JP3195332B2 - Electron beam drawing method and electron beam drawing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam drawing apparatus,
An electron beam lithography method for improving the positioning accuracy of a basic aperture group of an electron beam lithography apparatus which irradiates a rectangular electron beam onto one of a plurality of basic aperture groups of a collective exposure forming aperture and collectively transfers a complicated repetitive pattern. About.

[0002]

2. Description of the Related Art In a recent electron beam lithography system, an electron beam formed by a rectangular shaping aperture is applied to one of a plurality of basic aperture groups of a collective exposure shaping aperture to perform a complicated repetition such as a memory cell. It has been practiced to transfer patterns all at once to reduce the frequency of changing the forming aperture at the time of drawing a figure, prolong the life of the forming aperture, and increase the drawing speed.

In the above transfer method, a rectangular aperture is provided in the basic aperture group, and the rectangular electron beam is irradiated by overlapping the rectangular aperture of the basic aperture group. It is also practiced to change the irradiation position to change the size of the rectangle to be drawn, the aspect ratio, and the like. In the batch transfer method of the basic aperture group, since the deflection range for the electron beam passing through the rectangular shaping aperture is narrow, the required basic aperture group is selected by moving the aperture shaping aperture by a mechanical moving mechanism or a positioning mechanism. I was trying to do it.

FIG. 2 is a configuration diagram of the above-mentioned electron beam drawing apparatus. After the electron beam generated by the electron source 1 is shaped into a rectangle by the rectangular shaping diaphragm 2, an image is formed on the collective exposure shaping diaphragm 6 by the shaping lens 4, and the image is formed by the shaping deflection control circuit 17. To drive the batch exposure molding aperture 6
Are moved so as to pass through a group of basic openings.

As a result, the beam shape after passing through the collective exposure forming stop 6 changes according to the basic aperture group. For example, when the collective exposure molding stop 6 is a single rectangle, an arbitrary rectangular beam can be obtained depending on how the two rectangles overlap. When a group of basic apertures of a repetitive figure of the collective exposure molding stop 6 is selected, a collective transfer beam is obtained. The forming beam 11 having passed through the collective exposure forming aperture 6 is reduced and projected on the sample surface by the reducing lens 9 and the objective lens 12,
A fine pattern is exposed at a desired position on the sample surface by the positioning deflector 10 and the sample table 15.

A reference mark 14 is arranged on a sample or a sample table 15 and is scanned by a positioning deflector 10 to detect its reflected electrons by a reflected electron detector 13 and to determine the position of the shaped beam 11 with respect to the sample. Position. That is, the amount of displacement of the shaping beam 11 is calculated from the output waveform of the mark detection circuit 22 and fed back to the positioning / deflection control circuit 21 so that the shaping beam 11 is returned to the correct irradiation position. These series of correction operations are executed at high speed by the control computer 24.

FIG. 3 is an example of a plan view of the forming aperture 6 for collective exposure. As shown in FIG. 3A, a plurality of basic aperture groups 6 according to the type of electron beam writing are provided in the forming aperture 6 for collective exposure.
1 to 6n are provided. Further, as shown in FIG. 2B, each basic opening group is constituted by at least one rectangular opening 26 at the center and a plurality of collective exposure openings 28 at the periphery thereof. Selected.

As shown in FIG. 2, the collective exposure forming stop 6 is mechanically moved by a forming stop moving mechanism 7 to select a required basic aperture group 61 to 6n . Assuming that the required positioning accuracy on the sample surface is x and the beam reduction ratio from the collective exposure forming stop to the sample surface is M, the positioning accuracy X of the forming stop moving mechanism 7 is x / M, so x = 0.1 μm , M = 1 /
If it is 25, the positioning accuracy X of the forming-aperture moving mechanism 7 is 2.5 μm . In the conventional apparatus, the forming iris moving mechanism 7
Is driven by a pulse motor to move the collective exposure molding stop 6 with an accuracy of about several μm so that the positioning error x of the basic aperture group on the sample surface is set to about 0.1 μm.

