JPH11195589A - Multiple electron beam exposure method and its apparatus, and manufacture of device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiple electron beam exposure method and its apparatus, and a method for manufacturing the device capable of preventing decrease in the throughput under existing fractional patterns in the exposure pattern, by classifying an exposure pattern into a plurality of groups conforming to design rules and varying a minimum width of deflection for each group. SOLUTION: When there are pattern groups for different design rules in a sub-field SF0 to be exposed, the sub-field SF0 is divided into a plurality of sub-fields SF1 and SF2 for pattern groups of only one design rule. Pattern groups PG1 in the sub-field SF1 are written by setting the minimum width of deflection, for instance, 25 nm and prohibiting each electron beam irradiation, except to the region where the corresponding beam is in the sub-field SF1. A pattern group PG2 in the sub-field SF2 is written by setting the minimum width of deflection, for instance, 45 nm. This makes enables reduction of the setting number of an electron beam with the existence of the fractional pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the technical field of electron beam exposure, and more particularly to a multi-electron beam exposure method and apparatus for performing pattern writing using a plurality of electron beams for direct wafer writing or mask and reticle exposure. Belongs to the technical field of a device manufacturing method using the same.

[0002]

2. Description of the Related Art An electron beam exposure apparatus includes a point beam type in which a beam is used in the form of a spot, a variable rectangular beam type in which a variable-size rectangular section is used, and a stencil mask having a desired sectional shape using a stencil. There are devices such as molds.

[0003] Point beam electron beam exposure apparatuses are used only for research and development because of their low throughput. The variable rectangular beam type electron beam exposure apparatus has a throughput of one to two orders of magnitude higher than that of the point type electron beam exposure apparatus. However, when exposing a pattern in which a fine pattern of about 0.1 μm is packed with a high degree of integration, the throughput is still high. There are many problems. On the other hand, a stencil mask type electron beam exposure apparatus uses a stencil mask in which a plurality of repeating pattern transmission holes are formed in a portion corresponding to a variable rectangular aperture. Therefore, a stencil mask type electron beam exposure apparatus has a great advantage in exposing a repetitive pattern. However, for a semiconductor circuit requiring a large number of transfer patterns that cannot be accommodated in one stencil mask, a plurality of stencil masks are required. It is necessary to take out one sheet at a time and use it one by one, which requires a time for mask replacement, which causes a problem that the throughput is significantly reduced.

As an apparatus for solving this problem, a sample surface is irradiated with a plurality of electron beams along design coordinates, and the sample surface is scanned by deflecting the plurality of electron beams along design coordinates. In addition, there is a multi-electron beam type exposure apparatus which draws a pattern by individually turning on / off a plurality of electron beams according to a pattern to be drawn. The multi-electron beam type exposure apparatus has a feature that the throughput can be further improved because an arbitrary drawing pattern can be drawn without using a stencil mask.

FIG. 17 shows an outline of a multi-electron beam type exposure apparatus. 501a, 501b, 501c individually turn on the electron beam
An electron gun that can be turned off. 502 is an electron gun 501a, 501b, 501
A reduction electron optical system for reducing and projecting a plurality of electron beams from c onto the wafer 503, and a deflector 504 for deflecting the plurality of electron beams reduced and projected on the wafer 503.

A plurality of electron beams from the electron guns 501a, 501b, and 501c are given the same amount of deflection by a deflector 504. Thus, with respect to each beam reference position, each electron beam is deflected by sequentially setting its position on the wafer in accordance with an arrangement having an arrangement interval determined by the minimum deflection width of the deflector 504. And each electron beam
A pattern to be exposed is exposed in different element exposure regions.

FIGS. 17A, 17B, and 17C show the electron gun 50, respectively.
The figure shows that the electron beams from 1a, 501b, and 501c expose the respective element exposure areas (EF1, EF2, EF3) to patterns to be exposed according to the same arrangement. Each electron beam indicates the position on the array at the same time as (1,1), (1,2) ... (1,1
6), (2,1), (2,2) .... (2,16), (3,1) .. A beam is irradiated at a position where (P1, P2, P3) is present, and a pattern (P1, P2, P3) to be exposed is exposed in each element exposure region.

[0008]

In a multi-electron beam type exposure apparatus, a plurality of electron beams are deflected by a common minimum deflection width to simultaneously draw a pattern, so that only a certain electron beam has an integral multiple of the minimum deflection width. Unable to draw fractional size patterns. In such a case, it is necessary to set and draw the minimum deflection width, which is the greatest common divisor of the integer pattern and the fractional pattern, which is an integral multiple of the current minimum deflection width, and usually, the reset minimum deflection width is the original minimum deflection width. Since it is smaller than the minimum deflection width, there is a problem that the data amount for drawing increases.

The above problem will be specifically described with reference to FIG. When the patterns P1, P2, and P3 to be exposed are all patterns having a design rule of 100 (nm), the minimum deflection width is set to 25 (nm), and 100 (nm) is drawn by scanning the electron beam four times.
However, when only the pattern P3 has a design rule of 180 (nm), the minimum deflection width is set to 20 (nm), which is the greatest common divisor of 100 (nm) and 180 (nm). Assuming that the element exposure area of each electron beam is 3.6 × 3.6 (μm 2), when the minimum deflection width is 25 (nm), the integer constant for exposing the element exposure area is 20736, and the minimum deflection width is 20 (nm). Hour integer constant is 32400
Becomes That is, with a fractional pattern, the integer constant is approximately
It becomes 1.5 times, and the amount of data for drawing also becomes about 1.5 times.

When only the pattern P3 has a design rule of 180 (nm), the minimum deflection width is actually 25
(Nm), a pattern having a line width of 180 (nm) may be drawn by approximation by scanning with the electron beam seven times, but in this case, the drawing accuracy is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and provides a multi-electron beam type exposure method and apparatus capable of reducing a decrease in throughput even when a drawing pattern has a fractional pattern. The purpose is to: It is another object of the present invention to provide a device manufacturing method capable of manufacturing a device with higher precision than before using the device.

