JPH0757983A - Charged particle beam writing method - Google Patents

Abstract

PURPOSE:To realize a charged particle beam writing method in which the writing time can be shortened by shortening the time required for measurement of deflection distortion. CONSTITUTION:The difference of deflection distortion of a subdeflector between a specific small region and other small region is determined for each small region stored in a memory 17. Correction data for the distortion of a main deflector 5 is generated by a control computor 8 based on a measurement of deflection distortion of the main deflector 5. The correction data is transferred to a memory 19 and stored therein. On the other hand, deflection distortion is measured for a specific small region and the control computor 8 operates the deflection distortion for other small region based on thus measured deflection distortion and the difference of deflection distortion stored in the memory 17. Furthermore, a correction data is generated based on the deflection distortion for each small region and stored in a memory 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle beam drawing method for drawing a fine pattern using an electron beam or an ion beam.

[0002]

2. Description of the Related Art In recent years, in electron beam drawing used in semiconductor memory devices and the like, an electron beam from an electron gun is focused by an electron lens and projected onto a drawing material, and the electron beam is formed into a drawing pattern. The material is deflected accordingly and a desired pattern is drawn on the material. Due to the problem of deflection distortion of the deflector, drawing by deflection of the electron beam is performed in units of a predetermined area (called a field). When the drawing of a pattern within a predetermined field is completed, the material is moved to move the next field. The electron beam is positioned below the optical axis.

In deflecting the electron beam,
The main deflector and the sub deflector may be used. FIG. 1 is a diagram showing the outline of such a system, where MD is the main deflector and S
D is a sub-deflector, and W is a material to be drawn. A region (referred to as a field) F on which the electron beam is deflected on the material W is virtually divided into small regions R _{1 to} R _n . In this example, the field F is divided into 25 small areas. In this manner, the electron beam is projected onto the central portion of each small region by the main deflector MD, and the electron beam is deflected according to the pattern in the small region by the sub deflector SD. There is.

[0004]

By the way, as the main deflector MD and the sub deflector SD, an electrostatic type or an electromagnetic type deflector is used, but in both cases, the electric field and magnetic field by the deflector are not uniform. When the electron beam is deflected by these deflectors, the deflection includes deflection distortion of each deflector. Therefore, the deflection distortion must be corrected in order to perform accurate drawing. For this reason, the deflection distortion of each deflector is measured before the pattern is drawn, and at the time of actual drawing, the deflection signal according to the pattern is corrected based on this deflection distortion.

That is, the deflection distortion of the main deflector MD and the deflection distortion of the sub-deflector SD in each small area are measured and stored in a memory before drawing. This stored deflection distortion is
The deflection signal is read when the pattern of each small area is drawn, and the deflection signal is corrected according to these two types of deflection distortion.

In such deflection deflection measurement and its value storage operation, since the deflection distortion amount changes due to changes in the acceleration voltage of the electron beam and changes in the temperature of the apparatus, when the electron beam drawing apparatus is started up, It must be carried out frequently when the acceleration voltage is changed. The deflection distortion of the main deflector is measured only once, but the number of times the deflection distortion of each small area is measured must be 25 times if the number of small areas is 25. It takes a lot of time. In particular, if the number of divisions of the small area is increased in order to improve the drawing accuracy, the distortion measurement will take more time.

The present invention has been made in view of the above circumstances, and an object thereof is to realize a charged particle beam drawing method capable of shortening the measurement time of deflection distortion and consequently shortening the drawing time. There is.

[0008]

A charged particle beam drawing method according to the present invention includes a charged particle beam source, a focusing means for focusing a charged particle beam from the charged particle beam source, and a main deflection for deflecting the charged particle beam. The charged particle beam is relatively largely deflected by the main deflector and projected onto a virtual small area portion on the material by the main deflector, and the drawing pattern in the small area is formed by the sub deflector. In the charged particle beam drawing method in which the charged particle beam is deflected in accordance with the deflection distortion of the sub-deflector for each small area in advance, the deflection distortion of the sub-deflector in a specific small area and other small areas are determined. The difference between the deflection distortion of the sub-deflector in the area is calculated and stored, and during actual drawing, the deflection distortion of the main deflector and the deflection distortion of the sub-deflector in the specific small area are measured. , When drawing each small area, The distortion of the sub-deflector in the small area is calculated by calculation based on the measured deflection distortion of the sub-deflector in the specific small area and the stored difference signal, and the calculated distortion of the sub-deflector and the measurement It is characterized in that the deflection distortion of the charged particle beam is corrected based on the deflection distortion of the main deflector.