[0009]

However, in the above-mentioned conventional method, it was difficult to reduce the positioning error X of the basic aperture group to about 0.1 μm or less. For example, when the required positioning accuracy x on the sample surface becomes 0.01 μm, X = 0.
Since 25 μm is required, the control accuracy of the pulse motor needs to be improved accordingly, and the mechanical mechanism is excessively complicated, which is not practical. In addition, it was necessary to precisely detect the position of the basic aperture group.

Further, when there is a setting error in the exchanged forming aperture, or when the arrangement of the aperture groups is irregular, it is necessary to detect the position and arrangement of the apertures. There were also problems such as an increase in the time required for positioning. SUMMARY OF THE INVENTION It is an object of the present invention to provide an electronic apparatus capable of detecting the opening position of a collective exposure molding aperture and automatically correcting a positioning error when the molding aperture is moved or replaced, and electronically improving the positioning accuracy. An object of the present invention is to provide a line drawing method.

[0011]

In order to solve the above-mentioned problems, an electron beam drawing method according to the present invention comprises a method called “batch exposure”.
The forming aperture is moved mechanically to prepare for the batch exposure forming aperture.
From the group of openings with rectangular openings
Step of selecting the first opening, which was formed by a rectangular forming draw
A rectangular electron beam is applied to the rectangular opening provided in the first opening.
Pass the electron beam so that it partially overlaps
Scanning the reference mark by deflecting the
Detecting reflected electrons reflected from the fiducial mark to obtain
The edge of the obtained trapezoidal waveform is detected to detect the reference mark.
The process of calculating the center position, to obtain position correction data,
Comparing the position data with pre-stored reference data
Process, the batch exposure based on the obtained correction data.
The forming aperture is moved mechanically by moving the forming aperture from the first opening.
A process for selecting the second aperture provided in the batch exposure molding aperture
Method characterized by having a process. "

In order to solve the above-mentioned problems, the present invention
The configuration of the electron beam lithography system is as follows.
To be prepared for the batch exposure molding aperture
Select the first aperture from a group of apertures all with rectangular apertures
Moving mechanism, rectangular electron beam formed by a rectangular forming aperture
Partially into the rectangular opening provided in the first opening.
Let it pass so as to wrap and deflect the electron beam
Forming deflector for scanning fiducial marks, for obtaining position data
To detect reflected electrons reflected from the reference mark
To obtain the position correction data,
Equipped with a control calculator to compare with stored reference data,
The signal obtained by the detector has a trapezoidal waveform, and the controller
The computer detects the edge of the trapezoidal waveform and detects the reference mark.
The moving mechanism calculates the center position of
Move the collective exposure molding stop based on the positive data
From the first opening was provided in the collective exposure molding aperture
The device is characterized by selecting the second opening " . Further, in the electron beam lithography apparatus, the “controller
The computer calculates a correction amount relating to rotation of the collective exposure molding stop.
A device characterized by calculating. " further,
In the electron beam lithography apparatus, "the control computer is
The plurality of aperture groups provided in the collective exposure molding
Arrangement of the group of openings obtained by the detector by passing through a sagittal wire
Error of rotation of the collective exposure forming aperture based on the inclination of
Device that detects the

[0013]

The reflected signal of the backscattered electron detector for mark detection gives a position signal of the reference mark on the sample table. Since one of the two edges of the reflection signal corresponds to one edge of the rectangular shaping diaphragm, the shape (width) of the rectangular beam is corrected by correcting the position of the rectangular shaping diaphragm.

Since the center position between the two edges of the reflection signal gives the position of the rectangular beam, the position error is corrected by the positioning deflector. In addition, the rectangular bead
The shape error of the system is obtained by comparing the edge interval of the reflection signal with a reference value of the shape stored in advance. Similarly, the positional displacement of the rectangular beam can be obtained by comparing the center position between two edges of the reflection signal with a position reference value stored in advance. Also, by displaying the reflected signal waveform of the backscattered electron detector for mark detection, the rectangular beam can be displayed.
The state of the reference mark irradiation of the system is monitored. Further, by scanning a plurality of basic aperture groups in the collective exposure forming aperture and knowing the inclination of the arrangement, an in-plane rotation error of the collective exposure forming stop is detected.

