JPH09330680A - Electron beam exposing device and electron beam exposing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To draw a desired pattern on a wafer by detecting the reflected electrons or secondary electrons from a lattice-like mark, and controlling the image forming state of an electron beam based on the intensity of the periodic signal determined by the pitch of the lattice-like mark. SOLUTION: A control system 22 scans three electron beams in the X- direction, and it synthesizes and receives the reflected electrons or secondary electrons corresponding to the electron beams via a reflected electron detector 9. The control system 22 stores the mark signal corresponding to the deflection quantity, converts it into the signal in the spatial frequency region by discrete Fourier transformation, and stores the intensity of the frequency determined by the pitch of the lattice-like mark. The setting of a dynamic focus coil is changed by a focal point/astigmatic control circuit 2 (16), the electron beams are again scanned on the mark, the work storing the intensity when two other marks are used is likewise repeated, the dynamic astigmatic correction data when the intensity becomes the maximum are obtained, and the optimum dynamic astigmatic correction data are determined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam exposure apparatus, and more particularly to an electron beam exposure apparatus and an electron beam exposure method having an image forming state detecting means of a reduction electron optical system.

[0002]

2. Description of the Related Art In an electron beam exposure apparatus, an electron beam is deflected and a pattern is drawn in the deflection area. At this time, when the electron beam is deflected, the image formation state of the electron beam deteriorates due to the deflection aberration. Therefore, it is necessary to correct the image formation state according to the deflection position of the electron beam.

FIG. 16A shows a conventional point beam type electron beam exposure apparatus which uses a conventional beam in the form of a spot.

An electron gun 201 emits an electron beam and turns on / off the electron beam according to a pattern to be drawn.
Reference numeral 202 denotes a reduction electron optical system for reducing and projecting an electron beam from an electron gun into a point shape on a wafer 203, and 204 denotes a deflector for scanning the wafer with a point shape electron beam, 205
Is an XY stage on which a wafer is placed and moves, and 206 is a detector that detects backscattered electrons and secondary electrons generated when an electron beam scans a reference mark on a reference plate 207 fixed to the XY stage. is there.

Conventionally, the reference mark SM, which is a linear mark as shown in FIG. 16B, is scanned by the electron beam B0. At that time, reflected electrons and secondary electrons generated from the reference mark are detected by the detector 206, a mark signal as shown in FIG. 16C is detected, and image formation state correction data is obtained from the mark signal. When the electron beam is deflected to draw a pattern, the characteristic of the reduction electron optical system is corrected by the image formation state correction data corresponding to the deflected position.

[0006]

As shown in FIG. 16 (C), the mark signal is small and very noisy. Moreover, if the electron beam is narrowed down to draw a fine pattern, the signal becomes smaller. Therefore, there is a problem that the reduction electron optical system cannot be properly corrected with the image formation state correction data obtained from such a mark signal, and a desired pattern cannot be drawn on the wafer.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an embodiment of the electron beam exposure apparatus of the present invention is to provide an electron beam substrate through a reduction electron optical system. In an electron beam exposure apparatus that draws the substrate by irradiating the substrate and deflecting the substrate by a deflector, and a stage on which the substrate is placed,
A first grid-shaped mark in which a linear pattern is arranged in a first direction is formed, and a reference plate fixed on the stage and an image formation state of the electron beam on the reference plate are set. Imaging state setting means, displacement means for relatively displacing the electron beam with respect to the reference plate in a direction orthogonal to the optical axis, and reflected electrons generated when the reference plate is irradiated with the electron beam. The image forming state of the electron beam on the reference plate is changed by the electron detecting means for detecting secondary electrons and the image forming state setting means, and in each state, the electron beam is made to be the first by the displacing means. 1
Of the reflected electrons or secondary electrons from the first grid-like mark by the electron detecting means while displacing on the grid-like mark, and the relationship between the displacement amount of the displacing means and the detection result of the electron detecting means. Control means for determining a periodic signal determined by the pitch of the grid-like marks included in the signal relating to the above, and for determining the image formation state of the electron beam based on the intensities of the plurality of periodic signals.

