JP2003021910A - Method for electron-beam lithography, base material plotted by the same and electron-beam lithographic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for electron-beam lithography by which the increase of a dose is prevented even if when plotting is carried out in the minimum dose stationary time and a low dose region required for a grating, etc., with a three-dimensional structure is satisfactorily formed without the restrictions of plotting patterns to be plotted, and to provide a base material plotted by the same and electron beam lithographic equipment. SOLUTION: The method for electron-beam lithography is for plotting the base material by scanning the base material with an electron beam at least in a curved line. The method has a calculation step to carry out calculation for specifying the positions of at least two point on a scan line in advance. The method has further a scan step to carry out serial scanning between the positions of the specified individual points with the electron beam. Thereby, the plotting can be carried out in the low dose region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam drawing method, a substrate drawn by the method, and an electron beam drawing apparatus, and more particularly, a method of drawing a region with a small dose in an electron beam by digital control. It relates to what is needed for later patterning applications.

[0002]

2. Description of the Related Art For example, an electron beam drawing apparatus is widely known as an apparatus for drawing an electron beam on a substrate coated with a resist. When, for example, circular coordinates are drawn on a substrate by using a general electron beam drawing apparatus of this kind, an X deflection system (X coordinate system) and a Y deflection system (for setting an irradiation position of an electron beam) ( A sin wave and a cos wave of desired magnitudes are output to the Y coordinate system), and these are combined to draw a circular coordinate of radius A by an electron beam by A2 sin2 Θ + A2 cos2 Θ = A2.

Specifically, for example, as shown in FIG. 13A, a scanning clock is input to the X coordinate system, an angle voltage generator 420 generates a voltage 421 corresponding to an angle, and this voltage 421 is cos. The cos wave 423 is obtained by inputting to the wave generator 422. Similarly, in the Y coordinate system, the scanning clock is input, and the angle voltage generator 424 outputs the voltage 42 corresponding to the angle.
5 is generated, and this voltage 425 is applied to the sin wave generator 426.
To obtain a sin wave 427. And the obtained s
With the in-wave 427 and the cos-wave 423, a circle having a desired size is drawn with an electron beam.

Here, the angle voltage generator 420 is shown in FIG.
As shown in (B), the window limit fixed type up / down with fixed upper and lower window limits.
It comprises a counter 31 and a D / A converter 32. When the scan clock 433 is input to the up / down counter 431, a triangular wave 434 is generated according to the preset upper and lower limits of the window, which is converted into an analog angular voltage 421 by the D / A converter 432 and output. To be done. The angle voltage generator 424 is similarly configured and operates in the same manner, and outputs the angle voltage 425.

[0005]

By the way, in the electron beam drawing apparatus, as a scanning method, for example, as shown in FIG. 2, a digital scanning method for performing drawing by digital control and an analog scanning method for performing drawing by analog control. In analog control, it is possible to perform a desired dose distribution in the case of a predetermined shape (for example, a circle), but a method of generating a sine wave, a cosine wave, and drawing a circle. Therefore, the function of the drawing shape such as the drawing pattern is extremely limited, there is no degree of freedom, and there is a problem that it is not possible to draw other various shapes (ellipse etc.).

On the other hand, in the conventional electron beam drawing apparatus, when it is attempted to draw a plurality of circles having different radii uniformly and concentrically on a base material coated with a resist by a digital scan method, one dot ( A method of scanning each dot) is adopted. Therefore, even if the electron beam drawing apparatus uses a high-performance DA converter having a relatively high resolution, the response of the DA converter causes
Electron beam stagnation time per dot is, for example, 0.0
This extends from 3 μS to 0.1 μS, and as a result, the stagnation time is long and the dose amount occupying one dot increases or becomes too strong. Therefore, for example, even if an attempt is made to form a low-dose region that is required when drawing a three-dimensional structure such as a blazed diffraction grating or a photonic crystal, the low-dose region is excessively dug to form the low-dose region. It will be difficult.

As described above, the dose stagnation time is approximately 0.1.
When μS / dot or the dose amount per dot corresponding to the stagnation time or less, digital control cannot be generally performed and an arbitrary pattern cannot be drawn.

The present invention has been made in view of the above circumstances, and it is an object of the present invention that there is no limitation on a drawing pattern that can be drawn and that even if drawing is performed within the minimum dose stagnation time, the dose is reduced. An electron beam drawing method, a substrate drawn by the method, and an electron beam drawing apparatus capable of preventing an increase in the amount and favorably forming a low dose region required for a diffraction grating having a three-dimensional structure. To provide.

[0009]

In order to achieve the above object, the invention according to claim 1 is an electronic device for drawing a substrate by scanning the substrate with an electron beam in a substantially curved shape. A beam drawing method, which comprises an operation step of performing an operation for designating at least two point positions on the scanning line in advance,
A scanning step of linearly scanning the designated point positions with the electron beam.

According to a ninth aspect of the present invention, there is provided an electron beam drawing apparatus which scans a substrate with an electron beam to draw a curve having a desired size. A calculation means for calculating each position of at least two points corresponding to a distance corresponding to a time corresponding to an integer multiple of the minimum time resolution of the DA converter, and a substantially straight line between the positions calculated by the calculation means by the electron beam. And a control means for controlling so as to perform scanning.

According to a tenth aspect of the present invention, there is provided an electron beam drawing apparatus for drawing the substrate by scanning the substrate with the electron beam in a substantially curved shape.
An arithmetic means for calculating each vertex position of a polygon whose side is a distance corresponding to an integer multiple of the minimum time resolution of the DA converter on a scanning line scanned in a substantially circular shape, and the arithmetic means. Control means for controlling so that the calculated positions are scanned substantially linearly by the electron beam.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of a preferred embodiment of the present invention will be specifically described with reference to the drawings.

