JP4018197B2 - Electron beam exposure method and electron beam exposure apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electron beam exposure method and an exposure apparatus therefor, and more particularly to an electron beam exposure method and pattern exposure apparatus that perform pattern drawing using a plurality of electron beams for wafer direct drawing or mask / reticle exposure.
[0002]
[Prior art]
The electron beam exposure apparatus includes a point beam type that uses a beam in the form of a spot, a variable rectangular beam type that uses a variable-size rectangular cross section, and a stencil mask type apparatus that uses a stencil to obtain a desired cross-sectional shape. is there.
[0003]
The point beam type electron beam exposure apparatus has low throughput and is used only for research and development. In the variable rectangular beam type electron beam exposure apparatus, the throughput is one to two orders of magnitude higher than that of the point type. However, in the case of exposing a pattern in which a fine pattern of about 0.1 μm is packed with a high degree of integration, it is still a point of throughput. 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 repetitive pattern transmission holes are formed in a portion corresponding to a variable rectangular aperture. Therefore, the stencil mask type electron beam exposure apparatus has a great advantage when exposing repeated patterns, but a plurality of stencil masks are required for a semiconductor circuit that requires a large number of transfer patterns that do not fit in one stencil mask. Since it is necessary to take out and use them one by one, and it takes time to replace the mask, there is a problem that the throughput is significantly reduced.
[0004]
As a device to solve this problem, the sample surface is irradiated with a plurality of electron beams along the design coordinates, and the sample surface is scanned along with the deflection of the plurality of electron beams along the design coordinates, There is a multi-electron beam exposure apparatus that draws a pattern by individually turning on / off a plurality of electron beams according to the pattern to be drawn. The multi-electron beam exposure apparatus has a feature that throughput can be further improved because an arbitrary drawing pattern can be drawn without using a stencil mask.
[0005]
FIG. 16 shows an outline of a multi-electron beam type exposure apparatus. 501a, 501b, and 501c are electron guns that can individually turn on / off the electron beam. Reference numeral 502 denotes a reduction electron optical system that reduces and projects a plurality of electron beams from the electron guns 501a, 501b, and 501c onto the wafer 503. Reference numeral 504 denotes a deflector that deflects the plurality of electron beams reduced and projected onto the wafer 503. is there.
[0006]
A plurality of electron beams from the electron guns 501a, 501b, and 501c are given the same deflection amount by the deflector 504. As a result, each electron beam is deflected with its position on the wafer sequentially set according to an array having an array interval defined by the minimum deflection width of the deflector 504 with reference to each beam reference position. Each electron beam exposes a pattern to be exposed in different element exposure regions.
[0007]
FIGS. 16A, 16B, and 16C show how the electron beams from the electron guns 501a, 501b, and 501c expose the patterns to be exposed in the same arrangement in the respective element exposure regions. The position of each electron beam on the array at the same time is (1,1), (1,2) ... (1,16), (2,1), (2,2) ... 2,16), (3,1) .. The position is set and moved, and at the position where the pattern (P1, P2, P3) to be exposed exists, the beam is irradiated, A pattern (P1, P2, P3) to be exposed is exposed in the element exposure region.
[0008]
[Problems to be solved by the invention]
In the multi-electron beam exposure apparatus, since each electron beam simultaneously draws different patterns, the minimum deflection width of the deflector 504 is set from the minimum line width in the pattern to be exposed. As the minimum line width becomes finer, the minimum deflection width becomes finer, and the number of times of exposure by setting the position of the electron beam increases. As a result, there is a problem that the throughput decreases.
[0009]
The pattern to be exposed does not have a uniform minimum line width pattern. However, conventionally, even in an area composed of a pattern coarser than the minimum line width, since the exposure is performed with the minimum deflection width determined by the minimum line width in the entire pattern, the minimum line width of the pattern is miniaturized. When it came, the throughput was decreasing.
[0010]
[Means for Solving the Problems]
  In one embodiment of the electron beam exposure method of the present invention for solving the above-mentioned problem, while continuously moving the stage on which the object to be exposed is placed,The object to be exposed is irradiated with a plurality of electron beams.It is composed of the plurality of element exposure areas by deflecting the upper part in units of the minimum deflection width, individually controlling the irradiation of each electron beam for each deflection, and drawing a pattern in the element exposure area for each electron beam. Draw a subfield,Move continuouslyA main field composed of the plurality of subfields is drawn by sequentially drawing a plurality of subfields arranged in a direction orthogonal to the direction, andSaidIn an electron beam exposure method for sequentially drawing a plurality of main fields arranged in a continuous movement direction,
  Of the plurality of main fieldsA first decision for switching and exposing the minimum deflection width when exposing at least one subfield of at least one main field;StepWhen,
  The plurality of main fieldsCalculate exposure time for each main fieldStepWhen,
  The moving speed of the stageThe moving speed according to the exposure time calculated for each main field of the plurality of main fieldsDecide onThereafter, the determined stage moving speed is re-determined so that the difference in the determined stage moving speed between the main fields adjacent to each other in the continuous moving direction is not more than a predetermined value.Second decisionStepIt is characterized by having.
