JP6754481B2 - Multi-charged particle beam drawing device and multi-charged particle beam drawing method - Google Patents

Description

The present invention relates to a multi-charged particle beam drawing device and a multi-charged particle beam drawing method, and for example, a multi-beam drawing device and a method for correcting misalignment due to distortion of a stage and distortion of a mirror for position measurement. Regarding.

Lithography technology, which is responsible for the progress of miniaturization of semiconductor devices, is the only extremely important process for generating patterns in the semiconductor manufacturing process. In recent years, with the increasing integration of LSIs, the circuit line width required for semiconductor devices has been miniaturized year by year. In order to form a desired circuit pattern on these semiconductor devices, a high-precision original image pattern (also referred to as a reticle or a mask) is required. Here, the electron beam (EB: Electron beam) drawing technique has essentially excellent resolvability and is used for producing a high-precision original image pattern.

For example, there is a drawing device using one beam. For example, there is a raster type drawing device. In such a raster type drawing apparatus, for example, an electron beam emitted from an electron gun is passed through a mask having one hole to form one beam, and one beam is formed by a deflector so as to trace the sample in order. The blanking is controlled so that the beam is radiated to the required location while deflecting the forming beam.

In addition, for example, there is a drawing device using a multi-beam. Compared with the case of drawing with one electron beam, by using the multi-beam, many beams can be irradiated at one time, so that the throughput can be significantly improved. In such a multi-beam type drawing device, 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 beam is blanked-controlled and unshielded. It is reduced by the optical system, deflected by the deflector, and irradiated to the desired position on the sample.

In a drawing device including multi-beam drawing, a laser length measuring device may be used when measuring the position of the stage. In such a laser length measuring device, there is a problem that an error occurs in the measured position due to the distortion of the reflecting surface of the mirror arranged on the stage. Further, if the sample surface to be drawn is distorted, there is a problem that an error occurs in the drawing position. Conventionally, in a vector type single beam drawing apparatus such as a variable molding type drawing apparatus, in order to correct the coordinate system of the drawing apparatus to an ideal coordinate system, the entire surface of the sample to be drawn is meshed with a predetermined grid size. Divide into and measure the position of the vertices of each mesh. Then, the coordinate system of the drawing device is corrected from the error between the measured position and the design position (this function is called a "grid matching collection: GMC" function. Hereinafter, the correction by such a function is called GMC correction. .). Specifically, a pattern for GMC measurement is drawn at a position corresponding to the position of the apex of each mesh described above in the mask blanks coated with the resist. Then, the mask was subjected to a phenomenon and process processing such as etching, and the position accuracy was measured from the drawn pattern. Then, the coordinate system of the drawing apparatus is corrected from the obtained result (see, for example, Patent Document 1). In such GMC correction, position correction is performed for each shot after the shot data is generated.

On the other hand, in the multi-beam drawing method, a large number of beams are irradiated at one time, and even when the beams are deflected, the entire multi-beam is deflected at once, so that it is difficult to correct the position for each individual beam. In order to correct the position, the pattern shape is converted so as to be approximated by a bit (pixel) pattern, the irradiation amount of each pixel is calculated, and the irradiation amount of the own pixel is distributed to the adjacent pixels. There is a method such as modulation. However, in such a method, the irradiation amount of the pixel located at the end of the pattern is distributed to the surrounding pixels, so that the inclination of the beam profile is not steep (it becomes small). As a result, there is a problem that the resolution is deteriorated. If the resolution deteriorates, the accuracy of the pattern drawing position and line width deteriorates.

Japanese Unexamined Patent Publication No. 2008-0851120

As described above, in multi-beam drawing, it is difficult to individually correct the distortion of the reflecting surface of the mirror on the stage and / or the misalignment due to the distortion of the sample surface to be drawn. As a result, it was difficult to sufficiently correct such misalignment.

Therefore, an object of the present invention is to provide a device and a method capable of correcting distortion of the reflecting surface of a mirror and / or misalignment of a sample surface to be drawn due to distortion or the like for multi-beam drawing. ..

The multi-charged particle beam drawing apparatus according to one aspect of the present invention is
A dividing part that divides the drawing area of the sample into a plurality of mesh-shaped pixel areas irradiated with a multi-charged particle beam,
A group processing unit that groups a plurality of pixel areas into a plurality of pixel blocks composed of at least one pixel area.
For each pixel block of a plurality of pixel blocks, a correction unit that corrects the position of an area on the drawing data to be processed by the pixel block in pixel block units.
An irradiation amount calculation unit that calculates the irradiation amount to irradiate the pixel for each pixel whose position has been corrected,
A drawing unit that draws a pattern on the sample using the multi-charged particle beam so that each pixel has an calculated irradiation amount.
It is characterized by being equipped with.

Further, it is preferable that the correction unit corrects the position of the representative point of the pixel block for each pixel block by using the inverse conversion amount of the correction function for correcting the positional deviation at the representative point of the pixel block.

Further, it is preferable that each complementary pixel block is further provided with a first calculation unit that calculates an inverse conversion term used for the inverse conversion processing of the correction function.

Further, it is preferable to further provide a second calculation unit for calculating the correction amount of each position that specifies the shape of the pixel block by using a function that uses the partial differential value of the correction function as a coefficient for each pixel block. ..

