JP2003178967A - Charged-particle-beam exposure system and calibration method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a calibration method for a charged-particle-beam exposure system capable of reducing time needed to calibrate the optics system. <P>SOLUTION: In conducting calibration of the beam, the deflection center of the electron optics system is positioned at the center of the group of sub- fields 66-1 to 66-20, the sub-fields 66-1 to 66-20 are sequentially scanned by the beam, and the beam property is measured at each position. Then, the deflection center of the electron optics system is positioned at the center of the group of the sub-fields 66-21 to 66-40, by moving the reticle stage and the wafer stage. By keeping this positional relation, the sub-fields 66-21 to 66-40 are sequentially scanned by the beam, and the beam property is measured at each position. Based on the above measurements, calibration factors on the optics system for each sub-field 66 are set, and the calibrations on the electron optics system (for example, deflection position error, image magnification, image rotation, etc.), are conducted. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of calibrating a charged particle beam exposure apparatus used for lithography of semiconductor integrated circuits and the like. In particular, the present invention relates to a method for calibrating a charged particle beam exposure apparatus, which can reduce the time required for calibrating an optical system.

[0002]

2. Description of the Related Art In recent years, studies have been conducted on a method of an electron beam exposure apparatus having both high resolution and high throughput of exposure. Recently, the method that has been well studied is not a method of exposing one die or a plurality of dies that require a large optical field at one time, but a method of transferring and exposing the entire pattern of one die into small areas (subfields). There is (here, referred to as a division transfer method).
In this method, the reticle stage and the wafer stage are continuously moved, and the arrayed subfield groups are exposed while the electron beam is periodically deflected and scanned. At this time, since the distortion of the projected image is different at each deflection position in the electron optical system, it is necessary to calibrate the electron optical system for each deflection position and set the correction coefficient to perform the correction.

FIG. 10 is a diagram for explaining a conventional calibration method for an exposure apparatus. FIG. 11 is a diagram showing an optical system calibration index provided on the reticle of the exposure apparatus. Figure 11
11A is a diagram showing a deflection position measurement mark, and FIG.
FIG. 9B is a diagram showing measurement marks for rotation, magnification, distortion, etc. of the collective exposure area. At the upper part of FIG. 10, a reticle 110 placed on a reticle stage 111 is shown. A position detector 112 using a laser interferometer is attached to the reticle stage 111, and the position of the reticle stage 111 can be accurately grasped in real time.

The reticle 110 is provided with marks 110a for calibrating the optical system. Mark 110
In FIG. 11A, for example, as shown in FIG. 11A, a vertically long line-and-space pattern is arranged in the central portion of the subfield on the reticle, and the deflection position of the electron beam is measured using this mark. be able to. Further, as shown in FIG. 11 (B), by using marks in which line and space patterns extending in the XY directions are arranged at nine positions of the subfield on the reticle, the rotation / magnification / It is possible to measure distortion and the like.

Below the reticle 110 is a projection lens 11.
5 and 119 and a deflector 116 are provided.

The backscattered electron detector 1 is located directly above the wafer 123.
22 are arranged. This backscattered electron detector 122 is
The amount of electrons reflected by the exposed surface of the wafer 123 or the mark on the stage is detected.

The wafer 123 is a wafer stage 1 which is movable in XY directions via an electrostatic chuck (not shown).
24 is mounted. Also on the wafer stage 124,
A position detector 12 similar to the reticle stage 111 described above.
5 is equipped.

A mark 124a for calibrating the optical system is provided beside the wafer 123 on the wafer stage 124. This mark 124a is formed on the reticle 110
It corresponds to the mark 110a provided above.
The property of the beam can be measured by scanning the mark 124a on the wafer 123 with the electron beam EB that has passed through the mark 110a and detecting the backscattered electrons generated at that time with the backscattered electron detector 122. And both stages 11
By moving 1 and 124, the mark 110
a and 124a are moved to the corresponding deflection positions (the positions of the corresponding subfields, see FIG. 7 described later).
Based on the measurement at each position, the optical system correction coefficient at that position can be set.