The electron beam has a plurality of electron beams arranged in a direction orthogonal to the first direction.

The control means changes the deflection position of the electron beam by the deflector and obtains the image formation state of the electron beam at each position.

A second grid-shaped mark having a linear pattern arranged in a direction orthogonal to the first direction is formed on the reference plate, and the control means sets the second grid-shaped mark. It is characterized in that the imaging state of the electron beam is obtained by using the electron beam.

The image formation state setting means has a focus correction means for correcting the focus position of the electron beam, and the control means sets the obtained image formation state of the electron beam when drawing the substrate. Based on this, the focus position of the electron beam is corrected by the focus correction means.

The image formation state setting means has astigmatism correction means for correcting astigmatism of the electron beam, and the control means forms the image formation of the electron beam obtained when drawing the substrate. The astigmatism correction means corrects the astigmatism of the electron beam based on the state.

An embodiment of the electron beam exposure method of the present invention is an electron beam exposure method for drawing a substrate by irradiating the substrate with an electron beam through a reduction electron optical system and deflecting the substrate by a deflector. In an image forming state setting step of setting an image forming state of the electron beam on the reference plate on which the first lattice-shaped marks in which the linear patterns are arranged in the first direction are formed, On the other hand, the image forming state of the electron beam on the reference plate is changed by the displacement step of relatively displacing the electron beam in the direction orthogonal to the optical axis and the image forming state setting step. In the above, in the displacement step, the electron beam is displaced on the first lattice-shaped mark, and the reflected electrons or secondary electrons generated when the electron beam is irradiated to the reference plate are Then, a periodic signal determined by the pitch of the grid-like marks, which is included in the signal relating to the displacement amount of the electron beam and the detected electron amount, is obtained, and the electron beam is calculated based on the intensities of the plurality of periodic signals. And the step of obtaining the image formation state of.

The electron beam has a plurality of electron beams arranged in a direction orthogonal to the first direction.

The method further comprises the step of changing the deflection position of the electron beam by the deflector and obtaining the image formation state of the electron beam at each position.

The reference plate is formed with a second lattice mark in which a linear pattern is arranged in a direction orthogonal to the first direction, and the electron beam is formed by using the second lattice mark. It is characterized in that it has a step of obtaining an image formation state of.

Focusing means for correcting the focal position of the electron beam is provided, and when the electron beam is deflected by the deflector to draw the substrate, the electron beam results obtained at the plurality of deflection positions are combined. There is a step of correcting the focus position of the electron beam by the focus correction means based on the image state.

The electron beam has astigmatism correction means for correcting astigmatism of the electron beam, and the electron beam is obtained at the plurality of deflection positions when the electron beam is deflected by the deflector to draw the substrate. The astigmatism correcting means corrects the astigmatism of the electron beam based on the image formation state.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

[Explanation of components of electron beam exposure apparatus] FIG. 1 is a schematic view of a main part of an electron beam exposure apparatus according to the present invention.

In FIG. 1, reference numeral 1 denotes an electron gun comprising a cathode 1a, a grid 1b, and an anode 1c.
Electrons emitted from 1a form a crossover image between the grid 1b and the anode 1c (hereinafter, these crossover images are referred to as a light source).

The electrons emitted from this light source become a substantially parallel electron beam by the condenser lens 2 whose front focal position is at the light source position. The substantially parallel electron beam enters the element electron optical system array 3. The element electron optical system array 3 is formed by arranging a plurality of element electron optical systems each including a blanking electrode, an opening, and an electron lens in a direction orthogonal to the optical axis AX. Details of the element electron optical system array 3 will be described later.

The element electron optical system array 3 forms a plurality of intermediate images of the light source, and each intermediate image is reduced and projected by a reduction electron optical system 4 described later to form a light source image on the wafer 5.

