Patent Application
20120286174
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2011-107082 filed on May 12, 2011 in Japan, and the prior Japanese Patent Application No. 2011-261563 filed on Nov. 30, 2011 in Japan, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a charged particle beam writing apparatus and a charged particle beam writing method, and, for example, it relates to an apparatus and a method for writing that can estimate the number of shots used for predicting a writing time and an area density used for performing dose correction calculation.
2. Description of Related Art
The lithography technique that advances microminiaturization of semiconductor devices is extremely important as being a unique process whereby patterns are formed in the semiconductor manufacturing. In recent years, with high integration of LSI, the line width (critical dimension) required for semiconductor device circuits is decreasing year by year. In order to form a desired circuit pattern on semiconductor devices, a master or “original” pattern (also called a mask or a reticle) of high precision is needed. Thus, the electron beam writing technique, which intrinsically has excellent resolution, is used for producing such a highly precise master pattern.
When writing a chip pattern by a writing apparatus, the time for writing the chip pattern is predicted and the predicted time is provided for the user (refer to, e.g., Japanese Patent Application Laid-open (JP-A) No. 2009-088213). Therefore, it is necessary to estimate the number of shots to be used for writing the chip pattern. Conventionally, as for the chip pattern writing, a chip region is divided into a plurality of mesh regions. Moreover, the region of each of cells configuring a chip is divided into mesh regions. Furthermore, each figure pattern in a cell is also divided into mesh regions.
In accordance with one aspect of the present invention, a charged particle beam writing apparatus includes a storage unit configured to store chip data in which there is defined each figure pattern data indicating a shape, alignment coordinates, and a size of each of a plurality of figure patterns included in a chip, a shot division image information generation unit configured to input the each figure pattern data in the chip data, and for the each of the plurality of figure patterns, when the each of the plurality of figure patterns is divided into a plurality of shot figures each having a size to be irradiated with one shot of a charged particle beam, to generate shot division image information for discriminating a size of each of the plurality of shot figures and an arrangement position in the each of the plurality of figure patterns of the each of the plurality of shot figures, an allotting processing unit configured, by using the shot division image information and information on alignment coordinates of the each of the plurality of figure patterns, to allot the each of the plurality of shot figures to be arranged in each of a plurality of mesh regions virtually divided by a predetermined size from a reference position different from an end portion of a figure pattern concerned in a chip region concerned indicated by the chip data, a shot number calculation unit configured, for the each of the plurality of mesh regions, to calculate a number of shots of the charged particle beam used when writing inside of a mesh region concerned based on a number of allotted shot figures, a writing time prediction unit configured to predict a writing time for writing a chip concerned based on the number of shots for the each of the plurality of mesh regions, and a writing unit configured to write a pattern in the chip concerned on a target workpiece, using the charged particle beam.
In accordance with another aspect of the present invention, a charged particle beam writing method includes inputting each figure pattern data in chip data, from a storage unit storing the chip data in which there is defined the each figure pattern data indicating a shape, alignment coordinates, and a size of each of a plurality of figure patterns included in a chip, and generating, for the each of the plurality of figure patterns, when the each of the plurality of figure patterns is divided into a plurality of shot figures each having a size to be irradiated with one shot of a charged particle beam, shot division image information for discriminating a size of each of the plurality of shot figures and an arrangement position in the each of the plurality of figure patterns of the each of the plurality of shot figures, allotting, by using the shot division image information and information on alignment coordinates of the each of the plurality of figure patterns, the each of the plurality of shot figures to be arranged in each of a plurality of mesh regions virtually divided by a predetermined size from a reference position different from an end portion of a figure pattern concerned in a chip region concerned indicated by the chip data, calculating, for the each of the plurality of mesh regions, a number of shots of the charged particle beam used when writing inside of a mesh region concerned based on a number of allotted shot figures, predicting a writing time for writing a chip concerned based on the number of shots for the each of the plurality of mesh regions, and writing a pattern in the chip concerned on a target workpiece, using the charged particle beam.
With the recent tendency to miniaturization and high density of patterns, the division size of each hierarchical region needs to be small in order to make a calculation result high accurate in each mesh region. As shown in
As described above, there is a problem that the calculation processing time increases when the division size of the region in each hierarchy is made to be small with the recent tendency to miniaturization and high density of patterns. Then, without dividing into the divided pattern region 505, the figure in the region is allotted to each divided cell region 503 at the stage of the cell region 503. It is examined to transmit the figure code and the figure size of the figure in the divided cell region 503 to the shot number calculation function and to divide the figure into figures of a shot size to be beam-shaped in the shot number calculation function in order to omit the calculation processing in the divided pattern region 505. This aims to shorten the processing time as a whole. However, in the case of not dividing into the divided pattern regions 505, the following problem will occur.
In the following Embodiments, there will be described a writing apparatus and method whereby a figure is not divided into shot figures of an erroneous size and generation of minute figures is suppressed even when not setting a division region further up to a divided pattern region.
In the following Embodiments, there will be described a structure in which an electron beam is used as an example of a charged particle beam. The charged particle beam is not limited to the electron beam, and other charged particle beam, such as an ion beam, may also be used. Moreover, a variable-shaped electron beam writing apparatus will be described as an example of a charged particle beam apparatus.
The control unit 160 includes control computers 110 and 120, a memory 112, a control circuit 130, and storage devices 140, 142, 144, and 146, such as a magnetic disk drive. The control computers 110 and 120, the memory 112, the control circuit 130, and the storage devices 140, 142, 144, and 146 are mutually connected through a bus (not shown).