[0018]
  An embodiment of the electron beam exposure apparatus of the present invention includes a stage on which an object to be exposed is placed and moved,
  Multiple electron beamsOf the object to be exposedDeflection means for deflecting the top,
  Every deflectionOf the plurality of electron beamsControl the irradiation of each electron beam individuallyElectron opticsWhen,
  While moving the stage continuously,The deflecting means applies a plurality of electron beams on the object to be exposed.Is deflected in units of the minimum deflection width,Electron opticsThe irradiation of each electron beam is individually controlled for each deflection by drawing a pattern in the element exposure region for each electron beam, thereby drawing a subfield composed of the plurality of element exposure regions, and by the deflection means Deflects multiple electron beams,Direction of continuous movementThe main field composed of the plurality of subfields is drawn by sequentially drawing a plurality of subfields arranged in a direction perpendicular to the direction, and a plurality of electron beams are deflected by the deflecting means, and the continuous movement is performed. Draw multiple main fields in sequence,Of the plurality of main fieldsControl means for switching and exposing the minimum deflection width when exposing at least one subfield of at least one main fieldIn an electron beam exposure apparatus having
  The control means calculates an exposure time for each main field of the plurality of main fields, determines a moving speed of the stage to a moving speed according to the exposure time calculated for each main field of the plurality of main fields, Thereafter, the determined stage moving speed is re-determined so that a difference in the determined moving speed between the main fields adjacent to each other in the continuous moving direction is equal to or less than a predetermined value.It is characterized by that.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
(Description of components of electron beam exposure apparatus)
FIG. 1 is a schematic view of the main part of an electron beam exposure apparatus according to the present invention.
[0026]
In FIG. 1, reference numeral 1 denotes an electron gun including a cathode 1a, a grid 1b, and an anode 1c, and electrons emitted from the cathode 1a form a crossover image between the grid 1b and the anode 1c. (Hereafter, this crossover image is referred to as an electron source.)
[0027]
The electrons emitted from this electron source become a substantially parallel electron beam by the illumination electron optical system 2 whose front focal position is at the electron source position. The substantially parallel electron beam illuminates the element electron optical system array 3. The illumination electron optical system 2 includes electron lenses 2a, 2b, and 2c. Then, by adjusting the electron optical power (focal length) of at least two of the electron lenses 2a, 2b, and 2c, the illumination electron optics is maintained while maintaining the focal position on the electron source side of the illumination electron optical system 2. The focal length of 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.
[0028]
The 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 including an aperture, 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.
[0029]
The element electron optical system array 3 forms a plurality of intermediate images of the electron source, and each intermediate image is reduced and projected by a reduction electron optical system 4 described later to form an electron source image of substantially the same size on the wafer 5. . Here, the size Wm of the intermediate image of the electron source is Ws as the size of the electron source, Fi as the focal length of the illumination electron optical system 2, and Fe as the focal length of each electron optical system of the element electron optical system. It is represented by the following formula.
[0030]
Wm = Ws * Fe / Fi
Therefore, when the focal length of the illumination electron optical system 2 is changed, the sizes of the intermediate images of the plurality of electron sources can be changed at the same time. Therefore, the sizes of the plurality of electron source images on the wafer 5 can be changed at the same time. Further, the focal lengths and the like of the element electron optical systems are set so that the electron source images on the wafer 5 have substantially the same size. Further, the element electron optical system array 3 varies the position of each intermediate image in the optical axis direction according to the field curvature of the reduced electron optical system 4, and each intermediate image is reduced to the wafer 5 by the reduced electron optical system 4. Aberrations that occur during projection are corrected in advance.
[0031]
The reduction electron optical system 4 includes a symmetric magnetic doublet including a first projection lens 41 (43) and a second projection lens 42 (44). When 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 the two lenses is f1 + f2. The object point on the optical axis AX is at the focal position of the first projection lens 41 (43), and the image point is connected to the focal point of 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, the five aberrations of spherical aberration, isotropic astigmatism, isotropic coma aberration, field curvature aberration, and axial chromatic aberration are determined. Except for aberrations, other Seidel aberrations and chromatic aberrations related to rotation and magnification are canceled out.