The method for drawing a multi-charged particle beam according to one aspect of the present invention is
The process of dividing the drawing area of the sample into a plurality of mesh-shaped pixel areas irradiated with the multi-charged particle beam, and
A process of grouping a plurality of pixel areas into a plurality of pixel blocks composed of at least one pixel area, and
A process of correcting the position of an area on drawing data to be processed by the pixel block for each pixel block of a plurality of pixel blocks,
The process of calculating the irradiation amount to irradiate the pixel for each pixel whose position has been corrected, and
The process of drawing a pattern on the sample using a multi-charged particle beam so that each pixel has the calculated irradiation amount,
It is characterized by being equipped with.

According to one aspect of the present invention, in multi-beam drawing, distortion of the reflecting surface of the mirror and / or misalignment due to distortion of the sample surface to be drawn can be corrected. Therefore, the pattern can be drawn at a highly accurate position and dimension.

It is a conceptual diagram which shows the structure of the drawing apparatus in Embodiment 1. FIG. It is a conceptual diagram which shows the structure of the molded aperture array member in Embodiment 1. FIG. It is sectional drawing which shows the structure of the blanking aperture array part in Embodiment 1. FIG. FIG. 5 is a top conceptual diagram showing a part of the configuration in the membrane region of the blanking aperture array portion in the first embodiment. It is a flowchart which shows the main part process of the drawing method in Embodiment 1. FIG. It is a figure for demonstrating the drawing order in Embodiment 1. FIG. It is a figure which shows the example of the pixel block in Embodiment 1 and the example of the state in which the pixel block is corrected. It is a figure for demonstrating the equation of a straight line and the distance to a straight line in Embodiment 1. FIG. It is a figure which shows an example of the simulation result of the beam profile at the time of drawing the rectangular pattern rotated by 10 ° using the pixel which performed the position shift correction in Embodiment 1. FIG. It is a figure which shows an example of the simulation result at the time of drawing a triangle pattern in the case of the presence / absence of correction in Embodiment 1. FIG. It is a figure which shows another example of the simulation result at the time of drawing a triangle pattern in the case of presence / absence of correction in Embodiment 1. FIG.

Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to the electron beam, and a beam using charged particles such as an ion beam may be used.

Embodiment 1.
FIG. 1 is a conceptual diagram showing a configuration of a drawing apparatus according to the first embodiment. In FIG. 1, the drawing device 100 includes a drawing unit 150 and a control unit 160. The drawing device 100 is an example of a multi-charged particle beam drawing device. The drawing unit 150 includes an electronic lens barrel 102 and a drawing chamber 103. An electron gun 201, an illumination lens 202, a molded aperture array member 203, a blanking aperture array unit 204, a reduction lens 205, a limiting aperture member 206, an objective lens 207, and a deflector 208 are arranged in the electron barrel 102. There is. An XY stage 105 is arranged in the drawing chamber 103. A sample 101 such as a mask, which serves as a drawing target substrate at the time of drawing, is arranged on the XY stage 105. The sample 101 is held on the XY stage 105 by, for example, a three-point support (not shown). The sample 101 includes an exposure mask for manufacturing a semiconductor device, a semiconductor substrate (silicon wafer) on which the semiconductor device is manufactured, and the like. In addition, the sample 101 includes mask blanks coated with resist and not yet drawn. A mirror 210 for measuring the position of the XY stage 105 is further arranged on the XY stage 105.

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, 142, 144 such as a magnetic disk device. The control computer 110, the memory 112, the deflection control circuit 130, the stage position detector 139, and the storage devices 140, 142, 144 are connected to each other via a bus (not shown). Drawing data in which putter data of a plurality of graphic patterns to be drawn is defined is input from the outside of the drawing device 100 and stored in the storage device 140 (storage unit). Here, as the drawing data, for example, drawing data of an evaluation pattern for evaluating the distortion of the reflection surface of the mirror 210 and / or the positional deviation due to the distortion or the like on the sample surface of the sample 101 to be drawn is used. ..

Further, in the control computer 110, a pixel division unit 50, a pixel block creation unit 52, a pixel block setting unit 54, an acquisition unit 55, a fitting processing unit 56, a correction map creation unit 58, a representative point position correction amount calculation unit 60, Pixel block shape calculation unit 62, correction unit 64, judgment unit 65, judgment unit 66, proximity effect correction irradiation coefficient Dp calculation unit 67, irradiation amount D calculation unit 68, irradiation time t calculation unit 70, and drawing control unit 72 are arranged. Will be done. Pixel division unit 50, pixel block creation unit 52, pixel block setting unit 54, acquisition unit 55, fitting processing unit 56, correction map creation unit 58, representative point position correction amount calculation unit 60, pixel block shape calculation unit 62, correction unit Each function such as 64, judgment unit 65, judgment unit 66, proximity effect correction irradiation coefficient Dp calculation unit 67, irradiation amount D calculation unit 68, irradiation time t calculation unit 70, and drawing control unit 72 is composed of software such as a program. You may. Alternatively, it may be configured by hardware such as an electronic circuit. Alternatively, it may be a combination of these. The input data required in the control computer 110 or the result of calculation is stored in the memory 112 each time. Further, the pixel division unit 50, the pixel block creation unit 52, the pixel block setting unit 54, the acquisition unit 55, the fitting processing unit 56, the correction map creation unit 58, the representative point position correction amount calculation unit 60, the pixel block shape calculation unit 62, At least one of the correction unit 64, the determination unit 65, the determination unit 66, the proximity effect correction irradiation coefficient Dp calculation unit 67, the irradiation amount D calculation unit 68, the irradiation time t calculation unit 70, and the drawing control unit 72 is composed of software. In that case, a calculator such as a CPU or GPU is arranged.