[0009]

In the electron optical system of the above-mentioned exposure apparatus, in order to achieve thermal stability of each part of the optical system,
It is desirable to keep the deflection cycle constant during electron optics calibration. Therefore, during calibration, the reticle stage 1
11 and the wafer stage 124 are moved to a predetermined position, and then the deflection position of the electron optical system is changed to each mark 110.
The mark is detected when it coincides with a and 124a. At this time, the time required to move the stage is much longer than the time required to deflect the electron beam. That is, most of the time spent for the calibration of the electron optical system is the movement time of the stage, and the calibration time accounts for a large proportion of the downtime of the apparatus.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for calibrating a charged particle beam exposure apparatus and the like, which can shorten the time required for calibrating an optical system. To do.

[0011]

In order to solve the above problems, the calibration method of the charged particle beam exposure apparatus according to the present invention is such that a pattern to be transferred on a sensitive substrate is formed by being divided into a plurality of subfields. A reticle stage on which a reticle is mounted, an illumination optical system that sequentially applies a charged particle beam illumination beam to each subfield of the reticle, a sensitive substrate stage on which the sensitive substrate is mounted, and a subfield that passes through each subfield of the reticle. Charged particle beam (projection beam)
A projection optical system for sequentially projecting the subfields to appropriate positions on the sensitive substrate, wherein the subfields are arranged in a grid pattern in the X direction and the Y direction on the reticle. Direction, the illumination beam is deflected in the illumination optical system to scan the beam, and in the Y direction,
A charged particle beam exposure apparatus that mainly performs mechanical scanning by mechanically moving the both stages and also performs exposure in the projection optical system while deflecting the projection beam for adjusting a pattern transfer position on the sensitive substrate. A calibration method of the reticle stage or the reticle, and the sensitive substrate stage or the sensitive substrate along a beam scanning path corresponding to the charged particle beam deflection configuration and the mechanical scanning configuration of both stages. By forming a series of optical system calibration indexes (marks) and continuously beam scanning the series of marks, the beam property is measured at a plurality of scanning positions of the marks, and each of the scans is performed based on the measurement. It is characterized in that an optical system correction coefficient at a position is set. As a result, the number of stage movements during the calibration of the electron optical system can be reduced, and the calibration time can be greatly shortened.

In the present invention, it is preferable to form, as the optical system calibration index, a plurality of types of marks for measuring a plurality of types of the charged particle beam deflection form or a plurality of types of the beam properties. By arranging a plurality of types of calibration indexes on the reticle stage, the wafer stage, etc., calibration corresponding to various beam deflection forms can be performed without replacing the reticle or stage.

In the present invention, it is preferable to form, as the optical system calibration index, a mark that can be commonly used in a plurality of the charged particle beam deflection modes. That is, even if a plurality of beam deflection modes are different from each other, a series of marks can be commonly used for all the beams of the deflection modes. By doing so, the types of marks to be prepared can be reduced.

The charged particle beam exposure apparatus of the present invention includes a reticle stage on which a reticle on which a pattern to be transferred is divided and formed in a plurality of subfields is mounted, and a subfield of each reticle. An illumination optical system for sequentially applying a charged particle beam illumination beam, a sensitive substrate stage on which the sensitive substrate is mounted, a charged particle beam (projection beam) passing through each subfield of the reticle at an appropriate position on the sensitive substrate. A charged particle beam exposure apparatus comprising: a projection optical system for sequentially projecting onto
On the reticle stage and the sensitive substrate stage,
It is characterized in that a series of optical system calibration indexes are formed along the beam scanning path corresponding to the charged particle beam deflection mode and the mechanical scanning modes of the both stages.

[0015]

DETAILED DESCRIPTION OF THE INVENTION A description will be given below with reference to the drawings. First, an outline of a split transfer type electron beam projection exposure technique will be described with reference to the drawings. FIG. 5 is a diagram showing an outline of an image formation relationship and a control system in the entire optical system of the split transfer type electron beam projection exposure apparatus. The electron gun 1 arranged in the uppermost stream of the optical system emits an electron beam downward. Below the electron gun 1, two stages of condenser lenses 2 and 3 are provided.
It is converged by 3 and the crossover CO is imaged on the blanking aperture 7.