In the control computer 110, there are arranged a figure pattern read-out unit 10, a shot division processing unit 12, an allotting processing unit 14, a cell division shot number calculation unit 16, a chip division shot number calculation unit 18, a frame shot number calculation unit 20, a chip shot number calculation unit 22, a writing time prediction unit 24, a cell division pattern density calculation unit 30, a chip division pattern density calculation unit 32, a frame pattern density calculation unit 34, and a chip pattern density calculation unit 36. Functions of the units described above may be configured by hardware such as an electronic circuit or by software such as a program executing these functions. Alternatively, they may be configured by a combination of hardware and software. Information input/output from/to the units described above and information being calculated are stored in the memory 112 each time.
In the control computer 120, there are arranged a shot data generation unit 40, a dose calculation unit 42, and a writing processing unit 44 are arranged. Functions of the units described above may be configured by hardware such as an electronic circuit or by software such as a program executing these functions. Alternatively, they may be configured by a combination of hardware and software. Information input/output from/to the units described above and information being calculated are stored in a memory (not shown) each time.
As described above,
Chip data of a chip including a plurality of cells each configured by at least one figure pattern is input from the outside the apparatus to be stored in the storage device 140 (storage unit). Figure pattern data indicating the shape, alignment coordinates, and the size of each figure pattern is defined in the chip data. In other words, each figure pattern data indicating the shape, alignment coordinates, and the size of each figure pattern in a chip, which includes a plurality of figure patterns, is defined in the chip data.
For writing a figure pattern by the writing apparatus 100, it is necessary to divide each figure pattern defined in the chip data such that a divided figure pattern has a size to be beam-irradiated by one beam shot. First, the number of shots for writing the chip is estimated by calculation by the control computer 110. Then, the writing time for writing the chip is predicted by using the calculated number of shots. On the other hand, a pattern density ρ of each of the regions of a plurality of sizes is respectively calculated by the control computer 110. It is preferable to use the pattern density ρ for correcting a dose in writing.
In a figure pattern data read-out step, the figure pattern read-out unit 10 reads each figure pattern data in each cell in the chip data. Each read figure pattern data is output to the shot division processing unit 12.
In a shot division image information generation step, the shot division processing unit 12 assumes each shot figure obtained by dividing each figure pattern into shot figures. Specifically, the shot division processing unit 12 inputs each figure pattern data in the chip data, and, divides each figure pattern into a plurality of shot figures each having a size which can be irradiated with one shot of an electron beam 200. Then, the shot division processing unit 12 generates shot division image information by which the size and the arrangement position of each shot figure in the figure pattern after the dividing can be discriminated. The shot division processing unit 12 is an example of a shot division image information generation unit.
As described above, if a part of the figure pattern 60 is allotted, intact, to the divided cell region 50, and figure data of the figure in each divided cell region 50 is output to the shot division processing unit 12, there may be a case where the size of the allotted figure is incorrect. This occurs because the divided cell region 50 is generated regardless of the end portion of the figure pattern 60. Moreover, there may be a case where when the shape of the allotted figure is divided into shot figures such as a pentagon, there is a possibility of easily generating a minute figure. This arises because the divided cell region 50 is generated based on a mesh size unrelated to the size of dividing the figure pattern 60 into shot figures. Then, according to Embodiment 1, it is configured not to output figure data in each divided cell region 50 to the shot division processing unit 12 but to output figure data based on each figure pattern to the shot division processing unit 12. In the example of
First, as shown in
Therefore, in the example of
Shot division image information is generated with respect to shot figures made by dividing a figure into shots as described above.
In the example of
In this case, since the width is the maximum shot size, “0.5000” is defined. Next, the size in the y direction is to be defined. In this case, since the length is also the maximum shot size, “0.5000” is defined. Next, the number of identical shot figures continuously arranged in the x direction is to be defined. In this case, since there are two, “2” is defined. Next, the number of identical shot figures continuously arranged in the y direction is to be defined. In this case, since there are three, “3” is defined.
Next, in the remaining two columns in the x direction, with respect to the shot figure in the last column but one which is closer to the reference position, “0x11” indicating a quadrangle is defined as a figure code, and then, the size in the x direction is to be defined. In this case, since the width is 0.3003 μm, “0.3003” is defined. Next, the size in the y direction is to be defined. In this case, since the length is the maximum shot size, “0.5000” is defined. Next, the number of identical shot figures continuously arranged in the x direction is to be defined. In this case, since there is one, “1” is defined. Next, the number of identical shot figures continuously arranged in the y direction is to be defined. In this case, since there are three, “3” is defined.
Next, in the remaining two columns in the x direction, with respect to the shot figure in the last column which is farther from the reference position, “0x11” indicating a quadrangle is defined as a figure code, and then, the size in the x direction is to be defined. In this case, since the width is 0.3002 μm, “0.3002” is defined. Next, the size in the y direction is to be defined. In this case, since the length is the maximum shot size, “0.5000” is defined. Next, the number of identical shot figures continuously arranged in the x direction is to be defined. In this case, since there is one, “1” is defined. Next, the number of identical shot figures continuously arranged in the y direction is to be defined. In this case, since there are three, “3” is defined.
Next, concerning the last row but one, closer to the reference position, in the remaining two rows in the y direction, with respect to the shot figure in the first column in the x direction, “0x11” indicating a quadrangle is defined as a figure code, and then, the size in the x direction is to be defined. In this case, since the width is the maximum shot size, “0.5000” is defined. Next, the size in the y direction is to be defined. In this case, since the length is 0.3002 μm, “0.3002” is defined. Next, the number of identical shot figures continuously arranged in the x direction is to be defined. In this case, since there are two, “2” is defined. Next, the number of identical shot figures continuously arranged in the y direction is to be defined. In this case, since there is one, “1” is defined.
