JP3555484B2 - Electron beam drawing apparatus and drawing method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electron beam drawing apparatus, an electron beam drawing system, and a drawing method for drawing a desired pattern by irradiating a sample with an electron beam.
[0002]
[Prior art]
FIG. 10 shows a functional block diagram of a drawing data generator in the case of a conventional electron beam drawing apparatus. In the conventional electron beam drawing apparatus, the drawing data (coordinates, dimensions, irradiation amount) of the irradiation unit generated by the electron beam drawing data generating unit 13 is corrected by a predetermined electron beam correcting unit 14, and the corrected drawing data is corrected. The electron beam designated on the sample is irradiated by the electron beam drawing means 16 onto the photosensitive agent applied on the sample.
[0003]
There are various types of electron beam correction by the electron beam correction means 14, but here the proximity effect correction is targeted. Proximity effect means that the electron beam irradiated on the sample passes through the layer of photosensitive agent on the surface, and the electron beam scattered back inside the sample passes through the photosensitive agent on the sample surface again. Is a phenomenon in which overexposure occurs in a high portion of the image. For this reason, in an electron beam lithography apparatus, Japanese Patent Application Laid-Open No. 3-225816 discloses an exposure amount map based on an exposure area density of a pattern to be drawn on a sample by performing blank drawing without irradiating an electron beam before actual drawing. Is created in the memory, and at the time of actual drawing, the exposure dose of the electron beam becomes relatively small in a place where the exposure area density is high while referring to the contents of the memory by the exposure map creating means 15 shown in FIG. There is disclosed a technique for performing drawing by correcting so that the irradiation amount of an electron beam becomes relatively large in a place where the exposure area density is low.
[0004]
[Problems to be solved by the invention]
In the prior art, in order to perform optimal drawing, conditions such as a mesh size for dividing a drawing pattern and the number of times of smoothing are changed, an exposure map is created each time, and a blank drawing operation is performed accordingly. , Have evaluated. Therefore, in order to optimally write the writing data of one pattern, it is necessary to create the exposure map a plurality of times and perform the empty writing operation. Further, in the conventional technique, since the exposure map is re-created every time the condition changes, the exposure map before the re-creation cannot be held. Therefore, in order to perform optimum drawing again, the same drawing data must be created again. These lower the throughput of the electron beam lithography apparatus. In particular, a mask electron beam lithography apparatus has a problem in that only one mask can be drawn for one piece of drawing data, and one piece of drawing data cannot be used repeatedly, thus lowering the throughput.
[0005]
The present invention has been made in view of such problems of the related art, and has as its object to provide an electron beam lithography apparatus, an electron beam lithography system, and a lithography method capable of improving throughput.
[0006]
[Means for Solving the Problems]
In order to solve the above object, the present invention provides a drawing data generating unit that generates drawing data for forming a drawing pattern on a sample, an exposure map creating unit that creates an exposure map of an electron beam from the drawing data, A plurality of drawing data generation units each including an electron beam correction unit that corrects the irradiation amount of the electron beam to be irradiated on the sample with reference to the exposure amount map , and each of the drawing data generation units has a condition for one drawing pattern. as well as create different exposure map, the electron beam based on the corrected value by referring to different exposure map of the condition performs drawing by irradiating the sample with the electron beam correction means, the condition sequentially performs drawing based on different exposure map of, der those with electron beam drawing means for drawing with exposure map results optimum conditions of the evaluation of the drawing results .
[0007]
By providing a plurality of drawing data generation units and enabling a plurality of exposure maps different in conditions and types to be created in parallel, it is possible to quickly evaluate optimum drawing conditions and achieve the above object. be able to. Examples of drawing data generation conditions include the mesh size when creating an exposure map, the number of times the area density is smoothed between adjacent meshes, and the like.