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

FIG. 2 is a conceptual diagram showing the configuration of the molded aperture array member according to the first embodiment. In FIG. 2A, in the molded aperture array member 203, holes (openings) 22 of vertical (y direction) m row × horizontal (x direction) n rows (m, n ≧ 2) are arranged at a predetermined arrangement pitch. It is formed in a matrix. In FIG. 10A, for example, 512 × 8 rows of holes 22 are formed. Each hole 22 is formed by a rectangle having the same dimensions 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. A part of the electron beam 600 passes through each of the plurality of holes 22, so that the multi-beam 20 is formed. Here, an example in which holes 22 having two or more rows in both vertical and horizontal directions (x and y directions) are arranged 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 have a plurality of columns and the other may have only one column. Further, the method of arranging the holes 22 is not limited to the case where the holes 22 are arranged in a grid pattern in the vertical and horizontal directions as shown in FIG. 2A. 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 arranged so as to be offset by the dimension a in the horizontal direction (x direction). May be good. Similarly, the holes in the second row in the vertical direction (y direction) and the holes in the third row may be arranged so as to be offset by the dimension b in the horizontal direction (x direction).

FIG. 3 is a cross-sectional view showing the configuration of the blanking aperture array portion according to 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 portion in the first embodiment. In addition, in FIGS. 3 and 4, the positional relationship between the control electrode 24, the counter electrode 26, and the control circuits 41 and 43 is not shown in agreement. In the blanking aperture array unit 204, as shown in FIG. 3, a semiconductor substrate 31 made of silicon or the like is arranged on a support base 33. The central portion of the substrate 31 is thinly scraped from the back surface side, for example, 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 so as to be at the same height position or substantially the same height position. The substrate 31 is held on the support base 33 on the back surface of the outer peripheral region 32. The central portion of the support base 33 is open, and the position of the membrane region 30 is located in the open region of the support base 33.

In the membrane region 30, a passage hole 25 (opening) for passing each beam of the multi-beam is opened at a position corresponding to each hole 22 of the molded aperture array member 203 shown in FIG. Then, on the membrane region 30, as shown in FIGS. 3 and 4, a set of a control electrode 24 for blanking deflection and a counter electrode 26 (a set of a control electrode 24 for blanking deflection and a counter electrode 26 with a passage hole 25 corresponding to a position in the vicinity of each passage hole 25 interposed therebetween Blankers: blanking deflectors) are placed respectively. Further, a control circuit 41 (logic circuit) that applies a deflection voltage to the control electrode 24 for each passage hole 25 is arranged in the vicinity of each passage hole 25 on the membrane region 30. The counter electrode 26 for each beam is ground-connected.

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

The electron beam 20 passing through each of the passing holes 25 is deflected by the voltage applied to the two paired electrodes 24 and 26, which are independently applied to each other. Blanking is controlled by such deflection. In other words, the pair of the control electrode 24 and the counter electrode 26 blanket deflects the corresponding beam of the multi-beams that have passed through the plurality of holes 22 (openings) of the molded aperture array member 203.

Next, the operation of the drawing unit 150 in the drawing device 100 will be described. The electron beam 200 emitted from the electron gun 201 (emission unit) illuminates the entire molded aperture array member 203 substantially 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 an area including all 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 molded aperture array member 203, respectively, so that, for example, a plurality of rectangular electron beams (multi-beams) 20a to e 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. Each such blanker deflects the electron beams 20 that pass individually (performs blanking deflection).

The multi-beams 20a to 20e that have passed through the blanking aperture array unit 204 are reduced by the reduction lens 205 and proceed 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 shielded by the limiting aperture member 206. On the other hand, the electron beam 20 not 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. By turning ON / OFF of the individual blanking mechanism, blanking control is performed and ON / OFF of the beam is controlled. In this way, the limiting aperture member 206 shields each beam deflected so that the beam is turned off by the individual blanking mechanism. Then, for each beam, a beam for one shot is formed by a beam that has passed through the limiting aperture member 206, which is formed from when the beam is turned on to 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 obtain a pattern image having a desired reduction ratio, and the deflector 208 causes each beam (the entire multi-beam 20) that has passed through the limiting aperture member 206 to be focused. It is collectively deflected in the same direction and irradiated to each irradiation position on the sample 101 of each beam. Further, for example, when the XY stage 105 is continuously moving, the irradiation position of the beam 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 one time are ideally arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of holes of the molded aperture array member 203 by the desired reduction ratio described above. The drawing device 100 draws a multi-beam 20 that becomes a shot beam while following the movement of the XY stage 105 during each tracking operation, and is controlled by the drawing control unit 70 one pixel at a time by the movement of the beam deflection position by the deflector 208. Performs a drawing operation in which irradiation is performed according to a sequence. When drawing a desired pattern, the required beam is controlled to be turned on by blanking control according to the pattern.

FIG. 5 is a flowchart showing a main process of the drawing method according to the first embodiment. In FIG. 5, the drawing method according to the first embodiment is a pixel division step (S102), a pixel block creation step (S104), an evaluation pattern drawing step (S106), a misalignment amount measurement step (S107), and pixels. Block setting process (S108), position shift amount measurement process (S110), correction function fitting process (S116), correction map creation process (S118), representative point position correction amount calculation process (S120), and pixel block. Shape calculation step (S122), pixel block correction step (S124), determination step (S126), pattern area density ρ calculation step (S130), proximity effect correction irradiation coefficient Dp calculation step (S132), and irradiation amount. A series of steps of D calculation, irradiation time calculation step (S134), and drawing step (S136) are carried out.

