. Edge regions are drawn with an irradiation amount based on the first irradiation amount information. Overlapping regions where the original figure and the reduced figure overlap are drawn with an irradiation amount based on the sum of the first irradiation amount information and the second irradiation amount information.

[0072] A program that implements at least some of the functions of the control computer 110 may be distributed via a communication line such as the Internet (including wireless communication). Furthermore, the program may be encrypted, modulated, or compressed and then distributed via a wired or wireless line such as the Internet, or stored on a recording medium.

[0073] In the above embodiment, a multi-beam lithography apparatus that irradiates multiple beams simultaneously using a multi-beam system was described, but the same method can be applied to a single-beam lithography apparatus that irradiates a substrate with a single beam.

[0074] It should be noted that the present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Moreover, components from different embodiments may be appropriately combined.

[0075] 100 Drawing device 110 Control computer 111 Bias amount acquisition unit 112 Reduced figure generation unit 113 Irradiation amount calculation unit 114 Irradiation time control data generation unit 115 Drawing control unit 116 Bias processing unit

Claims

1. A beam drawing method for drawing a pattern on a substrate using a beam, comprising: a step of reducing a figure defined in drawing data and generating a reduced figure inside the figure; a step of rasterizing the figure and calculating a first area density for each pixel; a step of rasterizing the reduced figure and calculating a second area density for each pixel; a step of calculating a beam irradiation amount for the region of the figure outside the reduced figure based on the first area density and a predetermined positive first coefficient; a step of calculating a beam irradiation amount for the overlapping region where the figure and the reduced figure overlap by summing a value based on the first area density and the first coefficient and a value based on the second area density and a predetermined negative second coefficient; and a step of drawing the pattern on the substrate using the beam based on the calculated beam irradiation amount.

2. The beam drawing method according to claim 1, further comprising the steps of: performing a biasing process on the figure by expanding or contracting it by different amounts in a first direction and a second direction perpendicular to the first direction to generate a biased figure; reducing the biased figure to generate a reduced figure inside the biased figure; and performing a rasterization process on the biased figure and the reduced figure.

3. A beam lithography apparatus for drawing a pattern on a substrate using a beam, comprising: a reduced shape generation unit that reduces a figure defined in drawing data and generates a reduced figure inside the figure; an irradiation amount calculation unit that rasterizes the figure and calculates a first area density for each pixel, rasterizes the reduced figure and calculates a second area density for each pixel, calculates a beam irradiation amount for the region of the figure outside the reduced figure based on the first area density and a predetermined positive first coefficient, and calculates a beam irradiation amount by summing a value based on the first area density and the first coefficient and a value based on the second area density and a predetermined negative second coefficient for the overlapping region where the figure and the reduced figure overlap; and a drawing unit that draws the pattern on the substrate using the beam based on the calculated beam irradiation amount.

4. A beam lithography apparatus for drawing a pattern on a substrate using a beam, comprising: a control computer to which drawing data including a figure to be drawn, a reduced figure obtained by reducing the figure, first irradiation dose information assigned to the figure, and negative second irradiation dose information assigned to the reduced figure is input; and a drawing unit that draws the area of ​​the figure outside the reduced figure on the substrate using the beam based on the first irradiation dose information, and draws the overlapping area where the figure and the reduced figure overlap on the substrate using the beam based on the sum of the first irradiation dose information and the second irradiation dose information.

Images