[0032]
A drawing deflector 6 deflects a plurality of electron beams from the element electron optical system array 3 and deflects a plurality of electron source images on the wafer 5 in the X and Y directions by substantially the same deflection width. The drawing deflector 6 includes a main deflector 61 having a wide deflection width but a long time until settling, that is, a long settling waiting time, and a sub deflector 62 having a small deflection width but a short settling waiting time. 61 is an electromagnetic deflector, and the sub-deflector 62 is an electrostatic deflector.
[0033]
SDEF is a stage following deflector for causing a plurality of electron beams from the element electron optical system array 3 to follow the continuous movement of the XY stage 12. The stage following deflector SDEF is an electrostatic deflector.
[0034]
7 is a dynamic focus coil that corrects the deviation of the focus position of the electron source image due to deflection aberration that occurs when the drawing deflector 6 is operated, and 8 is a deflection that occurs due to deflection in the same way as the dynamic focus coil 7. This is a dynamic stig coil for correcting astigmatism of aberration.
[0035]
9 is a refocusing coil, which reduces the electron beam blur due to the Coulomb effect when the number of multiple electron beams irradiated on the wafer or the sum of the currents irradiated on the wafer increases. The focal position of the electron optical system 4 is adjusted.
[0036]
10 detects the charge amount of the electron source image formed by the electron beam from the element electron optical system in a Faraday cup having two single knife edges extending in the X and Y directions.
[0037]
Reference numeral 11 denotes a θ-Z stage on which a wafer is placed and can move in the optical axis AX (Z-axis) direction and the rotational direction around the Z-axis. The stage reference plate 13 and the Faraday cup 10 described above are fixedly installed. ing.
[0038]
Reference numeral 12 denotes an XY stage on which a θ-Z stage is mounted and which can move in the XY directions orthogonal to the optical axis AX (Z axis).
[0039]
Next, the element electron optical system array 3 will be described.
[0040]
In the element electron optical system array 3, a plurality of element electron optical systems are grouped (subarrays), and a plurality of subarrays are formed. For example, as shown in FIG. 2, five subarrays A to E are formed, and each subarray has a plurality of element electron optical systems arranged two-dimensionally. In each subarray of this embodiment, C ( 27 element electron optical systems are formed as 1, 1) to C (3, 9).
[0041]
A sectional view of each element electron optical system is shown in FIG.
[0042]
In FIG. 3, AP-P is a substrate having an aperture (AP1) that defines the shape of an electron beam that is illuminated and transmitted by an electron beam that is substantially parallel by the illumination electron optical system 2, and is another element electron optical system. And a common substrate. That is, the substrate AP-P is a substrate having a plurality of openings.
[0043]
A blanking electrode 301 includes a pair of electrodes and has a deflection function. 302 is a substrate having an aperture (AP2) and is common to other element electron optical systems. In addition, a blanking electrode 301 and a wiring (W) for electrode on / of are formed on the substrate 302. That is, the substrate 302 is a substrate having a plurality of openings and a plurality of blanking electrodes.
[0044]
303 is composed of three aperture electrodes, and uses two unipotential lenses 303a and 303b having a convergence function in which the upper and lower electrodes are the same as the acceleration potential V0 and the intermediate electrode is maintained at another potential V1 or V2. It was an electron optical system. Each aperture electrode is laminated on the 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.
[0045]
The shapes of the upper, middle and lower electrodes of the unipotential lens 303a and the upper and lower electrodes of the unipotential lens 303b are as shown in FIG. 4A. The upper and lower electrodes of the unipotential lenses 303a and 303b are A common electric potential is set in all the element electron optical systems by a first focus / astigmatism control circuit described later.
[0046]
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.
[0047]
Further, the intermediate electrode of the unipotential lens 303b is composed of four electrodes as shown in FIG. 4B, and the potential of each electrode can be individually set by a focus / astigmatism control circuit, for each element electron optical system. Since the unipotential lens 303b can have different focal lengths in the orthogonal cross section, it can be set individually for each element electron optical system.
[0048]
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 formation position, the size of the intermediate image is determined by the ratio of the focal length of the illumination electron optical system 2 and the focal length of the electron optical system 303 as described above. The position of the intermediate image system is moved by moving the principal point position with a constant focal length. Thereby, the sizes of the intermediate images formed by all the element electron optical systems are substantially the same, and the positions in the optical axis direction can be varied.
[0049]
The electron beam made substantially parallel by the illumination electron optical system 2 forms an intermediate image of the electron source via the aperture (AP1) and the electron optical system 303. Here, the 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, unless an electric field is applied between the blanking electrodes 301, the electron beam bundle 305 is not deflected. On the other hand, when an electric field is applied between the electrodes of the blanking electrode 301, it is deflected like an electron beam bundle 306. Then, since the electron beam 305 and the electron beam bundle 306 have different angular distributions on the object plane of the reduction electron optical system 4, the electron beam bundle 305 is at the pupil position (on the P plane in FIG. 1) of the reduction electron optical system 4. And the electron beam bundle 306 are incident on different regions. Therefore, a blanking aperture BA for transmitting only the electron beam bundle 305 is provided at the pupil position (on the P plane in FIG. 1) of the reduction electron optical system.