[0015]

1 is a flowchart showing a procedure for positioning a basic aperture group according to the present invention. When the collective exposure forming aperture 6 is replaced, the collective exposure forming stop 6 is mechanically scanned by the forming aperture moving mechanism 7, and the forming aperture reflection electron detector 5 on the collective exposure forming aperture 6 or the reflection for mark detection is used. The positions of the basic aperture groups 61 to 6n are detected by the electronic detector 13.

FIG. 4 shows an example of a scanned image of the basic aperture groups 61 to 6n. Reference numeral 30 denotes the mechanical scanning range, which normally includes all the basic aperture groups 61 to 6n, but scans only a specific aperture group or an alignment mark provided on the surface of the collective exposure molding stop 6 and its peripheral portion depending on the purpose. Or If a rotary encoder is attached to the forming diaphragm moving mechanism 7 and a signal is detected in synchronization with the output, an image signal can be taken in at a high speed. Further, the position of each basic aperture group is determined and stored from the peak position of the output waveform of the backscattered electron detector, and is used as reference data when selecting the aperture group.

In FIG. 1, the rotation angle θ of the collective exposure forming aperture 6 is calculated from the position of the basic aperture group in FIG. 4, and this information is input to the rotation correcting lens 8 via the rotating lens control circuit 20 to form the forming beam. 11 is corrected.

The second half of FIG. 1 shows a procedure for correcting a position error when a basic aperture group is selected according to the present invention. In the present invention, a rectangular aperture 26 as shown in FIG. 3 is provided in all of the basic aperture groups 61 to 6n, and a rectangular beam formed by the rectangular shaping diaphragm 2 is partially overlapped therewith. A rectangular beam having a predetermined shape is obtained by irradiation, and the rectangular beam is scanned by the positioning deflector 10 onto a reference mark on the sample surface, and the rectangular beam is obtained from the reflection signal of the reflection electron detector 13 for mark detection.
The shape error of the system and the amount of displacement are calculated and corrected.

That is, the control computer 24 has the rectangular opening 2
The shape value of the rectangular beam passing through 6 and the set value of the irradiation position of the reference mark are stored in advance as reference values, and the actual shape value of the rectangular beam and the reference value are obtained from the reflection signal of the reflected electron detector 13 for mark detection. A mark irradiation position is calculated, and these are compared with the respective reference values to calculate a rectangular beam shape error and a positional shift amount. The rectangular beam shape error is fed back to the shaping deflector 3 and corrected. Then, the positional deviation amount is fed back to the positioning deflector 10 and corrected.

In the method of the present invention, since the alignment is performed using the rectangular opening 26 having the simplest shape among the group of collective exposure openings 28, the backscattered electron detector 13 for mark detection is used.
Is a symmetric trapezoidal waveform, and the center position of the fiducial mark is easily calculated from the edge of the trapezoidal waveform.
The positioning of the rectangular beam, that is, the collective exposure forming stop 6, can be performed with an accuracy of 01 μm or less. Further, in the present invention, since the positioning of the collective exposure forming diaphragm 6 is performed electronically, it is not necessary to mechanically increase the precision of the forming diaphragm moving mechanism 7, and the conventional one can be used as it is.

Incidentally, the method of the present invention described above employs a rectangular shaping
The same applies to the case where there are a large number of openings. By displaying the reflected signal waveform of the backscattered electron detector for mark detection, the reference mark irradiation state of the rectangular beam can be monitored. On the other hand, batch exposure aperture group 2
When the collective exposure aperture 28 in FIG. 8 is used, the reflection signal waveform of the backscattered electron detector 13 for mark detection becomes asymmetric and complicated, so that the calculation procedure of the reference mark position becomes complicated, and errors tend to occur. Become.

[0022]

According to the present invention, the shape error of the rectangular beam is electronically corrected by the shaping deflector 3 using the reflection signal of the backscattering electron detector 13 for detecting the mark, and the positioning deflector 10 Since the position error is electronically corrected, the positioning of the collective exposure forming stop 6 can be performed with an accuracy of 0.01 μm or less without increasing the accuracy of the forming stop moving mechanism 7.

