JPH06188181A - Charge particle beam lithography - Google Patents

Abstract

PURPOSE:To improve lithography throughput by dynamically correct an irradiation position on a workpiece of lithography with a charge particle beam through column vibration. CONSTITUTION:An amount of vibration of a column 10 is measured by vibrometers 19,20. The outputs of the vibrometers 19,20 each make only a vicinity of the natural frequency of the primary mode vibration of the column 10 pass and are supplied to filters 2I,22 which cut both low frequency side and high frequency side. A vibrometer output based only on the primary mode vibration having passed through the filters is supplied to a subtractor circuit 23 to obtain its error signal. The error signal supplied to a corrector circuit 24, which reads out a correction signal stored in a memory 25 in response to this error signal. The signal read out by the corrector circuit 24 is supplied to an adder circuit 18, added to a deflection signal for pattern lithography, and supplied to a deflector 15.

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 capable of improving drawing throughput in a charged particle beam drawing apparatus which draws a fine pattern using an electron beam or an ion beam. .

[0002]

2. Description of the Related Art For example, in an electron beam drawing apparatus, a drawing area of a material to be drawn is virtually divided into small sections (referred to as fields), the material is moved for each field, and after the movement, an electron is drawn based on drawing pattern data. The material is irradiated with a beam to draw a desired pattern.
A method in which the material is moved in each field and drawing is performed after the material is stopped is called a step-and-repeat method. With this method, the material is placed on the moving stage, and the stage is moved in field units. However, as the stage moves, the entire device moves due to the reaction, and the components such as the electron beam optical system column move. . This is the vibration generated as the stage moves.

[0003]

Because of this vibration,
If the drawing is started immediately after the stage is moved, the electron beam is not irradiated to a predetermined position of the material, and the drawing accuracy is deteriorated. Therefore, the drawing is waited for a certain period of time until the vibration is attenuated to a negligible degree after the stage is moved. Such time is a factor of deteriorating drawing throughput.

Regarding the vibration of the stage itself, there is no particular problem because the movement of the stage is constantly monitored by a length measuring system using a laser interferometer and the movement amount due to the vibration is dynamically corrected by deflection of the electron beam. However,
When the electron beam optical system column is displaced with respect to the stage due to vibration, the irradiation position of the electron beam on the material changes according to the displacement regardless of the movement of the stage. Depending on the system, the displacement of the electron beam irradiation position due to column vibration cannot be corrected.

The present invention has been made in view of the above circumstances, and an object thereof is to dynamically correct the irradiation position of a charged particle beam on a material to be drawn by vibration of a charged particle beam optical system column, It is intended to realize a charged particle beam drawing method capable of improving drawing throughput.

[0006]

A charged particle beam drawing method according to the present invention comprises a charged particle beam source, a focusing lens for focusing the charged particle beam from the charged particle beam source, and a deflection means for deflecting the charged particle beam. In the charged particle beam optical system column having a charged particle beam optical system column having the above, and a moving stage provided below the charged particle beam optical system column and on which the material to be drawn is placed, the charged particle beam optical system column The relationship between the amount of vibration at a specific location of the charged particle beam optical system column and the amount of correction of the charged particle beam irradiation position on the material to be drawn is determined and stored in the vibration mode that is uniquely determined by the natural frequency of At the time of drawing, the amount of vibration by the vibration mode at a specific location of the charged particle beam optical system column is measured, and the stored amount of vibration and correction are measured. It is characterized in that to perform the deflection correction of the charged particle beam based on the relationship between.

[0007]

The outline of the charged particle beam drawing apparatus is shown in FIG.
In this figure, reference numeral 1 is an anti-vibration table provided with an anti-vibration spring 2. On the anti-vibration table 1, a drawing chamber 3 having a moving stage on which a material to be drawn is placed is provided. A charged particle beam optical system column 4 is provided on the drawing chamber 3.
The column 4 in such an apparatus has one end fixed to the drawing chamber 3 and the other end open. As typical vibrations of such a system, the vibration modes shown in FIGS. 2 and 3 can be considered. FIG. 2 shows a primary vibration mode, and FIG. 2 shows a secondary vibration mode. In the vibration modes of FIGS. 2 and 3, even if the displacement or acceleration at any one point of the column is obtained, the behavior of the column cannot be correctly grasped.