[0012]

A preferred embodiment of the multi-electron beam exposure method according to the present invention for solving the above-mentioned problems is a method for simultaneously drawing a plurality of regions on a surface to be exposed using a plurality of electron beams, The writing pattern is classified into a plurality of groups according to the design rule, and writing is performed by changing the minimum deflection width of the electron beam for each group.

Preferably, drawing is performed sequentially for each area of the plurality of groups. Further, the beam diameter or settling time of the electron beam is changed according to the switching of the minimum deflection width.

In another preferred embodiment of the multi-electron beam exposure method according to the present invention, a plurality of electron beams are deflected on a surface to be exposed of an object in units of a minimum deflection width based on drawing data. By controlling the beam irradiation individually,
A method of drawing a pattern in an element exposure area for each electron beam to draw a subfield composed of the plurality of element exposure areas and sequentially writing a plurality of subfields, Classifying the pattern groups into a plurality of groups based on design rules, determining an optimum minimum deflection width for each group when drawing the pattern group of each group, and the drawing data in units of the subfields A first dividing step for dividing;
A second division step of dividing a subfield having a plurality of pattern groups into subfields having only one group of patterns, and a minimum deflection width when exposing a subfield having only one group of pattern groups. Is switched to an optimum minimum deflection width corresponding to the group, and the plurality of electron beams are deflected and drawn by using the optimum minimum deflection width as a unit.

Here, preferably, the second dividing step includes the following:
The drawing time when dividing into sub-fields having only one group of pattern groups and sequentially drawing each sub-field in units of the optimum minimum deflection width corresponding to the group, and the sub-field before division into the sub-field Determining whether to divide the data into subfields having only one group of pattern groups by comparing the writing time when writing is performed with the optimum minimum deflection width for a plurality of groups to which the group belongs. More preferably,
The optimum minimum deflection width for the plurality of groups is a greatest common divisor of the minimum line width of each of the plurality of groups.

Preferably, when exposing each subfield, the method further comprises the step of switching the beam diameters of the plurality of electron beams in accordance with the switching of the minimum deflection width.

Preferably, when exposing each of the sub-fields, the method further comprises a step of switching the settling time of the plurality of electron beams in response to the switching of the minimum deflection width.

In a preferred embodiment of the device manufacturing method according to the present invention, the device is manufactured by a manufacturing process including a process of drawing a pattern using the above method.

In a preferred embodiment of the multi-electron beam exposure apparatus according to the present invention, a pattern group to be drawn is classified into a plurality of groups based on a pattern size, and when each of the classified groups is drawn, the optimum minimum size for the group is determined. An apparatus for deflecting a plurality of electron beams with a deflection width to draw a pattern group on the surface to be exposed, a deflecting unit for deflecting the plurality of electron beams on the surface to be exposed, An irradiation control unit for individually controlling the irradiation of the electron beam; and the deflection unit deflects the plurality of electron beams on a surface to be exposed in a unit of a minimum deflection width. Irradiating a subfield composed of the plurality of element exposure regions by individually controlling the irradiation of the plurality of element exposure regions by drawing a pattern in an element exposure region for each electron beam. When sequentially drawing a plurality of subfields, in order to draw a subfield having a pattern group of a plurality of groups into subfields having only a pattern of one group, the irradiation control means may be used to draw the plurality of subfields. Control means for prohibiting irradiation of a part of the electron beam, switching to an optimum minimum deflection width corresponding to the divided subfield group, and performing drawing.

Here, preferably, the control means switches the beam diameter of the plurality of electron beams in response to the switching of the minimum deflection width. Further, the control means switches the settling time of the plurality of electron beams by the deflection means in response to the switching of the minimum deflection width.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS <Basic Principle of the Present Invention> First, before describing an embodiment, FIG.
A specific description will be given using (A). Here, a subfield SF0 is defined as a region composed of element exposure regions (EF1, EF2, and EF3) of each electron beam in which a plurality of electron beams are deflected by a common minimum deflection width and simultaneously drawn. In the case where the pattern group PG1 to be exposed is a pattern group having a design rule of 100 (nm) and the pattern group PG2 is a pattern group having a design rule of 180 (nm), conventionally, when the subfield SF0 is drawn, 100 20 (nm), which is the greatest common divisor of (nm) and 180 (nm), is set as the minimum deflection width. The integer constant of the electron beam at this time is 32400. However, the element exposure area (EF1, EF2, EF3) of each electron beam is set to 3.6 × 3.6 (μm ² ).

In the present invention, the subfield SF0 to be exposed is
Figure 1 shows a pattern group with different design rules
As shown in (B), the subfield SF0 is divided into a plurality of subfields SF1 and SF2 so that only one design rule pattern group exists. And the minimum deflection width is 25 (n
m) and the corresponding electron beam is subfield SF1
Prohibit the irradiation of each electron beam except for being located within
The pattern group PG1 of the subfield SF1 is drawn. next,
The minimum deflection width is set to 45 (nm), and the irradiation of each electron beam is prohibited, except that the electron beam corresponding to the element exposure area is located in the subfield SF2.
The second pattern group PG2 is drawn. At this time, the integer constant of the electron beam is 27136, without lowering the drawing accuracy.
The integer constant becomes about 84% compared to the conventional case.

<First Embodiment><Description of Components of Electron Beam Exposure Apparatus> FIG. 2 is a schematic view of a main part of an electron beam exposure apparatus according to the present invention.

In FIG. 2, reference numeral 1 denotes an electron gun comprising a cathode 1a, a grid 1b, and an anode 1c.
The electrons emitted from form a crossover image between the grid 1b and the anode 1c. (Hereinafter, this crossover image is referred to as an electron source.)

The electrons emitted from this electron source are converted into substantially parallel electron beams by the illumination electron optical system 2 whose front focal position is at the position of the electron source. A substantially parallel electron beam
The element electron optical system array 3 is illuminated. Lighting electron optical system 2
Is composed of electronic lenses 2a, 2b and 2c. By adjusting the electro-optical power (focal length) of at least two of the electronic lenses 2a, 2b, and 2c, while maintaining the focal position on the electron source side of the illumination electron optical system 2,
The focal length of the illumination electron optical system 2 can be changed. That is, the focal length of the illumination electron optical system 2 can be changed while making the electron beam from the illumination electron optical system 2 substantially parallel.