Among such process groups, as pre-processing of the drawing process of the sample 101 which is an actual product, a pixel dividing step (S102), a pixel block creating step (S104), an evaluation pattern drawing step (S106), and a misalignment amount The measurement step (S107) is carried out. Then, after the preprocessing, as the actual drawing process, a pixel block setting step (S108), a misalignment amount acquisition step (S110), a correction function fitting step (S116), and a correction map creation step (S118) are performed. Representative point position correction amount calculation step (S120), pixel block shape calculation step (S122), pixel block correction step (S124), determination step (S126), pixel inside / outside determination step (S130), proximity effect correction The irradiation coefficient Dp calculation step (S132), the irradiation amount D calculation, the irradiation time calculation step (S134), and the drawing step (S136) are carried out.

As a pixel division step (S102), the pixel division unit 50 (division unit) divides the drawing area of the sample 101 into a plurality of mesh-like pixel areas irradiated with the multi-beam 20.

FIG. 6 is a diagram for explaining the drawing order in the first embodiment. The drawing area 10 (or the chip area to be drawn) of the sample 101 is divided into a stripe area 35 (another example of the drawing area) on the strip with a predetermined width. Then, the pixel dividing unit 50 divides each stripe area 35 into a plurality of mesh-shaped pixel areas 36 (pixels). The size of the pixel region 36 (pixels) is preferably, for example, a beam size or a size smaller than that. For example, it is preferable to set the size to about 10 nm. The pixel area 36 (pixel) is an irradiation unit area per one beam of the multi-beam.

When drawing the sample 101 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 collectively irradiated by the movement of the beam deflection position by the deflector 208, for example, one pixel at a time. To go. Then, which pixel on the sample 101 is irradiated by which beam of the multi-beam 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 (x direction) x the beam pitch (y direction) between the beams adjacent to each other in the x and y directions on the sample 101 surface. The area is composed of an area of n × n pixels (sub-pitch area). For example, when the XY stage 105 moves by the beam pitch (x direction) in the −x direction in one tracking operation, n while shifting the irradiation position by one beam in the x direction or the y direction (or diagonal direction). Pixels are drawn. In the next tracking operation, the other n pixels in the same n × n pixel region are similarly drawn by a beam different from the beam described above. By drawing n pixels by different beams in the tracking operation n times in this way, all the pixels in the area of one n × n pixels are drawn. Similar operations are performed at the same time for other n × n pixel regions in the multi-beam irradiation region, and the plots are drawn in the same manner. By such an operation, all the pixels in the irradiation area 34 can be drawn. By repeating these operations, the entire corresponding stripe area 35 can be drawn. Then, the drawing apparatus 100 can draw a desired pattern by combining pixel patterns (bit patterns) formed by irradiating the required pixels with a beam of a required irradiation amount.

As a pixel block creation step (S104), the pixel block creation unit 52 groups a plurality of pixel regions 36 into a plurality of pixel blocks composed of at least one pixel region 36. The pixel block creation unit 52 is an example of a group processing unit.

FIG. 7 is a diagram showing an example of a pixel block and an example of a state in which the pixel block is corrected according to the first embodiment. In the example of FIG. 7, an example is shown in which four columns in the x direction and four columns of 4 × 4 pixel regions 36 groups in the y direction are defined as one pixel block 38 (42).

Here, as described above, the sample 101 is held on the XY stage 105 by, for example, a three-point support (not shown). Such a sample support method causes the sample 101 to bend due to its own weight according to the distance from the support point. Therefore, the projected image of the electron beam is distorted on the sample surface, and the drawing position (exposure position) is deviated. In addition, the reflective surface of the mirror 210 for position measurement on the XY stage 105 is also distorted. Therefore, the measurement position of the stage shifts. As a result, the drawing position (exposure position) shifts. In the first embodiment, in the multi-beam drawing, the distortion of the reflecting surface of the mirror 210 and / or the displacement of the sample surface of the sample 101 to be drawn due to the distortion or the like is corrected. Specifically, in the first embodiment, the position and shape of the region on the drawing data to be processed by the pixel block 38 (42) are corrected for each of the pixel blocks 38 (42). The number of constituent pixels of the pixel block 38 (42) can be set in at least one pixel area 36, but in the calculation for each pixel, a huge amount of calculation time is required to correct all the pixel areas 36. Therefore, it is preferable that the pixel group is composed of several pixels. For example, by defining the 4 × 4 pixel region 36 group as one pixel block 38 (42), the amount of calculation can be reduced to 1/16 as compared with the calculation for each pixel. On the contrary, if there are too many constituent pixels, position-dependent correction becomes difficult. Therefore, it is preferable that the width size of the pixel block 38 (42) is, for example, a size equal to or less than the width on the short side side of the stripe region 35. Further, in the example of FIG. 7, each pixel block 38 (42) is composed of 36 groups of adjacent 4 × 4 pixel regions, each of which is the same square, but the present invention is not limited to this. The number of constituent pixels and the shape of the pixel block 38 (42) may be different for each pixel block 38 (42).