The vibration mode of the column is peculiar to the column, and its shape does not change at node points (nodes), but the amplitude changes depending on the magnitude of the exciting force. As a result, the mode is measured in advance, and when the actual vibration occurs, the amplitude and shape of the entire column can be known by measuring the amplitude of the column eigenvalue at any one point of the column. As a result of an experiment by the inventor, it was found that the vibration of the column had a shape in which the column was bent in the first-order mode as shown in FIG. As a result, the optical axis of the charged particle beam in the column is bent according to the bending of the column, and the charged particle beam reaches the surface of the material to be drawn along the curved tangent line.

Therefore, an error occurs in the charged particle beam irradiation position on the material surface. This error can be obtained by measuring vibration or acceleration at at least one point of the column and multiplying the measured value by a coefficient according to a mode obtained in advance. By giving a signal corresponding to this error to the deflection system of the charged particle beam, it is possible to correct the error in the irradiation position of the charged particle beam due to vibration.

Therefore, in the charged particle beam drawing method according to the present invention, the vibration amount at a specific location of the charged particle beam optical system column in the vibration mode uniquely determined in advance by the natural frequency of the charged particle beam optical system column, The relationship with the correction amount of the charged particle beam irradiation position on the drawing material is obtained and stored, and at the time of actual drawing, the vibration amount at the specific position of the charged particle beam optical system column is measured and stored. The deflection of the charged particle beam is corrected based on the relation between the vibration amount and the correction amount.

In measuring the actual vibration, since the column 3 shown in FIG. 1 is in a state of floating on the vibration isolation table 1, the vibration of the vibration isolation spring itself should be taken into consideration. This vibration of the vibration isolation spring causes the column 3 and the drawing chamber 2 to integrally vibrate in the horizontal direction. Therefore, there is no need to correct the irradiation position of the charged particle beam. The system can measure the movement of the material vibrating stage and correct the amount of movement. The natural vibration of the column itself has a high frequency and is superposed on the vibration waveform of the vibration isolation spring. Therefore, to measure only the natural vibration of the column, use a filter that allows the signal from the vibrometer attached to the column to pass only the frequencies near the natural frequency of the column, or perform the Fourier transform of the signal to determine the frequency. It is necessary to analyze and extract only the necessary frequency components.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 shows an electron beam writing system for carrying out the method according to the invention. In the figure, 5 is a vibration isolation spring 6
A vibration isolation table having a drawing chamber 7 is provided on the vibration isolation table 6. A moving stage 9 on which a material 8 to be drawn is placed is housed in the drawing chamber 7. An electron beam optical system column 10 is installed on the drawing chamber 7. An electron gun 11, electron lenses 12, 1 are provided in the electron beam optical system column 10.
3, 14 and a deflector 15 are included. 16 is a drawing control unit, and this unit 16 is a memory 17
A deflection signal of the electron beam is created based on the drawing data stored in and is supplied to the deflector 15 via the adder circuit 18 or, although not shown, the blanking electrode of the electron beam optical system is blanked. Supply ranking signals,
The movement of the moving stage 9 is controlled.

Arbitrary vibrometers (which may be accelerometers) 19 and 20 are attached to the position corresponding to the deflector 15 of the column 10 and the position corresponding to the moving stage 9 of the drawing chamber 7. The output signals of the vibrometers 19 and 20 are supplied to the subtraction circuit 23 via the filter circuits 21 and 22, respectively. The output of the subtraction circuit 23 is supplied to the correction circuit 24. The correction circuit 24 uses the output of the subtraction circuit 23 and the memory 2
A deflection correction signal of the electron beam is created based on the data stored in 5, and is supplied to the adding circuit 18. The operation of such a configuration will be described below.