Next, concerning the last row but one, closer to the reference position, in the remaining two rows in the y direction, with respect to the shot figure in the last column but one, closer to the reference position, in the remaining two columns in the x direction, “0x11” indicating a quadrangle is defined as a figure code, and then, the size in the x direction is to be defined. In this case, since the width is 0.3003 μm, “0.3003” is defined. Next, the size in the y direction is to be defined. In this case, since the length is 0.3002 μm, “0.3002” is defined. Next, the number of identical shot figures continuously arranged in the x direction is to be defined. In this case, since there is one, “1” is defined. Next, the number of identical shot figures continuously arranged in the y direction is to be defined. In this case, since there is one, “1” is defined.
Next, concerning the last row but one, closer to the reference position, in the remaining two rows in the y direction, with respect to the shot figure in the last column, farther from the reference position, in the remaining two columns in the x direction, “0x11” indicating a quadrangle is defined as a figure code, and then, the size in the x direction is to be defined. In this case, since the width is 0.3002 μm, “0.3002” is defined. Next, the size in the y direction is to be defined. In this case, since the length is 0.3002 μm, “0.3002” is defined. Next, the number of identical shot figures continuously arranged in the x direction is to be defined. In this case, since there is one, “1” is defined. Next, the number of identical shot figures continuously arranged in the y direction is to be defined. In this case, since there is one, “1” is defined.
Next, concerning the last row, farther from the reference position, in the remaining two rows in the y direction, with respect to the shot figure in the first column in the x direction, “0x11” indicating a quadrangle is defined as a figure code, and then, the size in the x direction is to be defined. In this case, since the width is the maximum shot size, “0.5000” is defined. Next, the size in the y direction is to be defined. In this case, since the length is 0.3001 μm, “0.3001” is defined. Next, the number of identical shot figures continuously arranged in the x direction is to be defined. In this case, since there are two, “2” is defined. Next, the number of identical shot figures continuously arranged in the y direction is to be defined. In this case, since there is one, “1” is defined.
Next, concerning the last row, farther from the reference position, in the remaining two rows in the y direction, with respect to the shot figure in the last column but one, closer to the reference position, in the remaining two columns in the x direction, “0x11” indicating a quadrangle is defined as a figure code, and then, the size in the x direction is to be defined. In this case, since the width is 0.3003 μm, “0.3003” is defined. Next, the size in the y direction is to be defined. In this case, since the length is 0.3001 μm, “0.3001” is defined. Next, the number of identical shot figures continuously arranged in the x direction is to be defined. In this case, since there is one, “1” is defined. Next, the number of identical shot figures continuously arranged in the y direction is to be defined. In this case, since there is one, “1” is defined.
Next, concerning the last row, farther from the reference position, in the remaining two rows in the y direction, with respect to the shot figure in the last column, farther from the reference position, in the remaining two columns in the x direction, “0x11” indicating a quadrangle is defined as a figure code, and then, the size in the x direction is to be defined. In this case, since the width is 0.3002 μm, “0.3002” is defined. Next, the size in the y direction is to be defined. In this case, since the length is 0.3001 μm, “0.3001” is defined. Next, the number of identical shot figures continuously arranged in the x direction is to be defined. In this case, since there is one, “1” is defined. Next, the number of identical shot figures continuously arranged in the y direction is to be defined. In this case, since there is one, “1” is defined.
As described above, the defining is repeatedly performed until all the shot figures made by dividing the figure pattern concerned are covered in order in the shot division image information. By defining in order according to a certain fixed rule, it becomes possible in the shot division image information to discriminate, after dividing the figure pattern into shot figures, the size and the arrangement position of each shot figure in the figure pattern. The generated shot division image information is stored in the storage device 142 and output to the allotting processing unit 14. Alternatively, the allotting processing unit 14 may read the generated shot division image information from the storage device 142.
According to Embodiment 1, since each figure pattern is divided into shot figures, when an identical figure pattern is repeatedly arranged, it is enough to generate shot division image information for one of them, for example, for the first one of the identical figure patterns, and then, to share the generated shot division image information with other identical figure patterns. As a result, the processing contents of the shot division processing unit 12 can be reduced, and the processing time can be further shortened. Particularly, it is effective for array patterns.
Next, in an allotting processing step, by using shot division image information and alignment coordinates information of each figure pattern, the allotting processing unit 14 allots each of shot figures, which are obtained by dividing the figure pattern, to each divided cell region so that each shot figure may be arranged in the divided cell region concerned. The alignment coordinates of the figure pattern can be referred to from the pattern data of the figure pattern concerned.
According to Embodiment 1 as described above, by outputting data of a figure pattern itself, without dividing a figure pattern into mesh regions, to the shot division processing unit 12, it becomes possible to avoid the conventional case that the shape of a figure in a mesh, which is to be output to a function equivalent to the shot division processing unit 12, becomes a figure, such as a pentagon, being easy to generate a minute figure. Moreover, it becomes possible to avoid the conventional case that the size of a figure in a mesh is defined based on a division size of a mesh region. Therefore, when dividing a figure pattern into shot figures by the processing unit 12, it can be avoided to perform the dividing based on an erroneous figure size.
In a cell division shot number calculation step, the cell division shot number calculation unit 16 calculates, for each divided cell region 50 (mesh region), the number of shots of the electron beam 200 used when writing the inside of the divided cell region 50 concerned, based on the number of allotted shot figures.