[0009]
The electron beam lithography apparatus further includes a drawing data generating unit that generates drawing data for forming a drawing pattern on the sample, an exposure map creating unit that generates an electron beam exposure map from the drawing data, and irradiates the sample. A plurality of drawing data generating units each including an electron beam correcting unit for correcting an irradiation amount of an electron beam with reference to the exposure amount map, and each of the drawing data generating units includes an exposure amount map created for a different drawing pattern. And electron beam drawing means for generating different drawing data by correcting the irradiation amount of the electron beam with reference to the above, and drawing the next different drawing pattern after the completion of drawing of one drawing pattern. It is . With these configurations , even for a large drawing pattern that exceeds the range in which the exposure amount map to be drawn can be generated by one drawing data generation unit, the creation of the exposure amount map is shared by a plurality of drawing data generation units. Therefore, a decrease in throughput can be prevented.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
First, the configuration of an example of an electron beam lithography apparatus according to the present invention will be described with reference to the cross-sectional view shown in FIG. In FIG. 1, the section shown on the right side in the cross section is an electron beam mirror 100 for actually drawing a wafer, and the surrounding squares represent the functions for controlling the electron beam mirror 100 by blocks. The sample 108 is transferred from the transfer unit 102 to the sample table 101 inside the electron beam mirror 100. An electron beam 104 emitted from an electron gun 103 at the uppermost part of the electron beam mirror 100 is shaped by a lens 106 in the lens body, and further deflected by a deflector 107 including an electromagnetic deflector and an electrostatic deflector. The target 108 is irradiated on a target position of the sample 108 arranged on the sample stage 101. Several cross-sectional shapes of the irradiated electron beam 104 can be transferred onto the sample 108 by selecting the aperture 105.
[0013]
The left part of FIG. 1 is a block diagram of the system control function, and shares control of the entire system and an external interface. The drawing data of the pattern to be drawn held in the hard disk 121 is transmitted to the computer 112. A block group surrounded by a frame 111 is a control system digital processing group that converts drawing data transmitted from the computer 112 into electron beam deflection data continuously, in a pipeline, and at high speed. Are connected via a bus 119, and each processing unit shown in the figure performs the following processing.
[0014]
(1) Graphic data section 123
The compressed drawing data transmitted from the computer 112 is stored.
[0015]
(2) Graphic restoration unit 124
The compressed drawing data is restored to graphic data.
[0016]
(3) Graphic decomposition unit 125
Each restored figure is replaced with a shot that can be drawn with an electron beam, and data on the position, shape, and exposure of each shot is created.
[0017]
(4) Alignment correction unit 126
The displacement and deformation between the electron beam irradiation position and the sample 108 are monitored by the sensor 109, and correction is performed according to the displacement and deformation.
[0018]
(5) Proximity effect correction unit 127
A process for correcting the proximity effect is performed. An exposure map 129, which is an area map per unit area of a pattern to be drawn in advance, is obtained and stored in a memory, and a process of correcting the exposure in shot units is performed with reference to the value.
[0019]
(6) Following absolute calibration unit 128
In order to enable continuous writing, the electron beam 104 is irradiated onto a target position on the sample 108 based on the position of the sample stage 101 measured by the length measuring device 110 and the sample stage position measuring unit 120. , The electron beam deflection position is calculated, and the deflection distortion amount of the electron beam mirror 100 is also corrected.
[0020]
(7) Procedure control unit 122
Responsible for monitoring and control so that the processing of each of the above units moves smoothly.
[0021]
The data from the units in the frame 111 is D / A converted by the D / A converter 113 and transferred to the beam control unit 114, where the lens 106 and the deflector 107 are controlled. In addition, the high-voltage power supply 115 generates an accelerating voltage for the electron gun 103, the aperture control unit 116 controls the aperture exchanging unit 131 to select the shape of the aperture 105, and the sample stage control unit 117 moves the sample stage 101. The control is performed, and the transfer system control unit 118 controls the transfer unit 102 that transfers the sample 108 to the sample table 101. The units are connected by a bus 119 and exchange signals via an interface. The computer 112 can also control these units.
[0022]
2 to 7 show a first embodiment of the present invention.
[0023]
FIG. 2 is a block diagram showing functions of the proximity effect correction unit 127 shown in FIG. The electron beam drawing apparatus includes a plurality of drawing data generators 12a, 12b,..., 12n controlled by the drawing data generator controller 11, and one electron beam drawing unit 16. Each of the drawing data generating units 12a, 12b,..., 12n includes drawing data generating units 13a, 13b,..., 13n, electron beam correcting units 14a, 14b,. 15n. The drawing data generation unit control means 11 issues instructions such as drawing data conditions to the plurality of drawing data generation units 12a, 12b,..., 12n, and outputs data electron beams from the drawing data generation units 12a, 12b,. An instruction to select data to be output to the drawing means 16 is issued.
[0024]
FIG. 3 is a flowchart showing the procedure for creating the exposure map, and FIG. 4 shows an example of the pattern shape. In step S41 of FIG. 3, the pattern 51 is divided by the mesh size 52 as shown in FIG. 4, and in step S42, the pattern area density in each mesh is obtained. Next, in step S43, smoothing is performed to reduce a dimensional change in a portion where the area density greatly changes between adjacent meshes, and an exposure map is created in step S44. When creating the exposure map, the electron beam data (for example, coordinates, dimensions, and irradiation amount) from the drawing data generation unit 13 is sent to the exposure map creation unit 15.