A substantially parallel electron beam from the illumination electron optical system 2 enters the element electron optical system array 3. The element electron optical system array 3 is formed by two-dimensionally arranging a plurality of element electron optical systems each including an opening, an electron optical system, and a blanking electrode in a direction orthogonal to the optical axis AX. Details of the element electron optical system array 3 will be described later.

The elementary electron optical system array 3 forms a plurality of intermediate images of the electron source, and each intermediate image is formed by a reduced electron optical system 4 described later.
To form an electron source image having substantially the same size on the wafer 5. Where the size of the intermediate image of the electron source, Wm
Sets the size of the electron source to Ws and the focal length of the illumination electron optical system 2.
Assuming that the focal length of each of the electron optical systems of Fi and the elementary electron optical system is Fe, the focal length is represented by the following equation.

Wm = Ws * Fe / Fi Therefore, when the focal length of the illumination electron optical system 2 is changed, the size of the intermediate image of a plurality of electron sources can be changed at the same time.
Therefore, the sizes of a plurality of electron source images on the wafer 5 can be changed at the same time. Further, the focal length and the like of each element electron optical system are set so that the sizes of the electron source images on the wafer 5 are substantially the same. Further, the elementary electron optical system array 3 makes the position of each intermediate image in the optical axis direction different according to the field curvature of the reduction electron optical system 4, and each intermediate image
Thus, aberration generated when the image is reduced and projected on the wafer 5 is corrected in advance.

The reduction electron optical system 4 includes a first projection lens 41 (4
3) and a second projection lens 42 (44). Assuming that the focal length of the first projection lens 41 (43) is f1 and the focal length of the second projection lens 42 (44) is f2, the distance between these two lenses is f1 + f2. The object point AX on the optical axis is at the focal position of the first projection lens 41 (43), and its image point is focused on the second projection lens 42 (44).
This image is reduced to -f2 / f1. In addition, since the two lens magnetic fields are determined so as to act in opposite directions, theoretically, spherical aberration, isotropic astigmatism, isotropic coma,
Except for the five aberrations of curvature of field and axial chromatic aberration, other Seidel aberrations and chromatic aberrations related to rotation and magnification are canceled out.

Reference numeral 6 denotes a drawing deflector that deflects a plurality of electron beams from the elementary electron optical system array 3 and deflects a plurality of electron source images on the wafer 5 by substantially the same deflection width in the X and Y directions. is there. The drawing deflector 6 includes a main deflector 61 having a large deflection width but a long time until settling, that is, a long settling wait time, and a sub deflector 62 having a small deflection width but a short settling wait time. 61 is an electromagnetic deflector, and the sub deflector 62 is an electrostatic deflector.

SDEF is a stage following deflector for making a plurality of electron beams from the elementary electron optical system array 3 follow the continuous movement of the XY stage 12. The stage following deflector SDEF is an electrostatic deflector.

Reference numeral 7 denotes a dynamic focus coil which corrects a shift in the focus position of the electron source image due to deflection aberration generated when the drawing deflector 6 is operated. This is a dynamic stig coil for correcting astigmatism of the generated deflection aberration.

Reference numeral 9 denotes a refocus coil, which corrects the blurring of the electron beam due to the Coulomb effect when the number of a plurality of electron beams applied to the wafer or the total current applied to the wafer increases. Therefore, the focal position of the reduction electron optical system 4 is adjusted.

Reference numeral 10 denotes a Faraday cup having two single knife edges extending in the X and Y directions, and detects a charge amount of an electron source image formed by an electron beam from the elementary electron optical system.

Numeral 11 denotes a θ-Z stage on which a wafer is placed and which can be moved in the direction of the optical axis AX (Z axis) and in the direction of rotation around the Z axis. The stage reference plate 13 and the Faraday cup
10 are fixed.

12 is a case where the θ-Z stage is mounted and the optical axis AX
The XY stage is movable in the XY directions orthogonal to the (Z axis).

Next, the elementary electron optical system array 3 will be described. The element electron optical system array 3 includes a plurality of element electron optical systems as a group (subarray), and a plurality of subarrays are formed. For example, as shown in FIG. 3, five sub-arrays A to E are formed, and each sub-array
A plurality of element electron optical systems are two-dimensionally arranged. In each of the sub-arrays of this embodiment, two sub-arrays such as C (1,1) to C (3,9) are used.
Seven element electron optical systems are formed.

FIG. 4 is a sectional view of each element electron optical system.

In FIG. 4, AP-P is an illumination electron optical system 2
This is a substrate having an aperture (AP1) that defines the shape of an electron beam that is illuminated and transmitted by the electron beams that are substantially parallel to each other, and is a substrate common to other element electron optical systems. That is, the substrate AP-P is a substrate having a plurality of openings.

Numeral 301 denotes a blanking electrode having a pair of electrodes and having a deflecting function. Numeral 302 denotes a substrate having an opening (AP2), which is common to other element electron optical systems. Also,
The wiring (W) for turning on / of the electrode with the blanking electrode 301 is formed on the substrate 302. That is, the substrate 302
Is a substrate having a plurality of openings and a plurality of blanking electrodes.

Reference numeral 303 denotes three opening electrodes, the upper and lower electrodes are set to the same accelerating potential V0, and the middle electrode is set to a different potential.
This is an electron optical system using two unipotential lenses 303a and 303b having a converging function maintained at V1 or V2. Each of the aperture electrodes is laminated on a substrate with an insulator interposed therebetween, and the substrate is a substrate common to other element electron optical systems. That is, the substrate is a substrate having a plurality of electron optical systems 303.

The shape of the upper, middle, and lower electrodes of the unipotential lens 303a and the shape of the upper and lower electrodes of the unipotential lens 303b are as shown in FIG. The electrodes are set to a common potential in all element electron optical systems by a first focus / astigmatism control circuit described later.

Since the potential of the intermediate electrode of the unipotential lens 303a can be set for each element electron optical system by the first focus / astigmatism control circuit, the focal length of the unipotential lens 303a can be set for each element electron optical system.

The intermediate electrode of the unipotential lens 303b is composed of four electrodes as shown in FIG.
Since the potential of each electrode can be set individually by the focus / astigmatism control circuit and can be set individually for each element electron optical system, the unipotential lens 303b can have a different focal length in a cross section orthogonal to the element electron optics. It can be set individually for each system.