Further, since the reference mark on the sample or the sample table is detected by a simple rectangular beam, the calculation of the center position of the reference mark can be simplified. Further, it becomes easy to select an opening after the exchange of the collective exposure forming aperture 6. Further, since the rotation error of the forming aperture can be easily calculated from the arrangement of the basic aperture groups in the collective exposure forming aperture 6 detected by the backscattering electron detector 13 for mark detection, this can be quickly corrected. As described above, it is possible to provide an electron beam writing method capable of quickly and economically positioning the collective exposure molding stop 6.

[Brief description of the drawings]

FIG. 1 is a flowchart of an electron beam drawing method according to the present invention.

FIG. 2 is a configuration diagram of an electron beam drawing apparatus.

FIG. 3 is a plan view of a collective exposure molding stop.

FIG. 4 is a scanning pattern diagram of a plurality of basic aperture groups in a collective exposure molding stop;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron source, 2 ... Rectangle forming aperture, 3 ... Forming deflector, 4 ...
Molded lens, 5: formed aperture reflection electron detector, 6: collective exposure formed aperture, 7: formed aperture moving mechanism, 8: rotation correction lens, 9: reduction lens, 10: positioning deflector, 11: shaped beam, 12 ... Objective lens, 13: backscattered electron detector for mark detection, 14: reference mark, 15: sample stage, 16 ...
Sample stage positioning mechanism, 17 ... Molding deflection control circuit, 18 ...
Aperture position detection circuit, 19: Formed aperture positioning circuit, 20
... Rotating lens control circuit, 21 ... Positioning deflection control circuit,
22: mark detection circuit, 23: sample stage position control circuit, 2
Reference numeral 4: control computer, 26: rectangular aperture, 28: collective exposure aperture, 29: aperture image, 30: mechanical scanning area, 61 to 6n ...
Each basic aperture group.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Nakayama 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Hitachi, Ltd. Central Research Laboratory (56) References JP-A-4-71219 (JP, A) JP-A-3 JP-A-138842 (JP, A) JP-A-4-123419 (JP, A) JP-A-59-61134 (JP, A) JP-A-4-240718 (JP, A) JP-A-3-232217 (JP, A) JP-A-6-163377 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7/20 504 G03F 9/00 H01J 37/09 H01J 37/305

Claims (4)

(57) [Claims] 1. A process of selecting the first opening from the opening group of all with a rectangular opening with collectively by mechanically moving the exposure draw forming provided in the diaphragm the collective exposure molded is molded in a rectangular shaped aperture The rectangular electron beam partially overlaps the rectangular opening provided in the first opening .
Uni passed, the step of scanning the reference mark by deflecting the electron beam, the detecting edge of the trapezoidal waveform is obtained by detecting reflected electrons reflected from the reference mark for positional data acquisition
Calculating the center position of the fiducial mark ; comparing the position data with pre-stored reference data in order to obtain position correction data; mechanically moving the collective exposure molding stop based on the obtained correction data. An electron beam lithography method, comprising a step of moving and selecting a second opening provided in the collective exposure molding stop from the first opening. 2. A movement mechanism for selecting the first opening from the opening group of all with a rectangular opening with collectively by mechanically moving the exposure draw forming provided in the diaphragm the shot exposure, molding a rectangular shaped aperture The formed rectangular electron beam partially overlaps the rectangular opening provided in the first opening .
A deflection deflector that scans the reference mark by deflecting the electron beam, a detector that detects reflected electrons reflected from the reference mark for obtaining position data, and that obtains position correction data by using the position data. A control computer for comparing with reference data stored in advance, wherein a signal obtained by the detector has a trapezoidal waveform;
The computer detects the edge of the trapezoidal waveform and detects the reference mark.
The moving mechanism moves the collective exposure molding stop based on the obtained correction data, and moves the collective exposure forming stop from the first opening to a second opening provided in the collective exposure forming stop. An electron beam drawing apparatus characterized by selecting: 3. An electron beam lithography apparatus according to claim 2, wherein said control computer calculates a correction amount relating to rotation of said collective exposure molding stop. 4. The control computer according to claim 2, wherein the control computer is provided in the collective exposure forming stop.
The electron beam passes through a plurality of aperture groups and is obtained by the detector.
The collective exposure based on the inclination of
An electronic device characterized by detecting a rotation error of a forming draw.
Line drawing device.