[0025]
FIG. 5 is a block diagram showing the exposure map creating means 15 in more detail. The exposure map creating means 15 creates an exposure map on the exposure map memory 61 from the drawing data generated by the drawing data generating means 13 shown in FIG. And an area density calculating means 63 for generating an area density from the data indicating the dimensions of the pattern. The generated value is smoothed by the area density smoothing means 64 for smoothing. The obtained values are stored in the exposure amount map memory 61 while being accumulated. When the value stored in the exposure map memory 61 is to be smoothed again, the value is read from the exposure map memory 61, smoothed by the area density smoothing means 64, and stored in the exposure map memory 61.
[0026]
At the time of drawing, the electron beam correcting unit 14 corrects the irradiation amount data in the drawing data input from the drawing data generating unit 13 by the value of the corresponding address of the previously generated exposure amount map. That is, a value corresponding to the drawing data and several values around the drawing data are read out from the values in the exposure map memory 61 created by the exposure map creating means 15, and the density around the drawing data is calculated therefrom. The dose is adjusted so as to be inversely proportional thereto. The electron beam drawing unit 16 outputs the irradiation amount, the coordinates, and the size of the electron beam corrected by the electron beam correcting unit 14 to the electron gun to perform the correction drawing.
[0027]
Next, in FIG. 2, the drawing data generation unit control means 11 issues an instruction of conditions such as a different mesh size and the number of times of smoothing for each of the drawing data generation units 12a, 12b,..., 12n. , 12n, based on the drawing data generated by the respective drawing data generating means 13a, 13b,..., 13n, the respective exposure amount map generating means 15a, 15b,. The area density calculation means 63 shown in FIG. 5 calculates the area density for each mesh size, and stores the calculated value in the exposure map memory 61 in correspondence with the memory address output from the coordinate-address conversion means 62. Store. In this way, a plurality of exposure maps with different conditions can be created in the same time as the conventional exposure map creation time.
[0028]
Next, one of the drawing data generators 12a, 12b,..., 12n is selected by the drawing data generator controller 11, and the selected drawing data generator 12n outputs the drawing data from the drawing data generator 13. When it is output, the corresponding address of the exposure map memory 61 shown in FIG. 5 is output from the coordinate-address conversion means 62 as in the case of the previous exposure map generation, and the corresponding value and its neighboring values are read. It is. The electron beam correcting means 14 corrects the irradiation amount with reference to the read value so that the irradiation amount is relatively small at a place where the exposure density is high and relatively large at a place where the exposure density is low. The electron beam drawing means 16 receives the drawing data corrected by the electron beam correcting means 14 and executes corrected drawing. This operation is continuously performed on the drawing data of all the drawing data generators 12a, 12b,..., 12n, the drawing result is evaluated, and the drawing operation is performed again based on the optimum drawing data as a result of the evaluation. Becomes possible.
[0029]
FIG. 6 is a time chart showing the magnitudes of the exposure time map creation time and the drawing time, comparing the case of the prior art with the case of the first embodiment of the present invention.
[0030]
In FIG. 6, the drawing data under three different conditions is evaluated, and the time ratios when drawing with the data of the optimum evaluation result (in FIG. 6, drawing data under condition 2) are compared again. . In the case of the prior art, an exposure map is created under the condition 1, empty drawing is performed based on the exposure map, and then an exposure map is created under the condition 2 to perform blank drawing. After that, an exposure map is created under the condition 3, and a blank drawing is performed. Then, the result of the blank drawing under each condition is evaluated. If it is found that the condition 2 is optimal, the exposure map is created again under the condition 2 and the actual drawing is performed.
[0031]
On the other hand, in the first embodiment of the present invention, exposure maps having different conditions are simultaneously created. That is, the exposure amount map of condition 1 is created in parallel by the drawing data generation unit 12a, the exposure map of condition 2 is created by the drawing data generation unit 12b, and the exposure amount map of condition 3 is created by the drawing data generation unit 12c in parallel. You. The created exposure map is held in each drawing data generation unit. The electron beam drawing means 16 sequentially performs drawing under the condition 1, condition 2, and condition 3 based on the exposure map held in each of the drawing data generating units 12a, 12b, 12c. As a result of evaluating the drawing result, when it is determined that the condition 2 is optimal, it is possible to immediately start drawing under the condition 2 by using the exposure amount map held in the drawing data generating unit 12b. As described above, the drawing throughput can be greatly improved as compared with the related art.