[0050]
In addition, the electron lens of each element electron optic is used to correct field curvature and astigmatism generated when the intermediate image formed by each element is reduced and projected onto the exposure surface by the reduction electron optical system 4. The electric potentials of the two intermediate electrodes of the electron optical system 303 are individually set to make the electron optical characteristics (intermediate image forming 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 subarray have the same electron optical characteristics, and the electron optics of the element electron optical system The characteristics (intermediate image forming position, astigmatism) are controlled for each subarray.
[0051]
Furthermore, in order to correct distortion aberration that occurs when a plurality of intermediate images are reduced and projected on the exposure surface by the reduced electron optical system 4, in advance know the distortion characteristics of the reduced electron optical system 4, based on it, The position of each element electron optical system in the direction orthogonal to the optical axis of the reduced electron optical system 4 is set.
[0052]
Next, a system configuration diagram of this embodiment is shown in FIG.
[0053]
The focal length control circuit FC adjusts the electron optical power (focal length) of at least two electron lenses 2a, 2b, and 2c of the illumination electron optical system 2 to thereby adjust the electron source side of the illumination electron optical system 2. This is a circuit for controlling the focal length of the illumination electron optical system 2 while maintaining the focal position.
[0054]
The blanking control circuit 14 is a control circuit that individually controls on / off of the blanking electrode of each element electron optical system of the element electron optical array 3, and the first focus / astigmatism control circuit 15 is the element electron optical array 3 2 is a control circuit that individually controls the electro-optical characteristics (intermediate image forming position, astigmatism) of each of the element electron optical systems.
[0055]
The second focus / astigmatism control circuit 16 is a control circuit that controls the dynamic stig coil 8 and the dynamic focus coil 7 to control the focus position and astigmatism of the reduction electron optical system 4, and the drawing deflection control circuit 17 draws the image. A control circuit for controlling the deflector 6, a stage following control circuit SDC, a control circuit for controlling the stage following deflector SDEF so that the electron beam follows the continuous movement of the XY stage 12, and a magnification control circuit 18 are a reduction electron optical system. A control circuit that adjusts the magnification of 4 and the refocus control circuit 19 are control circuits that adjust the focal position of the reduced electron optical system 4 by controlling the current flowing through the refocus coil 9.
[0056]
The stage drive control circuit 20 is a control circuit that drives and controls the XY stage 12 in cooperation with a laser interferometer 21 that drives and controls the θ-Z stage and detects the position of the XY stage 12.
[0057]
The control system 22 controls the plurality of control circuits, the backscattered electron detector 9 and the Faraday cup 10 in synchronization for exposure and alignment based on 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.
[0058]
(Explanation of exposure operation)
The exposure operation of the electron beam exposure apparatus of this embodiment will be described with reference to FIG.
[0059]
The control system 22 commands the drawing deflection control circuit 17 based on the exposure control data from the memory 23, and deflects a plurality of electron beams from the element electron optical system array by the sub deflector 62 of the drawing deflector 6, The blanking control circuit 14 is commanded to turn on / off the blanking electrode of each element electron optical system according to the pattern to be exposed on the wafer 5. At this time, the XY stage 12 is continuously moving in the X direction. The stage tracking control circuit is instructed to deflect the plurality of electron beams by the stage following deflector SDEF so that the plurality of electron beams follow the movement of the XY stage. Then, the electron beam from the element electron optical system scans and exposes the element exposure region (EF) on the wafer 5 as shown in FIG. In this embodiment, Sx = Sy = 4 μm. The element exposure areas (EF) of a plurality of element electron optical systems in the element electron optical system array are set so as to be adjacent to each other in two dimensions. Then, a subfield (SF) composed of a plurality of element exposure areas (EF) exposed at the same time is exposed. In the present embodiment, a plurality of element exposure regions (EF) are arranged with M = 64 (pieces) in the X direction and N = 64 (pieces) in the Y direction, and the size of the subfield (SF) is 256 × 256. (Μm²).
[0060]
The control system 22 instructs the deflection control circuit 17 to expose the subfield 2 (SF2) after exposing the subfield 1 (SF1) shown in FIG. A plurality of electron beams from the element electron optical system array are deflected in a direction orthogonal to the scanning direction. Then, as described above, the drawing deflection control circuit 17 is commanded again, and the sub deflector 62 of the drawing deflector 6 deflects a plurality of electron beams from the element electron optical system array, and the blanking control circuit 14 is commanded. The blanking electrode of each element electron optical system is turned on / off according to the pattern to be exposed on the wafer 5, and the subfield 2 (SF2) is exposed. Then, as shown in FIG. 6, the subfields (SF <b> 1 to SF <b> 16) 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 is exposed on the wafer 5. Here, L = 16 (pieces) are arranged in the Y direction, and the size of the main field (MF) is 256 × 4096 (μm).²).