[First Embodiment] (Entire Structure of Electron Beam Writing Apparatus) First, a feature of the present invention is that the substrate is subjected to digital control (digital scanning method) as shown in FIG. 2 in the electron beam writing apparatus. When drawing with respect to a curve such as a circle, each point position corresponding to a time distance that is an integral multiple of the minimum time resolution of the DA converter used in the electron beam drawing apparatus is designated and By linearly scanning the point position, the curve is approximated by a straight line, the minimum dose stay time per dot is shortened, and a low dose region required for drawing such as a blazed diffraction grating is obtained. It is possible to draw.

In the present embodiment, for example, as an example of a drawing pattern on a base material coated with a resist,
When drawing multiple circles with different radii evenly and concentrically, a regular n-gon (polygon) is applied to one circle.
An example of the case of approximating is described below.

Prior to the description of the principle and method for drawing a base material in the low dose region having such a characteristic structure and the detailed structure of each part for achieving those functions, first of all, it is assumed that The overall schematic configuration of the electron beam drawing apparatus itself will be described with reference to FIG. Figure 1
[FIG. 3] is an explanatory diagram showing a configuration of an electron beam drawing apparatus according to the present embodiment.

The electron beam drawing apparatus 1 of this embodiment is
As shown in FIG. 1, a high-resolution electron beam probe is formed with a large current to scan the substrate 2 to be drawn at high speed, and the high-resolution electron beam probe is formed to generate an electron beam. Then, an electron gun 12 which is an electron beam generating means for irradiating the target with a beam, a slit 14 for passing an electron beam from the electron gun 12, and a slit 1
4, an electron lens 16 for controlling the focal position of the electron beam passing through the substrate 2 with respect to the substrate 2, an aperture 18 arranged on the path through which the electron beam is emitted, and a target by deflecting the electron beam. It is configured to include a deflector 20 that controls a scanning position and the like on a certain base material 2 and a correction coil 22 that corrects the deflection, and is capable of so-called three-dimensionally scanning an arbitrary curved surface on the base material 2. To do.
It should be noted that each of these parts is arranged in the lens barrel 10 and is maintained in a vacuum state when the electron beam is emitted.

Further, the electron beam drawing apparatus 1 conveys the base material 2 to an XYZ stage 30 which is a mounting table on which the base material 2 to be drawn is mounted and a mounting position on the XYZ stage 30. A loader 40 that is a transporting means for
To measure a reference point on the surface of the base material 2 on the XYZ stage 30, a measuring device 80, a stage driving means 50 that is a driving means for driving the XYZ stage 30, and a loader. Loader drive device 60
And a housing 11 including the inside of the lens barrel 10 and the XYZ stage 30.
A vacuum exhaust device 70 for exhausting the interior to a vacuum;
A control circuit 100 which is a control means for controlling these;
It is configured to include.

The electronic lens 16 includes coils 17a, 17 which are installed at a plurality of locations along the height direction at a distance from each other.
A plurality of electronic lenses are generated according to the current values of b and 17c, respectively, so that the electronic lenses are controlled and the focal position of the electron beam is controlled.

The measuring device 80 includes a first laser length measuring device 82 for measuring the base material 2 by irradiating the base material 2 with a laser, and a laser emitted by the first laser length measuring device 82. Light (first irradiation light) is reflected by the base material 2 and the first light receiving portion 84 for receiving the reflected light and the first laser length measuring device 82 perform irradiation from different irradiation angles. A laser length measuring device 86, and a second light receiving portion 88 for reflecting the laser light (second irradiation light) emitted from the second laser length measuring device 86 on the substrate 2 and receiving the reflected light. , Is included.

The stage driving means 50 includes an X-direction driving mechanism 52 for driving the XYZ stage 30 in the X-direction, and an XYZ.
Y-direction drive mechanism 54 for driving the stage 30 in the Y-direction
, A Z-direction drive mechanism 56 that drives the XYZ stage 30 in the Z direction, and θ that drives the XYZ stage 30 in the θ direction.
The direction drive mechanism 58 is included. Thereby, the XYZ stage 30 can be operated three-dimensionally and alignment can be performed.

The control circuit 100 includes an electron gun power supply section 102 for supplying power to the electron gun 12, an electron gun control section 104 for adjusting and controlling the current and voltage in the electron gun power supply section 102, and an electron lens. A lens power supply unit 106 for operating 16 (each of a plurality of electronic lenses) and a lens control unit 108 for adjusting and controlling each current corresponding to each electronic lens in the lens power supply unit 106 are included. Composed of.

Further, the control circuit 100 includes a coil control section 110 for controlling the correction coil 22 and the deflector 2.
The shaping deflecting unit 112a for deflecting the shaping direction at 0, and the sub-deflecting unit 1 for deflecting the sub-scanning direction at the deflector 20.
12b and a main deflector 112c for deflecting the deflector 20 in the main scanning direction.

Further, the control circuit 100 corrects the position error in the deflector 20, that is, supplies a position error correction signal or the like to each of the shaping deflecting portions 112a, the sub deflecting portion 112b, and the main deflecting portion 112c. A position error correction circuit 116 that performs position error correction by the correction coil 22 by urging error correction or by supplying the signal to the coil control unit 110, and assigns each supply signal to each deflection as necessary. These position error correction circuits 1 are controlled and
16 and each shaping deflecting unit 112a, sub-deflecting unit 112b,
An electric field control circuit 118, which is an electric field control unit that controls the main deflection unit 112c to control the electric field of the electron beam.

Furthermore, the control circuit 100 moves the first laser length-measuring device 82 vertically and horizontally to move the laser irradiation position and control the drive of the laser irradiation angle. A second laser drive control circuit 132 that controls the drive of the laser irradiation position and the angle of the laser irradiation angle by moving the drive control circuit 130 and the second laser length measuring device 86 vertically and horizontally.
And a first laser output control circuit 134 for adjusting and controlling the output of laser irradiation light (light intensity of laser) in the first laser length measuring device 82, and the second laser length measuring device 8.
2nd for adjusting and controlling the output of the laser irradiation light in 6
Of the laser output control circuit 136 and the first light receiving unit 84, the first measurement calculating unit 140 for calculating the measurement result, and the second light receiving unit 88 based on the light receiving result, Second measurement calculation unit 1 for calculating the measurement result
42 and.

