JP5009199B2 - Charged particle beam drawing apparatus and charged particle beam drawing method - Google Patents

Description

  The present invention relates to a charged particle beam drawing apparatus and a charged particle beam drawing method, and for example, relates to a drawing apparatus that draws a pattern on a sample using an electron beam and a method for correcting the position of a stage in the apparatus.

  Lithography technology, which is responsible for the progress of miniaturization of semiconductor devices, is an extremely important process for generating a pattern among semiconductor manufacturing processes. In recent years, with the high integration of LSI, circuit line widths required for semiconductor devices have been reduced year by year. In order to form a desired circuit pattern on these semiconductor devices, a highly accurate original pattern (also referred to as a reticle or a mask) is required. Here, the electron beam (electron beam) drawing technique has an essentially excellent resolution, and is used for producing a high-precision original pattern.

FIG. 5 is a conceptual diagram for explaining the operation of a conventional variable shaping type electron beam drawing apparatus.
The operation of the variable electron beam (EB) drawing apparatus will be described below. In the first aperture 410, a rectangular opening for forming the electron beam 330, for example, a rectangular opening 411 is formed. Further, the second aperture 420 is formed with a variable shaping opening 421 for shaping the electron beam 330 having passed through the opening 411 of the first aperture 410 into a desired rectangular shape. The electron beam 330 irradiated from the charged particle source 430 and passed through the opening 411 of the first aperture 410 is deflected by the deflector, passes through a part of the variable shaping opening 421 of the second aperture 420, and passes through a predetermined range. The sample 340 mounted on a stage that continuously moves in one direction (for example, the X direction) is irradiated. That is, the drawing area of the sample 340 mounted on the stage in which the rectangular shape that can pass through both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is continuously moved in the X direction. Drawn on. A method of creating an arbitrary shape by passing both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is referred to as a variable shaping method.

  Here, the position of the above-described stage is measured by, for example, a laser interferometer. A highly accurate beam irradiation position can be set by feeding back the obtained position to the beam irradiation position. Therefore, a highly accurate mask can be drawn. When measuring the position of the stage, normally, two reflecting mirrors are arranged so that fluctuations in the wavelength variation of the laser used in the laser interferometer do not appear as position measurement errors. Then, one is arranged on a movable stage and the other is arranged at a fixed position near the stage. Such a differential two-beam (or multiple bundle) interferometer is used as the laser interferometer.

  However, the laser wavelength variation can be completely eliminated only when the distance between the interferometer and the stage position and the distance between the interferometer and the fixed mirror completely match. On the other hand, since it is necessary for the drawing apparatus to move the stage during drawing, it is impossible in principle to completely match the above-mentioned distances in all cases. Here, it is assumed that a laser generally used in an interferometer has a stability of ± 0.02 ppm (1 Hz or more). For example, when drawing a mask of about 6 inches, if the movable range of the stage is ± 75 mm, for example, a position measurement error of ± 75 mm × 0.02 ppm × 2 = ± 3.75 nm may occur. Therefore, depending on the drawing position in the mask, a fluctuation of about 3 nm may occur during drawing. Conventionally, this level of error has been negligible. However, with the recent miniaturization of patterns, this error cannot be ignored.

Here, an example of a technique for calibrating a laser wavelength using an iodine-stabilized helium neon laser is disclosed in the literature (for example, see Non-Patent Document 1).
Jun Ishikawa “633nm Laser Wavelength Calibration and Uncertainty”, AIST Metrology Report Vol. 4, no. July 1, 2005

  With the miniaturization of the circuit line width, the position measurement error caused by the wavelength variation of the laser used in the laser interferometer has become a level that cannot be ignored. However, conventionally, a method for eliminating this error has not been established.

  In view of the above, an object of the present invention is to provide a drawing apparatus and method that can overcome such problems and correct position measurement errors due to laser wavelength fluctuations.

A charged particle beam drawing apparatus according to one embodiment of the present invention includes:
A stage on which a sample is placed, which is movably arranged;
A reflection mirror arranged on the stage;
A laser length measuring device that irradiates the first laser light and measures the position of the stage using the reflected light reflected by the reflecting mirror;
An iodine stabilized laser light source for irradiating the iodine stabilized second laser light;
A detector that detects combined light obtained by combining the first and second laser lights on the coaxial optical axis and outputs a beat signal;
A frequency variation measuring unit that measures the frequency variation of the first laser beam using the beat signal;
A correction coefficient calculation unit for calculating a correction coefficient for correcting the position of the stage using the frequency fluctuation amount;
A drawing unit for irradiating a charged particle beam to a drawing position corrected using a correction coefficient and drawing a predetermined pattern on the sample;
It is provided with.