[0009]

The deflection distortion of the sub-deflector in each small region changes due to changes in the accelerating voltage of the electron beam and changes in the temperature of the apparatus, but the mutual relation of the deflection distortion in each small region is constant. In the present invention, by utilizing this point, the deflection distortion of the sub-deflector for each small area is obtained in advance, and the deflection distortion of the sub-deflector in a specific small area and the deflection distortion of the sub-deflector in another small area are calculated. The difference between is calculated and stored, and at the time of actual drawing, the deflection distortion of the main deflector and the deflection distortion of the sub-deflector of the specific small area are measured to draw each small area. Is
Based on the measured deflection distortion of the sub-deflector in the specific small area and the stored difference signal, the distortion of the sub-deflector in the small area is calculated, and the calculated distortion of the sub-deflector and The deflection distortion of the charged particle beam is corrected based on the measured deflection distortion of the main deflector.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 shows an example of an electron beam writing system for carrying out the method according to the invention. An electron beam from the electron gun 1 is focused by an electron lens 2 on a drawing material 3 such as a wafer or a reticle material. The material 3 is placed on the moving stage 4.

The irradiation position of the electron beam on the material 3 is determined by the deflection of the electron beam by the main deflector 5 and the sub deflector 6. Further, the drawing of the material by the electron beam is performed while blanking the electron beam, and therefore the blanker 7 is provided. 8 is a control computer, and the drawing pattern data from the control computer 8 is
It is sent to the pattern data transfer circuit 9. The blanking data is transferred from the transfer circuit 9 to the blanker control circuit 10, and the deflection data according to the drawing pattern is transferred to the deflector control circuit 11 of the main deflector 5 and the deflector control circuit 12 of the sub deflector 6. The stage position data corresponding to the drawing pattern is transferred to the stage control circuit 13.

Secondary electrons generated by irradiating the material 3 with an electron beam are detected by a secondary electron detector 14. The detection signal of the detector 14 is supplied to the control computer 8 via the amplifier 15 and the AD converter 16. Reference numeral 17 is a memory for storing the result calculated by the control computer 8, and 18 is a memory for storing the drawing data. Further, 19 is a memory for storing the correction data of the deflection distortion of the main deflector 5, and 20 is the sub deflector 6 in each small area.
This is a memory for storing the correction data of the deflection distortion of. Two
Reference numeral 1 is a laser length measuring device for measuring the amount of movement of the stage 4, and the measurement result of the laser length measuring device is a control computer 8
Is supplied to. The operation of such a configuration will be described below.

First, the measurement of the deflection distortion of the main deflector 5 and the sub deflector 6 will be described. For the measurement of the deflection strain, first, the material 3 on which the mark is formed is prepared, held in the material holder, and placed on the material stage 4 of the apparatus of FIG. At this time, the mark is arranged immediately below the optical axis of the electron beam. In this state, data for measuring the deflection distortion is supplied from the control computer 8 to the pattern data transfer circuit 9.

As a result, the pattern data transfer circuit 9 supplies the stage control circuit 13 with a signal for moving the stage 4 by a predetermined distance. At this time, the moving distance of the stage 4 is constantly monitored by the laser length measuring machine 21, and the material 3 is moved by an accurate distance. The mark position on the material 3 also moves as the material 3 moves by a predetermined distance. Each time the mark position moves by a predetermined distance, the deflector control circuit 11 supplies the main deflector 5 with a deflection signal for detecting the mark position after the movement.

As a result, the electron beam is scanned at the mark portion which has moved a predetermined distance. Secondary electrons generated in response to the scanning of the electron beam are detected by the secondary electron detector 14. The detection signal of the detector 14 is the amplifier 15, AD
It is supplied to the control computer 8 via the converter 16.
The control computer 8 determines the mark position based on the deflection of the main deflector 5 by the deflection of the electron beam by the main deflector 5 and the secondary electron detection signal.

The deflection distortion of the main deflector 5 is measured based on the difference between the obtained mark position and the actually moved distance. Since the deflection distortion is measured each time the mark position in the field is moved, the deflection distortion of the main deflector 5 in the entire field is measured. The measured deflection distortion is stored in the memory 17.

Next, the measurement of the deflection distortion of the sub deflector 6 will be described. The deflection distortion of the sub-deflector 6 is also measured by moving the mark position and detecting the mark position by deflecting the electron beam as in the case of the main deflector. However, in the measurement of the deflection distortion of the sub-deflector 6, the main deflector 5 deflects the electron beam to a small area in the field, and in this state, the sub-deflector 6 further deflects the electron beam to obtain a small area in the small area. Measure the mark position of. The deflection distortion of the sub-deflector 6 is measured for all of the small areas, and the deflection distortion is stored in the memory 17.

By the way, the control computer 8 determines the deflection distortion of the sub-deflector stored in the memory 17 for each small area, such as the deflection distortion of a specific small area, for example, the small area immediately below the electron beam optical axis. Then, the difference from the deflection distortion of each small area is calculated. This difference is stored in the memory 17.