As the evaluation pattern drawing step (S106), the drawing unit 150 draws the evaluation pattern on the sample 101 under the control of the drawing control unit 72. For that purpose, first, the ρ calculation unit 66 reads the drawing data (evaluation data) for the evaluation pattern from the storage device 140, and calculates the pattern area density ρ for each pixel area 36.

Further, the Dp calculation unit 67 virtually divides the drawing area (here, for example, the stripe area 35) into a plurality of proximity mesh areas in a mesh shape having a predetermined size. The size of the proximity mesh region is preferably set to about 1/10 of the influence range of the proximity effect, for example, about 1 μm. Then, the correction irradiation coefficient Dp (x) for correcting the proximity effect is calculated for each such proximity mesh region. The correction model of the correction irradiation coefficient Dp (x) and the calculation method thereof may be the same as the conventional ones.

Then, the irradiation amount D calculation unit 68 calculates the irradiation amount D (x) by multiplying the obtained corrected irradiation coefficient Dp (x), the area density (ρ), and the reference irradiation amount D ₀ for each pixel area 36. To do. As described above, it is preferable that the irradiation amount D (x) is obtained in proportion to the area density of the pattern calculated for each pixel region 36. Then, the irradiation time t calculation unit 70 calculates the irradiation time t of the pixel by dividing the obtained irradiation amount D (x) by the current density J for each pixel region 36. The irradiation time data obtained for each pixel is stored in the storage device 144 as shot data in the shot order.

Then, the drawing unit 150 draws (exposes) an evaluation pattern on the evaluation sample 101 using the multi-beam so that each pixel has the calculated irradiation amount. The drawn (exposed) evaluation sample 101 is developed to form a resist pattern.

As the misalignment amount measuring step (S107), the drawing position in each grid can be measured by measuring the position of the grid which is each evaluation position of the resist pattern with a position measuring device (not shown). Then, the amount of misalignment of the corresponding measurement position from the design position of the evaluation pattern is calculated for each evaluation target grid. The misalignment amount data is input from the outside of the drawing device 100 and stored in the storage device 142.

As the pixel block setting step (S108), the pixel block setting unit 54 sets one pixel block from the created plurality of pixel blocks.

As the misalignment amount acquisition step (S110), the acquisition unit 55 reads out the misalignment amount data stored in the storage device 142 and acquires the misalignment amount of each position in the set pixel block.

In the correction function fitting step (S116), the fitting processing unit 56 approximates (fits) the correction amount for correcting the positional deviation at each position in the pixel block 38 with the correction function. In other words, each coefficient of the polynomial correction function is calculated. As an example of the correction function, for example, a fourth-order polynomial can be used. The fourth-order polynomial can be defined by the following equations (1-1), equations (1-2), equations (1-3), and equations (1-4). The correction amount g _x (x, y) in the x direction is defined by the equation (1-1). The correction amount _gy (x, y) in the y direction is defined by the equation (1-2). Further, here, the primary term and the other terms are shown separately.

As the correction map creation step (S118), the correction map creation unit 58 describes the correction amounts (Gx (x, y), Gy (x, y)) for correcting the uneven positional deviation that cannot be completely corrected by the correction function. Create a correction map defined for each grid. The position correction amount (Gx (x, y), Gy (x, y)) from the correction map at the position (x, y) is the interpolation of the correction amount at the four corners of the map grid corresponding to the position (x, y). You can use the value.

Therefore, the correction amount (δ _x , δ _y ) of the pattern position shift due to the distortion of the reflection surface of the mirror 210 and / or the distortion of the sample surface of the sample 101 to be drawn is as follows using the matrix notation. It can be defined by equation (2).

As described above, in the first embodiment, the position and shape of the region on the drawing data to be processed by the pixel block 38 of interest are corrected for each of the pixel blocks 42. First, the position correction amount of the representative point 40 position correction of the pixel block 38 of interest is calculated.

In the representative point position correction amount calculation step (S120), the representative point position correction amount calculation unit 60 reversely converts the correction function for correcting the positional deviation at the representative point 40 of the pixel block 38 of interest for each pixel block 42. The amount is used to calculate the amount of position correction for the representative point 40a of the pixel block 38a of interest. As the position of the representative point 40a, for example, it is preferable to use the center position of the pixel block 38a. As will be described later, the shape of the region on the drawing data to be processed by the pixel block 38 corresponds to the above-mentioned position correction correction function equations (1-1) to (1-4) and the correction amount from the correction map. Distortion may occur. However, the distortion is usually sufficiently small, and therefore, the shape correction in the pixel block can be easily performed by assuming that the distortion is the same as that of the representative point 40 even at a position near the representative point 40.

The inverse conversion formula obtained by inversely converting the correction functions represented by the formulas (1-1) and (1-2) can be defined by the following formulas (3-1) and (3-2).

The representative point position correction amount calculation unit 60 calculates the coefficient k used in the equations (3-1) and (3-2). The coefficient k can be defined by the following equation (4).

Further, in calculating the equations (3-1) and (3-2), the representative point position correction amount calculation unit 60 (first calculation unit) first performs an inverse conversion process of the correction function for each pixel block. The inverse conversion term g _Δx ^-1 (x, y) of the function g _Δx (x, y) that summarizes the functions other than the linear term shown in the equation (1-3) and the linear term shown in the equation (1-4). The inverse conversion term g _Δy ^-1 (x, y) of the function g _Δy (x, y) that summarizes the above is calculated. The inverse transformation term g _Δx ^-1 (x, y) and the inverse transformation term g _Δy ^-1 (x, y) can be defined by the following equations (5-1) and (5-2).