At this time, each element of the element electron optical system array 3 is set so that the distance between the light source images on the wafer 5 is an integral multiple of the size of the light source image. Further, the elementary electron optical system array 3 makes the position of each intermediate image in the optical axis direction different according to the field curvature of the reduction electron optical system 4, and reduces each intermediate image to the wafer 5 by the reduction electron optical system 4. The aberration that occurs when the image is projected is corrected in advance.

The reduction electron optical system 4 includes a first projection lens 41 (4
3) and the second projection lens 42 (44). Let the focal length of the first projection lens 41 (43) be f
1. Assuming that the focal length of the second projection lens 42 (44) is f2, the distance between these two lenses is f1 + f2. AX on optical axis
Is located at the focal position of the first projection lens 41 (43), and its image point is focused on the second projection lens 42 (44). This image is -f
Reduced to 2 / f1. In addition, since the two lens magnetic fields are determined so as to act in opposite directions, theoretically, there are five spherical aberrations, isotropic astigmatism, isotropic coma, field curvature aberration, and axial chromatic aberration. Except for aberrations, other Seidel aberrations and chromatic aberrations related to rotation and magnification are canceled.

Reference numeral 6 deflects a plurality of electron beams from the element electron optical system array 3 to form a plurality of light source images on the wafer 5.
This is a deflector that displaces in the X and Y directions by substantially the same amount of displacement. Although not shown, the deflector 6 is composed of a main deflector used when the deflection width is wide and a sub deflector used when the deflection width is narrow.The main deflector is an electromagnetic deflector. The sub deflector is an electrostatic deflector.

Reference numeral 7 is a dynamic focus coil for correcting the deviation of the focus position of the light source image due to deflection aberration generated when the deflector 6 is operated, and reference numeral 8 is generated by deflection, like the dynamic focus coil 7. It is a dynamic stig coil that corrects astigmatism of deflection aberration.

9 is a method for detecting reflected electrons or secondary electrons generated when the electron beam from the elementary electron optical system array 3 irradiates the alignment mark formed on the wafer 5 or the mark on the stage reference plate 13. Backscattered electron detector.

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

Reference numeral 11 denotes a θ-Z stage on which a wafer is placed and which can be moved in the optical axis AX (Z axis) direction and the rotation direction around the Z axis, and includes the stage reference plate 13 and the Faraday cup described above.
10 are fixed.

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

Next, an element electron optical system array will be described with reference to FIG.
3 will be described.

The element electron optical system array 3 includes a plurality of element electron optical systems as a group (subarray), and a plurality of subarrays are formed. In this embodiment, seven sub-arrays A to G are formed. In each subarray, a plurality of element electron optical systems are two-dimensionally arranged. In each subarray of the present embodiment, 25 element electron optical systems such as D (1,1) to D (5,5) are formed, and each element electron optical system On the wafer, light source images arranged in the X direction and the Y direction at intervals of the pitch Pb (μm) are formed.

FIG. 3 is a sectional view of each element electron optical system.

In FIG. 3, 301 is a blanking electrode having a deflection function, which is composed of a pair of electrodes, and 302
Is a substrate having an aperture (AP) for defining the shape of a transmitted electron beam, which is common to other element electron optical systems. Wiring for turning on / off the blanking electrode 301 and the electrode on it (W)
Are formed. 303 is composed of three aperture electrodes, and uses two unipotential lenses 303a and 303b having a converging function in which the upper and lower electrodes have the same acceleration potential V0 and the middle electrode is kept at another potential V1 or V2. It was an electronic lens.

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. 4 (A). The electrodes are the focus and
The astigmatism control circuit 1 sets a common potential in all the element electron optical systems.

Since the potential of the intermediate electrode of the unipotential lens 303a can be set for each element electron optical system by the focus / astigmatism control circuit 1, the focal length of the unipotential lens 303a can be set for each element electron optical system.

The intermediate electrode of the unipotential lens 303b is composed of four electrodes as shown in FIG. 4 (B),
Since the potential of each electrode can be set individually by the focus / astigmatism control circuit and can be set individually for each element electron optical system, the unipotential lens 303b can have a different focal length in a cross section orthogonal to the element electron optics. It can be set individually for each system.