Furthermore, the control circuit 100 includes a stage control circuit 150 for controlling the stage driving means 50.
And a loader control circuit 15 for controlling the loader driving device 60
2 and the above-mentioned first and second laser drive circuits 130, 1
32. First and second laser output control circuits 134, 13
6. A mechanism control circuit 154 that controls the first and second measurement calculation units 140 and 142, the stage control circuit 150, and the loader control circuit 152, and a vacuum exhaust control circuit 156 that controls the vacuum exhaust of the vacuum exhaust device 70. A measurement information input unit 158 for inputting measurement information, various data (corresponding to the radius of the circle) necessary for approximating a regular polygon (including an indefinite polygon) at the time of drawing a circle described later, and Is not limited to circle drawing, various data necessary for linear approximation when drawing various curves, various drawing patterns (rectangle, triangle, polygon, vertical line, horizontal line, diagonal line, disk, circle, triangle) Circumference, arc,
Memory 160, which is a storage means for storing data regarding a fan shape, an ellipse, etc.) or input information or a plurality of other pieces of information, and for example, for calculating the regular polygon or distributing a “remainder” described later. A program memory 162 that stores various necessary arithmetic programs and control programs for performing various controls, and points corresponding to a drawing pattern for the base material 2 and a time distance that is an integral multiple of the minimum time resolution of a DA converter described later. A characteristic control system 300 of the present invention, which generates various signals for linearly scanning each side of a regular polygon depending on the position, and includes each unit that is a characteristic configuration of the present invention described later (details) Will be described later) and a control unit 1 formed by, for example, a CPU or the like that controls the respective units.
70, and is comprised.

Although the details will be described later, the information in the memory 160 may be stored in the memory in the control system 300, or the information may be stored in both the memory and the memory 160 in terms of their functions. However, the storage form of various information is not limited to such a hardware configuration.

Further, the electron beam drawing apparatus 1 of this embodiment
In the so-called “operation system” or “operation means” including the measurement information input unit 158, etc., selection of analog scan method, digital scan method, selection of vector scan, raster scan, etc., vector scan, raster scan Basics such as selection of each pixel number, selection of each drawing pattern of basic shape, selection of various editing commands (for example, creation, deletion, character pattern, move, enlargement, reduction, copy, reverse pattern, etc.) Needless to say, it is possible to perform specific operations. The control unit 170 of the present embodiment can configure the “control means” of the present invention.

In the electron beam drawing apparatus 1 having the above-mentioned structure, the substrate 2 conveyed by the loader 40.
Is placed on the XYZ stage 30, the air and dust in the lens barrel 10 and the housing 11 are exhausted by the vacuum exhaust device 70, and then an electron beam is emitted from the electron gun 12.

The electron beam emitted from the electron gun 12 is
The electron beam B deflected by the deflector 20 through the electron lens 16 and deflected (hereinafter, only the electron beam B which has been deflection-controlled after passing through the electron lens 16 may be given a symbol "electron beam B". (A) is irradiated on a surface of the base material 2 on the XYZ stage 30, for example, a drawing position on a curved surface portion (curved surface) to perform drawing.

At this time, the substrate 2 is measured by the measuring device 80.
Upper drawing position (at least height position of drawing position),
Alternatively, the position of a predetermined reference point is measured and the control circuit 10
0 adjusts and controls each current value flowing through the coils 17a, 17b, 17c, etc. of the electron lens 16 based on the measurement result to control the position of the focal depth of the electron beam B, that is, the focal position. The movement is controlled so that the position becomes the drawing position. Or, based on the measurement results,
The control circuit 100 controls the stage driving means 50 to move the XYZ stage 30 so that the focus position of the electron beam B becomes the drawing position. In addition,
In this example, electron beam control, XYZ stage 3
The control may be performed by either one of the controls of 0 or both of them.

Here, the base material 2 is preferably formed of an optical element such as an optical lens made of resin or the like, for example, and has a flat portion having a substantially flat cross section and a curved surface protruding from the flat portion. And a curved surface portion. The curved surface of the curved surface portion is not limited to a spherical surface, and may be a free curved surface having a change in any other height direction such as an aspherical surface.
Alternatively, the base material 2 may be a flat plate having no curved surface portion. In any case, it is preferable that the surface of the base material 2 is coated with a resist layer or the like that constitutes the layer to be drawn.

In such a base material 2, a substantially circular shape, more specifically, a concentric circular shape as shown in FIG. 2, for example, is drawn to draw a blazed diffraction grating structure. However, at this time, in the XY plane,
As will be described later, while the circle is approximated to a regular polygon and the circle drawing is linearly scanned, in the Z direction (when the surface has a curved surface), the measurement device 80 draws three-dimensionally. The position is calculated, the focal position of the electron beam is controlled, and writing is performed.

Although the description is out of the regular polygonal approximation which is the feature of this embodiment, the three-dimensional drawing will be briefly described. Specifically, the depth of focus F of the electron beam shown in FIG.
The focus position of Z (beam waist BW) is adjusted and controlled to the drawing position within one field (m = 1) of the unit space in the three-dimensional reference coordinate system. (This control is performed by adjusting the electric current value by the electronic lens 16 or XYZ as described above.
It is performed by one or both of the drive control of the stage 30. In this example, the field is set so that the height of one field is longer than the depth of focus FZ, but the present invention is not limited to this. Here, the depth of focus FZ indicates the height of the effective range of the beam waist BW in the electron beam B emitted through the electron lens 16 as shown in FIG. In the case of the electron beam B, as shown in FIG.
And the depth f from the electron lens 16 to the beam waist (where the beam diameter is the smallest) BW, D / f is
It is about 0.01, has a resolution of, for example, about 50 nm, and the depth of focus is, for example, about several tens of μ.