Below the condenser lens 3 in the second stage, a rectangular opening 4 is provided. This rectangular aperture (illumination beam shaping aperture) 4 allows only an illumination beam that illuminates one subfield (a pattern small region that is one unit of exposure) of the reticle (mask) 10. The image of the opening 4 is formed on the reticle 10 by the lens 9.

A blanking deflector 5 is arranged below the beam shaping aperture 4. The deflector 5 deflects the illumination beam to hit the non-aperture portion of the blanking aperture 7 when necessary so that the beam does not strike the reticle 10. Below the blanking aperture 7, an illumination beam deflector 8
Are arranged. The deflector 8 mainly sequentially scans the illumination beam in the lateral direction (X direction) of FIG. 5 to illuminate each subfield of the reticle 10 within the field of view of the illumination optical system. An illumination lens 9 is arranged below the deflector 8. The illumination lens 9 images the beam shaping aperture 4 on the reticle 10.

The reticle 10 actually spreads (described later with reference to FIG. 6) in a plane perpendicular to the optical axis (XY plane),
It has a number of subfields. On the reticle 10,
A pattern (chip pattern) forming one semiconductor device chip as a whole is formed. Of course, a pattern forming one semiconductor device chip may be divided and arranged on a plurality of reticles.

The reticle 10 is placed on a movable reticle stage 11, and by moving the reticle 10 in the directions perpendicular to the optical axis (XY directions), the reticle 10 is spread over a wider area than the field of view of the illumination optical system. Each subfield can be illuminated. On the reticle stage 11,
A position detector 12 using a laser interferometer is additionally provided, and the position of the reticle stage 11 can be accurately grasped in real time.

Below the reticle 10, projection lenses 15 and 19 and a deflector 16 are provided. Reticle 1
The electron beam that has passed through one subfield of 0 is imaged at a predetermined position on the wafer 23 by the projection lenses 15 and 19 and the deflector 16. Regarding the detailed operation of the projection lenses 15 and 19 and the deflector 16 (image position adjusting deflector),
It will be described later with reference to FIG. 7. An appropriate resist is applied onto the wafer 23, and a dose of an electron beam is applied to the resist to reduce the pattern on the reticle to reduce the wafer 2
3 is transferred onto.

A crossover CO is formed at a point where the reticle 10 and the wafer 23 are internally divided by a reduction ratio, and a contrast aperture 18 is provided at the crossover position. The opening 18 blocks the electron beam scattered by the non-patterned portion of the reticle 10 from reaching the wafer 23.

Directly above the wafer 23 is a backscattered electron detector 22.
Are arranged. The backscattered electron detector 22 detects the amount of electrons reflected by the exposed surface of the wafer 23 or the mark on the stage. For example, by scanning the mark on the wafer 23 with a beam that has passed through the mark pattern on the reticle 10,
By detecting the reflected electrons from the mark at that time,
The relative positional relationship between the reticle 10 and the wafer 23 can be known.

The wafer 23 is a wafer stage 2 which is movable in XY directions via an electrostatic chuck (not shown).
4 is mounted on. By synchronously scanning the reticle stage 11 and the wafer stage 24 in opposite directions, each part in the chip pattern that extends beyond the field of view of the projection optical system can be sequentially exposed. The wafer stage 24 is also equipped with the same position detector 25 as the reticle stage 11 described above.

The respective lenses 2, 3, 9, 15, 19 and the respective deflectors 5, 8, 16 are provided with respective coil power source control units 2
a, 3a, 9a, 15a, 19a and 5a, 8a, 16
It is controlled by the controller 31 via a. In addition, the reticle stage 11 and the wafer stage 2
4 is also controlled by the controller 31 via the stage control units 11a and 24a. Stage position detector 1
Reference numerals 2 and 25 send signals to the controller 31 via interfaces 12a and 25a including an amplifier and an A / D converter. The backscattered electron detector 22 also sends a signal to the controller 31 via the same interface 22a.

The controller 31 grasps the control error of the stage position and the position error of the projection beam, and corrects the error by the image position adjusting deflector 16. This allows the reticle 1
The reduced image of the subfield on 0 is accurately transferred to the target position on the wafer 23. Then, the subfield images are joined together on the wafer 23, and the entire chip pattern on the reticle is transferred onto the wafer.