As a result, the electro-optical characteristics (intermediate image forming position, astigmatism) of the element electron optical system can be controlled by controlling the potentials of the intermediate electrodes of the element electron optical system.

The electron beam made substantially parallel by the condenser lens 2 passes through the blanking electrode 301 and the aperture (AP),
The electron lens 303 forms an intermediate image of the light source. At this time, the beam is not deflected like the electron beam bundle 305 unless an electric field is applied between the blanking electrodes 301. On the other hand, when an electric field is applied between the electrodes of the blanking electrode 301, they are deflected like an electron beam bundle 306. Then, since the electron beam 305 and the electron beam 306 have different angular distributions on the object plane of the reduction electron optical system 4, the electron beam 305 at the pupil position of the reduction electron optical system 4 (on the P plane in FIG. 1). And electron beam bundle 306
Are incident on mutually different regions. Therefore, a blanking aperture BA that transmits 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.

Further, each element electron optical system corrects the field curvature and astigmatism generated when the intermediate image formed by each element electron is reduced and projected on the surface to be exposed by the reduction electron optical system 4. The electric potentials of the two intermediate electrodes of each element electron optical system 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, the element electron optical systems in the same sub-array have the same electro-optical characteristics in order to reduce the wiring between the intermediate electrode and the focus / astigmatism control circuit 1, and the electro-optical characteristics of the element electron optical systems (Intermediate image formation position, astigmatism) is controlled for each sub-array.

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

Next, a system configuration diagram of this embodiment is shown in FIG.

The blanking control circuit 14 turns on / of the blanking electrodes of each element electron optical system of the element electron optical array 3.
control circuit for individually controlling f, focus / astigmatism control circuit 1 (1
5) is a control circuit for individually controlling the electron optical characteristics (intermediate image formation position, astigmatism) of each element electron optical system of the element electron optical array 3.

The focus / astigmatism control circuit 2 (16) is a control circuit for controlling the focal position and astigmatism of the reduction electron optical system 4 by controlling the dynamic stig coil 8 and the dynamic focus coil 7, and the deflection control circuit. Reference numeral 17 is a control circuit for controlling the deflector 6, magnification adjustment circuit 18 is a control circuit for adjusting the magnification of the reduction electron optical system 4, and optical characteristic circuit 19 is an excitation current of an electromagnetic lens constituting the reduction electron optical system 4. This is a control circuit that changes the rotational aberration and adjusts the optical axis.

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

The control system 22 includes a plurality of control circuits and a backscattered electron detector for the purpose of exposure and alignment based on the data from the memory 23 in which information about the drawing pattern is stored.
9. Synchronously control the Faraday cup 10. Control system 22
Are controlled by a CPU 25 that controls the entire electron beam exposure apparatus via an interface 24.

(Description of Operation) The operation of the electron beam exposure apparatus of this embodiment will be described with reference to FIG.

Prior to the wafer exposure of the exposure apparatus, the CPU 25
Commands the “calibration” to the control system 22 via the interface 24, the control system 22 executes the following steps.

As shown in FIG. 6, on the stage reference plate 13, the center of the deflection area by the main deflector of the deflector 6 is set to (0, 0) and the position of each matrix is divided into nine matrices. The mark M is formed at the corresponding position. The mark M is composed of a grid-shaped mark MX having linear patterns arranged in the X direction and a grid-shaped mark MY having linear patterns arranged in the Y direction. The pitch of both grid marks is Pm (μm).

If the electron beam from the element electron optical system D (3,3) at the center of the element electron optical system array 3 shown in FIG. The control system 22 commands the stage drive control circuit 20 to move the XY stage 12 and position the center of the mark M (0,0) on the stage reference plate 13 at the beam reference position.