Then, for example, by scanning within one field in the Y and X directions, drawing within one field is performed. Furthermore, if there is an area that is not drawn in one field, that area also moves in the Z direction while controlling the focus position as described above,
Drawing processing by the same scanning will be performed.

Next, after the drawing in one field is performed, the drawing process is performed in real time in the other fields as well, while measuring and calculating the drawing position in the same manner as described above. In this way, when all the drawing is completed for the drawing area to be drawn, the drawing process on the surface of the base material 2 is completed.

In this example, this drawing area is the drawing layer, and the portion corresponding to the curved surface of the curved surface of the drawing layer is the drawing surface. Further, the processing programs for performing the various kinds of arithmetic processing, measurement processing, control processing, and the like as described above are stored in the program memory 162 in advance as control programs.

(Characteristic Configuration of this Embodiment) Next, with reference to FIGS. 2 to 6, the features of this embodiment, that is, the outline of the principle of performing the digital drawing in the electron beam drawing apparatus 1 will be described. explain. FIG. 2 discloses a drawing pattern drawn on the base material and a drawing shape of the details thereof. As shown in the figure, circle drawing is disclosed as an example of a drawing pattern drawn on the base material 2.
When enlarging the portion A, which is a part of the drawing portion, the base material 2 has a diffraction grating structure formed of a plurality of blaze 3 in the case of digital control.

The blaze 3 has an inclined portion 3a and a side wall portion 3b.
The side wall portion 3b is formed in a planar shape along the circumferential direction. The circle drawing is constructed so as to be approximated by a plurality of straight line portions. It is conceivable to use various methods for this approximation method, but for example, the following method may be performed.

For example, as shown in FIGS. 3 and 4, one side of the straight line portion is formed at a distance corresponding to an integral multiple of the minimum clock (minimum time resolution) of the DA converter. In the example of FIG. 3, the point positions a1 and b1 to the point position a2,
A straight line portion L1 for 4 clocks (4 times the minimum clock) between b2 and a straight line portion L2 for 8 clocks (8 times the minimum clock) between the point positions a2, b2 and the point positions a3, b3. I am configuring. This is formed by Y deflection and X deflection, respectively, as shown in FIG. No, straight part L
1 is decomposed into a linear portion LY1 for Y deflection and a linear portion LX1 for X deflection, and both have a distance of 4 clocks.
Further, the straight line portion L2 is divided into a straight line portion LY2 for Y deflection and a straight line portion LX2 for X deflection, and both have a distance of 8 clocks. Then, from the point positions a1 and b1 to the point position a
It is preferable that the scanning between 2 and b2 and the scanning between the point positions a2 and b2 and the point positions a3 and b3 are continuously performed without being stagnated at the point positions a2 and b2. Therefore, these 12 clocks are defined by the blanking signal BL as a blanking cancellation period.

An example of a circle drawing pattern is disclosed in FIG. 5 (A). As shown in the figure, when a circle is drawn, a curve (circle) is approximated by a regular n-sided polygon. For example, for a circle with a radius of 0.5 mm, for example, n = 75
7 、 Nochimasa 757 A polygon is approximated by a polygon. At this time, the length of one side is about 4 microns. The distance of one side is set to a distance corresponding to 10 times the minimum clock of the DA converter.

In a region of 45 degrees of a circle of 0.5 mm, as shown in FIG. 5 (B), the distance resolution in the radial direction becomes relatively coarse, so that the line of the next circle is scanned. In some cases, the resolution is insufficient, and the same point position may be used as in the case of the drawing line 2 and the drawing line 3, for example, and some overlapping portions may occur. In addition, in FIG. 5B, one grid has a length of about 8.3 nm at 1 dot. Also, due to the spatial resolution of 1 dot, the calculated regular n-gon vertex position and the actually specifiable position are different (or the value of n of the approximate regular n-gon differs depending on each circle). The center of each point position is deviated from the straight line in the radial direction by each drawing line 1, 2, 3, 4, 5, ..., And it exists at a different position. Further, for example, with respect to the drawing line 1, a line a and a line b are formed with the point position as a boundary. In FIG. 5 (B), for example, the drawing line 1 is shown as a mountain (top) of the inclined portion 3b of the blaze 3 shown in FIG.
, The drawing lines 2, 3 and
4 and so on, the slopes 3b are formed in the valley portions.

By the way, as described above, the drawing line 2
And an overlapping part like drawing line 3 occurs,
An area that is scanned twice is generated at a certain portion, and as a result, the dose distribution as shown in FIG. That is, in the dose pattern 211 shown in FIG. 6 (A), the dose distribution 21 for at least one blaze is 21.
In 2, the area 213 is formed by scanning a plurality of times at adjacent positions.

In this way, the dose pattern 212
Has a structure inclining from the high dose region to the low dose region so as to correspond to the blaze shape of the base material. Further, FIG. 6B shows an energy distribution 221 in the resist when the dose pattern as shown in FIG. 6A is used, and FIG. 6C shows the development result 231 thereof. . As shown in these figures, it is understood that a good development result can be obtained even in a relatively low dose region.

As described above, in the present embodiment, when the circle drawing is performed as described above, the electron beam stay time is reduced by performing the drawing by linearly approximating the regular polygon. Thus, as a result, drawing is possible in the low dose region.

In the example shown in FIG. 5A, when approximated by a regular polygon, a surplus portion or a shortage portion will occur. As the allowance for the surplus portion or the lacking portion, the following processing can be mentioned. First,
The first is to determine whether or not to make the remaining portion correspond to the drawing line based on the ratio of the remaining portion and the random number. Secondly, when one side is not an integral multiple of the minimum clock number, the length of the remainder or shortage when assigned by the predetermined integer multiple is further set to an integer of the minimum clock different from the multiple value. It is to be sorted by a double value. Furthermore, when approximating a circle with a regular n-gon,
It is preferable to change the multiple of the minimum clock for each circle (curve) having a different diameter to specify each point. Also, when formed by a plurality of curved lines in a substantially contour line,
In each of the curved portions adjacent to each other, the allocation position of the remainder or the deficiency on one of the curved portions and the allocation position of the remainder or the deficiency on the other of the curved portions are different positions. It is preferable to specify as follows.