[0061]
The control system 22 exposes the main field 1 (MF1) shown in FIG. 6 and then instructs the drawing deflection control circuit 17 to sequentially arrange the element electron optical system array in the main fields (MF2, MF3, MF4...) Arranged in the stage scanning direction. A plurality of electron beams are deflected to expose the pattern on the wafer 5.
[0062]
That is, the electron beam exposure apparatus of this embodiment deflects a plurality of electron beams on the wafer while continuously moving the stage on which the wafer is placed, and individually controls the irradiation of each electron beam for each deflection. By drawing a pattern in the element exposure area for each electron beam, drawing a subfield composed of the plurality of element exposure areas, and sequentially drawing a plurality of subfields arranged in a direction perpendicular to the continuous movement direction A main field composed of the plurality of subfields is drawn, and a plurality of main fields arranged in the continuous movement direction are sequentially drawn.
[0063]
(Explanation of exposure control data creation process)
A method of creating exposure control data for the electron beam exposure apparatus of this embodiment will be described.
[0064]
When the pattern data of the pattern to be exposed on the wafer is input, the CPU 25 executes exposure control data creation processing as shown in FIG.
[0065]
Each step will be described.
[0066]
(Step S101)
The input pattern data is divided into data in units of main fields determined by the electron beam exposure apparatus of this embodiment.
[0067]
(Step S102)
At the time of exposure, the main field to be exposed first is selected.
[0068]
(Step S103)
The pattern data of the selected main field is divided into data in units of subfields determined by the electron beam exposure apparatus of this embodiment.
[0069]
(Step S104)
Select one subfield.
[0070]
(Step S105)
Pattern feature information (minimum line width, line width type, shape) is detected from the pattern data of the selected subfield. In this embodiment, the minimum line width is detected.
[0071]
(Step S106)
Based on the detected pattern information, the minimum deflection width and electron beam diameter (the size of the electron source image formed on the wafer) given to the electron beam by the sub deflector 62 are determined. In this embodiment, the integral multiple of the minimum deflection width is the arrangement pitch (on the wafer) of a plurality of electron beams. The minimum deflection width is determined to be approximately a quarter of the minimum line width. Further, the electron beam diameter is determined so as to be approximately equal to a square circumscribed circle having the minimum deflection width as a side.
[0072]
(Step S107)
A deflection position (reference position) determined by the main deflector 61 when the selected subfield is exposed is determined.
[0073]
(Step S108)
The pattern data of the selected subfield is divided into the pattern data for each element exposure region of each element electron optical system, and the common composed of the array elements FME with the determined minimum deflection width of the sub deflector 62 as the array interval The pattern data is converted into data represented on a common array for each element electron optical system. Hereinafter, in order to simplify the description, processing relating to pattern data when performing exposure using the two element electron optical systems a and b will be described.
8A and 8B show patterns Pa and Pb to be exposed by the element electron optical systems a and b adjacent to the common deflection array DM. That is, each element electron optical system irradiates the wafer with an electron beam with the blanking electrode turned off at the hatched arrangement position where the pattern exists. Therefore, from the data of the arrangement position to be exposed for each element electron optical system as shown in FIGS. 8A and 8B, the CPU 25 determines that the element electron optical systems a and b are as shown in FIG. A first region FF (blackened portion) composed of an array position when at least one of them is exposed and a second region NN composed of an array position when both element electron optical systems a and b are not exposed in common (Outlined portion) is determined. When a plurality of electron beams are located in the first region FF on the array, the electron beam is deflected and exposed by the deflector 6 with the minimum deflection width (array array interval) as a unit. All patterns to be exposed can be exposed. Further, when a plurality of electron beams are located in the second region NN on the array, the electron beam position is deflected without being settled, so that unnecessary deflection of the electron beam can be reduced and exposure can be performed and wasteful control data can be obtained. Can be omitted. In other words, after exposing the first area (FF), jumping over the second area (NN), deflecting to the next first area (FF), and exposing, the deflection with settling time It can be exposed in a shorter time by reducing. The CPU 25 determines the array position of the array elements to be exposed from the data relating to the areas FF and NN shown in FIG. 8C, and further, the electron beam is settled from the data shown in FIGS. 8A and 8B. On / off of the blanking electrode for each element electron optical system corresponding to the arranged position is determined. Here, since the minimum deflection width and the deflection order in the array have already been determined, an array number is determined for each array element, so the array number is determined as the array position.