Next, a detailed example of the reticle used in the division transfer type electron beam projection exposure will be described with reference to FIG. FIG. 6 is a diagram schematically showing a configuration example of a reticle for electron beam projection exposure. (A) is a plan view of the whole, (B) is a partial perspective view, and (C) is a plan view of one small membrane region. Such a reticle can be manufactured, for example, by performing electron beam drawing / etching on a silicon wafer.

FIG. 6A shows the overall pattern division arrangement state of the reticle 10. The area indicated by many squares 41 in the figure is a small membrane area (thickness 0.1 μm to several μm) including a pattern area corresponding to one subfield. As shown in FIG. 6C, the small membrane area 41 includes a pattern area (subfield) 42 at the center and a frame-shaped non-pattern area (skirt 43) around the pattern area 42. The subfield 42 is a portion where a pattern to be transferred is formed. The skirt 43 is a non-patterned part, which hits the edge of the illumination beam. Patterns can be formed in a stencil type in which a perforated portion is provided in the membrane, or in a scattering membrane type in which a pattern layer made of a high electron beam scatterer is formed on the membrane.

One subfield 42 has a size of about 1 mm square on the reticle, which is currently under consideration. The reduction ratio of the projection is 1/4, and the size of the projected image in which the subfield is reduced and projected on the wafer is 0.
It is 25 square. A portion 45 called a grid-shaped crossing, which is orthogonal to the periphery of the small membrane region 41, is a beam having a thickness of, for example, about 0.5 to 1 mm for maintaining the mechanical strength of the reticle. The width of the grease 45 is, for example, about 0.1 mm. The width of the skirt 43 is, for example, 0.05
It is about mm.

As shown in FIG. 6A, the horizontal direction (X
Direction), a plurality of small membrane regions 41 are arranged side by side to form one group (electrical stripe 44), and a large number of such electric stripes 44 are arranged side by side in the vertical direction (Y direction) of the drawing to form one mechanical stripe 4
9 is formed. The length of the electrical stripe 44 (width of the mechanical stripe 49) is limited by the size of the deflectable field of view of the illumination optical system.

A plurality of mechanical stripes 49 are arranged in parallel in the X direction. Adjacent mechanical stripes 49
The thick beam, shown as struts 47 between, is to keep the deflection of the entire reticle small. The strut 47 is integral with the grerage 45.

According to the method currently considered to be influential,
A row (electrical stripe 44) of subfields 42 in the X direction in one mechanical stripe (hereinafter simply referred to as stripe) 49 is sequentially exposed by electron beam deflection. On the other hand, the columns in the Y direction within the stripe 49 are sequentially exposed by continuous stage scanning.

FIG. 7 is a perspective view schematically showing how patterns are transferred from the reticle to the wafer. One stripe 49 on the reticle 10 is shown at the top of the figure.
As described above, the stripe 49 includes a large number of subfields 42 (the skirt is not shown) and the graduations 4.
5 is formed. The wafer 23 facing the reticle 10 is shown in the lower part of the figure.

In this figure, the stripe 49 on the reticle is shown.
The sub-field 42-1 at the left corner of the foremost electrical stripe 44 is illuminated by the illumination beam IB from above. Then, the projection beam PB that has passed through the subfield 42-1 is processed by the two-stage projection lens and the image position adjusting deflector (reference numeral 16 in FIG. 5) to cause the wafer 23 to move.
The image is reduced and projected onto the predetermined area 52-1. The projection beam PB is deflected twice between the reticle 10 and the wafer 23 by the action of the two-stage projection lens, from the direction parallel to the optical axis to the direction intersecting the optical axis and vice versa.

The transfer position of the subfield image on the wafer 23 is determined by the image position adjusting deflector provided in the optical path between the reticle 10 and the wafer 23, and the transferred small region corresponding to each pattern small region 42 is transferred. 52 are adjusted so that they touch each other. That is, if the projection beam PB that has passed through the small pattern area 42 on the reticle is converged on the wafer 23 by the first and second projection lenses, not only the small pattern area 42 of the reticle 10 but also the regret 45 and the skirt. Even an image is transferred at a predetermined reduction ratio, and a non-exposed area corresponding to a non-patterned area such as the greige 45 is generated between the transferred small areas 52. To prevent this, the image transfer position is shifted by an amount corresponding to the width of the non-pattern area.