  A beat signal can be obtained by synthesizing the iodine stabilized second laser beam and the first laser beam on the coaxial optical axis. If the beat signal is used, the frequency fluctuation amount of the first laser beam can be measured. Then, the correction coefficient for the wavelength variation can be calculated using the frequency variation amount. By using this to correct an error in the position of the stage, it is possible to irradiate a charged particle beam to a highly accurate drawing position.

  Further, it is preferable to use a helium neon (HeNe) laser as the first and second laser beams.

The correction coefficient calculation unit calculates the correction coefficient in real time according to the movement of the stage during drawing,
It is preferable that the drawing unit irradiates the charged particle beam to the drawing position corrected using the correction coefficient calculated in real time.

  Further, it is preferable that the correction coefficient is calculated using the frequency fluctuation amount and the wavelength of the first laser beam.

The charged particle beam drawing method of one embodiment of the present invention includes:
Irradiating a first mirror light on a reflecting mirror placed on a stage on which a sample is placed and movably arranged, and measuring the position of the stage using the reflected light reflected by the reflecting mirror; ,
Irradiating a second laser beam stabilized with iodine;
Detecting a synthesized light obtained by synthesizing the first and second laser lights on the coaxial optical axis, and outputting a beat signal;
Using the beat signal to measure the frequency variation of the first laser beam;
A step of calculating a correction coefficient for correcting the position of the stage using the frequency fluctuation amount;
Irradiating a charged particle beam to a drawing position corrected using a correction coefficient and drawing a predetermined pattern on the sample; and
It is provided with.

  According to the present invention, it is possible to correct a position measurement error due to laser wavelength fluctuation. Therefore, a pattern can be drawn at a position where the position measurement error is corrected.

  Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and may be a beam using other charged particles such as an ion beam.

Embodiment 1 FIG.
FIG. 1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the first embodiment.
In FIG. 1, a drawing apparatus 100 is an example of a charged particle beam drawing apparatus. The drawing apparatus 100 includes a drawing unit 150 and a control unit 160. The drawing unit 150 includes a drawing chamber 103 and an electronic lens barrel 102 disposed on the upper portion of the drawing chamber 103. In the electron column 102, an electron gun 201, an illumination lens 202, a first aperture 203, a projection lens 204, a deflector 205, a second aperture 206, an objective lens 207, and a deflector 208 are provided. In the drawing chamber 103, an XY stage 105 and a motor 222 that drives the XY stage 105 are arranged. On the XY stage 105, a sample 101 to be drawn and a reflection mirror 30 used for a length measuring device using laser interference are arranged. A reflection mirror 32 serving as a reference position is fixed in the drawing chamber 103. In addition, a laser length measuring device 130, an iodine stabilized laser light source 136, an optical system 138, and a photodetector (APD) 140 are disposed outside the drawing chamber 103. Examples of the sample 101 include a wafer on which a semiconductor device is formed and an exposure mask that transfers a pattern to the wafer. Further, this mask includes, for example, mask blanks on which no pattern is formed. The control unit 160 includes a magnetic disk device 109, a drawing control circuit 110, a digital-analog converter (DAC) 112, an amplifier 114, a deflection control circuit 120, a stage control unit 122, a control computer 124, and a frequency counter 142. . The magnetic disk device 109, the drawing control circuit 110, the deflection control circuit 120, the stage control unit 122, the control computer 124, and the frequency counter 142 are connected to each other via a bus (not shown). Drawing data is stored in the magnetic disk device 109. In FIG. 1, description of components other than those necessary for describing the first embodiment is omitted. Needless to say, the drawing apparatus 100 may normally include other necessary configurations.

  Further, in FIG. 1, an XY stage is shown in FIG. 1 for easy understanding of the reflection mirrors 30 and 32, the laser length measuring device 130, the iodine stabilized laser light source 136, the optical system 138, the photodetector 140, and the frequency counter 142. Although only one direction (for example, the x direction) of the 105 moving directions is described, it is needless to say that the y direction is similarly configured.