(Specific Structure of Control System) With reference to FIG. 7, the specific structure of the control system for performing various processes when the circle drawing is approximated by a regular polygon and linearly scanned. While explaining. FIG. 7 discloses a detailed configuration of a control system of the electron beam writing apparatus according to this embodiment.

As shown in FIG. 7, the control system 300 of the electron beam drawing apparatus is required to approximate a regular polygon (including an indefinite polygon) at the time of drawing a circle (according to the radius of the circle).
Various data (for example, for one circle with a radius of kmm, the number of divisions n by the polygon, coordinate information of the position of each side, the coordinate value of the position of each point, the multiple value of the number of clocks, and the position of each circle in the Z direction. Information, etc.), and various data required for linear approximation when drawing various curves, not limited to circle drawing, and various drawing patterns (rectangle, triangle, polygon, vertical line, horizontal line, diagonal line) , Disk, circle, triangle, arc,
A drawing pattern data memory 301 which is a drawing pattern storing means for storing data regarding a fan shape, an ellipse, etc., and a drawing condition calculating means 310 for calculating a drawing condition based on the drawing pattern data of the drawing pattern data memory 301, From the drawing condition calculation means 310, (2n +
1) If the line ((n = 0, 1, 2, ...) Is (2
(n + 1), but (n = 1, 2, ...) May be set to (2n-1)). Here, the drawing condition of odd lines is calculated (2n + 1) line drawing condition calculation means 311.
And a time constant setting circuit 312 for setting the time constant of one line based on the (2n + 1) line drawing condition calculation means 311.
And (2n + 1) line drawing condition calculation means 311 is used to set the start point and end point voltage of one line.
End point voltage setting circuit 313, counter number setting circuit 314 for setting the number of counters based on (2n + 1) line drawing condition calculation means 311 and enable signal for generating an enable signal based on (2n + 1) line drawing condition calculation means 311 It is configured to include a generation circuit 315 and a deflection signal output circuit 320 for outputting a deflection signal of an odd line.

Further, the control system 300 calculates (2n) line drawing condition calculation means 331 from the drawing condition calculation means 310 to calculate drawing conditions for (2n) lines and even lines.
And (2n) a time constant setting circuit 332 for setting the time constant of one line based on the line drawing condition calculation means 331,
(2n) start / end point voltage setting circuit 333 for setting the start point and end point voltage of one line based on the line drawing condition calculating means 331, and (2n) line drawing condition calculating means 3
A counter number setting circuit 334 for setting the counter number based on 31, an enable signal generation circuit 335 for generating an enable signal based on the (2n) line drawing condition calculation means 331, and a deflection signal for outputting even lines. A deflection signal output circuit 340, and a blanking amplifier 350 for performing blanking when moving to the next contour line based on the (2n) line drawing condition calculation means 310,
A switching circuit for switching between odd line processing and even line processing based on the drawing conditions in the drawing condition calculation means 310 and the information from the odd line deflection signal output circuit 320 and the even line deflection signal output circuit 340. 360
And are included.

The odd line deflection signal output circuit 320 is
A counter circuit 321 that is a counting unit that performs count processing based on the scan clock CL1, the odd line count signal CL6 from the counter number setting circuit 314, and the enable signal of the enable signal generation circuit 315, and the count from the counter circuit 321. Timing and odd line drawing condition signal CL3 in the start point / end point voltage setting circuit 313
A DA conversion circuit 322 that performs DA conversion based on
And a smoothing circuit 323 for performing processing for smoothing the analog signal converted by the DA conversion circuit 322 (processing for removing high-frequency components of the deflection signal).

The even-numbered deflection signal output circuit 340 is
A counter circuit 341 that is a counting unit that performs counting processing based on the scan clock CL1, the even line count signal CL7 from the counter number setting circuit 334, and the enable signal of the enable signal generation circuit 335, and the count from the counter circuit 341. Timing and even line drawing condition signal CL5 in the start point / end point voltage setting circuit 333
A DA conversion circuit 342 that performs DA conversion based on
And a smoothing circuit 343 that performs a process of smoothing the analog signal converted by the DA conversion circuit 342.

It should be noted that each of the parts constituting the control system 300 is configured to be controllable by the control part 170 (control means) such as the CPU shown in FIG. Further, these control systems 300 may be configured to form a control system for X deflection and a control system for Y deflection, respectively.

The control system 300 including the drawing pattern data memory 310 and the drawing condition calculating means 310 of this embodiment can constitute the "calculating means" of the present invention. This "arithmetic means", on the scan line to be scanned,
It has a function of calculating each position of at least two points corresponding to a distance corresponding to a time that is an integral multiple of the minimum time resolution of the DA converter. In this case, the “control means” of the control unit 170 is
Control is performed so that the positions between the positions calculated by the calculation means are scanned substantially linearly by the electron beam. Similarly, in the "calculating means" of another aspect of the present invention, a distance corresponding to an integer multiple of the minimum time resolution of the DA converter is defined as one side on a scan line scanned in a substantially circular shape. It has a function of calculating the position of each vertex of the polygon. Further, the control means similarly scans the respective positions calculated by the calculation means with the electron beam substantially linearly.

Furthermore, the (2n + 1) line drawing condition calculation means 311, the time constant setting circuit 312, the start point / end point voltage setting circuit 313, the counter number setting circuit 31 of the present embodiment.
4, the enable signal generation circuit 315, and the deflection signal output circuit 320 can configure the “first generation unit” in the present invention. Here, the "first generating means" has a function of generating a drawing condition for scanning a certain side and outputting a first deflection signal based on the drawing condition. Further, the "first deflection signal" according to the present invention can be configured by the odd line deflection signal CL9 of the present embodiment. Further, the (2n) line drawing condition calculation means 331, the time constant setting circuit 332, the start point / end point voltage setting circuit 333, the counter number setting circuit 334, the enable signal generating circuit 335 of the present embodiment,
The deflection signal output circuit 340 can constitute the “second generating means” according to the present invention. Here, "second generation means"
Has a function of generating a drawing condition for scanning one side adjacent to the one side and outputting a second deflection signal based on the drawing condition. Further, the “second deflection signal” referred to in the present invention can be configured by the even line deflection signal CL10 of the present embodiment.