[0032]
FIG. 7 is a time chart of another example of the elapse of time shown in FIG. In this example, a plurality of drawing data generators 12a, 12b,..., 12n shown in FIG. 2 generate drawing data for drawing different patterns.
[0033]
The drawing data generation unit control means 11 shown in FIG. 2 generates different drawing data in each of the five drawing data generation units 12a, 12b, 12c, 12d, and 12e in FIG. Give instructions to do so. The five drawing data generators 12a, 12b, 12c, 12d, and 12e create an exposure map based on the drawing data output from the respective drawing data generators 13. As a result, as shown in the figure, in the prior art, the time required to write the two patterns A and B is the same as the time spent in writing the six patterns A, B, C, D, E and F in the present invention. Becomes possible. Further, during the correction drawing of the patterns A to F, the drawing data generation units 12b to 12e can create the exposure map of the pattern G to J. Therefore, after the completion of the correction drawing of the pattern F, Corrected drawing becomes possible.
[0034]
As described above, a plurality of exposure maps of different types can be created in the same time as the creation time of one exposure map in the related art. Then, the next electron beam drawing can be continuously performed with different drawing data for each exposure amount map. Further, during the electron beam drawing, the drawing data generating unit that is not used can create the exposure map of the new drawing data in parallel, and the throughput is greatly improved.
[0035]
Further, in the electron beam lithography apparatus shown in FIG. 2, it is possible to easily generate an exposure amount map exceeding a range that can be generated by one system of drawing data generation units. In other words, when the exposure map to be drawn exceeds the range that can be generated by one system of drawing data generators, the entire exposure map is divided into exposure map units that can be processed by one system of drawing data generators. An exposure map is created. First, the drawing data generation unit control unit 11 instructs how many divisions of the entire exposure amount map are to be made, and the drawing data generation units 12a, 12b,. Next, drawing is performed by the electron beam drawing unit 16 with reference to the exposure amount map generated by the drawing data generation unit 12a, and subsequently, the electron beam drawing unit 16 is referred to by referring to the exposure amount map generated by the drawing data generation unit 12b. When the drawing data generator 12n is controlled by the drawing data generator controller 11 such that the drawing is performed in the following manner, it is possible to draw an exposure amount map of any size.
[0036]
FIG. 8 shows a second embodiment according to the present invention, and is a block diagram corresponding to FIG. This embodiment is characterized in that it includes two drawing data generating units 12a and 12b and an output comparing unit 81. The output comparing unit 81 compares the output of the electron beam correcting unit 14a of the drawing data generating unit 12a with the output of the electron beam correcting unit 14b of the drawing data generating unit 12b.
[0037]
In FIG. 8, first, the drawing data generation unit control unit 11 causes the two systems of the drawing data generation unit 12a and the drawing data generation unit 12b to perform the same operation, and the output comparison unit 81 compares the outputs from the two systems. If the output of the electron beam correction means 14a and the output of the electron beam correction means 14b do not match, the information is transmitted to the drawing data generation unit control unit 11, and the drawing data generation unit control unit 11 again outputs each drawing data. The start is instructed to the generators 12a and 12b, and the output comparing means 81 compares both outputs. If the result of the output comparison indicates a match, it is determined to be normal, and by performing the drawing operation, a drawing failure can be prevented beforehand, and the reliability of the device and system can be greatly improved.
[0038]
FIG. 9 shows a third embodiment of the present invention, and is a block diagram corresponding to FIG. In the present embodiment, a first electron beam drawing apparatus 91 having the same configuration as that shown in FIG. 8 and a second electron beam having only the electron beam drawing means 16a mounted on the configuration shown in FIG. This is a combination of a drawing apparatus 92a and an electron beam drawing apparatus 92n having only the electron beam drawing means 16n via a communication means 93. In the first electron beam drawing apparatus 91, if the result of the output comparison means 81 is normal, the data storage means 94 holds the output of the drawing data generation unit 12a or the drawing data generation unit 12b.
[0039]
In the electron beam drawing apparatus 91, the drawing data generation unit control unit 11 causes the two systems of the drawing data generation unit 12 a and the drawing data generation unit 12 b to perform the same operation, and the output comparison unit 81 compares both outputs. If the result of the output comparison means 81 is normal, the drawing data generation unit control means 11 issues a drawing work instruction to the drawing data generation unit 12a based on the information, and sends a drawing work instruction to the drawing data generation unit 12b. Then, an instruction to transmit the output to the data storage means 94 is issued. The output of the electron beam drawing data generation unit 12b is held in the data storage unit 94. By transferring the held data to the second electron beam lithography devices 92a to 92n via the communication means 93, the plurality of electron beam lithography devices are the same as the first electron beam lithography device. Drawing becomes possible.