FIG. 2 is a conceptual diagram showing an internal configuration of the laser length measuring apparatus of FIG. 1 and a configuration involved in correction of a measurement position error caused by wavelength variation of laser light and beam deflection.
In FIG. 2, a laser length measurement device 130 includes a length measurement helium neon (HeNe) laser light source 10, half mirrors 12, 14, reflection mirror 16, interferometers (IFM) 20, 22, light receivers 24, 26, and A length measuring unit 28 is provided. The optical system 138 includes analyzers 50 and 52, a half mirror 51, expanders 54 and 56, and ND filters 58 and 59. In FIG. 2, as in FIG. 1, only one direction (for example, the x direction) of the moving direction of the XY stage 105 is described for easy understanding of the explanation, but similarly for the y direction. Needless to say, it is composed.

FIG. 3 is a flowchart showing the main steps of the method for correcting the measurement position error caused by the wavelength variation of the laser beam in the first embodiment.
In step (S) 102, the length measuring laser light is irradiated from the length measuring HeNe laser light source 10 as a length measuring laser light irradiation step. The measuring HeNe laser light source 10 oscillates simultaneously at two frequencies with two orthogonal deflection surfaces (linear deflection). As the laser beam for length measurement (first laser beam), a HeNe laser is used in accordance with the laser irradiated from the iodine stabilized laser light source 136. The irradiated laser beam for length measurement is branched by the half mirror 12. One is used to measure the position of the XY stage 105. The other is used for correcting laser wavelength fluctuations.

In S <b> 104, the laser length measuring device 130 measures the position of the XY stage 105 as a stage position length measuring step. Specifically, the position of the XY stage 105 is measured as follows. One length measuring laser beam that has passed through the half mirror 12 is branched by the half mirror 14. One is reflected on the IFM 20, and the other is reflected by the reflection mirror 16 and irradiated on the IFM 22. One length measurement laser beam that has passed through the IFM 20 is applied to the reflection mirror 32 that indicates the reference position, and the reflected light is received by the light receiver 24 via the IFM 20. The other laser beam for length measurement that has passed through the IFM 22 is applied to the reflecting mirror 30 on the movable XY stage 105, and the reflected light is received by the light receiver 26 via the IFM 22. The signals of the reflected lights received by the light receivers 24 and 26 are transmitted to the length measuring unit 28. Here, it is assumed that the optical path length from the half mirror 14 to the IFM 20 and the optical path length from the half mirror 14 to the IFM 22 are the same. In this case, assuming that the wavelength of the laser beam for length measurement is λ, the reciprocating distance from the IFM 20 to the reflecting mirror 32 is Lr, and the reciprocating distance from the IFM 22 to the reflecting mirror 30 is Lm, the XY stage 105 is moved by the movement amount ΔL. In this case, the difference (phase change amount Δφ) between the phase of the reflected light received by the light receiver 24 and the phase of the reflected light received by the light receiver 26 can be expressed by the following equation (1).
(1) Δφ = (Lm−Lr) · 2π / λ = ΔL · 2π / λ

  Therefore, the movement amount ΔL of the XY stage 105 can be obtained by the length measurement unit 28 by dividing the phase change amount Δφ by 2π / λ. The position coordinate of the XY stage 105 can be measured by adding the movement amount ΔL to the base position.

Here, when the wavelength λ of the laser beam for length measurement fluctuates by Δλ, the observed phase change amount Δφ ′ is defined by the following equation (2).
(2) Δφ ′ = (Lm−Lr) · 2π / (λ + Δλ)

Therefore, the movement amount ΔL ′ of the XY stage 105 can be defined by the following equation (3) when the distance measurement unit 28 calculates the distance at the wavelength λ before the change from the observed phase change amount Δφ ′. it can.
(3) ΔL ′ = (Lm−Lr) · λ / (λ + Δλ)
= (Lm−Lr) − (Lm−Lr) · Δλ / (λ + Δλ)

Here, since Δλ is very small, when approximated as λ + Δλ≈λ, the equation (3) can be transformed into the following equation (4).
(4) ΔL′≈ (Lm−Lr) − (Lm−Lr) · Δλ / λ

  As described above, when the wavelength λ varies by Δλ, a position measurement error of (Lm−Lr) · Δλ / λ occurs with respect to the movement amount of the XY stage 105. If the movement amount of the XY stage 105 is, for example, ± 75 mm as described above and Δλ / λ is, for example, ± 0.02 ppm as described above, an error of about 3 nm is generated. Therefore, in the first embodiment, this error is corrected as follows.

  In S106, as an iodine stabilization laser light irradiation step, the iodine stabilization laser light source 136 irradiates iodine stabilized single wavelength HeNe laser light (second laser light).