As a result, by controlling the intermediate electrodes of the electron optical system 303, the electron optical characteristics (intermediate image forming position, astigmatism) of the element electron optical system can be controlled. Here, when controlling the intermediate image forming position, the size of the intermediate image is determined by the ratio between the focal length of the illumination electron optical system 2 and the focal length of the electron optical system 303 as described above. The intermediate image system formation position is moved by moving the principal point position while keeping the focal length of the intermediate image system constant. Thereby, the sizes of the intermediate images formed by all the element electron optical systems can be substantially the same, and the positions in the optical axis direction can be different.

The electron beam made substantially parallel by the illumination electron optical system 2 forms an intermediate image of the electron source through the aperture (AP1) and the electron optical system 303. Here, a corresponding aperture (AP1) is located at or near the front focal position of the electron optical system 303, and at or near the intermediate image forming position of the electron optical system 303 (the rear focal position of the electron optical system 303). , The corresponding blanking electrode 301 is located. As a result, the blanking electrode 301
Unless an electric field is applied between the electrodes, the beam is not deflected like the electron beam bundle 305. On the other hand, when an electric field is applied between the blanking electrodes 301, it is deflected like an electron beam bundle 306.
Then, since the electron beam 305 and the electron beam 306 have different angular distributions on the object plane of the reduction electron optical system 4,
At the pupil position of the reduction electron optical system 4 (on the P plane in FIG. 2), the electron beam bundle 305 and the electron beam bundle 306 are incident on mutually different areas. Therefore, the blanking aperture BA that allows only the electron beam 305 to pass through is set at the pupil position of the reduced electron optical system (see FIG. 2).
(On P surface).

The electron lens of each element electron optics corrects the field curvature and astigmatism generated when the intermediate image formed by each is reduced and projected on the surface to be exposed by the reduction electron optical system 4. Then, the electric potentials of the two intermediate electrodes of each electron optical system 303 are individually set to make the electron optical characteristics (intermediate image formation position, astigmatism) of each element electron optical system different. However, in this embodiment, in order to reduce the wiring between the intermediate electrode and the first focus / astigmatism control circuit, the element electron optical systems in the same sub-array have the same electro-optical characteristics. The characteristics (intermediate image formation position, astigmatism) are controlled for each sub-array.

Further, a plurality of intermediate images are formed by the reduction electron optical system 4.
In order to correct the distortion that occurs when the image is reduced and projected on the surface to be exposed, the distortion characteristics of the reduction electron optical system 4 are known in advance, and based on that, the direction orthogonal to the optical axis of the reduction electron optical system 4 The position of each element electron optical system is set.

Next, FIG. 6 shows a system configuration diagram of this embodiment.

The focal length control circuit FC includes an illumination electron optical system 2
By adjusting the electron optical power (focal length) of at least two electron lenses of the electronic lenses 2a, 2b, and 2c, the illumination electron optical system can be maintained while maintaining the focal position on the electron source side of the illumination electron optical system 2. 2 is a circuit for controlling the focal length.

The blanking control circuit 14 turns on / of the blanking electrode of each element electron optical system of the element electron optical array 3.
Control circuit for individually controlling f, first focus / astigmatism control circuit 15
Is a control circuit for individually controlling the electron optical characteristics (intermediate image formation position, astigmatism) of each element electron optical system of the element electron optical array 3.

The second focus / astigmatism control circuit 16 includes a dynamic stig coil 8 and a dynamic focus coil 7.
Is a control circuit for controlling the focal position and astigmatism of the reduction electron optical system 4 by controlling the drawing deflection control circuit 17.
Control circuit, stage follow-up control circuit SDC is XY
A control circuit for controlling the stage following deflector SDEF so that the electron beam follows the continuous movement of the stage 12, a magnification control circuit 18, a control circuit for adjusting the magnification of the reduction electron optical system 4,
The refocus control circuit 19 is a control circuit that controls the current flowing through the refocus coil 9 to adjust the focal position of the reduction electron optical system 4.

The stage drive control circuit 20 is a control circuit that drives and controls the θ-Z stage and controls the drive of the XY stage 12 in cooperation with a laser interferometer 21 that detects the position of the XY stage 12.

The control system 22 controls the plurality of control circuits, the backscattered electron detector 9, and the Faraday cup 10 in synchronization with each other for exposure and alignment based on the exposure control data from the memory 23. The control system 22 is controlled by a CPU 25 that controls the entire electron beam exposure apparatus via an interface 24.

<Exposure Operation> The exposure operation of the electron beam exposure apparatus of this embodiment will be described with reference to FIG.

The control system 22 instructs the drawing deflection control circuit 17 based on the exposure control data from the memory 23,
The six sub-deflectors 62 deflect a plurality of electron beams from the element electron optical system array, and instruct the blanking control circuit 14 to expose the blanking electrodes of each element electron optical system to the wafer 5 in accordance with the pattern to be exposed. on / off.
At this time, the XY stage 12 is continuously moving in the X direction.
The stage following control circuit is instructed so that a plurality of electron beams follow the movement of the Y stage.
EF deflects multiple electron beams. Then, the electron beam from the element electron optical system is transferred to the wafer as shown in FIG.
The element exposure area (EF) on 5 is scanned and exposed. In the present embodiment, Sx = Sy = 3.6 μm. The element exposure areas (EF) of the plurality of element electron optical systems of the element electron optical system array are set to be two-dimensionally adjacent, and as a result, are arranged on the wafer 5 so as to be two-dimensionally adjacent. Then, a subfield (SF) composed of a plurality of element exposure areas (EF) that are simultaneously exposed is exposed. In the present embodiment, the plurality of element exposure areas (EF) are M = 64 (pieces) in the X direction and N in the Y direction.
= 64 (pieces), and the size of the subfield (SF) is 230.4 × 230.4 (μm ² ).