[0074]
(Step S109)
From the data obtained in step S108, the number of settling positions (the number of settling times) and the maximum deflection width from the settling position of the sub deflector 62 to the next settling position are detected.
[0075]
(Step S110)
The exposure time of the selected subfield is calculated. Before that, the deflection period of the sub deflector 62 when exposing the subfield is constant, the settling time (so-called exposure time) Ts (sec) at the deflection position of each electron beam, and deflection from the deflection position where the electron beam is located If the maximum settling waiting time in the subfield is set to To (sec) among the settling waiting times until set to the desired deflection position, the deflection period Td (sec) of the sub deflector 62 is Td = Ts + To It becomes. In addition, this settling time is longer as the deflection width is wider. Therefore, the settling wait time To when the subfield is exposed based on the detected maximum deflection width is obtained from the relationship between the maximum deflection width and the settling wait time obtained in advance through experiments or the like, and the deflection cycle Td (sec ) Then, the exposure time Tsub of the selected subfield is calculated from the number N of the detected settling positions as follows.
Tsub = Td * N
[0076]
(Step S111)
For all the subfields of the selected main field, it is determined whether or not the processing of steps S105 to S110 has been completed. If there is an unprocessed subfield, the process returns to step S104 to select an unprocessed subfield. . If not, the process proceeds to step S112.
[0077]
(Step S112)
The exposure time of each selected subfield of the main field is added to calculate the exposure time of the selected main field.
[0078]
(Step S113)
Based on the calculated exposure time for each main field, the moving speed of the stage when exposing each main field is determined. FIG. 9A shows an example of the relationship between each main field (MF (N)) and exposure time (T (n)). As described above, when at least one subfield of at least one main field is exposed, when exposure is performed by switching the minimum deflection width based on the pattern data of the subfield, the exposure time differs between the main fields. There is. Therefore, in this embodiment, the stage moving speed (V (n)) that is inversely proportional to the exposure time is determined. For example, the length (LMF) of the main field in the stage moving direction is 256 μm, so that the stage moving speed V (n) = 100 mm / s (= LMF / T (n) when the exposure time T (n) = 2.56 ms. )). The relationship between each main field and the stage moving speed is shown in FIG. Thus, since exposure is performed at the stage moving speed for each main field corresponding 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 exposure apparatus, when the next main field is exposed from the main field having a short exposure time, the next main field is 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 the interruption time.
[0079]
(Step S114)
Stage moving speed of selected main field, reference position determined by main deflector 61 for each subfield of selected main field, minimum deflection width, beam diameter, deflection cycle of sub deflector 62, determined by sub deflector 62 Data relating to the arrangement position and opening / closing of electron beam irradiation of each element electron optical system at each arrangement position is stored.
[0080]
(Step S115)
At the time of exposure, if there is a main field to be exposed next, the main field is selected and the process returns to step S103. If there is no main field to be exposed at the time of exposure, the process proceeds to step S116.
[0081]
(Step S116)
As shown in FIG. 10, the stage moving speed for each main field, the reference position defined by the main deflector 61 for each subfield, the minimum deflection width of the sub deflector 61, the electron beam diameter, the deflection cycle of the sub deflector 62 The exposure control data is stored with the arrangement position determined by the sub deflector 62 and the data related to the opening / closing of the electron beam irradiation of each element electron optical system at each arrangement position as elements.
[0082]
In the present embodiment, these processes are performed by the CPU 25 of the electron beam exposure apparatus. However, the purpose and effect are not changed even if the exposure control data is transferred to the CPU 25 by other processing apparatuses.
[0083]
(Explanation of exposure based on exposure control data)
When the CPU 25 commands the control system 22 to “execute exposure” via the interface 24, the control system 22 executes the steps shown in FIG. 11 based on the exposure control data on the transferred memory 23. .
[0084]
Each step will be described.
[0085]
(Step S201)
The stage drive control circuit 20 is commanded to switch to a stage moving speed corresponding to the main field to be exposed, and the XY stage 12 is controlled.
[0086]
(Step S202)
The drawing deflection control circuit 17 is instructed so that the first subfield of the main field to be exposed is exposed by a plurality of electron beams from the element electron optical system array, and the sub beam exposed by the main deflector 61 is positioned. A plurality of electron beams are deflected to the field.
[0087]
(Step S203)
The focal length control circuit FC is commanded to change the focal length of the illumination electron optical system 2 to switch to the electron beam diameter corresponding to the subfield to be exposed.
[0088]
(Step S204)
The drawing deflection control circuit 17 is commanded, and the minimum deflection width of the sub deflector 61 is switched to the minimum deflection width corresponding to the subfield to which light is emitted.