First, the data to be stored in the memory 25 is created before the desired drawing on the material is performed using the system of FIG. This data relates to the vibration of the primary mode of the column 10, and although not shown, a large number of vibrometers are attached from the electron gun portion at the top of the column 10 to the drawing chamber 7 and the stage 9 is moved to cause the vibration. The vibration mode (primary) of the column 10 is measured from the output of each vibrometer by forcibly adding. At this time, together with the vibration mode, the variation of the irradiation position of the electron beam on the material 8 is also measured according to the strength of each vibration. The measurement of the variation of the irradiation position of this electron beam is
For example, it can be determined by coating the material 8 with a resist, exposing the locus of the irradiation position of the electron beam, and then developing the locus, and measuring the locus with a scanning electron microscope or the like.

In this way, the variation of the irradiation position of the electron beam is obtained for each vibration intensity, and the data corresponding to this variation is stored in the memory 25. Note that this fluctuation amount is stored in the memory 25 against the vibration of the column in the primary mode.
Memorized in. Further, each vibration amount is measured by passing the output of each vibrometer only near the natural frequency of the column in the primary mode and passing through a filter that cuts both the low frequency side and the high frequency side. Furthermore, the measurement of this data may be performed for each device individually, and if it is the same model, it may be representatively measured for any device and the result may be applied to another device.

The data in the memory 25 is created as described above. Next, the drawing operation after the data is stored in the memory 25 will be described. First, a normal drawing operation when there is no vibration will be described. Electron gun 11
The electron beam from is finely focused by each focusing lens 12, 13 and 14, and is irradiated onto the material 8. The drawing control unit 16 drives the moving stage 9 based on the drawing data stored in the memory 17 to position the desired field of the material 8 under the electron beam optical axis. Then, a deflection signal for pattern drawing is supplied to the deflector 15 via the adder circuit 18 to deflect the electron beam according to the pattern. At this time, although not shown, the electron beam is appropriately blanked. By the stepwise movement of the stage 9 in units of fields and the deflection of the electron beam, a desired pattern is drawn on the material 8.

Now, as the stage 9 moves, the column 1
0 vibrates. The amount of this vibration is measured by the vibrometer 19 of the deflector 15 and the vibrometer 20 of the stage 9. The outputs of the vibrometers 19 and 20 pass only near the natural frequency of the vibration of the primary mode of the column 10, respectively, and a filter 21 that cuts both the low frequency side and the high frequency side.
22 is supplied. The vibrometer output based on only the vibration of the first-order mode that has passed through the filters 21 and 22 is supplied to the subtraction circuit 23, and the difference signal thereof is obtained. When obtaining the difference between the outputs of both vibrometers, not only the magnitude of vibration but also the phase is considered.

The difference signal is supplied to the correction circuit 24. The correction circuit 24 corresponds to the difference signal and stores it in the memory 25.
The correction signal stored in is read. This correction signal corresponds to the amount of change in the irradiation position of the electron beam due to the vibration of the primary mode of the column as described above. The signal read by the correction circuit 24 is added by the addition circuit 18
Is supplied to the deflector 15 and is added to the deflection signal for pattern drawing. As a result, even when the vibration of the column occurs, the variation of the irradiation position of the electron beam due to the vibration is always dynamically corrected, and the precise pattern drawing can be executed even during the vibration. Although not described in detail, the above correction operation is performed in X, Y
It is performed in two directions.