  In S108, as a synthesis step, the iodine stabilized HeNe laser beam emitted from the iodine stabilized laser light source 136 and the other length measuring laser beam branched by the half mirror 12 are synthesized. Specifically, first, the other length measuring laser beam branched by the half mirror 12 passes through the ND filter 59, the expander 56, and the analyzer 52. Similarly, the iodine stabilized HeNe laser light passes through the ND filter 58, the expander 54, and the analyzer 50. The laser beam for length measurement is attenuated by the ND filter 59. Then, the expander 56 matches the wave front with the iodine stabilized HeNe laser light after passing through the expander 54. Then, one of the two frequencies is shielded by the analyzer 52. The iodine stabilized HeNe laser light is attenuated by the ND filter 58. Then, the expander 54 aligns the wavefront with the laser beam for length measurement after passing through the expander 56. Since the analyzer 50 originally has a single frequency, it passes through the analyzer 50 as it is. Then, the length measurement laser light that has passed through the ND filter 59, the expander 56, and the analyzer 52, and the iodine-stabilized HeNe laser light that has passed through the ND filter 58, the expander 54, and the analyzer 50 are included in the half mirror 51. Is synthesized on the coaxial optical axis. The arrangement order of the ND filter 59, the expander 56, and the analyzer 52 is not limited to this, and other different orders may be used. Similarly, the arrangement order of the ND filter 58, the expander 54, and the analyzer 50 is not limited to this, and may be other different orders.

In S110, as a light detection / beat signal output step, the light detector 140 detects the combined light of the laser beam for length measurement and the iodine stabilized HeNe laser light, and outputs a beat signal. The electric field intensity Em (t) of the laser beam for length measurement can be defined by the following formula (5), where Em is the amplitude, ωm is the oscillation frequency, φm is the phase, and t is the time.
(5) Em (t) = Em · cos (ωm · t + φm)

The electric field intensity Ei (t) of the iodine stabilized HeNe laser beam can be defined by the following formula (6), where Ei is the amplitude, ωi is the oscillation frequency, φi is the phase, and t is the time.
(6) Ei (t) = Ei · cos (ωi · t + φi)

The intensity I of the interference wave (synthetic wave) when the wavefronts of these two light waves are combined on the same optical axis can be defined by the following equation (7).
(7) I = | Em (t) + Ei (t) | ²
= (Em ² + Ei ² ) / 2 + Em · Ei · cos (Δω · t + Δφ)

  However, Δω = ωm−ωi and Δφ = φm−φi. When this interference wave is incident on a high-speed photodetector 140 such as an avalache photodiode (APD), a signal indicating the intensity I shown in Expression (7) is output from the photodetector 140. That is, a beat signal (AC signal) that vibrates at Δω shown in the second term of Expression (7) is output as its component.

In S112, as a frequency variation measuring step, the frequency counter 142 receives the output of the photodetector 140 and measures the frequency variation of the length measuring laser beam using the beat signal described above. The frequency counter 142 is an example of frequency variation measurement. Since Δω is defined by the difference between the oscillation frequency ωm of the laser beam for length measurement and the oscillation frequency ωi of the iodine stabilized HeNe laser beam, the oscillation frequency ωi of the iodine stabilized HeNe laser beam is assumed to be sufficiently stable. , Δω can be defined as the variation of the oscillation frequency ωm of the laser beam for length measurement. Here, in general, the frequency of the laser beam for the interferometer is stabilized by a technique such as temperature control, but the fluctuation is about several minutes to several hours. Therefore, by observing the frequency difference Δω (t = T) at an interval T shorter than the time, the frequency fluctuation amount Δfr of the laser beam for length measurement can be obtained by the following equation (8).
(8) Δfr (t = T) = Δω (t = 0) −Δω (t = T)

  The measured frequency fluctuation amount Δfr of the laser beam for length measurement is output to the control computer 124 as a difference frequency signal.

In S114, as a correction coefficient calculation step, the control computer 124 inputs the difference frequency signal and calculates a correction coefficient for correcting the position of the XY stage 105 using the frequency fluctuation amount Δfr. The control computer 124 is an example of a correction coefficient calculation unit. Using this frequency variation Δfr, if the wavelength of the laser beam for length measurement is λ, the wavelength variation is Δλ, and the speed of light is C, Δλ / λ is defined by the following equation (9).
(9) Δλ / λ = Δfr · λ / C

  Let Δλ / λ be a correction coefficient. The correction coefficient Δλ / λ is applied to the deflection control circuit 120. Here, the position coordinates (Xl, Yl) of the XY stage 105 obtained in the stage position length measuring step (S104) are input to the deflection control circuit 120. Further, the drawing control circuit 110 reads the drawing data from the magnetic disk device 109 and generates shot data after a plurality of stages of conversion. Then, shot data is output to the deflection control circuit 120. The shot data includes coordinate data (Xp, Yp) of a pattern to be shot.