Then, the representative point position correction amount calculation unit 60 uses the calculated inverse conversion term g _Δx ^-1 (x, y), the inverse conversion term g _Δy ^-1 (x, y), and the coefficient k to obtain an equation ( The g _x ^-1 (x, y) shown in 3-1) and the g _y ^-1 (x, y) shown in the equation (3-2) may be calculated. Therefore, the representative point position correction amount calculation unit 60 has an inverse conversion term g _Δx ^-1 (Xb, Yb) and an inverse conversion term g at the position Cb = (Xb, Yb) of the representative point 40a of the pixel block 38a of interest. _Δy ^-1 (Xb, Yb) and seeking, using these results, the position correction amount ^{_{(g x -1 (Xb, Yb}} ), g y -1 (Xb, Yb)) for calculating a. As described above, the position correction amount of the representative point 40a of the pixel block 38a of interest defined by the coordinates Cb = (Xb, Yb) is the inverse conversion amount of the correction function (g _x ^-1 (Xb, Yb), g. It can be obtained from _y ^-1 (Xb, Yb)). As a result, the coordinates of the representative point 40b of the pixel block 38b, which is the corrected position of the representative point 40a of the pixel block 38a as shown in FIG. 7, are (Xb + g _x ^-1 (Xb + g _x ^-1 ) using the coordinates (Xb, Yb) of 40a. ^{_{Xb, Yb), Yb + g}} y -1 (Xb, obtained from Yb)).

The area on the drawing data to be processed by each pixel block is distorted due to the distortion of the reflection surface of the mirror 210 and / or the displacement of the sample surface of the sample 101 to be drawn due to the distortion or the like. Usually, the change of this distortion from position to position is small enough. Therefore, the distortion of the area on the drawing data to be processed by the pixel block can be represented by linear transformations such as translation, scaling, rotation, and shear at the position on the drawing data corresponding to the pixel block representative point. .. Therefore, next, the shape correction coefficient representing the distortion of the position on the drawing data corresponding to the pixel block representative point is calculated.

As the pixel block shape calculation step (S122), the pixel block shape calculation unit 62 (second calculation unit) uses a function that uses the partial differential value of the correction function as a coefficient (or a matrix element) for each pixel block 42. Then, the shape correction coefficient of the pixel block 38b is calculated. Specifically, the calculation is performed as follows. The correction coefficient Δg (x, y) for linearly correcting the distortion for each pixel block can be defined by the following equation (6).

Further, each partial differential value g _x ^(x) , g _x ^(y) , _gy ^(x) , _gy ^(y) of the correction function used as the coefficient of the equation (6) is _x of the correction function or It is defined by the partial differential value with respect to y, and specifically, it is defined by the following equations (7-1), (7-2), (7-3), and (7-4).

As a determination step (S126), the determination unit 65 determines whether or not the processing has been completed for all the pixel blocks. If there is a pixel block that has not been processed yet, the process returns to the pixel block setting step (S108). Then, each step from the pixel block setting step (S108) to the determination step (S126) is carried out until the processing is completed for all the pixel blocks.

As described above, the position and shape of each pixel region 36 are corrected in pixel block units so as to correct the distortion of the reflection surface of the mirror 210 and / or the displacement of the sample surface of the sample 101 to be drawn due to distortion or the like. You can get the coefficient to correct. The pixel region 36 is a reference region for defining irradiation time data. In the first embodiment, the area density of the pattern is calculated using each pixel area 36 before correction, the irradiation time data is defined in each pixel area 36, and then the position of each pixel area is not corrected. Before performing these processes, the position and shape of each pixel area 36 itself, which is the source, is corrected.

As a pixel inside / outside determination step (S130), the determination unit 66 reads drawing data from the storage device 140, and for each graphic pattern defined in the drawing data, the pixel region 36 is either inside or outside of each graphic pattern for each pixel region 36. Determine if it is located in.

FIG. 8 is a diagram for explaining the equation of the straight line and the distance to the straight line in the first embodiment. The linear equation l (x, y) is defined by l (x, y) = dy (x-x0) -dx (y-y0). The x-direction distance dx'and the y-direction distance dy'from the corrected pixel region (for example, the center of the pixel) shown in FIG. 8B to the straight line corresponding to one side of the graphic pattern are the uncorrected distance dy'shown in FIG. 8A. Using the x-direction distance dx, the y-direction distance dy, the equation (6), the pixel block representative point Cb, and the relative position δ (Cb) of the pixel from the pixel block representative point from the pixel region (for example, the center of the pixel) to the straight line. Therefore, it is defined by the following equation (8).

Next, the equation Lb of the straight line of the relative position (x', y') of the target pixel seen from the corrected pixel block representative point is described below by using the equation lb of the straight line of the corrected pixel block representative point. It is defined by equation (9).

However, the equation lb of the straight line of the pixel block representative point is defined by the following equation (10).

Further, the position δ ^-1 (Cb) of the calculation area viewed from the representative point of the pixel block is defined by the following equation (11). However, the coordinates of the pixel block representative point Cb are (Xb, Yb).

Then, if the equation (9) has a positive value, it is determined that the straight line is within the graphic pattern. If it is a negative value, it is determined that the straight line is out of the graphic pattern. The determination is made for each side of the graphic pattern. Then, the determination unit 66 determines that the pixel is located in the graphic pattern if the equation (9) has a positive value for all the sides of the graphic pattern. The inside / outside determination result f is stored in, for example, the storage device 142 for each pixel. The inside / outside determination result f defines “1” if the pixel is in any of the graphic patterns, and “0” if the pixel is not in any of the graphic patterns.