The switching circuit 360 of this embodiment can constitute the "switching means" according to the present invention. The "switching means" has a function of alternately switching and controlling the first deflection signal generated by the first generation means and the second deflection signal generated by the second generation means. Have. In this case, the control means of the control unit 170 controls the drawing of each side alternately by the first deflection signal and the second deflection signal.

Further, the blanking amplifier 350 of this embodiment can constitute the "moving means" of the present invention. The "moving means" has a function of moving the irradiation position of the electron beam with respect to another circle formed on a contour line adjacent to the circle when the period for drawing the circle in the circle is completed. In this case, the control means of the control unit 170 controls the movement of the movement means based on the end of the period of the circle drawing.

The control system 300 having the above structure
Generally operates as follows. That is, when the drawing condition calculation means 310 acquires information necessary for scanning (drawing) by linear approximation from the drawing pattern data memory 301, calculation processing of a predetermined drawing condition is performed, and for example, one circle is formed into a regular polygon. Information about the first and odd lines of each side when approximated to each side is (2n + 1)
The information regarding the next side and the even-numbered line is transmitted to the line drawing condition calculating means 311 to the (2n) line drawing condition calculating means 331, respectively.

Thereby, for example, the (2n + 1) line drawing condition calculation means 311 generates the drawing condition for the odd line, and outputs the deflection signal based on the scanning clock CL1 and the generated odd line drawing condition generation signal CL2. The circuit 320 outputs the odd line deflection signal CL9.

On the other hand, for example, the (2n) line drawing condition calculation means 331 generates drawing conditions for even lines, and based on the scan clock CL1 and the generated even line drawing condition generation signal CL4, the deflection signal output circuit. 34
An even line deflection signal CL10 is output from 0.

The output of the odd-numbered line deflection signal CL9 and the even-numbered line deflection signal CL10 is alternately switched by the switching circuit 360 based on the drawing condition calculation means 310. Therefore, for one circle, if it is approximated to a regular polygon and each side is calculated, then one side, an odd side, is drawn, then the next side, an even side, Further, each side is drawn (scanned) in a straight line alternately such that the next side and the odd-numbered side are drawn.

When the drawing of one circle is completed, the drawing condition calculation means 310 transmits a message to that effect to the blanking amplifier 350, and performs processing for prompting the drawing of another circle. In this way, polygonal approximation is performed for each circle.

(Regarding Processing Procedure) Next, a processing procedure for drawing a circle on the base material in the control system of the electron beam drawing apparatus having the above-described structure will be described with reference to FIG.

As shown in the timing chart of FIG.
In the scanning clock CL, for example, the even line drawing condition output signal CL5 is turned on at the timing of time t1, and then the even line count signal CL7 is turned on at the timing of time t2. In addition, when the switching signal CL8 is turned on at the timing of time t3, the odd line deflection signal CL9 becomes L level, while the even line deflection signal CL10 becomes H level. The odd line deflection signal CL9 and the even line deflection signal CL10 are switched between the H level and the L level based on the rising edge of the switching signal CL8. Therefore, until the time t8 when the switching signal CL8 rises next time, No, time t3 to time t
Up to 8, the odd line deflection signal CL9 remains at the L level and the even line deflection signal CL10 remains at the H level.

At time t4, the odd line drawing condition generation signal CL2 becomes H level, and the odd line drawing condition is generated during the period up to time t5.

Next, after the drawing condition of the odd line is generated, the drawing condition output signal CL3 of the odd line is turned on at the timing of time t6, whereby the drawing condition of the odd line is output, and further, the time t7. The odd line count signal CL6 is turned on at the timing. Then, at the timing of time t8, the odd line deflection signal CL
9 goes high while the even line deflection signal CL10
Becomes L level. As a result, under the above-described odd line drawing condition, the odd line is drawn by the odd line deflection signal CL9.

At time t9, the even-line drawing condition generation signal CL4 becomes H level, and the even-line drawing condition is generated during the period up to time t10.

Next, after the even line drawing conditions are generated, the even line drawing condition output signal CL5 is turned on at the timing of time t11, whereby the even line drawing conditions are output, and at time t12. The even line count signal CL7 is turned on at the timing. Then, at the timing of time t13, the odd line deflection signal C
L9 becomes L level, while even line deflection signal CL1
0 becomes H level. As a result, even lines are drawn by the even line deflection signal CL10 under the above-mentioned even line drawing conditions.

In this way, the odd-numbered line deflection signal and the even-numbered line deflection signal are alternately output, so that drawing can be performed alternately.

At this time, when drawing an odd line,
A predetermined drawing condition is generated by the odd line drawing condition generation signal CL2, the condition is output after the predetermined drawing condition is generated, the odd line is counted, and the predetermined line is set by the odd line deflection signal CL9 under the predetermined condition. Is drawn to.

Similarly, when drawing an even line, a predetermined drawing condition is generated by the even line drawing condition generation signal CL3, and after this is generated, the condition is output and the even line is counted. A predetermined line is drawn under a predetermined condition by the even line deflection signal CL10.

As the drawing conditions, linear scanning is performed under the linear scanning conditions such as the above-mentioned X deflection and Y deflection.

As described above, according to the present embodiment, when a circle is drawn, the stagnation time of the electron beam is reduced by approximating with a regular polygon and linearly scanning between the points that are the vertices. Therefore, the dose amount per dot can be reduced, and writing in a low dose region can be performed.