[0040]
As described above, according to the present invention, the optimum drawing data can be quickly evaluated, and the throughput is improved. Further, it is possible to hold the data of the exposure amount map, and it is possible to omit the operation of creating the same data when drawing again, so that it is possible to further improve the throughput. Further, the reliability of the device and the system can be improved.
[0041]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain an electron beam lithography apparatus, an electron beam lithography system, and a lithography method capable of improving the throughput.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of an electron beam writing apparatus according to the present invention.
FIG. 2 is a block diagram showing functions of a proximity effect correction unit shown in FIG.
FIG. 3 is a flowchart illustrating a procedure for creating an exposure amount map.
FIG. 4 is an explanatory diagram showing an example of a pattern shape.
FIG. 5 is a block diagram showing an exposure map creating means in more detail;
FIG. 6 is a time chart showing the magnitude of an exposure map creation time and a drawing time.
FIG. 7 is a time chart showing the magnitude of an exposure map creation time and a drawing time.
FIG. 8 is a block diagram illustrating functions of a proximity effect correction unit illustrated in FIG. 1;
FIG. 9 is a block diagram illustrating functions of a proximity effect correction unit illustrated in FIG. 1;
FIG. 10 is a block diagram showing functions of a conventional electron beam drawing apparatus.
[Explanation of symbols]
11 drawing data generation unit control means, 12a, 12b, ..., 12n drawing data generation units, 13a, 13b, ..., 13n drawing data generation means, 14a, 14b, ..., 14n electron beam correction means, 15a, 15b,..., 15n: Exposure amount map creating means, 16, 16a, 16n: Electron beam drawing means, 51: Pattern, 52: Mesh size, 61: Exposure amount map memory, 62: Coordinate-address conversion means, 63: Area Density calculating means, 64 area density smoothing means, 81 output comparing means, 91 first electron beam drawing apparatus, 92a second electron beam drawing apparatus, 92n electron beam drawing apparatus, 93 communication means, Reference numeral 94: data storage means, 100: electron beam mirror, 101: sample table, 102: transport unit, 103: electron gun, 104: electron beam, 105: aperture, 106: lens, 10 ... deflector, 108 ... sample, 109 ... sensor, 110 ... length measuring instrument, 111 ... frame, 112 ... computer, 113 ... D / A converter, 114 ... beam control unit, 115 ... high voltage power supply, 116 ... aperture control unit 117: sample stage control unit, 118: transport system control unit, 119: bus, 120: sample stage position measurement unit, 121: hard disk, 122: procedure control unit, 123: graphic data unit, 124: graphic restoration unit, Reference numeral 125: graphic decomposition unit, 126: alignment correction unit, 127: proximity effect correction unit, 128: tracking absolute calibration unit, 129: exposure amount map, 130: vacuum control unit, 131: aperture exchange unit.

Claims (3)

A drawing data generating unit for generating drawing data for forming a drawing pattern on a sample, an exposure map creating unit for creating an electron beam exposure map from the drawing data, and an irradiation amount of an electron beam for irradiating the sample. A plurality of drawing data generating units each including an electron beam correcting unit for performing correction with reference to the exposure amount map are provided. Each of the drawing data generating units generates an exposure amount map having different conditions for one drawing pattern, An electron beam drawing unit that irradiates the sample with the electron beam based on the value corrected by the line correction unit with reference to the exposure amount map under the different condition to perform drawing, and An electron beam lithography apparatus, which sequentially performs writing based on different exposure amount maps, and performs writing using an exposure amount map under optimum conditions as a result of evaluation of the writing result. 2. The electron beam lithography apparatus according to claim 1, wherein the exposure amount maps having different conditions are created in parallel by the respective drawing data generation units. A plurality of drawing data for forming a drawing pattern on a sample is generated from one drawing pattern, an exposure map having different conditions is created from the plurality of drawing data, and an irradiation amount of an electron beam for irradiating the sample is determined. Correction is performed with reference to the exposure map different in the condition, and the sample is irradiated with the electron beam based on the value corrected with reference to the exposure map different in the condition to perform drawing. A drawing method characterized by sequentially performing drawing based on different exposure amount maps, and performing drawing using an exposure amount map having optimum conditions as a result of evaluation of the drawing result.

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