[0089]
(Step S205)
The drawing deflection control circuit 17 is commanded, and the deflection cycle of the sub deflector 62 is switched to the deflection cycle corresponding to the subfield to be exposed. Further, it is generated as a periodic signal determined by the deflection period.
[0090]
(Step S206)
In synchronization with the periodic signal, the sub-deflector 62 deflects the plurality of electron beams from the element electron optical system array to the deflection position determined by the exposure control data in units of the switched minimum deflection width. At the same time, in synchronization with the periodic signal, the blanking control circuit 14 is commanded to turn on / off the blanking electrodes of each element electron optical system according to the pattern to be exposed on the wafer 5. Furthermore, in order to correct the electron beam blur due to the Coulomb effect, the refocusing circuit 9 orders the refocusing circuit and reduces the electron beam by the refocusing coil 9 based on the number of electron beams irradiated to the wafer without being blocked by the blanking electrode. Adjust the focus position of system 4. At this time, the XY stage 12 continuously moves 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. As described above, as a result, the electron beam from the element electron optical system scans and exposes the element exposure region (EF) on the wafer 5 as shown in FIG. The element exposure areas (EF) of a plurality of element electron optical systems in the element electron optical system array are set so as to be adjacent to each other in two dimensions. Then, a subfield (SF) composed of a plurality of element exposure areas (EF) exposed at the same time is exposed.
[0091]
(Step S207)
If there is a subfield to be exposed next, the process returns to step S203; otherwise, the process proceeds to step S208.
[0092]
(Step S208)
If there is a main field to be exposed next, the process returns to step S201, and if not, the exposure ends.
[0093]
(Second 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 adjacent main feels in the continuous moving direction is large, excessive acceleration will be given to the stage, making it difficult to control the stage and degrading the position stability of the stage. To do. Therefore, in this 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 adjacent main fields in the continuous moving direction is equal to or less than a predetermined value (Vp). It has been determined to be lower than the moving speed.
[0094]
The specific process will be described with reference to FIG.
[0095]
(Step S301)
The relationship between each main field and the stage moving speed determined in the first embodiment (FIG. 9B) is input.
[0096]
(Step S302)
At the time of exposure, the main field to be exposed first is selected. The redetermination flag F is set to F = 0.
[0097]
(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 (if there is no previous main field, the process jumps to step S305) .) If the difference is not less than a predetermined value that can ensure the controllability and stability of the stage, the process proceeds to step S304. If it is less than or equal to the predetermined value (Vp), the process jumps to step S305.
[0098]
(Step S304)
The moving speed of the main field having the higher moving speed is re-determined so that the difference in moving speed is less than or equal to a predetermined value. The redetermination flag F is set to F = 1.
[0099]
(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 (if there is no main field immediately after, the process jumps to step S305. ). If the difference is not less than or equal to the predetermined value, the process proceeds to step S306. If it is less than or equal to the predetermined value, the process jumps to step S307.
[0100]
(Step S306)
The moving speed of the main field having the higher moving speed is re-determined so that the difference in moving speed is less than or equal to a predetermined value.
[0101]
(Step S307)
The main field to be exposed is selected immediately after the selected main field is exposed, and the process returns to step S303. If there is no immediately following main field, the process proceeds to step S308.
[0102]
(Step S308)
If the redetermination flag F is F = 1, the process returns to step S302. If the redetermination flag F is F = 0, the process is terminated.
[0103]
FIG. 9C shows a result obtained by performing the above processing on the relationship between each main field and the stage moving speed determined in the first embodiment.
[0104]
(Third embodiment)
In this embodiment, as shown in FIG. 13, after exposing a frame (FL1) composed of a plurality of main fields in which the exposure areas on the wafer 5 are arranged in the continuous movement direction, the stage 12 is stepped in the Y direction, The next frame (FL2) is exposed with the continuous moving direction of the stage 12 reversed. That is, the frames arranged in the direction perpendicular to the continuous movement direction of the stage 12 are sequentially exposed.
[0105]
In the first embodiment, the stage moving speed is determined for each main field, but in this embodiment, the stage moving speed is determined for each frame. Specifically, the stage moving speed in the corresponding frame is determined based on the exposure time of the main field having the longest exposure time among the main fields constituting the frame. Then, when the drawing frame changes, the moving speed of the XY stage is switched to the determined moving speed, and the inside of the frame is drawn at the same stage moving speed.
[0106]
(Description of device production method of the present invention)
An embodiment of a device production method using the above-described electron beam exposure apparatus will be described.
[0107]
FIG. 14 shows a flow of manufacturing a microdevice (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.). In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (exposure control data creation), exposure control data for the exposure apparatus is created based on the designed circuit pattern. On the other hand, in step 3 (wafer manufacture), 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 is input. The next step 5 (assembly) is referred to as a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 4, such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. including. 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, the semiconductor device is completed and shipped (step 7).