The control system 22 is a blanking control circuit.
14 and the deflection control circuit 17 are commanded by the main deflector of the deflector 6 in the Y direction with respect to the electron beam B0 from the element electron optical system D (3,3) and the element electron optical system D (3,3). Electron beams from arrayed element electron optical systems D (2,3) and D (4,3)
The three electron beams BX1 and BX2 are deflected to the position of the mark M (1,1). Then, three electron beams are scanned on the mark MX of the mark M (1,1) in the X direction as shown in FIG. 6 (B), and reflected electrons or secondary electrons from the lattice marks corresponding to each electron beam are scanned. The electrons are combined, detected by the backscattered electron detector 9 at the same time, and taken into the control system 22. The mark signal is shown in FIG.

Then, the control system 22 stores a mark signal (discrete signal train) which is a signal of the detected electron amount corresponding to the deflection amount (sampling interval Ls (μm) of this discrete electric signal).
Is determined by the resolution of the deflector 6).

At this time, the starting point positions (white circles in the figure) of the respective electron beams satisfy the same position in the X direction.
As a result, since the positional relationship between the starting point position of each electron beam and the corresponding grid mark to be scanned is the same for all electron beams, the relationship between the deflection amount in each electron beam and the detected electron amount is The mark signals remain almost the same. Further, the combined signals are substantially the same, the noise is reduced due to the averaging effect, and the signal is large as compared with the case of one electron beam. Further, this discrete signal is subjected to Fourier transform as described later to detect blur of the electron beam (imaging state). To facilitate the process, the scan width 2Ld is 2Ld = M ×
It is set to satisfy Pm (M is a positive integer) and 2Ld = N × Ls (N is a positive integer, M <N).

The control system 22 uses the obtained discrete electric signal sequence S
(x) is transformed into a spatial frequency domain signal by the discrete Fourier transform, and the frequency (1 /
Calculate the Fourier coefficient of Pm).

The method is known, and when the sampling frequency 1 / 2Ld is normalized to 1, 1 / Pm = M / 2L from the above.
Since d is satisfied, the spatial frequency of the periodic signal determined by the pitch of the lattice mark is M, and the complex Fourier coefficient X (M) of the spatial frequency M is X (M) = ΣS (n × Ls) e ^{-j2π (M / N) (n × Ls)} (where j is the imaginary unit). The intensity of the periodic signal when the E (M), phase theta (M), respectively E (M) = ((Re (X (M)) 2 + (Im (X (M)) 2) Θ (M ) = tan -1 (Im (X (M)) / (Re (X (M))) (where Re (X (M)) and Im (X (M)) are each the complex number X (k) Real part and imaginary part).

The intensity E (M) of the periodic signal of frequency 1 / Pm obtained by the above method has a small value when the blur of the electron beam is large, and a large value when the blur of the electron beam is small. . The control system 22 controls the intensity E (M) that represents the blur of the electron beam.
Is stored.

Further, the control system 22 includes the blanking control circuit 14
And the deflection control circuit 17 by the main deflector of the deflector 6 in the X direction with respect to the electron beam B0 from the element electron optical system D (3,3) and the element electron optical system D (3,3). Electron beams from arrayed element electron optical systems D (3,2) and D (3,4)
The three electron beams of BY1 and BY2 are deflected to the position of the mark M (1,1). Then, the three electron beams are scanned on the mark MY of the mark M (1,1) in the Y direction as shown in FIG. 6 (C), and reflected electrons or secondary electrons from the lattice marks corresponding to each electron beam are scanned. The electrons are combined, detected by the backscattered electron detector 9 at the same time, and taken into the control system 22. Then, the mark signal (discrete signal sequence) which is the signal of the detected electron amount corresponding to the deflection amount is stored, and the stored discrete signal sequence S (x) is converted into a signal in the spatial frequency domain by the discrete Fourier transform. , The intensity E (M) of the frequency (1 / Pm) determined by the pitch of the lattice mark is stored.