When the apparatus is started up and the actual drawing on the material 3 is started, the deflection distortion correction data of the main deflector 5 and the deflection distortion correction data of the sub-deflector 6 in each small area are beforehand obtained. And are created. The deflection distortion correction data of the main deflector 5 is created by the control computer 8 from the measurement value obtained by measuring the deflection distortion of the main deflector described above. This correction data is transferred to and stored in the memory 19.

Next, the generation of the correction data of the deflection distortion of the sub-deflector of each small area will be described. First, the main deflector 5 projects an electron beam onto a specific small area, that is, a small area at the center of the field, and the sub-deflector deflects the electron beam in this small area to measure the deflection distortion. Based on the difference between the deflection distortion in the small area in the central portion thus measured and the deflection distortion in the other small area stored in the memory 17, the control computer 8 determines the deflection in the other small area. The distortion is calculated. Further, the control computer 8 creates the correction data based on the obtained deflection distortion in each small area, and transfers the created correction data to the memory 20 to be stored therein.

After creating the correction data prior to such drawing, the control computer 8 reads the drawing data stored in the memory 18 and sends it to the pattern transfer circuit 9.
In the pattern data transfer circuit 9, the stage control circuit 13 is controlled according to the drawing data to move the moving stage 4, and the field to be drawn is positioned below the optical axis of the electron beam. Then, the deflection data is supplied to the control circuit 11 and the control circuit 12 of the sub-deflector 6 to the main deflector 5, and the main deflector 5 deflects the electron beam to each small area.
The electron beam is deflected in a small area according to the pattern. At this time, the deflection signal supplied to the main deflector 5 is assumed to have the deflection distortion corrected by the deflection distortion correction data stored in the memory 19. In addition, the sub deflector 6
The deflection signal supplied to is corrected in deflection distortion by the deflection distortion correction data stored in the memory 20.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, the present invention can be applied to not only an electron beam drawing apparatus but also an ion beam drawing apparatus. Further, when measuring the deflection distortion of the sub-deflector, the deflection distortion of the small area in the central portion of the field is obtained as a specific small area, and all the small areas are calculated by the difference between this deflection distortion and the other small areas. However, the specific small area does not necessarily have to be the small area at the center of the field.

[0023]

As described above, in the charged particle beam drawing method according to the present invention, the deflection distortion of the sub-deflector for each small area is obtained in advance, and the deflection distortion of the sub-deflector in a specific small area is calculated. The difference between the deflection distortion of the sub-deflector of the other small area is obtained and stored, and at the time of actual drawing, the measurement of the deflection distortion of the main deflector and the deflection distortion of the sub-deflector of the specific small area are performed. When drawing each small area, the distortion of the sub-deflector in the small area is calculated by calculation based on the measured deflection distortion of the sub-deflector of the specific small area and the stored difference signal. Then, the deflection distortion of the charged particle beam is corrected based on the obtained distortion of the sub deflector and the measured deflection distortion of the main deflector. As a result, the measurement of the sub-deflection strain in the small area prior to the drawing can be performed only in a specific single small area, and the measurement time can be remarkably shortened. Therefore, the drawing time can also be shortened.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a drawing method using a main deflector and a sub deflector.

FIG. 2 is a diagram showing an electron beam writing system for carrying out the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron gun 2 Electron lens 3 Material 4 Moving stage 5 Main deflector 6 Sub deflector 7 Blanker 8 Control computer 9 Pattern data transfer circuit 10 Blanker control circuit 11, 12 Deflector control circuit 13 Stage control circuit 14 Secondary electron detector 15 amplifier 16 AD converter 17-20 memory 21 laser length measuring device

Claims (1)

[Claims] 1. A charged particle beam source, a means for focusing a charged particle beam from the charged particle beam source, a main deflector and a sub deflector for deflecting the charged particle beam, and the main deflector. A charged particle beam in which a charged particle beam is deflected comparatively largely and projected onto a virtual small area portion on a material, and the charged particle beam is deflected by a sub-deflector according to a drawing pattern in the small area. In the drawing method, the deflection distortion of the sub-deflector for each small area is calculated in advance, and the difference between the deflection distortion of the sub-deflector in a specific small area and the deflection distortion of the sub-deflector in another small area is calculated and stored. Incidentally, at the time of actual drawing, the deflection distortion of the main deflector and the deflection distortion of the sub-deflector of the specific small area are measured, and when the drawing of each small area is performed, the measured specific distortion is measured. Distortion of the sub-deflector in the small region of The distortion of the sub-deflector in the small area is calculated by calculation based on the signal of the above, and the deflection distortion of the charged particle beam is calculated based on the distortion of the sub-deflector thus obtained and the measured deflection distortion of the main deflector. A charged particle beam drawing method characterized in that correction is performed.