As the proximity effect correction irradiation coefficient Dp calculation step (S132), the Dp calculation unit 67 virtually divides the drawing area (here, for example, the stripe area 35) into a plurality of proximity mesh areas in a mesh shape with a predetermined size. The size of the proximity mesh region is preferably set to about 1/10 of the influence range of the proximity effect, for example, about 1 μm. Then, the correction irradiation coefficient Dp (x) for correcting the proximity effect is calculated for each such proximity mesh region. The correction model of the correction irradiation coefficient Dp (x) and the calculation method thereof may be the same as the conventional ones. The Dp calculation unit 67 calculates the area density ρ'for each proximity mesh region, for example. Then, the Dp calculation unit 67 calculates an unknown Dp (x) that satisfies the following equation (12) by using the proximity effect correction coefficient η, the distribution function R (x), and the threshold value Dth. As the distribution function R (x), for example, it is preferable to use the Gaussian distribution function. In the equation (12), x indicates the position of the proximity mesh.

In the irradiation amount D calculation and irradiation time calculation step (S134), the irradiation amount D calculation unit 68 calculates the irradiation amount for irradiating the pixel region for each pixel region in which the positional deviation is corrected. Specifically, the irradiation amount D calculation unit 68 has obtained a corrected irradiation coefficient Dp (x + g _x ^-1 (x, y), y + _gy ^{− for} each pixel region 36 in which the positional deviation has been corrected. ^The irradiation amount D (x, y) is calculated by multiplying ¹ (x, y)), the internal / external determination result f, and the reference irradiation amount D ₀ . As described above, it is preferable that the irradiation amount D (x, y) is obtained in proportion to the area density of the pattern calculated for each of the pixel regions 36 in which the positional deviation is corrected. Then, the irradiation time t calculation unit 70 calculates the irradiation time t of the pixel region 36 by dividing the obtained irradiation amount D (x, y) by the current density J for each pixel region 36 in which the positional deviation is corrected. Calculate. The irradiation time data obtained for each of the pixel regions 36 in which the misalignment has been corrected is stored in the storage device 144 as shot data in the shot order.

As a drawing step (S136), the drawing unit 150 draws (exposes) a pattern on the sample 101 using the multi-beam 20 so that each pixel region 36 has the calculated irradiation amount. The drawn (exposed) sample 101 is developed to form a resist pattern. Then, the mask substrate is formed by etching the light-shielding film under the resist pattern as a mask.

FIG. 9 is a diagram showing an example of a beam profile simulation result in the case of drawing a rectangular pattern rotated by 10 ° using the pixels subjected to the positional deviation correction in the first embodiment. FIG. 9 shows an example of a beam profile simulation result in which two hypotenuses inclined at an angle of 10 ° from the y-axis are drawn in the x-direction at equal intervals in the y-direction by rotating the rectangular pattern by 10 °. Shown. When drawing in the x direction at equal intervals in the y direction, the line width of the pattern at each position in the y direction should be the same line width by design. Then, the line width should be shifted at equal intervals by design. As shown in FIG. 9, it can be seen that the beam profiles having the same line width are shifted at equal intervals by using the pixels subjected to the misalignment correction in the first embodiment.

FIG. 10 is a diagram showing an example of a simulation result when a triangular pattern is drawn with or without correction in the first embodiment. Here, it is assumed that the position is simply displaced in the two-dimensional direction without enlargement, reduction, and rotation. FIG. 10A shows an example of a triangular pattern when drawn without performing the positional deviation correction in the first embodiment. In the design, the triangular pattern should have been formed at the position indicated by the dotted line, but it is shown that the position is shifted to the solid line due to the misalignment. On the other hand, when the drawing is performed with the misalignment correction in the first embodiment, it can be seen that the misalignment is eliminated as shown in FIG. 10B. Note that FIG. 10B shows an example in which the position of the center of the pixel block is corrected and the enlargement, reduction, and rotation are not corrected.

FIG. 11 is a diagram showing another example of the simulation result when the triangle pattern is drawn with or without correction in the first embodiment. Here, it is assumed that the position shifts due to rotation. FIG. 11A shows an example of a triangular pattern when drawn without performing the positional deviation correction in the first embodiment. In the design, a triangular pattern should have been formed at the position indicated by the dotted line, but it is shown that the position is shifted to the solid line due to the position shift due to rotation. On the other hand, when the drawing is performed with the misalignment correction in the first embodiment, it can be seen that the misalignment is eliminated as shown in FIG. 11B. Note that FIG. 11B shows an example in which enlargement, reduction, and rotation correction are performed in addition to position correction at the center of the pixel block.

As described above, according to the first embodiment, it is possible to correct the distortion of the reflection surface of the mirror 210 and / or the displacement of the sample 101 surface to be drawn due to the distortion or the like in the multi-beam drawing. Therefore, the pattern can be drawn at a highly accurate position and dimension.

The embodiment has been described above with reference to a specific example. However, the present invention is not limited to these specific examples.