Next, the focus / astigmatism control circuit 2 (16) is instructed,
The setting of the dynamic stig coil 8 is changed (change of the dynamic astigmatism correction data), the mark M (1,1) is scanned again with the electron beam, and the intensity E (M) when the mark MX is used is also obtained. The strength E (M) when the mark MY is used is calculated and stored. By repeating this operation, astigmatism setting amount of the dynamic stig coil 8 and strength E (M) when the mark MX is used as shown in FIG.
And the astigmatism setting amount of the dynamic stig coil 8 and the strength E (M) when the mark MY is used are obtained.
Then, the dynamic astigmatism correction data when the intensity E (M) when the mark MX is used and the intensity E (M) when the mark MY are used are obtained. As a result, the optimum dynamic astigmatism correction data at the deflection position corresponding to the mark M (1,1) is determined.

The above operation is performed for all the marks to determine the optimum dynamic astigmatism correction data at the deflection position corresponding to each mark.

Next, the control system 22 uses the blanking control circuit 14
The deflection control circuit 17 is instructed, and the main deflector of the deflector 6 deflects the electron beam B0 and the three electron beams BY1 and BY2 to the position of the mark M (1,1). At this time, the dynamic stig coil 8 is controlled based on the previously obtained dynamic astigmatism correction data.

Then, the three electron beams are marked M (1,1)
The mark MX is scanned in the X direction as shown in FIG. 6 (B), and the backscattered electrons or secondary electrons from the lattice marks corresponding to each electron beam are combined and simultaneously detected by the backscattered electron detector 9. Take in control system 22. Then, the mark signal (discrete signal sequence) which is the signal of the detected electron amount corresponding to the deflection amount is stored, and the stored discrete signal sequence S (x) is converted into a signal in the spatial frequency domain by the discrete Fourier transform. , The intensity E (M) of the frequency (1 / Pm) determined by the pitch of the lattice mark is stored.

Next, command the focus / astigmatism control circuit 2 (16),
Change the setting of the dynamic focus coil 7 (change the dynamic focus correction data) and mark with the electron beam M (1,1) again
The top is scanned, and similarly, the intensity E (M) when the mark MX is used and the intensity E (M) when the mark MY is used are obtained and stored. By repeating this operation, the relationship between the focus setting amount of the dynamic focus coil 7 and the intensity E (M) when the mark MX is used, as shown in FIG. 9, is obtained. Then, the dynamic astigmatism correction data when the intensity E (M) becomes maximum is obtained. This marks
The optimum dynamic focus correction data at the deflection position corresponding to M (1,1) is determined.

The above operation is performed for all the marks to determine the optimum dynamic focus correction data at the deflection position corresponding to each mark.

Next, when the CPU 25 commands the control system 22 to execute "exposure" via the interface 24, the control system 22
Performs the following steps.

(Step 1) The control system 22 is a deflection control circuit.
17 and deflects a plurality of electron beams from the element electron optical system array by the sub-deflector of the deflector 6.
The blanking control circuit 14 is instructed to expose the blanking electrodes of each element electron optical system on the wafer 5 according to the pattern to be exposed.
n / off At this time, the XY stage 12 is continuously moving in the X direction, and the deflection control circuit 17 controls the deflection position of the electron beam including the amount of movement of the XY stage 12.

As a result, the electron beam from one element electron optical system scans and exposes the exposure field (EF) on the wafer 5 starting from the black square as shown in FIG. Further, as shown in FIG. 11, the exposure fields (EF) of the plurality of element electron optical systems in the sub-array are set to be adjacent to each other, and as a result, the plurality of exposure areas (EF) on the wafer 5 are set. Sub-array exposure field consisting of
(SEF) is exposed. At the same time, as shown in FIG.
A subfield constituted by a subarray exposure field (SEF) formed by each of the subarrays A to G as shown in 2 is exposed.

(Step 2) After exposing the subfield shown in FIG. 13, the control system 22 commands the deflection control circuit 17 to expose the subfield, and the main deflector of the deflector 6 causes the element electron optical system to operate. Deflection multiple electron beams from the array. At this time, the control system 22 is a focus / astigmatism control circuit.
2 to control the dynamic focus coil 7 on the basis of the dynamic focus correction data obtained earlier to correct the focus position of the reduction electron optical system 4, and also based on the dynamic astigmatism correction data obtained earlier, the dynamic stig coil 8 is controlled to correct the astigmatism of the reduction electron optical system. Then, the operation of step 1 is performed to expose the subfield.