[Second Embodiment] Next, a second embodiment according to the present invention will be described with reference to FIGS. Note that, in the following, description of substantially the same configuration as that of the first embodiment will be omitted, and only different portions will be described.

In this embodiment, when approximating a circle drawing with a regular polygon, if one side is not an integral multiple of the minimum time resolution (minimum clock) of the DA converter, the remainder part is distributed. Examples are disclosed.

Specifically, as shown in FIG. 9, it is assumed that the nk-th line, the nk + 1-th line, and the nk + 2-th line are formed on the base material. At this time, the nk + 1th line and the nk + 2nd line are sequentially scanned from the nkth line.

Here, a processing procedure for performing the remainder processing will be described with reference to FIGS. 10 and 11. First, a process of determining whether or not Don ≠ Dt is performed (step, hereinafter “S” 101). Here, the relationship between the number of clocks required for one side of the polygon and the dose amount is as in the relational expression shown in FIG. 11, and each variable is also defined.

Returning to FIG. 10, if it is determined in S101 that Don ≠ Dt is not satisfied, the clock number intCLn is set to the clock number of one side (S102). On the other hand, in the determination process, Don ≠
If it is determined that Dt, it is determined whether or not Dot> Dt (S103).

When it is determined in this S103 that Dot> Dt is not satisfied, the value obtained by rounding intCLn + αCLn is used as the clock for one side (S1).
04). On the other hand, in the determination process of S103, Dot>
If it is determined that Dt, k = 0 is performed (S105).

Next, the stagnation time is extended by 1 clock only for the dot closest to the intersection of the dividing line obtained by dividing the line of the circumference nk by the total of the remainders of all sides and the line of the circumference nk ( S106). Here, "divide the line of the circumference nk by the total of the remainders of all sides" and 2π / (mn0 · αCLn)
Becomes

Then, the line of the circumference nk + 1 is set to the circumference n.
A division line divided by the sum of the remainders of all sides of the line of k and the line of the next circle nk + 1 adjacent to the circle nk, and the stagnation time is extended by one clock on the line of the circle nk. A process of increasing the stagnation time of one clock by one clock based on the intersection of the dividing line adjacent to the line and the line of the circumference nk + 1 is performed (S107). Here, “the line of the circumference nk + 1 is the line of the circumference nk and the line of the circumference nk
2π / {(mk + mk + 1) · αCL
n}}.

Then, it is determined whether k = end (S108). Next, in the determination process,
When it is determined that k = end is not satisfied, the process of setting k = K + 1 is performed (S109), and the process returns to S107.

On the other hand, in the determination processing of S108, k =
If it is determined to be end, the process ends.

As described above, according to the present embodiment, when the circle is drawn on the base material, the remainder generated when the scanning line is linearly approximated by a regular polygon is distributed and processed.
It is possible to draw accurately. In addition, when approximation is performed with a regular polygon, a portion that is not an integral multiple of the minimum clock occurs, but since this remainder portion is distributed almost evenly on the circle, the approximation error can be reduced.

It should be noted that although the apparatus and method according to the present invention have been described according to some specific embodiments thereof,
Those skilled in the art can make various modifications to the embodiments described in the text of the present invention without departing from the spirit and scope of the present invention. For example, in each of the above-described embodiments, an example in which a circle is drawn on a base material has been shown, but the present invention is not limited to this example, when an ellipse or the like is drawn on the base material, and further Needless to say, the same method can be applied to drawing an arbitrary curve on an arbitrary curved surface of.

Although a method of approximating with a regular polygon is disclosed when performing circle drawing, the present invention is not limited to this example, and a polygon may be approximated. Further, examples of the base material drawn by the electron beam drawing apparatus include optical elements such as a hybrid optical functional element, a blazed diffraction grating, a lens with an antireflection structure, and a lens with an optical filter.

In addition, the processing program processed in the electron beam drawing apparatus according to each of the above-described embodiments, the processing described, and the whole or each part of the data (various tables, etc.) in the memory is recorded on the information recording medium. It may be. As the information recording medium, for example, ROM, RA
M, a semiconductor memory such as a flash memory, an integrated circuit, or the like may be used, and the information may be recorded in another medium, for example, a hard disk or the like, and configured and used.

As concrete processing information, when drawing the substrate by scanning the substrate with an electron beam at least in a curvilinear manner, at least two points on the scanning line are designated in advance. The information includes processing information and processing information for linearly scanning the designated point positions with the electron beam. Furthermore, at least DA
It includes information for arithmetic processing so that two-point positions corresponding to a time distance that is an integral multiple of the minimum time resolution of the converter are designated.

Further, when the scanning line is formed in a substantially circular shape, each point is designated so as to approximate a polygon having one side as a distance corresponding to an integral multiple of the minimum time resolution of the DA converter. Contains information to be processed. Further, when the scanning line is formed by a plurality of curve groups in a substantially contour line shape, information for arithmetic processing is performed so as to specify each point by changing the multiple value of the minimum time resolution according to each curve. Including. Furthermore, when one side does not become an integer multiple of the minimum time resolution, information for performing a process of almost evenly distributing the remainder or shortage when assigned by the predetermined integer multiple on the circle, When the scanning line is formed by a plurality of curved lines in a substantially contour line shape, among the curved portions adjacent to each other,
Arithmetic processing is performed so that the allocation position of the remainder or the deficiency on one of the curved portions and the allocation position of the remainder or the deficiency on the other curved portion are designated to be different positions. And information.

Furthermore, it goes without saying that examples of the above-described respective embodiments and combinations of any of them with modifications are included.

[0089]

As described above, according to the present invention, in the area where one dot is conventionally curvedly scanned, by linearly scanning between two points on the curve, this area is scanned. By shortening the stagnation time of the electron beam at
The dose amount per dot can be reduced. Therefore, even if the stagnation time is limited to 0.1 μs due to the conventional time resolution of the DA converter, it is possible to perform drawing with the stagnation time shorter than that.