Next, an example of a deflection mode (beam scanning path) in the case of performing exposure while the stage is continuously moved while repeating the above-described periodic deflection of the electron optical system will be described. FIG. 8 is a diagram illustrating an example of a deflection mode when exposing a certain area on the wafer. FIG. 8A is a diagram showing the exposure order of the patterns seen on the wafer, and FIG. 8B is a diagram showing the deflection form of the electron optical system at that time. FIG. 9 is a diagram illustrating an example of a deflection mode when exposing a certain area on the reticle. FIG. 9A is a diagram showing the exposure order of the patterns seen on the reticle, and FIG. 9B is a diagram showing the deflection mode of the electron optical system at that time.

FIG. 8A shows a part of the wafer 23 (see FIG. 7 etc.) mounted on the wafer stage. In this figure, there are 11 subfields 52 in the X direction.
Four electrical stripes 54 (see FIG. 7 etc.) in which (see FIG. 7 etc.) are arranged side by side are shown side by side in the Y direction. As indicated by the arrows in the figure, while the wafer stage is being sent in the negative direction of the Y direction, the beam is emitted from the subfield 52-1-1 at the lower left end to the subfield 5 at the lower right end.
By scanning in the + X direction toward 2-1-11, one electrical stripe 54 is exposed. At this time, since the wafer 23 is mechanically continuously fed downward in the drawing, the actual beam deflection form is as shown in FIG.
As shown in (B), the deflection path is gradually inclined so that the wafer 23 is also deflected in the -Y direction so as to follow the movement in the Y direction. This Y-direction deflection is performed by the deflector in the illumination optical system and the deflector in the projection optical system. The deflection in the X direction (main deflection) is due to the action of the projection lens and the action of the deflector in the projection optical system, as described with reference to FIG.

After the subfield 52-1-11 is exposed, the beam is then deflected in the + Y direction and the subfield 52-2-1 at the right end of the upper electrical stripe.
The exposure is advanced to 1, and then the beam is scanned mainly in the −X direction to expose the subfield 52-2-1 at the left end of the second electrical stripe. At this time, as shown in FIG. 8B, as in the case described above,
The actual beam deflection form is oblique. And so on
Exposure of all subfields is performed while deflecting the beam in the XY directions.

FIG. 9A shows a part of the reticle 10 (see FIG. 7 etc.) placed on the reticle stage. In this figure, there are 11 subfields 4 in the X direction.
Four electrical stripes 44 (see FIG. 7 etc.) in which 2 (see FIG. 7 etc.) are arranged side by side are shown side by side in the Y direction. As indicated by the arrow in the figure, the beam is directed from the subfield 42-1-1 at the upper right end to the subfield 42-1-11 at the upper left end while sending the reticle stage in the positive Y direction. By scanning in the X direction, one electrical stripe 44 is exposed. At this time, since the reticle 10 is mechanically continuously fed in the upward direction of the drawing, the actual beam deflection form follows the feeding of the reticle 10 in the Y direction as shown in FIG. 9B. In this way, the deflection path is gradually inclined in the + Y direction as well. This Y-direction deflection and X-direction deflection (main deflection) are performed by the deflector in the illumination optical system.

After the sub-field 42-1-11 is exposed, the beam is then deflected in the -Y direction and the sub-field 42-2-1 at the left end of the electrical stripe one below.
The exposure is advanced to 1, and then the beam is mainly scanned in the + X direction to expose the subfield 42-2-1 at the right end of the second electrical stripe. At this time, as shown in FIG. 9B, as in the case described above,
The actual beam deflection form is oblique. And so on
Exposure of all subfields is performed while deflecting the beam in the XY directions.

As described above, the electron beam shown in FIGS. 8B and 9B has a deflection form in which the electron beam is periodically repeated so as to draw a figure 8. In this example, the number of exposures within the main deflection width in the X direction is 11 times, which is the same as the number of subfields arranged in the X direction. Therefore, as shown in FIG.
On the deflection path shown in FIG. 9B, a total of 22 deflection positions will be defined. The beam is calibrated at all these deflection positions.