By repeating the above steps 1 and 2,
As shown in FIG. 3, subfields are sequentially exposed to expose the entire surface of the wafer.

Next, an embodiment of a device manufacturing method using the electron beam exposure apparatus and the exposure method described above will be described.

FIG. 14 shows minute devices (semiconductor chips such as IC and LSI, liquid crystal panel, CCD, thin film magnetic head,
2 shows a flow of manufacturing a micromachine or the like. Step 1
In (circuit design), a circuit of a semiconductor device is designed.
In step 2 (exposure control data creation), exposure control data of the exposure apparatus is created based on the designed circuit pattern. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the wafer and the exposure apparatus to which the prepared exposure control data has been input. The next step 5 (assembly) is called the post-process, and step 4
Is a process of forming a semiconductor chip using the wafer produced by the above process, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 15 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 1
In 5 (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern is printed on the wafer by exposure using the above-described exposure apparatus. Step 17
In (development), the exposed wafer is developed. Step 18
In (etching), portions other than the developed resist image are scraped off. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of the present embodiment, it is possible to manufacture a highly integrated semiconductor device, which has been difficult to manufacture in the past, at a low cost.

[0073]

As described above, according to the present invention, the image formation state of the reduction electron optical system can be accurately detected, so that the reduction electron optical system can be used by using highly accurate image formation state correction data. With appropriate correction, a desired pattern can be drawn on the wafer.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a main part of an electron beam exposure apparatus according to the present invention.

FIG. 2 is a diagram illustrating 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 diagram illustrating a stage reference mark.

FIG. 7 is a diagram illustrating a mark signal.

FIG. 8 is a diagram illustrating the astigmatism setting amount and the strength of a Fourier coefficient.

FIG. 9 is a diagram illustrating the focus setting amount and the strength of the Fourier coefficient.

FIG. 10 is a diagram illustrating an exposure field (EF) of an element electron optical system.

FIG. 11 is a diagram illustrating a sub-array exposure field (SEF).

FIG. 12 is a diagram illustrating subfields.

FIG. 13 is a view for explaining exposure of the entire surface of the wafer.

FIG. 14 is a diagram illustrating a manufacturing flow of a micro device.

FIG. 15 is a diagram illustrating a wafer process.

FIG. 16 is a diagram illustrating a conventional electron beam exposure apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron gun 2 Condenser lens 3 Element electron optical system array 4 Reduction electron optical system 5 Wafer 6 Deflector 7 Dynamic focus coil 8 Dynamic stig coil 9 Backscattered electron detector 10 Faraday cup 11 θ-Z stage 12 XY stage 13 Stage reference plate Reference Signs List 14 blanking control circuit 15 focus / astigmatism control circuit 1 16 focus / astigmatism control circuit 2 17 deflection control circuit 18 magnification adjustment circuit 19 optical characteristic circuit 20 stage drive control circuit 21 laser interferometer 22 control system 23 memory 24 interface 25 CPU

Claims (14)