The control system 22 controls the subfield 1 shown in FIG.
After exposing (SF1), the deflection control circuit 17 is commanded to expose the subfield 2 (SF2), and the main deflector 61 of the drawing deflector 6 is exposed.
Thereby, a plurality of electron beams from the elementary electron optical system array are deflected in a direction orthogonal to the stage scanning direction. Then, as described above, the drawing deflector control circuit 17 is again commanded to deflect a plurality of electron beams from the elementary electron optical system array by the sub deflector 62 of the drawing deflector 6,
Command the blanking control circuit 14 to expose the blanking electrode of each element electron optical system to the wafer 5 according to the pattern to be exposed.
n / off to expose subfield 2 (SF2). Then, as shown in FIG. 7, the subfields (SF1 to SF16)
Are sequentially exposed to expose a pattern on the wafer 5. As a result, a main field (MF) composed of subfields (SF1 to SF16) arranged in a direction orthogonal to the stage scanning direction on the wafer 5 is exposed. Here, the subfields are arranged in L = 16 (pieces) in the Y direction, and the size of the main field (MF) is 230.4 × 3686.4 (μ).
m ² ).

After exposing the main field 1 (MF1) shown in FIG. 7, the control system 22 commands the drawing / deflection control circuit 17 to sequentially arrange the main field (MF1) arranged in the stage scanning direction.
2, MF3, MF4...), And deflects a plurality of electron beams from the elementary electron optical system array to expose a pattern on the wafer 5.

That is, the electron beam exposure apparatus of this embodiment continuously moves the stage on which the wafer is
A plurality of electron beams are deflected on the wafer, the irradiation of each electron beam is individually controlled for each deflection, and a pattern is drawn in an element exposure region for each electron beam. Draw a subfield, draw a main field composed of the plurality of subfields by sequentially drawing a plurality of subfields arranged in a direction orthogonal to the continuous movement direction, and further draw a plurality of Draw the main field sequentially.

<Explanation of Exposure Control Data Creation Processing> A method of creating exposure control data of the electron beam exposure apparatus of this embodiment will be described.

When drawing data (bitmap data) of a pattern to be exposed on the wafer is input, the CPU 25 proceeds to FIG.
A process for creating exposure control data as shown in FIG. 9 is executed.

Each step will be described.

(Step S101) As shown in FIG. 1A, the pattern groups in the drawing data are classified into groups based on the pattern dimensions. In the present embodiment, the patterns are classified into a plurality of groups based on the design rule (minimum line width) of the patterns.

(Step S102) For each of the classified groups, the optimum minimum deflection width and the optimum electron beam diameter given to the electron beam by the sub deflector 62 (the size of the electron source image formed on the wafer) To determine. In the present embodiment, the minimum deflection width is determined to be の of the minimum line width in the pattern group. In addition, the electron beam diameter is determined to be substantially equal to a circumscribed circle of a square having the minimum deflection width as a side.

(Step S103) The input drawing data is divided into data in units of a main field determined by the electron beam exposure apparatus of this embodiment.

(Step S104) At the time of exposure, a main field to be exposed first is selected.

(Step S105) The drawing data of the selected main field is divided into data in units of subfields determined by the electron beam exposure apparatus of this embodiment.

(Step S106) One subfield is selected.

(Step S107) A deflection position (reference position) determined by the main deflector 61 when exposing the selected subfield is determined.

(Step S108) It is determined how many groups exist in the data in the selected subfield. If only one group exists, step S10
Proceed to 9; otherwise, proceed to Step S110.

A specific description will be given with reference to FIG.
If both of the pattern groups PG1 and PG2 existing in the subfield SF0 are pattern groups of a design rule group of 100 (nm), the process proceeds to step S109. On the other hand, when the groups of the pattern groups PG1 and PG2 existing in the subfield SF0 are different from each other, the process proceeds to step S110.

(Step S109) The optimum minimum deflection width corresponding to the only group existing in the subfield is determined as the minimum deflection width of the sub deflector 62, and the optimum electron beam diameter corresponding to the group is set to the target sub-deflector. Determine the electron beam diameter when drawing the field. Further, the sub-deflector 62 calculates the number of times the electron beam is settled (settling constant) when drawing the subfield with the determined minimum deflection width, and sets the subfield based on the settling constant and the settling time of the electron beam. Calculate the drawing time To when drawing.

(Step S110) A subfield in which a pattern group of a plurality of groups is present is divided into subfields having only one group. More specifically, referring to FIG. 1B, when the groups of the pattern groups PG1 and PG2 existing in the subfield SF0 are different from each other, the subfield SF0 is divided into the subfield SF1 and the subfield SF2. Then, the sub-deflector 62 calculates the number of times the electron beam is settled (an integer constant) when drawing each of the divided sub-fields with the corresponding optimum minimum deflection width, and calculates the settling constant and the electron beam settling time. The drawing time for drawing each subfield is calculated on the basis of the drawing time, and the drawing time Ta, which is the total drawing time of each divided subfield, is calculated.

(Step S111) The optimum minimum deflection width for a plurality of groups in the subfield is calculated. Specifically, calculate the greatest common divisor of the minimum line width of each group,
The greatest common divisor is defined as the optimum minimum deflection width. Then, the sub-deflector 62 calculates the number of times the electron beam is settled (settling constant) when drawing the subfield with the optimum minimum deflection width, and draws the subfield based on the settling constant and the settling time of the electron beam. The drawing time Tb at the time of performing is calculated.

(Step S112) Drawing time Ta and drawing time T
b, and if the drawing time Ta is longer, step S11
Proceed to 3. On the other hand, if the drawing time Tb is longer, step S
Proceed to 114. For example, in FIG. 1B, the pattern group PG1
Is a pattern group of the design rule of 100 (nm), and the pattern group PG2 is a pattern group of the design rule of 180 (nm),
As described in the principle of the present invention, when the subfield SF0 is divided into the subfields SF1 and SF2, the settling of the electron beam is small, and the writing time Tb is longer than the writing time Ta, so the process proceeds to step S114. . Pattern group PG1 is 100 (nm)
Pattern group of the design rule, and the pattern group PG2 is 1
In the case of the pattern group of the design rule of 20 (nm), when the subfield SF0 is divided into the subfields SF1 and SF2, first, the minimum deflection width is set to 25 (nm), and the corresponding electron beam is set in the subfield SF1. The pattern group PG1 of the subfield SF1 is drawn except that the electron beam is not located in the subfield SF1. Next, set the minimum deflection width to 30 (nm),
The electron beam corresponding to the element exposure area is subfield SF
Except for the position within 2, the irradiation of each electron beam is prohibited and the pattern group PG1 of the subfield SF1 is drawn, so that the integer constant of the electron beam is 35136. On the other hand, when drawing the subfield SF0, 20 (nm) which is the greatest common divisor of 100 (nm) and 120 (nm) is set to the minimum deflection width. The integer constant of the electron beam at this time is 32400. Therefore,
In this case, subfield SF0 is replaced by subfield SF1,
If the beam is not divided into SF2, the settling of the electron beam is smaller and the writing time Ta is longer than the writing time Tb.
Proceed to 13.