In S114, as a deflection amount calculation step, the deflection control circuit 120 uses the position coordinates (Xl, Yl) of the XY stage 105, the pattern coordinate data (Xp, Yp), and the correction coefficient Δλ / λ to calculate the wavelength variation. A deflection amount (Xd, Yd) for deflecting the electron beam 200 to the drawing position in which is corrected is calculated. Here, the position error component ΔL ″ of the equation (4) can be obtained by the following equation (10).
(10) ΔL ″ = (Lm−Lr) · Δλ / λ

  Therefore, it is only necessary to correct the coordinate data (Xp, Yp) of the pattern of the XY stage 105 by ΔL ″ using the position error component ΔL ″ as a correction amount.

Therefore, the deflection amount (Xd, Yd) can be obtained by the following functional equation (11). However, the correction amount in the x direction is ΔLx ″, and the correction amount in the y direction is ΔLy ″.
(11) Xd = Fx (X1, Xp) + ΔLx ″
Yd = Fx (Yl, Yp) + ΔLy ″

  In S118, as a drawing step, the drawing unit 150 draws a desired pattern on the sample 101 by irradiating the drawing position corrected using the correction coefficient with the electron beam 200.

FIG. 4 is a diagram illustrating an example of a deflection position in the first embodiment.
In FIG. 4, a pattern 40 indicates a pattern that has already been drawn. When drawing a predetermined pattern, it is assumed that the coordinate data (Xp, Yp) of the pattern is within the deflectable area (main deflection area 42) of the deflector 208. A pattern can be drawn on the coordinate data (Xp, Yp) by deflecting the electron beam 200 by the deflection amount (Xd, Yd) from the beam center 44 in the deflectable region.

  The deflection control circuit 120 outputs a digital signal indicating the deflection amount (Xd, Yd) to the deflector 208. The digital signal is converted into an analog signal by the DAC 112, amplified by the amplifier 114, and applied to the deflector 208 as a deflection voltage. The operation in the drawing unit 150 is as follows.

  The electron beam 200 emitted from the electron gun 201 illuminates the entire first aperture 203 having a rectangular hole, for example, a rectangular hole, by the illumination lens 202. Here, the electron beam 200 is first formed into a rectangle, for example, a rectangle. Then, the electron beam 200 of the first aperture image that has passed through the first aperture 203 is projected onto the second aperture 206 by the projection lens 204. The position of the first aperture image on the second aperture 206 is deflection-controlled by the deflector 205, and the beam shape and size can be changed. Then, the electron beam 200 of the second aperture image that has passed through the second aperture 206 is focused by the objective lens 207, deflected by the deflector 208 controlled by the deflection control circuit 120, and controlled by the stage controller 122. The desired position of the sample 101 on the XY stage 105 that is continuously moved by being driven by the motor 222 is irradiated. Here, the control computer 124 calculates the correction coefficient in real time according to the movement of the XY stage 105 during drawing. Then, the drawing unit 150 irradiates the drawing position corrected using the correction coefficient calculated in real time with the electron beam 200. As a result, it is possible to correct position measurement errors caused by laser wavelength fluctuations in real time during drawing. For example, at each drawing start of each subfield, it is preferable to correct only the position error component ΔL ″ with respect to the drawing position of the subfield from the frequency fluctuation amount Δfr measured at the position of the XY stage 105 and the interval T at that time.

  As described above, according to the first embodiment, it is possible to correct the position measurement error due to the wavelength variation of the laser. Therefore, a pattern can be drawn at a position where the position measurement error is corrected. As a result, a highly accurate mask can be manufactured.