[Claims] 1. An electron beam exposure apparatus for drawing a substrate by irradiating the substrate with an electron beam through a reduction electron optical system and deflecting the substrate by a deflector, wherein a stage on which the substrate is placed is placed. , A first grid-shaped mark having a linear pattern arranged in a first direction, and a reference plate fixed on the stage, and an image formation state of the electron beam on the reference plate are set. Image forming state setting means, displacement means for relatively displacing the electron beam with respect to the reference plate in a direction orthogonal to the optical axis, and reflected electrons generated when the reference beam is irradiated with the electron beam. Alternatively, the image forming state of the electron beam on the reference plate is changed by electron detecting means for detecting secondary electrons and the image forming state setting means, and in each state, it is moved by the displacing means. The electron beam is displaced on the first grid-like mark, and the electrons detected by the electron-detecting means are reflected electrons from the first grid-like mark or 2
Detects secondary electrons, and obtains a periodic signal determined by the pitch of the grid-like marks, which is included in the signal relating to the displacement amount of the displacement means and the detection result of the electron detection means,
An electron beam exposure apparatus comprising: a control unit that obtains an image formation state of the electron beam based on a plurality of intensities of the periodic signals. 2. The electron beam exposure apparatus according to claim 1, wherein the electron beam has a plurality of electron beams arranged in a direction orthogonal to the first direction. 3. The electron beam according to claim 1, wherein the control means changes the deflection position of the electron beam by the deflector and obtains the image formation state of the electron beam at each position. Exposure equipment. 4. The second grid-shaped mark having a linear pattern arranged in a direction orthogonal to the first direction is formed on the reference plate, and the control unit is configured to control the second grid-shaped mark. 4. The electron beam exposure apparatus according to claim 1, wherein the image formation state of the electron beam is obtained by using a mark. 5. The image formation state setting means has a focus correction means for correcting the focus position of the electron beam, and the control means forms an image of the electron beam obtained when drawing the substrate. 4. The electron beam exposure apparatus according to claim 1, wherein the focus correction means corrects the focus position of the electron beam based on the state. 6. The image formation state setting means has astigmatism correction means for correcting astigmatism of the electron beam, and the control means controls the electron beam obtained when drawing the substrate. The electron beam exposure apparatus according to claim 4, wherein the astigmatism correction means corrects the astigmatism of the electron beam based on the image formation state. 7. A device manufacturing method comprising manufacturing a device using the electron beam exposure apparatus according to claim 1. 8. An electron beam exposure method for drawing a substrate by irradiating the substrate with an electron beam through a reduction electron optical system and deflecting the substrate by a deflector, wherein a linear pattern is formed in a first direction. An image forming state setting step of setting an image forming state of the electron beam on the reference plate on which the first grid-shaped marks in which are arranged are formed; and the electron beam with respect to the reference plate as the optical axis. The image forming state of the electron beam on the reference plate is changed by the displacement step of relatively displacing in the orthogonal direction and the image forming state setting step, and the electron beam is changed by the displacement step in each state. The displacement amount of the electron beam is detected by displacing the first grid-like mark and detecting backscattered electrons or secondary electrons generated when the reference plate is irradiated with the electron beam. Determining a periodic signal included in the signal relating to the relationship with the generated electron amount, the periodic signal being determined by the pitch of the grid-like marks, and determining the image formation state of the electron beam based on the intensities of the plurality of periodic signals. An electron beam exposure method characterized by the above. 9. The electron beam exposure method according to claim 8, wherein the electron beam includes a plurality of electron beams arranged in a direction orthogonal to the first direction. 10. The electron beam exposure method according to claim 8, further comprising the step of changing a deflection position of the electron beam by the deflector and obtaining an image formation state of the electron beam at each position. . 11. A second grid-shaped mark having a linear pattern arranged in a direction orthogonal to the first direction is formed on the reference plate, and the second grid-shaped mark is used to form the second grid-shaped mark. 11. The electron beam exposure method according to claim 8, further comprising a step of obtaining an image formation state of the electron beam. 12. An electron beam having focus correction means for correcting the focal position of the electron beam, the electron beam being obtained at the plurality of deflection positions when the electron beam is deflected by the deflector to draw the substrate. 11. The electron beam exposure method according to claim 8, further comprising the step of correcting the focus position of the electron beam by the focus correction means based on the image formation state of. 13. An astigmatism correction means for correcting astigmatism of the electron beam, wherein when the electron beam is deflected by the deflector to draw the substrate, the astigmatism is obtained at the plurality of deflection positions. 12. The electron beam exposure apparatus according to claim 11, further comprising the step of correcting the astigmatism of the electron beam by the astigmatism correction means based on the image formation state of the electron beam. 14. A device manufacturing method, which manufactures a device using the electron beam exposure apparatus according to claim 1.