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

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

10 Drawing area 20 Multi-beam 22 Hole 24,44 Control electrode 25, 45 Passing hole 26,46 Opposed electrode 30 Membrane area 31 Substrate 32 Outer peripheral area 33 Support base 34 Irradiation area 35 Stripe area 36 Pixels 47 Individual blanking mechanism 50 Pixel division Part 52 Pixel block creation unit 54 Pixel block setting unit 55 Acquisition unit 56 Fitting processing unit 58 Correction map creation unit 60 Representative point position correction amount calculation unit 62 Pixel block shape calculation unit 64 Correction unit 65 Judgment unit 66 ρ calculation unit 67 Dp calculation Part 68 D Calculation unit 70 t Calculation unit 72 Drawing control 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 detector 140, 142, 144 Storage device 150 Drawing unit 160 Control unit 200 Electron beam 201 Electron gun 202 Illumination lens 203 Molded aperture array member 204 Blanking aperture array unit 205 Reduction lens 206 Limiting aperture member 207 Objective lens 208 Deflator 210 Mirror

Claims (4)

A dividing part that divides the drawing area of the sample into a plurality of mesh-shaped pixel areas irradiated with a multi-charged particle beam,
A group processing unit that groups the plurality of pixel areas into a plurality of pixel blocks composed of at least one pixel area.
For each pixel block of the plurality of pixel blocks, a correction unit that corrects the position of an area on the drawing data to be processed by the pixel block in pixel block units.
An irradiation amount calculation unit that calculates an irradiation amount for irradiating the pixel for each pixel whose position has been corrected,
A drawing unit that draws a pattern on the sample using the multi-charged particle beam so that each pixel has an calculated irradiation amount.
Equipped with a,
The correction unit corrects the position on the drawing data corresponding to the representative point of the pixel block for each pixel block.
The correction unit relates to a correction function for correcting the position correction amount of the position on the drawing data corresponding to the representative point of the pixel block for each pixel block and the position of the representative point of the pixel block on the sample. Calculated using the inverse conversion formula,
Each pixel block is further provided with a calculation unit that calculates a correction amount at each position that specifies the shape of the pixel block by using a function that uses the partial differential value of the correction function as a coefficient. Charged particle beam drawing device. A dividing part that divides the drawing area of the sample into a plurality of mesh-shaped pixel areas irradiated with a multi-charged particle beam,
A group processing unit that groups the plurality of pixel areas into a plurality of pixel blocks composed of at least one pixel area.
For each pixel block of the plurality of pixel blocks, a correction unit that corrects the position of an area on the drawing data to be processed by the pixel block in pixel block units.
An irradiation amount calculation unit that calculates an irradiation amount for irradiating the pixel for each pixel whose position has been corrected,
A drawing unit that draws a pattern on the sample using the multi-charged particle beam so that each pixel has an calculated irradiation amount.
Equipped with a,
The correction unit corrects the position on the drawing data corresponding to the representative point of the pixel block for each pixel block.
The correction unit relates to a correction function for correcting the position correction amount of the position on the drawing data corresponding to the representative point of the pixel block for each pixel block and the position of the representative point of the pixel block on the sample. Calculated using the inverse conversion formula,
For each pixel block, a first calculation unit that calculates an inverse conversion term used for the inverse conversion processing for the correction function, and
A second calculation unit that calculates the correction amount at each position that specifies the shape of the pixel block by using a function that uses the partial differential value of the correction function as a coefficient for each pixel block.
A multi-charged particle beam drawing device characterized by further equipped with . The process of dividing the drawing area of the sample into a plurality of mesh-shaped pixel areas irradiated with the multi-charged particle beam, and
A step of grouping the plurality of pixel regions into a plurality of pixel blocks composed of at least one pixel region, and
A step of correcting the position of an area on the drawing data to be processed by the pixel block for each pixel block of the plurality of pixel blocks.
A step of calculating the irradiation amount to irradiate the pixel for each pixel whose position has been corrected, and
A step of drawing a pattern on the sample using the multi-charged particle beam so that each pixel has an calculated irradiation amount, and
Equipped with a,
For each pixel block, the position on the drawing data corresponding to the representative point of the pixel block is corrected.
For each pixel block, the amount of correction of the position on the drawing data corresponding to the representative point of the pixel block is calculated by using an inverse conversion formula for the correction function for correcting the position of the representative point of the pixel block on the sample. Calculated
Each pixel block is further provided with a step of calculating the correction amount of each position for specifying the shape of the pixel block by using a function using the partial differential value of the correction function as a coefficient. Particle beam drawing method. The process of dividing the drawing area of the sample into a plurality of mesh-shaped pixel areas irradiated with the multi-charged particle beam, and
A step of grouping the plurality of pixel regions into a plurality of pixel blocks composed of at least one pixel region, and
A step of correcting the position of an area on the drawing data to be processed by the pixel block for each pixel block of the plurality of pixel blocks.
A step of calculating the irradiation amount to irradiate the pixel for each pixel whose position has been corrected, and
A step of drawing a pattern on the sample using the multi-charged particle beam so that each pixel has an calculated irradiation amount, and
Equipped with a,
For each pixel block, the position on the drawing data corresponding to the representative point of the pixel block is corrected.
For each pixel block, the amount of correction of the position on the drawing data corresponding to the representative point of the pixel block is calculated by using an inverse conversion formula for the correction function for correcting the position of the representative point of the pixel block on the sample. Calculated
A step of calculating an inverse conversion term used for the inverse conversion process for the correction function for each pixel block, and
A step of calculating the correction amount of each position that specifies the shape of the pixel block by using a function that uses the partial differential value of the correction function as a coefficient for each pixel block.
A multi-charged particle beam drawing method characterized by further providing.

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