Next, the optical system calibration index (mark) according to the first embodiment of the present invention will be described. FIG. 1 is a diagram illustrating a mark arrangement state according to the first embodiment of the present invention. FIG. 1A is a diagram showing a deflection form of an electron beam, and FIG. 1B is a diagram showing an arrangement state of subfields having marks. FIG. 1A shows a deflection mode 6 when the number of exposures within the main deflection width in the X direction is 20 times.
0 is shown. In this case, the subfield 61-1 on the upper left is moved downward to the right on the subfield 61-2.
After reaching 0, and then going up to subfield 61-21, proceed to the lower left direction to reach subfield 61-40, and then return to subfield 61-1. Here, when the size of the collective exposure region is 0.25 mm square on the wafer, the deflection width, that is, the width of the deflection form 60 is 5 mm.

FIG. 1B shows a mark arrangement subfield group 65 arranged so as to correspond to the deflection mode 60 shown in FIG. 1A. This subfield group 65 is formed on the reticle stage 11 or reticle 10 and the wafer stage 24 or wafer 23 shown in FIG.

In this subfield group 65, subfields 66- are arranged side by side in a diagonally lower right direction in the X direction.
1 to 66-20 and subfields 66-21 to 66-4 arranged side by side in the diagonally lower left direction in the X direction from the subfield 66-21 next to the subfield 66-20 below.
A total of 40 sub-fields 66 of 0 are provided.
Refer to FIG. 11 and FIG. 3 etc. for what kind of marks are arranged in these subfields.

When calibrating the beam, first, the deflection center of the electron optical system is set to the upper subfield group 6 in FIG. 1 (B).
The reticle stage and the wafer stage are moved so as to be located at the center of 6-1 to 66-20 and stopped there. While maintaining this state, the beam property is measured at the position of each subfield by sequentially performing beam scanning on the subfields 66-1 to 66-20. Next, the reticle stage and the wafer stage are moved so that the deflection center of the electron optical system is located at the center of the subfield groups 66-21 to 66-40 shown in FIG. While maintaining this state, the beam properties are measured at the positions of the respective subfields by sequentially performing beam scanning on the subfields 66-21 to 66-40. The beam properties (magnification /
When measuring rotation and distortion, the beam is scanned in a small amount on the subfield. Then, the optical system correction coefficient in each subfield 66 is set based on the above measurement,
Calibration of the electron optical system (for example, deflection position error, image magnification, image rotation, etc.) is performed.

As a result, when the number of exposures within the deflection width is 20, it is possible to realize the calibration operation of the electron optical system, which has conventionally required 40 stage movements, by two stage movements. Therefore, the calibration time can be significantly shortened. In addition, by measuring the arrangement of each subfield pattern of the calibration index in advance, it is possible to obtain the same level of accuracy as in the conventional method of moving the stage for each subfield.

Next, an optical system calibration index according to the second embodiment of the present invention will be described. FIG. 2 shows the second aspect of the present invention.
It is a figure explaining the optical system calibration index (mark) which concerns on embodiment of FIG. FIG. 2A is a diagram showing a deflection form of an electron beam, and FIG. 2B is a diagram showing an arrangement of subfield groups in which marks are arranged. This is an example of the calibration index when the deflection width is narrower than the example shown in FIG.

In FIG. 2A, the number of exposures within the deflection width is 1
Deflection configuration 70 is shown for twice. In this deflection mode 70, the subfields 71-1 to 71-11 are scanned diagonally downward right in the X direction, and then the subfields 71-12 to 71-22 are scanned diagonally downward left.
Since it is necessary to change the deflection position by one subfield in the Y direction while deflecting the beam by the main deflection width in the X direction, in this example, as compared with the case of FIG. The inclination of deflection is getting stronger.

FIG. 2B shows a mark arrangement subfield group 75 arranged so as to correspond to the deflection mode 70 shown in FIG. 2A. This subfield group 75 includes subfields 76-1 to 76-11 arranged side by side in the diagonally lower right direction in the X direction, and diagonally in the X direction from the subfield 76-12 below the subfield 76-11. Subfield 7 arranged side by side in the lower left direction
22 subfields 76 in total, 6-12 to 76-22
Is provided.