(Step S113) The minimum deflection width of the subfield in which the pattern groups of a plurality of groups are present is determined as the optimum minimum deflection width for the plurality of groups calculated in step S111, and the optimal electron width for the determined minimum deflection width is determined. The beam diameter is determined to be the electron beam diameter when drawing a target subfield.

(Step S114) The optimum minimum deflection width corresponding to each divided subfield group is determined as the minimum deflection width of each subfield, and the optimal electron beam diameter corresponding to each divided subfield group is determined. Is determined as the electron beam diameter at the time of drawing the target divided subfield.

(Step S115) The drawing data for each element exposure area is divided using the determined minimum deflection width as the array interval, the array position of the array element to be exposed is determined, and the array position where the electron beam is settled The on / off of the blanking electrode for each element electron optical system corresponding to the above is determined. However, when the subfield is subdivided, it is determined for each subfield. In this case, the blanking electrode at the arrangement position of the electron beam in which the target subfield is not drawn is determined to be off.

(Step S116) Step S1 is executed for all the subfields of the selected main field.
It is determined whether the processing from 07 to S115 has been completed, and if there is an unprocessed subfield, the process returns to step S106 to select an unprocessed subfield. If not, step S1
Proceed to 17.

(Step S117) The drawing time in each subfield of the selected main field MF (n) is added to calculate the drawing time T (n) of the selected main field.

(Step S118) The moving speed of the stage when exposing each main field is determined based on the calculated exposure time for each main field. FIG.
(A) shows an example of the relationship between each main field (MF (n)) and the drawing time (T (n)). As described above, in at least one sub-field of at least one main field, when sub-fields are subdivided and each sub-field is further drawn by changing the minimum deflection width,
The drawing time may differ between main fields.
Therefore, in this embodiment, the stage moving speed (V (n)) that is inversely proportional to the exposure time is determined. For example, since the length of the main field (LMF) in the stage moving direction is 230.4 μm, if the exposure time T (n) = 2.304 ms, the stage moving speed V (n) = 100 mm / s (= LMF / T (n )). FIG. 9B shows the relationship between each main field and the stage moving speed.
Since the exposure is performed at the stage moving speed for each main field according to the exposure time of the main field, the wafer can be exposed in a shorter time. This is because, when the stage is controlled at a constant speed as in the conventional multi-electron beam type exposure apparatus, when exposing the next main field from the main field having a short exposure time, the next main field is controlled by the deflection range of the main deflector 61. This is because the exposure must be interrupted until it exists. However, the present invention does not require that downtime.

(Step S119) At the time of exposure, if there is a main field to be exposed next, select the main field and return to step S105. At the time of exposure, if there is no main field to be exposed next, the process proceeds to step S117.

(Step S120) As shown in FIG.
The stage movement speed for each main field and the exposure control data including the exposure control data for each subfield in the main field are stored, and the process is terminated. Here, the contents of the exposure control data for each subfield are, as shown in FIG. 11, the reference position determined by the main deflector 61, the number of subfield subdivisions, and the minimum deflection width of the subdeflector 62 corresponding to the subfield. , The electron beam diameter corresponding to the minimum deflection width, the arrangement position determined by the sub deflector 62, and the data regarding the opening and closing of the electron beam irradiation of each element electron optical system at each arrangement position.

In the present embodiment, these processes are performed by the CPU 25 of the electron beam exposure apparatus. However, even if the processing is performed by another processing apparatus and the exposure control data is transferred to the CPU 25, the purpose and effect do not change.

<Explanation of Exposure Based on Exposure Control Data> CP
When U25 instructs the control system 22 to execute "exposure" via the interface 24, the control system 22 transmits the transferred memory 23
The steps as shown in FIG. 12 are executed based on the above exposure control data.

Each step will be described.

(Step S201) Stage drive control circuit
20. The XY stage 12 is controlled by switching to a stage moving speed corresponding to the main field to be exposed.

(Step S202) The drawing deflection control circuit 17 is instructed so that the electron beams from the plurality of element electron optical systems are located at the reference positions of the subfields to be exposed, and the plurality of electron beams are deflected by the main deflector 61. I do.

(Step S203) It is determined whether or not there is a sub-divided sub-field. If not, the process proceeds to step S204. If there is, the process proceeds to step S206.

(Step S204) The drawing deflection control circuit 17 is instructed to set the minimum deflection width of the sub deflector 61 to the minimum deflection width corresponding to the subfield to be drawn. Further, it commands the focal length control circuit FC to change the focal length of the illumination electron optical system 2 to set the determined electron beam diameter.

(Step S205) The drawing deflection control circuit 17 is commanded to deflect a plurality of electron beams from the elementary electron optical system array using the set minimum deflection width as a unit by the sub deflector 62 according to the exposure control data. At the same time, a blanking control circuit 14 instructs the blanking control circuit 14 to turn on / off a blanking electrode of each element electron optical system in accordance with a pattern to be exposed on the wafer 5 to draw a subfield. At this time, the XY stage 12 is continuously moving in the X direction, and the drawing / deflection control circuit 17 controls the deflection position of the electron beam including the amount of movement of the XY stage 12.

(Step S206) The drawing deflection control circuit 17 is instructed to set the minimum deflection width of the sub deflector 61 to the minimum deflection width corresponding to the sub-divided subfield to be drawn. In addition, the focal length control circuit FC is ordered, and the illumination electron optical system 2
Is changed to set the determined electron beam diameter.