In a cell division pattern density calculation step, the cell division pattern density calculation unit 30 totalizes, for each divided cell region 50 (mesh region), areas of allotted shot figures to calculate a pattern density ρ (area density) of the divided cell region 50 concerned. With respect to a shot figure which extends from a divided cell region concerned, it is preferable to separate the area of the extending, and add the separated area to another divided cell region which is being extended. The calculated pattern density ρ is stored in the storage device 144.
In a chip division shot number calculation step, the chip division shot number calculation unit 18 totalizes, for each divided chip region (mesh region), the number of shots of the divided cell regions 50 allotted to a divided chip region concerned, in order to calculate the number of shots of the electron beam 200 used when writing the inside of the divided chip region concerned. As explained with reference to
In a chip division pattern density calculation step, the chip division pattern density calculation unit 32 totalizes, for each divided chip region (mesh region), pattern densities p of the divided cell regions 50 allotted to a divided chip region concerned in order to calculate the pattern density ρ of the divided chip region concerned. The calculated pattern density ρ is stored in the storage device 144.
Here, the chip region is virtually divided into a plurality of strip-like frame regions, for example, in the y direction, each having a predetermined width. In the writing apparatus 100, data processing is performed for each frame region or for each processing region made by dividing the frame region into a plurality of blocks. Therefore, it is desirable to totalize the number of shots and pattern densities in each frame.
In a frame shot number calculation step, the frame shot number calculation unit 20 totalizes, for each frame region, the number of shots of the divided chip regions? allotted to a frame region in order to calculate the number of shots of the electron beam 200 used when writing the inside of the frame region concerned. Moreover, the divided chip region may be allotted to a frame region with which the reference position, for example, the lower left vertex position of the divided chip region overlaps.
In a frame pattern density calculation step, the frame pattern density calculation unit 34 totalizes, for each frame region, pattern densities p of divided chip regions allotted to a frame region concerned in order to calculate the pattern density ρ in the frame region concerned. The calculated pattern density ρ is stored in the storage device 144.
In a chip shot number calculation step, the chip shot number calculation unit 22 totalizes, for each chip region, the number of shots of frame regions allotted to a chip region concerned in order to calculate the number of shots of the electron beam 200 used when writing the inside of the chip region concerned.
In a chip pattern density calculation step, the chip pattern density calculation unit 36 totalizes, for each chip region, pattern densities p of the frame regions allotted to a chip region concerned in order to calculate a pattern density ρ of the chip region concerned. The calculated pattern density ρ is stored in the storage device 144.
Although the case of writing one chip is assumed here, if there are a plurality of chips whose writing conditions are the same, it is also preferable to perform merge processing for them to configure one chip. In that case, the number of shots and the pattern density ρ are to be calculated for each chip after being merged.
As described above, the total number of shots used when writing the chip concerned can be obtained. By providing hierarchy in the region, calculating the number of shots and a pattern density ρ in order starting from a region of a smaller hierarchy, and accumulating the results, it becomes possible to highly accurately estimate the number of shots and the pattern density ρ. Moreover, since no divided pattern region is set according to Embodiment 1, though the setting has been performed conventionally, it is possible to eliminate calculation of the number of shots and the pattern density ρ of each divided pattern region, thereby greatly reducing the processing time as a whole. Moreover, although the processing contents of the processing unit 12 of dividing a figure which has been output to the processing unit 12 into shot size figures is unchanged, since the processing of dividing into shot figures is not performed for each divided pattern region, but performed for each figure pattern, the number of times of processing can also be reduced.
Using a shot number Ntotal of each chip acquired as described above, a writing time for writing the chip concerned is predicted.
In a writing time prediction step, the writing time prediction unit 24 predicts a writing time for writing a chip concerned, based on the number of shots of each mesh region, such as a divided cell region and a divided chip region. The writing time prediction unit 24 calculates a total writing time Tes for writing a chip on the target workpiece 101, using the following equation (1), for example.
Tes=α
1
·N
total+β1 (1)
The coefficient α1 indicates a time (shot cycle) necessary per shot. For example, it can be represented as the sum of a time t1 for obtaining a required dose D and a time t2 (settling time) for deflecting the electron beam 200. Expressing the current density as J, it can be represented as t1=D/J, for example. The coefficient β1 indicates a total time necessary when the XY stage 105 moves to the writing starting position of the next stripe region after one stripe region has been written. What is necessary is just to set these coefficients α1 and β1 as parameters in advance.
When writing with an electron beam, a chip region is divided into a plurality of strip-like stripe regions, for example, in the y direction, each having a predetermined width. Writing processing is executed per stripe region. When writing on the target workpiece 101 while the XY stage 105 is continuously moved, for example, in the x direction, the electron beam 200 irradiates one stripe region of the target workpiece 101, which is made by virtually dividing the writing (exposure) surface into a plurality of strip-like stripe regions where the electron beam 200 is deflectable. The movement of the XY stage 105 in the x direction is a continuous movement, and simultaneously, the shot position of the electron beam 200 is made to follow the movement of the stage. Writing time can be shortened by performing the continuous movement. After writing one stripe region, the XY stage 105 is moved in the y direction by step feeding, and then, returned in the x direction (this time, reverse direction) to the writing starting position of the next stripe region. From that position, the writing operation of the next stripe region is started. Thus, the writing operation is performed by forward(Fwd)-forward(Fwd) movement. It is possible to avoid positional deviation, generated between going and returning of the stage system, by proceeding in the forward(Fwd)-forward (Fwd) movement. However, it is also acceptable to perform forward (Fwd)-back forward (Bwd) movement, that is, after finishing writing one stripe region, the XY stage 105 is moved in the y direction by step feeding, and then, the writing operation of the next stripe region is performed in the x direction (this time, reverse direction). In this case, by performing the writing operation in a zigzag manner for each stripe region, the movement time of the XY stage 105 can be shortened.