In general, it is often advantageous in terms of throughput and transfer accuracy to change the deflection width according to the pattern to be exposed. In that case, it is necessary to calibrate the electron optical system at each deflection position in the deflection mode. that time,
As described above, the calibration can be performed by forming the calibration index according to the deflection form and scanning the beam.

Next, an example of the pattern of the above-mentioned optical system calibration mark will be described. FIG. 3 is a diagram showing an example of a pattern of the optical system calibration mark. FIG. 3 (A) is a diagram showing a pattern for measuring rotation, magnification, distortion, etc. of the collective exposure region, FIG. 3 (B) is a diagram showing a deflection position measuring pattern, and FIG. 3 (C) is a pattern. FIG. 7 is a diagram showing an example in which all are the same in each subfield in the X direction.

FIG. 3 (A) shows a mark group 82 corresponding to the deflection form shown in FIG. 2 (A). In this mark group 82, subfields 83-1 to 83-11 arranged side by side in the diagonally lower right direction in the X direction and a subfield 83-3-12 below the subfield 83-1 to the diagonal lower left direction in the X direction. 22 subfields 83 are provided, which are subfields 83-12 to 83-22 arranged side by side. A line-and-space pattern extending in the XY directions as shown in FIG. 11B is arranged at nine positions in each sub-field 83 (indicated by squares in the figure). By scanning the line-and-space pattern with a beam, it is possible to measure the rotation, magnification, distortion, etc. in the subfield of the collective exposure area.

FIG. 3 (B) shows a mark group 84 corresponding to the deflection form shown in FIG. 2 (A). The mark group 84 is provided with subfields 85-1 to 85-11 arranged side by side in the X direction. Here, the subfield 85-6 at the center is a square, but the length of the subfield in the Y direction becomes longer toward the ends, and the subfields 85-1 and 85-11 at both ends are formed.
Is about twice as long as the subfield 85-6. In the central portion of each subfield 85, a vertically long line and space pattern extending in the Y direction is arranged. The deflection position can be measured by beam scanning the line-and-space pattern.
With such an arrangement method, it is possible to reduce the size of the mark.

FIG. 3C shows a mark group 86 having the same pattern in each subfield in the X direction. The mark group 86 is provided with subfields 87-1 to 87-17 arranged side by side in the X direction. Here, the width of each subfield 87 in the X direction is equal to the width of one subfield, but its length in the Y direction is approximately twice the length of the subfield. In the central portion of each subfield 87, a vertically long line and space pattern extending in the Y direction is arranged. With such an arrangement method, the patterns can be made the same in each subfield in the X direction.

FIG. 4 is a diagram showing another example of the mark group. In this example, mark groups 65 (see FIG. 1B), 82 (see FIG. 3A), and 84 (see FIG. 3B) are arranged side by side on one mark plate 90. . By disposing such a mark plate 90 on the reticle stage 11 and the wafer stage 24, it is possible to realize an exposure apparatus that can perform calibration work of a plurality of types of deflection forms without exchanging the reticle or the like.

[0055]

As is apparent from the above description, according to the present invention, the time required for the calibration of the charged particle beam optical system mounted on the exposure apparatus can be shortened, and the maintenance required for the operation of the apparatus. The time can be shortened. Further, thereby, it is possible to reduce the total cost related to the operation of the device without lowering the accuracy of calibration.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a mark arrangement state according to a first embodiment of the present invention. FIG. 1A is a diagram showing a deflection form of an electron beam, and FIG. 1B is a diagram showing an arrangement state of subfields having marks.

FIG. 2 is a diagram illustrating an optical system calibration index (mark) according to a second embodiment of the present invention. FIG. 2A is a diagram showing a deflection form of an electron beam, and FIG. 2B is a diagram showing an arrangement of subfield groups in which marks are arranged.

FIG. 3 is a diagram showing an example of a pattern of an optical system calibration mark. FIG. 3 (A) is a diagram showing a pattern for measuring rotation, magnification, distortion, etc. of the collective exposure region, FIG. 3 (B) is a diagram showing a deflection position measuring pattern, and FIG. 3 (C) is a pattern. FIG. 7 is a diagram showing an example in which all are the same in each subfield in the X direction.