In addition, when drawing, for example, a circle on the base material, by approximating a polygon having a side corresponding to an integer multiple of the minimum clock number of the DA converter as one side, Drawing can be performed while shortening the stagnation time.

In addition, when approximation is performed with a regular polygon, a portion that is not an integral multiple of the minimum clock occurs, but since this remainder portion is distributed almost evenly on the circle, the approximation error can be reduced. .

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall schematic configuration of an electron beam drawing apparatus of the present invention.

FIG. 2 is an explanatory diagram showing an example of a drawing shape drawn by an electron beam drawing apparatus.

FIG. 3 is an explanatory diagram showing an example in which two preset address points are connected by a straight line in the electron beam drawing apparatus of FIG.

FIG. 4 is a view for explaining a correspondence relationship between the minimum clock number of the DA converter and Y deflection and X deflection when a preset two-point address is connected by a straight line in the electron beam drawing apparatus of FIG. FIG.

5A is an explanatory diagram showing an example of a drawing pattern drawn by the electron beam drawing apparatus of FIG. 1, and FIG. 5B shows details of FIG. FIG.

FIG. 6A is an explanatory diagram showing a dose pattern for a substrate by an electron beam writing apparatus, and FIG. 6B is an explanation showing energy distribution in a resist for a substrate by an electron beam writing apparatus. It is a figure, the same figure (C)
FIG. 6 is an explanatory diagram showing an example of simulating a development result on a base material.

7 is a functional block diagram showing the configuration of a more detailed control system of the electron beam drawing apparatus in FIG.

8 is a timing chart showing the processing of the control system of FIG.

FIG. 9 is an explanatory diagram for explaining a case of distributing a remainder when a circle drawing is approximated by a regular polygon.

FIG. 10 is a flowchart showing an example of a processing procedure for distribution in FIG.

FIG. 11 is an explanatory diagram showing details of a part of the processing procedure of FIG. 10;

FIG. 12 is an explanatory diagram for explaining a beam waist in the electron beam writing apparatus.

13A and 13B are block diagrams showing a schematic configuration of a conventional electron beam drawing apparatus.

[Explanation of symbols]

1 Electron beam lithography system 2 base materials 16 electronic lens 20 deflector 30 XYZ stage 100 control circuit 112a Forming deflection unit 112b Sub-deflection unit 112c Main deflection section 118 electric field control circuit 160 memory 162 program memory 170 control unit 300 control system 310 drawing condition calculation means 311 (2n + 1) line drawing condition calculation means 331 (2n) line drawing condition calculation means 360 switching circuit

Claims (12)

[Claims] 1. An electron beam drawing method for drawing a substrate by scanning the substrate with an electron beam in a substantially curved shape, wherein an operation for designating at least two point positions on a scanning line in advance is performed. An electron beam drawing method comprising: a calculation step to be performed; and a scanning step of linearly scanning the designated point positions with the electron beam. 2. The electronic device according to claim 1, wherein the calculation step is performed so that at least two point positions corresponding to a time distance that is an integer multiple of the minimum time resolution of the DA converter are designated. Beam drawing method. 3. The scanning line is formed in a substantially circular shape, and in the calculating step, each point is approximated to a polygon having a side corresponding to an integer multiple of the minimum time resolution of the DA converter as one side. The electron beam drawing method according to claim 1, wherein the calculation is performed so as to specify 4. The scanning line is formed of a plurality of curved lines in a substantially contour line shape, and the computing step changes the multiple value of the minimum time resolution according to each curve to specify each point. The electron beam writing method according to claim 1, wherein the electron beam writing method is performed. 5. In the calculation step, when the one side does not become an integral multiple of the minimum time resolution, the remainder or shortage when assigned by a predetermined integer multiple is approximately equalized on the circle. The electron beam writing method according to claim 3, wherein the electron beam writing method is performed. 6. The scanning line is formed of a plurality of curved lines in a substantially contour line shape, and in the calculating step, the surplus or the deficient portion on one of the curved portions is adjacent to each other. 6. The electronic device according to claim 1, wherein the assignment position of the above and the assignment position of the remainder or the shortage on the other curved portion are designated so as to be different positions. Beam drawing method. 7. A substrate drawn by the electron beam drawing method according to any one of claims 1 to 6. 8. The base material according to claim 7, wherein the base material is an optical element. 9. An electron beam drawing apparatus for scanning a substrate with an electron beam to draw a curve of a desired size, wherein an integer of a minimum time resolution of a DA converter is provided on a scanning line to be scanned. Calculation means for calculating each position of at least two points corresponding to a distance corresponding to double the time, and control for controlling so that the positions between the positions calculated by the calculation means are scanned substantially linearly by the electron beam. An electron beam drawing apparatus comprising: 10. An electron beam drawing apparatus that draws the substrate by scanning the substrate with the electron beam in a substantially curved shape, wherein DA is provided on a scanning line that is scanned in a substantially circular shape. Calculation means for calculating each vertex position of a polygon whose side corresponds to a time corresponding to an integer multiple of the minimum time resolution of the converter, and a substantially straight line between the positions calculated by the calculation means by the electron beam. An electron beam drawing apparatus, comprising: 11. The computing means generates a drawing condition for scanning a certain side, and outputs a first deflection signal based on the drawing condition, and a first side adjacent to the one side. And a second deflection signal generated by the first generation unit, which generates a drawing condition for scanning the scanning line and outputs a second deflection signal based on the drawing condition.
Switching means for alternately switching and controlling the second deflection signal generated by the second generation means, wherein the control means alternates between the first deflection signal and the second deflection signal. The electron beam drawing apparatus according to claim 9, wherein each side is controlled to be drawn. 12. When the curve drawing period ends, the apparatus further comprises a moving means for moving the irradiation position of the electron beam with respect to another curve formed on a contour line adjacent to the curve, and the control means. The electron beam drawing apparatus according to claim 9 or 10, wherein the electron beam drawing apparatus controls the movement of the moving means based on the end of the curve drawing period.