In the embodiment described above, the vibrometer 20 is attached to the drawing chamber 7 of the stage 9 and the vibrometer 19 is attached to the column 10 of the deflector 15 to obtain the difference between the vibrations of the two portions. The vibration may be measured by another method. For example, the drawing chamber 7 and the deflector 15 in the stage 9 part
The transmissibility of the amplitude between the columns 10 of the portions is obtained in advance, and the deflector 15 is determined from the vibration mode of the column 10.
The magnitude of deflection of the electron beam on the material surface corresponding to the amplitude of the part is obtained. Then, a vibrometer is attached only to the drawing chamber 7, and only the vibration in the drawing chamber is measured. Of course, the output of this vibrometer is passed through the filter 22 and the signal is supplied to the correction circuit 24. The correction circuit 24 multiplies the measured amplitude by the transmissibility to obtain the amplitude of the deflector 15 portion. The amplitude of the deflector 15 is multiplied by the coefficient according to the vibration mode to create the correction coefficient to be supplied to the adder circuit 18.

In the above example, the vibrometer is attached only to the drawing chamber 7, but the column 10 with the largest vibration is used.
A trigger vibrometer may be attached to the top of the. In that case, it is necessary to obtain the vibration transmissibility of the uppermost part of the column and the deflector 15 in advance. Of course, the output of the vibrometer at the top of the column is filtered and only the column-specific frequency in the primary mode is measured.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, although the electron beam writing apparatus has been described as an example, the present invention can be applied to an ion beam writing apparatus. Further, the place where the vibrometer is attached is not limited to the deflector portion, the stage portion, and the uppermost column. Further, although the filter is used to detect the vibration in the specific frequency region, the output of the vibrometer may be Fourier transformed to obtain only the specific frequency component.

[0022]

As described above, according to the charged particle beam drawing method based on the present invention, the specific portion of the charged particle beam optical system column in the vibration mode which is uniquely determined in advance by the natural frequency of the charged particle beam optical system column. And the amount of correction of the charged particle beam irradiation position on the material to be drawn are calculated and stored, and at the time of actual drawing, the vibration due to the vibration mode at a specific location of the charged particle beam optical system column The deflection of the charged particle beam is corrected based on the relationship between the stored vibration amount and the correction amount. The irradiation position can be dynamically corrected. As a result, when the moving stage of the material is moved, precise drawing can be executed even during the time when the vibration after the movement is still present, and the drawing throughput can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic body of a charged particle beam drawing apparatus.

FIG. 2 is a diagram for explaining vibration of a primary mode of a column.

FIG. 3 is a diagram for explaining vibration of a column in a secondary mode.

FIG. 4 shows an example of an electron beam writing system for implementing the method according to the invention.

[Explanation of symbols]

 5 Anti-vibration table 6 Anti-vibration spring 7 Drawing room 8 Drawing material 9 Moving stage 10 Electron beam optical system column 11 Electron gun 12, 13, 14 Focusing lens 15 Deflector 16 Drawing control unit 17, 25 Memory 18 Addition circuit 19, 20 Vibration meter 21,22 Filter 23 Subtraction circuit 24 Correction circuit

Claims (3)

[Claims] 1. A charged particle beam optical system column having a charged particle beam source, a focusing lens for focusing the charged particle beam from the charged particle beam source, a deflection means for deflecting the charged particle beam, and a charged particle beam. Charged particle beam optics in a vibration mode that is uniquely determined in advance by the natural frequency of the charged particle beam optical system column in a charged particle beam drawing device that has a moving stage that is placed under the optical system column and on which the material to be drawn is placed. The relationship between the amount of vibration at a specific position of the system column and the correction amount of the charged particle beam irradiation position on the material to be drawn is calculated and stored, and at the time of actual drawing, the relationship between the specific position of the charged particle beam optical system column The amount of vibration in the vibration mode is measured, and the deflection of the charged particle beam is corrected based on the stored relationship between the amount of vibration and the correction amount. A charged particle beam drawing method. 2. The charged particle beam drawing method according to claim 1, wherein vibrometers are provided in the deflecting means portion and the moving stage portion, and the correction amount of the deflection is obtained based on a difference signal between outputs of both vibrometers. 3. A vibrometer is provided at an arbitrary position of either the charged particle beam optical system column or the drawing chamber, the vibration of the deflection means is obtained from the output of the vibrometer, and the deflection correction amount is determined according to this vibration. The charged particle beam drawing method according to claim 1, wherein