FIG. 4 is a diagram showing another example of a mark group.

FIG. 5 is a diagram showing an outline of an image forming relationship and a control system in the entire optical system of the split transfer type electron beam projection exposure apparatus.

FIG. 6 is a diagram schematically showing a configuration example of a reticle for electron beam projection exposure. (A) is a plan view of the whole, (B)
FIG. 3A is a perspective view of a part, and FIG. 3C is a plan view of one small membrane region.

FIG. 7 is a perspective view schematically showing how a pattern is transferred from a reticle to a wafer.

FIG. 8 is a diagram illustrating an example of a deflection mode when exposing a certain area on a wafer. FIG. 8A is a diagram showing the exposure order of the patterns seen on the wafer, and FIG.
FIG. 4 is a diagram showing a deflection form of the electron optical system at that time.

FIG. 9 is a diagram illustrating an example of a deflection mode when exposing a certain area on a reticle. FIG. 9A is a diagram showing the exposure order of the patterns seen on the reticle.
FIG. 6B is a diagram showing a deflection form of the electron optical system at that time.

FIG. 10 is a diagram for explaining a conventional method of calibrating an exposure apparatus.

FIG. 11 is a diagram showing an optical system calibration index provided on the reticle of the exposure apparatus. FIG. 11A is a diagram showing deflection position measurement marks, and FIG. 11B is a diagram showing measurement marks for rotation, magnification, distortion, etc. of the collective exposure region.

[Explanation of symbols]

60 deflection form 61 subfield 65 Optical system calibration index 66 subfields

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Claims (4)

[Claims] 1. A reticle stage on which a reticle, on which a pattern to be transferred on a sensitive substrate is divided and formed into a plurality of subfields, is placed, and a charged particle beam illumination beam is sequentially applied to each subfield of the reticle. An illumination optical system, a sensitive substrate stage on which the sensitive substrate is placed, and a projection optical system for sequentially projecting a charged particle beam (projection beam) passing through each subfield of the reticle onto an appropriate position on the sensitive substrate. The subfields are arranged on the reticle in a grid pattern in the X direction and the Y direction, and a beam is generated by deflecting the illumination beam in the illumination optical system in the X direction. In the Y direction, the both stages are mechanically moved to perform mechanical scanning, and in the projection optical system, the scanning is performed on the sensitive substrate. A method for calibrating a charged particle beam exposure apparatus which exposes while deflecting the projection beam for adjusting a pattern transfer position, comprising the reticle stage or the reticle, and the sensitive substrate stage or the sensitive substrate ... By forming a series of optical system calibration indexes (marks) along the beam scanning path corresponding to the particle beam deflection pattern and the mechanical scanning patterns of the both stages, and continuously beam scanning the series of marks.
A method for calibrating a charged particle beam exposure apparatus, comprising: measuring a beam property at a plurality of scanning positions of the mark, and setting an optical system correction coefficient at each scanning position based on the measurement. 2. The plurality of types of marks for measuring a plurality of types of the charged particle beam deflection form or a plurality of types of the beam properties are formed as the optical system calibration index. Method for calibrating charged particle beam exposure apparatus. 3. The method for calibrating a charged particle beam exposure apparatus according to claim 1, wherein a mark that can be commonly used in a plurality of the charged particle beam deflection forms is formed as the optical system calibration index. 4. A reticle stage on which a reticle, on which a pattern to be transferred on a sensitive substrate is formed by being divided into a plurality of subfields, is mounted, and a charged particle beam illumination beam is sequentially applied to each subfield of the reticle. An illumination optical system, a sensitive substrate stage on which the sensitive substrate is placed, and a projection optical system for sequentially projecting a charged particle beam (projection beam) passing through each subfield of the reticle to an appropriate position on the sensitive substrate. A charged particle beam exposure apparatus comprising: a reticle stage and a sensitive substrate stage,
A charged particle beam exposure apparatus, wherein a series of optical system calibration indexes are formed along a beam scanning path corresponding to the charged particle beam deflection mode and the mechanical scanning modes of both stages.