It is possible to predict a writing time highly precisely by predicting the writing time based on highly accurate number of shots as described above. The predicted writing time is output to, for example, a monitor, a printer, a storage device, which are not shown, or the outside to be recognized by a user.
After predicting the writing time, writing processing is actually proceeded for the chip.
In a shot data generating step, the shot data generation unit 40 reads out chip data from the storage device 140, performs data conversion processing of several steps, and generates shot data unique to the apparatus. As described above, for writing a figure pattern by the writing apparatus 100, it is necessary to divide each figure pattern defined in the writing data so as to have the size which can be irradiated by one beam shot. Therefore, for actual writing, the shot data generation unit 40 divides each figure pattern so as to have the size which can be irradiated by one beam shot, in order to generate a shot figure. Then, shot data is generated for each shot figure. In the shot data, figure data, such as a figure type, a figure size, and an irradiation position, is defined. The generated shot data is stored in the storage device 146.
In a dose calculation step, the dose calculation unit 42 calculates a dose for each mesh region of a predetermined size. The dose can be calculated by multiplying a base dose Dbase by a correction coefficient. It is preferable to use as a correction coefficient, for example, a fogging-effect correction irradiation coefficient Df(ρ) which is for correcting a fogging effect. The fogging-effect correction irradiation coefficient Df(ρ) is a function depending on a pattern density ρ of a mesh of meshes used in calculation for correcting the fogging-effect. Since the influence radius of the fogging-effect is several mm, it is preferable for the size of the mesh for correcting the fogging-effect to be approximately 1/10 of the influence radius, for example, to be 1 mm, in order to perform correction calculation. As the pattern density ρ of the mesh for fogging, the pattern density calculated in each hierarchy mentioned above can be used. In addition, for correcting a dose, it is also preferable to use a correction coefficient for proximity effect correction, a correction coefficient for loading correction, etc. Also in such correction, the pattern density in the mesh region for each calculation can be used. As the pattern density, the pattern density calculated in each hierarchy mentioned above may also be used. The dose calculation unit 42 generates a dose map in which each calculated dose is defined for each region. As described above, according to Embodiment 1, since a highly precise pattern density ρ can also be obtained as a pattern density ρ used when performing dose correction, it is possible to calculate a highly accurately corrected dose. The generated dose map is stored in the storage device 146.
In a writing step, the writing processing unit 44 outputs a control signal in order to make the control circuit 130 perform writing processing. The control circuit 130 inputs shot data and a dose map from the storage device 146, and controls the writing unit 150 based on the control signal, through the writing processing unit 44. The writing unit 150 writes a pattern in a chip concerned on the target workpiece 100 using the electron beam 200. Specifically, the operation is performed as follows:
The electron beam 200 emitted from the electron gun 201 (emission unit) irradiates the entire first aperture plate 203 having a quadrangular opening by the illumination lens 202. At this point, the electron beam 200 is shaped to be a quadrangle. Then, after having passed through the first aperture plate 203, the electron beam 200 of a first aperture image is projected onto the second aperture plate 206 by the projection lens 204. The first aperture image on the second aperture plate 206 is deflection-controlled by the deflector 205 so as to change the shape and size of the beam to be variably shaped. After having passed through the second aperture plate 206, the electron beam 200 of a second aperture image is focused by the objective lens 207 and deflected by the main deflector 208 and the sub deflector 209, and reaches a desired position on the target workpiece 101 on the XY stage 105 which moves continuously.
According to Embodiment 1, even when not setting a division region further up to a divided pattern region which has been set conventionally, it is possible to suppress dividing into shot figures of an incorrect size. Moreover, it is possible to suppress generating of a minute figure. Therefore, accurate number of shots can be obtained. As a result, highly precise writing time can be predicted. Moreover, dose correction can be performed highly precisely.
In Embodiment 2, there will be explained shot division image information of a different format. The apparatus configuration is the same as that of
Shot division image information is generated with respect to shot figures made by dividing a figure into the shot figures as shown in
In the example of
Next, with respect to the remaining two columns in the x direction, the size in the x direction of the shot figure in the last column but one, closer to the reference position, is to be defined. In this case, since the width is 0.3003 μm, “0.3003” is defined.
Next, with respect to the remaining two columns in the x direction, the size in the x direction of the shot figure in the last column, farther from the reference position, is to be defined. In this case, since the width is 0.3002 μm, “0.3002” is defined.
Next, with respect to the remaining two rows in the y direction, the size in the y direction of the shot figure in the last row but one, closer to the reference position, is to be defined. In this case, since the width is 0.3002 μm, “0.3002” is defined.
Next, with respect to the remaining two rows in the y direction, the size in the y direction of the shot figure in the last row, farther from the reference position, is to be defined. In this case, since the width is 0.3001 μm, “0.3001” is defined.
Using the information described above, when the maximum shot size is set in advance, it is possible to discriminate all the division sizes. That is, with respect to the x direction, after twice dividing by the maximum shot size, when dividing the remaining width in the x direction by 0.3003 μm, a figure whose width is 0.3003 μm and a figure whose width is 0.3002 μm are formed. With respect to the y direction, after three times dividing by the maximum shot size, when dividing the remaining length in the y direction by 0.3002 μm, a figure whose length is 0.3002 μm and a figure whose length is 0.3001 μm are formed.