(Step S207) The drawing deflection control circuit 17 is instructed to deflect a plurality of electron beams from the elementary electron optical system array in units of the set minimum deflection width by the sub deflector 62 according to the exposure control data. At the same time, the blanking control circuit 14 instructs the blanking control circuit 14 to turn on / off the blanking electrodes of the respective element electron optical systems according to the pattern to be exposed on the wafer 5 so that the subdivided subfield to be drawn is formed. draw. At this time, the XY stage 12 is continuously moving in the X direction, and the drawing / deflection control circuit 17 controls the deflection position of the electron beam including the amount of movement of the XY stage 12.

(Step S208) It is determined whether or not there is a sub-field which has not been drawn and has been re-divided. If not, the process proceeds to step S209. If there is, the process returns to step S206.

(Step S209) If there is a main field to be exposed next, the flow returns to step S201; otherwise, the exposure is terminated.

<Second Embodiment> In the first embodiment,
The diameter of the electron beam is changed in order to change the size of the dot pattern formed on the wafer by each electron beam according to the determined minimum deflection width. In the present embodiment, the size of the point-like pattern is changed by fixing the electron beam diameter (the size of the electron beam imaged on the wafer) and changing the settling time (the so-called exposure time) at the deflection position of the electron beam. Has changed. That is, when the minimum deflection width is increased, the settling time is lengthened to enlarge the dot pattern. Normally, the settling time of the electron beam at the deflection position is Ts,
Assuming that the time until the electron beam is deflected and settles at a desired deflection position is Tn, the deflection cycle Td of the sub deflector 62 is Td =
Ts + Tn. Therefore, in the present embodiment, since Tn is substantially constant, the size of the dot pattern is changed by changing the deflection period Td of the sub deflector 62 according to the determined minimum deflection width. . Therefore, the determined minimum deflection width,
The deflection period Td of the sub deflector 62 is determined from the electron beam current density, the electron beam diameter, and the resist sensitivity. At this time, the size of the dot pattern is set so as to be substantially equal to a circumscribed circle of a square whose side is the minimum deflection width. When calculating the drawing times To, Ta, and Tb, the calculation is performed based on the deflection cycle and the number of set positions.

<Third Embodiment> In the first embodiment,
The stage moving speed for each main field is determined to be inversely proportional to the exposure time for exposing the main field. However, if the difference in the determined moving speed between the main feels adjacent in the continuous moving direction is large, an excessive acceleration is applied to the stage, which makes it difficult to control the stage and degrades the position stability of the stage. I do. Therefore, in the present embodiment, the moving speed of the main field having a high moving speed is determined so that the difference in the determined moving speed between the main fields adjacent in the continuous moving direction is equal to or less than a predetermined value (Vp). Is determined to be lower than the moving speed.

The specific processing will be described with reference to FIG.

(Step S301) The relationship between each main field determined in the first embodiment and the stage moving speed (FIG. 10B) is input.

(Step S302) At the time of exposure, a main field to be exposed first is selected. Set the redetermination flag F to F
= 0.

(Step S303) The difference between the stage moving speed of the selected main field and the stage moving speed of the main field exposed immediately before exposing the selected main field is calculated (there is no previous main field). If so, the process jumps to step S305.). If the difference is not smaller than or equal to a predetermined value that can ensure the controllability and stability of the stage, the process proceeds to step S304.
If the value is equal to or less than the predetermined value (Vp), the process jumps to step S305.

(Step S304) The moving speed of the main field having the higher moving speed is determined again so that the difference between the moving speeds becomes equal to or less than a predetermined value. Redetermination flag
Set F to F = 1.

(Step S305) The difference between the stage moving speed of the selected main field and the stage moving speed of the main field exposed immediately after exposing the selected main field is calculated (when there is no immediately following main field). Jumps to step S305.). If the difference is not smaller than the predetermined value, the process proceeds to step S306. If the value is equal to or less than the predetermined value, the process jumps to step S307.

(Step S306) The moving speed of the main field having the higher moving speed is determined again so that the difference between the moving speeds becomes equal to or less than a predetermined value.

(Step S307) Immediately after exposing the selected main field, a main field to be exposed is selected, and the process returns to step S303. If there is no immediately following main field, the process proceeds to step S308.

(Step S308) If the redetermined flag F is F =
In the case of 1, the process returns to step S302. Redetermination flag F is F
If = 0, the process ends.

FIG. 10C shows the relationship between each main field and the stage moving speed determined in the first embodiment, obtained by performing the above processing.

<Fourth Embodiment> In the present embodiment, FIG.
As shown in FIG. 4, after exposing a frame (FL1) composed of a plurality of main fields in which exposure regions on the wafer 5 are arranged in the continuous movement direction, the stage 12 is stepped in the Y direction, and the stage 12 is moved in the continuous movement direction. And the next frame (FL2) is exposed. That is, frames arranged in a direction orthogonal to the continuous movement direction of the stage 12 are sequentially exposed.

In the first embodiment, the stage moving speed is determined for each main field. In the present embodiment, the stage moving speed is determined for each frame. Specifically, in the main field that makes up the frame,
The stage moving speed in the corresponding frame is determined based on the exposure time of the main field having the longest exposure time. Then, when the frame to be drawn is changed, the moving speed of the XY stage is switched to the determined moving speed, and the frame is drawn at the same stage moving speed.

<Example of Device Manufacturing Method> An embodiment of a device manufacturing method using the above-described electron beam exposure apparatus will be described.

FIG. 15 shows a micro device (a semiconductor chip such as an IC or an LSI, a liquid crystal panel, a CCD, a thin film magnetic head,
2 shows a flow of manufacturing a micromachine or the like. Step 1
In (circuit design), a circuit of a semiconductor device is designed.
In step 2 (exposure control data creation), exposure control data of the exposure apparatus is created based on the designed circuit pattern. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the wafer and the exposure apparatus to which the prepared exposure control data has been input. The next step 5 (assembly) is called a post-process, and step 4
Is a process of forming a semiconductor chip using the wafer produced by the above process, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 16 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 1
In 5 (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern is printed on the wafer by exposure using the above-described exposure apparatus. Step 17
In (development), the exposed wafer is developed. Step 18
In (etching), portions other than the developed resist image are scraped off. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device, which was conventionally difficult to manufacture, at low cost.