The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, in the above-described example, the error (ΔLx ″, ΔLy ″) is added to the deflection amount (Fx (Xl, Xp), Fx (Yl, Yp)) before correction in Expression (11). This is not a limitation. The deflection amount (Xd, Yd) may be obtained by the following equation (12) using the coordinate (Xl, Xp), the coordinate (Yl, Yp), and the frequency fluctuation amount (Δfrx, Δfry) obtained from the correction coefficient as arguments. Absent. However, the amount of frequency fluctuation in the x direction is Δfrx, and the amount of correction in the y direction is Δfry.
(12) Xd = Fx (X1, Xp) + Fcx (X1, Δfrx)
Yd = Fx (Yl, Yp) + Fcy (Yl, [Delta] fly)

  In addition, although descriptions are omitted for parts and the like that are not directly required for the description of the present invention, such as a device configuration and a control method, a required device configuration and a control method can be appropriately selected and used. For example, although the description of the control unit configuration for controlling the drawing apparatus 100 is omitted, it goes without saying that the required control unit configuration is appropriately selected and used.

  In addition, all charged particle beam writing methods and apparatuses that include elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 1. FIG. FIG. 2 is a conceptual diagram showing an internal configuration of the laser length measuring apparatus of FIG. 1 and a configuration involved in correction of a measurement position error caused by wavelength variation of laser light and beam deflection. FIG. 3 is a flowchart showing main steps of a method for correcting a measurement position error caused by wavelength variation of laser light in the first embodiment. 6 is a diagram illustrating an example of a deflection position in the first embodiment. FIG. It is a conceptual diagram for demonstrating operation | movement of the conventional variable shaping type | mold electron beam drawing apparatus.

Explanation of symbols

10 HeNe laser light source for length measurement 12, 14, 51 Half mirror 16, 30, 32 Reflection mirror 20, 22 IFM
24, 26 Light receiver 28 Measuring section 40 Pattern 42 Main deflection area 44 Center 50, 52 Analyzer 54, 56 Expander 58, 59ND filter 100 Drawing apparatus 101, 340 Sample 102 Electron barrel 103 Drawing chamber 105 XY stage 109 Magnetic Disk device 110 Drawing control circuit 112 DAC
114 Amplifier 120 Deflection Control Circuit 122 Stage Control Unit 124 Control Computer 130 Laser Length Measuring Device 136 Iodine Stabilized Laser Light Source 138 Optical System 140 Photodetector 142 Frequency Counter 150 Drawing Unit 160 Control Unit 200 Electron Beam 201 Electron Gun 202 Illumination Lens 203 , 410 First aperture 204 Projection lens 205, 208 Deflector 206, 420 Second aperture 207 Objective lens 222 Motor 330 Electron beam 411 Opening 421 Variable shaping opening 430 Charged particle source

Claims (5)

A stage on which a sample is placed, which is movably arranged;
A reflecting mirror disposed on the stage;
A laser length measuring device that irradiates a first laser beam and measures the position of the stage using the reflected light reflected by the reflection mirror;
An iodine stabilized laser light source for irradiating the iodine stabilized second laser light;
A detector that detects combined light obtained by combining the first and second laser beams on a coaxial optical axis and outputs a beat signal;
A frequency fluctuation measuring unit that measures the frequency fluctuation of the first laser beam using the beat signal;
A correction coefficient calculation unit for calculating a correction coefficient for correcting the position of the stage using the frequency fluctuation amount;
A drawing unit for drawing a predetermined pattern on the sample by irradiating a charged particle beam to a drawing position corrected using the correction coefficient;
A charged particle beam drawing apparatus comprising:   The charged particle beam drawing apparatus according to claim 1, wherein helium neon (HeNe) laser is used as the first and second laser beams. The correction coefficient calculation unit calculates the correction coefficient in real time according to the movement of the stage during drawing,
The charged particle beam drawing apparatus according to claim 1, wherein the drawing unit irradiates the charged particle beam to a drawing position corrected using the correction coefficient calculated in real time.   The charged particle beam drawing apparatus according to claim 1, wherein the correction coefficient is calculated using the amount of frequency fluctuation and the wavelength of the first laser beam. A first mirror light is applied to a reflecting mirror placed on a stage on which a sample is placed and movably placed, and the position of the stage is measured using the reflected light reflected by the reflecting mirror. Process,
Irradiating a second laser beam stabilized with iodine;
Detecting combined light obtained by combining the first and second laser lights on a coaxial optical axis, and outputting a beat signal;
Measuring the amount of frequency fluctuation of the first laser beam using the beat signal;
Calculating a correction coefficient for correcting the position of the stage using the frequency fluctuation amount;
Irradiating a charged particle beam to a drawing position corrected using the correction coefficient, and drawing a predetermined pattern on the sample;
A charged particle beam drawing method comprising:

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