When divided into a grid of the division size described above, as shown in
First, as shown in
Therefore, in the example of
Shot division image information is generated with respect to shot figures made by dividing a figure pattern into shots as described above. The shot division image information which is based on the isosceles right triangle as the original figure pattern is generated according to the following rules as shown in
In the example of
Next, for example, with respect to the remaining two columns in the x direction, the width in the x direction of the shot figure in the last column but one, closer to the reference position, is to be defined. In this case, since the width is 0.3003 μm, “0.3003” is defined.
Next, for example, with respect to the remaining two columns in the x direction, the width in the x direction of the shot figure in the last column, farther from the reference position, is to be defined. In this case, since the width is 0.3002 μm, “0.3002” is defined.
Using the information described above, when the maximum shot size is set in advance, it is possible to discriminate all the division sizes.
According to Embodiment 2 as described above, in addition to the effects according to Embodiment 1, the data amount of the shot division image information can be further reduced compared with that of Embodiment 1.
It is possible to share shot division image information among figures having the same figure code and figure size. When adopting this method, processing time can be further shortened. In that case, in order to share shot division image information on more figures, it is desirable to have less amount of data of shot division image information on each figure. Therefore, in Embodiment 3, there will be explained shot division image information of a further different format. The apparatus configuration is the same as that of
Specifically, the amount of data of shot division image information on a figure, such as a trapezoid and a parallelogram, tends to be large. Therefore, it is desirable to reduce the data amount of shot division image information with respect to, especially, such figures. Now, there will be explained an example of shot division image information whose data amount can be reduced.
As shown in
If the x and y directions are reversed with respect to the arrangement direction of the trapezoid, what is necessary is just to read the x and y directions conversely for the shot division image information described above. Therefore, the shot division image information on the isosceles trapezoid of
As described above, when a figure pattern is a trapezoid composed of a base, and two oblique sides each having a 45 degree angle and a 135 degree angle at both ends, the shot division image information can be defined by specifying therein the figure code indicating a trapezoid and the number of shot figures having been divided, according to the pre-set order, by the maximum shot size with respect to one of the directions x and y. Now, the steps of discriminating each shot figure based on the shot division image information will be explained. First, as to the isosceles trapezoid described above, the figure code “0x07”, the upper base (L1), and the height (L2) have already been defined in the original pattern data.
The following can be understood from the shot division image information. Based on the figure code “0x07”, it can be understood that the figure concerned is an isosceles trapezoid. Next, based on “3”, the figure pattern can be divided in the x direction (the first direction) from the reference position (lower left vertex position) of the figure pattern concerned into three figures at the bottom part by the maximum shot size. Since the oblique side is inclined by 45 degrees in the isosceles trapezoid, the figure can also be similarly divided into three shot figures in the y direction by the maximum shot size. Therefore, the region 1 can be divided into three isosceles triangles (1-1, 1-4, 1-6) along the oblique side, two squares (1-2, 1-3) in the x direction next to the isosceles triangle (1-1), and one square (1-5) in the x direction next to the isosceles triangle (1-4).
Next, based on “4”, the region 2 can be divided into four shot figures in the x direction by the maximum shot size. As described above, since the region 1 can be divided into three shot figures in the y direction by the maximum shot size, it is also understood that the region 2 can be divided into three figures in the y direction by the maximum shot size. Therefore, the region 2 can be divided into twelve (4×3) squares (2-1 to 2-12).
Moreover, since there is configured the region 4 symmetrical to the region 1 with respect to the y-axis in the isosceles trapezoid, the region 4 can also be divided into three figures in the x and y directions by the maximum shot size. Therefore, the region 4 can be divided into three isosceles triangles (4-3, 4-5, 4-6) and three squares (4-1, 4-2, 4-4).
Next, since the length L1 of the upper base and the height L2 have already been known, the length of the lower base can be obtained. Therefore, one half of the width in the x direction of the region 3 can be obtained by excluding the regions 1, 2, and 4 and halving the remaining width in the x direction. Moreover, as described above, since the region 1 can be divided into three shot figures in the y direction by the maximum shot size, the region 3 can also be divided into three figures in the y direction by the maximum shot size. Therefore, the region 3 can be divided into six (2×3) rectangles (3-1 to 3-6).
Moreover, as described above, since the region 1 can be divided into three shot figures in the y direction by the maximum shot size and the height L2 has already been known, the remaining length in the height direction (y direction) can be obtained. Therefore, by halving the remaining length in the height direction (y direction), the length in the y direction of each of the regions 5, 7, 8, 9, 10, 11, and 12 can be obtained. Since isosceles triangles are configured at the right and left of the isosceles trapezoid, when the length in the y direction of the isosceles triangle is known, the width in the x direction can be obtained. Therefore, isosceles triangles (7-1, 8-1) can be configured in the regions 7 and 8 at the right and left in the lower row obtained by halving the remaining length in the height direction (y direction). Similarly, isosceles triangles (11-1, 12-1) can be configured in the regions 11 and 12 at the right and left in the upper row obtained by halving the remaining length in the height direction (y direction).
Next, based on “4”, the region in the lower row obtained by halving the remaining length in the height direction (y direction) can be divided into four figures in the x direction by the maximum shot size. Therefore, the region 5 can be divided into four (4×1) rectangles (5-1 to 5-4). Based on the widths in the x direction of the regions 5, 7, and 8, the remaining width in the x direction in the lower row can be obtained. The example of FIG. 7 shows the case where there is no remaining width.
Next, based on “1”, it can be understood that the region in the upper row obtained by halving the remaining length in the height direction (y direction) can be divided by the maximum shot size in the x direction into one shot figure. Therefore, the region 9 can be divided into one (1×1) rectangle (9-1). Based on the widths in the x direction of the regions 9, 11, and 12, the remaining width in the x direction in the upper row can be obtained. Then, the width in the x direction of the region 10-1 or 10-2 can be calculated by halving the remaining width in the x direction in the upper row.