[0108]
FIG. 15 shows a detailed flow of the wafer process. In step 11 (oxidation), the wafer surface is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern is printed onto the wafer by exposure using the exposure apparatus described above. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.
[0109]
By using the manufacturing method of this embodiment, a highly integrated semiconductor device that has been difficult to manufacture can be manufactured at low cost.
[0110]
【The invention's effect】
As described above, according to the present invention, since the stage speed is controlled in accordance with the shortening of the exposure time of the main field, it is possible to provide a multi-electron beam type exposure method and apparatus that can achieve a larger throughput.
[Brief description of the drawings]
FIG. 1 is a schematic view showing the main part of an electron beam exposure apparatus according to the present invention.
FIG. 2 is a diagram for explaining an element electron optical system array 3;
FIG. 3 is a diagram illustrating an element electron optical system.
FIG. 4 is a diagram illustrating electrodes of an element electron optical system.
FIG. 5 is a diagram illustrating a system configuration according to the present invention.
FIG. 6 is a view for explaining an exposure field (EF), a subfield (SF), and a main field (MF).
FIG. 7 is a view for explaining exposure control data creation processing;
FIG. 8 is a view for explaining determination of a pattern to be exposed by each element electron optical system and an array area determined by a drawing deflector;
FIG. 9 is a diagram for explaining the relationship between exposure time and stage moving speed for each main field, and the relationship between subfields and pattern areas;
FIG. 10 is a diagram for explaining exposure control data.
FIG. 11 is a view for explaining exposure based on exposure control data.
FIG. 12 is a diagram illustrating a method for determining a stage speed for each main field according to the second embodiment.
FIG. 13 is a diagram illustrating a frame.
FIG. 14 illustrates a manufacturing flow of a microdevice.
FIG. 15 is a diagram illustrating a wafer process.
FIG. 16 is a view for explaining a conventional multi-electron beam type exposure apparatus.
[Explanation of symbols]
1 electron gun
2 Illuminated electron optics
3 element electron optical system array
4 Reduction electron optical system
5 Wafer
6 Drawing deflector
7 Dynamic focus coil
8 Dynamic stig coils
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 Drawing 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 following deflector
SDC stage following control circuit

Claims (2)

While continuously moving the stage on which the object to be exposed is placed, the electron beam is deflected by a plurality of electron beams in units of the minimum deflection width, and irradiation of each electron beam is individually controlled for each deflection. By drawing a pattern in an element exposure area for each electron beam, a subfield composed of the plurality of element exposure areas is drawn, and a plurality of subfields arranged in a direction orthogonal to the continuously moving direction are sequentially drawn. in the plurality of drawing the main field consists of sub-fields, further, an electron beam exposure method sequentially rendering a plurality of main fields aligned in the direction of the continuous movement by,
A first determining step of determining to perform exposure by switching the minimum deflection width when exposing at least one subfield of at least one main field of the plurality of main fields ;
Calculating an exposure time for each main field of the plurality of main fields,
The moving speed of the stage is determined as a moving speed corresponding to the exposure time calculated for each main field of the plurality of main fields , and then the moving speed of the stage determined between adjacent main fields in the continuous moving direction is determined. And a second determining step for re-determining the determined moving speed of the stage so that the difference between the two becomes equal to or less than a predetermined value . A stage for moving an object to be exposed;
Deflecting means for deflecting a plurality of electron beams on the object to be exposed ;
An electron optical system that individually controls irradiation of each of the plurality of electron beams for each deflection; and
While the stage is continuously moved, the deflection means deflects the object to be exposed by a plurality of electron beams with a minimum deflection width as a unit, and the electron optical system individually controls the irradiation of each electron beam for each deflection. And drawing a pattern in the element exposure area for each electron beam to draw a subfield composed of the plurality of element exposure areas, deflecting the plurality of electron beams by the deflecting means, and continuously moving the direction. The main field composed of the plurality of subfields is drawn by sequentially drawing a plurality of subfields arranged in a direction perpendicular to the direction, and a plurality of electron beams are deflected by the deflecting means, and the continuous movement is performed. sequentially drawing a plurality of main fields aligned in a direction, at least one of said plurality of main fields When exposing at least one sub-field of the main field, the electron beam exposure apparatus and a control means for exposing switching the minimum deflection width,
The control means calculates an exposure time for each main field of the plurality of main fields, determines a moving speed of the stage to a moving speed according to the exposure time calculated for each main field of the plurality of main fields, Thereafter, the determined stage moving speed is re-determined so that a difference in the determined stage moving speed between the main fields adjacent to each other in the continuous moving direction is equal to or less than a predetermined value. An electron beam exposure apparatus.

Images