[0114]

As described above, according to the present invention, it is possible to provide a multi-electron beam type exposure method and apparatus capable of reducing an increase in the amount of data for writing even if a fractional pattern exists in the writing pattern. Also, if a device is manufactured using this, it is possible to manufacture a device with higher precision than before.

[Brief description of the drawings]

FIG. 1 illustrates a basic principle of the present invention.

FIG. 2 is a schematic view showing a main part of an electron beam exposure apparatus according to the present invention.

FIG. 3 is a diagram illustrating an element electron optical system array 3.

FIG. 4 is a diagram illustrating an element electron optical system.

FIG. 5 is a diagram illustrating electrodes of the elementary electron optical system.

FIG. 6 is a diagram illustrating a system configuration according to the present invention.

FIG. 7 is a view for explaining an exposure field (EF), a subfield (SF), and a main field (MF).

FIG. 8 is a view for explaining exposure control data creation processing;

FIG. 9 is a view for explaining exposure control data creation processing;

FIG. 10 is a view for explaining a relationship between an exposure time and a stage moving speed for each main field and a relationship between a subfield and a pattern area.

FIG. 11 is a view for explaining exposure control data.

FIG. 12 is a view for explaining exposure based on exposure control data.

FIG. 13 is a view for explaining a method of determining a stage speed for each main field according to the third embodiment.

FIG. 14 illustrates a frame.

FIG. 15 is a diagram illustrating a flow of manufacturing a micro device.

FIG. 16 illustrates a wafer process.

FIG. 17 is a diagram illustrating a conventional multi-electron beam type exposure apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electron gun 2 illumination electron optical system 3 element electron optical system array 4 reduction electron optical system 5 wafer 6 drawing deflector 7 dynamic focus coil 8 dynamic stig coil 9 refocus coil 10 Faraday cup 11 θ-Z stage 12 XY stage 13 stage Reference plate 14 Blanking control circuit 15 First focus / astigmatism control circuit 16 Second focus / astigmatism control circuit 17 Deflection control circuit 18 Magnification adjustment circuit 19 Refocus control circuit 20 Stage drive control circuit 21 Laser interferometer 22 Control system 23 Memory 24 Interface 25 CPU AP-P Substrate with Opening FC Focal Length Control Circuit SDEF Stage Tracking Deflector SDC Stage Tracking Control Circuit

Claims (12)

[Claims] 1. A method for simultaneously writing a plurality of regions on a surface to be exposed by using a plurality of electron beams, wherein a pattern to be drawn is classified into a plurality of groups according to a design rule, and an electron beam of each group is classified. A multi-electron beam exposure method, wherein writing is performed with different minimum deflection widths. 2. The multi-electron beam exposure method according to claim 1, wherein writing is performed sequentially for each of the plurality of groups. 3. The electron beam exposure method according to claim 1, wherein the beam diameter or the settling time of the electron beam is changed according to the switching of the minimum deflection width. 4. A method according to claim 1, wherein a plurality of electron beams are deflected on a surface to be exposed of an object in units of a minimum deflection width based on the drawing data, and irradiation of each electron beam is individually controlled for each deflection. A method of drawing a pattern in each element exposure area, drawing a subfield composed of the plurality of element exposure areas, and sequentially drawing a plurality of subfields, wherein a pattern group in the drawing data is Classifying into a plurality of groups based on design rules, determining an optimum minimum deflection width for each group when drawing a pattern group of each group, and dividing the drawing data in units of the subfields One division step, and a second division for dividing a subfield having a plurality of groups of pattern groups into subfields having only one group of patterns When exposing a subfield having only one group of pattern groups, the minimum deflection width is switched to an optimum minimum deflection width corresponding to the group, and the plurality of electron beams are deflected in units of the optimum minimum deflection width. And drawing. The multi-electron beam exposure method. 5. The second division step includes a step of dividing a subfield having only one group of pattern groups into a plurality of subfields and sequentially drawing each subfield in units of an optimum minimum deflection width corresponding to the group. Is divided into sub-fields having only one group of pattern groups by comparing the sub-field before division with the drawing time when the drawing is performed in units of the optimum minimum deflection width for a plurality of groups belonging to the sub-field. 5. The method of claim 4, comprising the step of determining whether or not. 6. The method of claim 5, wherein the optimum minimum deflection width for the plurality of groups is a greatest common divisor of a minimum line width of each of the plurality of groups. 7. The method according to claim 4, further comprising, when exposing each subfield, switching a beam diameter of the plurality of electron beams in response to the switching of the minimum deflection width. The described method. 8. The method according to claim 4, further comprising, when exposing each subfield, switching a settling time of the plurality of electron beams in response to the switching of the minimum deflection width. The described method. 9. A device manufacturing method, wherein a device is manufactured by a manufacturing process including a process of drawing a pattern using the method according to claim 1. 10. A pattern group to be drawn is classified into a plurality of groups based on pattern dimensions, and when drawing each of the classified groups, a plurality of electron beams are deflected with a minimum deflection width optimal for the group. An apparatus for drawing a pattern group on the surface to be exposed, a deflecting means for deflecting the plurality of electron beams on the surface to be exposed, and irradiation control for individually controlling the irradiation of each electron beam for each deflection. Means for deflecting the plurality of electron beams on the surface to be exposed in units of a minimum deflection width by the deflecting means, and individually controlling irradiation of each electron beam for each deflection by the irradiation control means, By drawing a pattern in each element exposure area, a subfield composed of the plurality of element exposure areas is drawn, and when a plurality of subfields are sequentially drawn, a plurality of In order to divide and draw a subfield having a pattern group of a group into subfields having only one group of patterns, the irradiation control unit prohibits irradiation of a part of the plurality of electron beams and performs division. Control means for switching to an optimum minimum deflection width corresponding to the selected subfield group and drawing. 11. The apparatus according to claim 10, wherein said control means switches the beam diameters of said plurality of electron beams in response to switching of said minimum deflection width. 12. The apparatus according to claim 10, wherein the control means switches the settling time of the plurality of electron beams by the deflection means in response to the switching of the minimum deflection width.