Since the length in the y direction of the region in the upper row has already been obtained, the region 10 can be divided into two (2×1) rectangles (10-1, 10-2).
As described above, based on “0x07, 3, 4, 4, 1” of the shot division image information shown in
As shown in
If the x and y directions are reversed with respect to the arrangement direction of the trapezoid, what is necessary is just to read the x and y directions conversely for the shot division image information described above. Therefore, the shot division image information on the one-legged trapezoid of
As described above, when a figure pattern is a trapezoid composed of an oblique side connected at an angle of 45 degrees to the base (lower base) and another oblique side connected at an angle of 90 degrees to the base (lower base), the shot division image information can be defined by specifying therein the figure code indicating a trapezoid and the number of shot figures having been divided, according to the pre-set order, by the maximum shot size with respect to one of the directions x and y. Now, the steps of discriminating each shot figure based on the shot division image information will be explained. First, as to the one-legged trapezoid, the figure code “0x09”, the upper base (L1), and the height (L2) have already been defined in the original pattern data.
The following can be understood from the shot division image information. Based on the figure code “0x09”, it can be understood that the figure concerned is a one-legged trapezoid having an oblique side at the left. Next, based on “3”, the figure pattern can be divided in the x direction (the first direction) from the reference position (lower left vertex position) of the figure pattern concerned into three figures at the bottom part by the maximum shot size. Since the oblique side is inclined by 45 degrees in the one-legged trapezoid which has an oblique side at the left as described above, the figure can also be similarly divided into three shot figures in the y direction by the maximum shot size. Therefore, the region 1 can be divided into three isosceles triangles (1-1, 1-4, 1-6) along the oblique side, two squares (1-2, 1-3) in the x direction next to the isosceles triangle (1-1), and one square (1-5) in the x direction next to the isosceles triangle (1-4).
Next, based on “3”, it can be understood that the region 2 can be divided into three shot figures in the x direction by the maximum shot size. As described above, since the region 1 can be divided into three shot figures in the y direction by the maximum shot size, it is also understood that the region 2 can be divided into three figures in the y direction by the maximum shot size. Therefore, the region 2 can be divided into nine (3×3) squares (2-1 to 2-9).
Next, since the length L1 of the upper base and the height L2 have already been known, the length of the lower base can be obtained. Therefore, one half of the width in the x direction of the region 3 can be obtained by excluding the regions 1 and 2 and halving the remaining width in the x direction. Moreover, as described above, since the region 1 can be divided into three shot figures in the y direction by the maximum shot size, the region 3 can also be divided into three figures in the y direction by the maximum shot size. Therefore, the region 3 can be divided into six (2×3) rectangles (3-1 to 3-6).
Moreover, as described above, since the region 1 can be divided into three shot figures in the y direction by the maximum shot size and the height L2 has already been known, the remaining length in the height direction (y direction) can be obtained. Therefore, by halving the remaining length in the height direction (y direction), the length in the y direction of each of the regions 4, 5, 6, 7, 8, and 9 can be obtained. Since an isosceles triangle is configured at the left of the one-legged trapezoid which has an oblique side at the left, when the length in the y direction of the isosceles triangle is known, the width in the x direction can be obtained. Therefore, one isosceles triangle (6-1) can be configured in the region 6 at the left in the lower row obtained by halving the remaining length in the height direction (y direction). Similarly, one isosceles triangle (9-1) can be configured in the region 9 at the left in the upper row obtained by halving the remaining length in the height direction (y direction).
Next, based on “3”, it can be understood that the region in the lower row obtained by halving the remaining length in the height direction (y direction) can be divided by the maximum shot size in the x direction into three figures. Therefore, the region 4 can be divided into three (3×1) rectangles (4-1 to 4-3).
Next, based on the widths in the x direction of the regions 4 and 6, the remaining width in the x direction in the lower row obtained by halving the remaining length in the height direction (y direction) can be calculated. Therefore, one half of the width in the x direction of the region 5 can be obtained by halving the remaining width in the x direction in the lower row. Since the length in the y direction of the region in the lower row obtained by halving the remaining length in the height direction (y direction) has already been obtained, the region 5 can be divided into two (2×1) rectangles (5-1 to 5-2).
Next, based on “2”, it can be understood that the region in the upper row obtained by halving the remaining length in the height direction (y direction) can be divided by the maximum shot size in the x direction into two shot figures. Therefore, the region 7 can be divided into two (2×1) rectangles (7-1, 7-2). Based on the widths in the x direction of the regions 7 and 9, the remaining width in the x direction in the upper row can be obtained. Then, the width in the x direction of the region 8-1 or 8-2 can be calculated by halving the remaining width in the x direction in the upper row. Since the length in the y direction of the region in the upper row has already been obtained, the region 8 can be divided into two (2×1) rectangles (8-1, 8-2).
As described above, based on “0x09, 3, 3, 3, 2” of the shot division image information shown in
As shown in
If the x and y directions are reversed with respect to the arrangement direction of the parallelogram, what is necessary is just to read the x and y directions conversely for the shot division image information described above. Therefore, the shot division image information on the parallelogram having 45 degree angles of
As described above, when a figure pattern is a parallelogram having 45 degree angles, the shot division image information can be defined by specifying therein in order the figure code indicating a parallelogram having 45 degree angles, the number of shot figures having been divided by the maximum shot size in the x direction, and the number of shot figures having been divided by the maximum shot size in the y direction. Now, the steps of discriminating each shot figure based on the shot division image information will be explained. First, as to the parallelogram having 45 degree angles, the figure code “0x0F”, the base (L1), and the height (L2) have already been defined in the original pattern data.
The following can be understood from the shot division image information. Based on the figure code “0x0F”, it can be understood that the figure concerned is a parallelogram having 45 degree angles. Next, based on “5”, the figure pattern can be divided in the x direction (the first direction) from the reference position (lower left vertex position) of the figure pattern concerned into five figures by the maximum shot size. Next, based on “2”, the figure pattern can be divided in the y direction (the second direction) from the reference position (lower left vertex position) of the figure pattern concerned into two figures by the maximum shot size. Therefore, the region 1 can be divided into two isosceles triangles (1-1, 1-6) along the oblique side, four squares (1-2, 1-3, 1-4, 1-5) in the x direction next to the isosceles triangle (1-1), and four squares (1-7, 1-8, 1-9, 1-10) in the x direction next to the isosceles triangle (1-6).
Moreover, in the parallelogram having 45 degree angles, an oblique side having a 45 degree angle exists also at the opposite side of the reference position of the figure pattern concerned. Therefore, similarly, it can be divided into two isosceles triangles (4-1, 4-2) along with the oblique side.
Next, since the base length L1 and the height L2 have already been known, one half of the width in the x direction of the region 2 or 3 can be obtained by excluding the region 1 and halving the remaining width in the x direction. Moreover, since the length in the y direction of the region 1 is the maximum shot size, the length in the y direction of the region 2 or 3 can be known. Therefore, the region 2 can be divided into two (2×1) rectangles (2-1, 2-2). Similarly, the region 3 can be divided into two (2×1) rectangles (3-1, 3-2).
Moreover, as described above, since the figure pattern can be divided into two figures in the y direction by the maximum shot size and the height L2 has already been known, the remaining length in the height direction (y direction) can be obtained. Therefore, by halving the remaining length in the height direction (y direction), the length in the y direction of each of the regions 5 to 12 can be obtained. In the parallelogram having 45 degree angles, isosceles triangles are configured at the right and left. Then, as to the isosceles triangle, when the length in the y direction is known, the width in the x direction can be obtained.
Therefore, it can be understood that one isosceles triangle (7-1 or 8-1) is configured respectively in the regions 7 and 8 at the right and left in the lower row obtained by halving the remaining length in the height direction (y direction). Similarly, one isosceles triangle (11-1 or 12-1) can be configured respectively in the regions 11 and 12 at the right and left in the upper row.
Next, based on “4”, the region in the lower row obtained by halving the remaining length in the height direction (y direction) can be divided into four figures in the x direction by the maximum shot size. Therefore, the region 5 can be divided into four (4×1) rectangles (5-1 to 5-4). Similarly, the region in upper row obtained by halving the remaining length in the height direction (y direction) can be divided into four figures in the x direction by the maximum shot size. Therefore, the region 9 can be divided into four (4×1) rectangles (9-1 to 9-4).
Next, based on the widths in the x direction of the regions 5 and 7, the remaining width in the x direction in the lower row obtained by halving the remaining length in the height direction (y direction) can be calculated. Therefore, one half of the width in the x direction of the region 6 can be obtained by halving the remaining width in the x direction in the lower row. Since the length in the y direction of the region in the lower row obtained by halving the remaining length in the height direction (y direction) has already been obtained, the region 6 can be divided into two (2×1) rectangles (6-1 to 6-2).
Next, based on the widths in the x direction of the regions 9 and 11, the remaining width in the x direction in the upper row obtained by halving the remaining length in the height direction (y direction) can be calculated. Therefore, one half of the width in the x direction of the region 10 can be obtained by halving the remaining width in the x direction in the upper row. Since the length in the y direction of the region in the upper row obtained by halving the remaining length in the height direction (y direction) has already been obtained, the region 10 can be divided into two (2×1) rectangles (10-1 to 10-2).
As described above, based on “0x0F, 5, 2, 4” of the shot division image information shown in
That is, in the shot division image information according to Embodiment 3, there is not defined information on the figure size, etc. and the number of shot figures which are not to be divided by the maximum shot size, but there is defined information on a figure code indicating the shape of a figure pattern concerned and the number of shot figures divided by the maximum shot size with respect to at least one direction of the first direction (for example, x direction) and the second direction (for example, y direction) perpendicular to the first direction, which are defined according to a pre-set order. Thereby, the amount of data of shot division image information on each figure can be reduced. For example, if the isosceles trapezoid shown in
That is, it is possible to greatly reduce the amount of data by using the shot division image information described above. Further, it is possible to greatly reduce the processing time when the shot division image information is shared among figures having the same figure code and figure size.
In addition, with respect to a quadrangle, such as a rectangle and a square, an isosceles right triangle, etc., it is also preferable to define shot division image information by using a figure code indicating the shape of the figure pattern concerned.
Referring to specific examples, Embodiments have been described above. However, the present invention is not limited to these examples.
While the apparatus structure, control method, etc. not directly necessary for explaining the present invention are not described, some or all of them may be suitably selected and used when needed. For example, although description of the structure of a control unit for controlling the writing apparatus 100 is omitted, it should be understood that some or all of the structure of the control unit is to be selected and used appropriately when necessary.
In addition, any other charged particle beam writing apparatus and a method thereof that include elements of the present invention and that can be appropriately modified by those skilled in the art are included within the scope of the present invention.
Additional advantages and modification will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-107082 | May 2011 | JP | national |
| 2011-261563 | Nov 2011 | JP | national |
