Charged particle beam lithography apparatus, charged particle beam lithography method, and method for adjusting a phase difference plate

Abstract

To measure stage positions with good accuracy and prevent a decrease in drawing accuracy.SOLUTION: A charged particle beam drawing device comprises a length measurement unit that measures the position of a stage using first and second frequency laser beams, and a wall surface displacement measurement unit that measures the wall surface displacement of a drawing chamber using the first and second frequency laser beams. The length measurement unit has a first laser interferometer that is provided to a wall surface of the drawing chamber, synthesizes the first frequency laser beam having reciprocated between the first laser interferometer and the stage and the second frequency laser beam having been reflected inside of the first interferometer, and outputs a first beat signal. The wall surface displacement measurement unit has a second laser interferometer that is provided to the wall surface of the drawing chamber, synthesizes the first frequency laser beam having reciprocated between the second laser interferometer and a fixed mirror in the drawing chamber and the second frequency laser beam having been reflected inside of the second interferometer, and outputs a second beat signal. The stage position is determined on the basis of a difference between the first and second beat signals.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a charged particle beam lithography apparatus, a charged particle beam lithography method, and a method for adjusting a phase plate.

Background Art

[0002] With the high integration of LSIs, the circuit line width of semiconductor devices has been gradually miniaturized year by year. In order to form a desired circuit pattern on a semiconductor device, a method of reducing and transferring a high-precision original pattern (mask, or particularly what is used in a stepper or scanner is also called a reticle) formed on quartz onto a wafer using a reduction projection exposure apparatus is adopted. The high-precision original pattern is drawn by an electron beam lithography apparatus, and so-called electron beam lithography technology is used.

[0003] A conventional electron beam lithography apparatus deflects an electron beam based on the stage position while moving a stage on which a substrate to be drawn is placed in a vacuum chamber, and irradiates the electron beam at a desired position on the substrate to draw a pattern. The actuator that drives the stage is fixed to the wall surface of the vacuum chamber.

[0004] A laser interferometer is used to measure the position of the stage. The laser interferometer has a plurality of optical components such as a polarization beam splitter, a λ / 4 plate, and a mirror fixed to the chamber wall surface. When laser light is incident on the polarization beam splitter, it is divided into measurement light (length measurement light) directed toward the stage and reference light directed toward the mirror. The measurement light reflected by the stage and the reference light reflected by the mirror are combined by the polarization beam splitter to become interference light. The stage position is measured from the interference fringes generated by the optical path difference between the measurement light and the reference light.

[0005] The chamber wall to which the polarizing beam splitter is fixed is constantly subjected to deformation on the order of sub-nm to several nanometers due to environmental changes such as atmospheric pressure fluctuations and temperature fluctuations, as well as the reaction force of the actuator's stage drive. If the position of the polarizing beam splitter changes due to the deformation of the chamber wall, measurement errors in the stage position may occur, potentially reducing the accuracy of the drawing. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2016-157968 [Patent Document 2] Japanese Patent Publication No. 2000-049071 [Patent Document 3] Japanese Patent Publication No. 2002-151401 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention aims to provide a charged particle beam lithography apparatus, a charged particle beam lithography method, and a method for adjusting a phase difference plate that can accurately measure the stage position and prevent a decrease in drawing accuracy. [Means for solving the problem]

[0008] A charged particle beam lithography apparatus according to one aspect of the present invention has a drawing chamber in which a movable stage for placing a sample is installed inside, a drawing unit for drawing a pattern by irradiating the sample with a charged particle beam, a laser source that outputs laser light of a first frequency and a second frequency, a length measuring unit for measuring the position of the stage using the laser light of the first frequency and the second frequency, a wall displacement measuring unit for measuring the wall displacement of the drawing chamber using the laser light of the first frequency and the second frequency, and a drawing control unit for controlling the drawing unit, wherein the length measuring unit has a first laser interferometer provided on the wall of the drawing chamber, and the first laser interferometer and the stage The first laser interferometer detects a first combined beam of light obtained by combining the first frequency laser beam that traveled back and forth between the first laser interferometer and the second frequency laser beam reflected within the first laser interferometer, and outputs a first beat signal. The wall displacement measuring unit has a second laser interferometer provided on the wall of the drawing room, and detects a second combined beam of light obtained by combining the first frequency laser beam that traveled back and forth between the second laser interferometer and a fixed mirror fixed at a predetermined position in the drawing room, and the second frequency laser beam reflected within the second laser interferometer, and outputs a second beat signal. The drawing control unit calculates the position of the stage based on the difference between the first beat signal and the second beat signal.

[0009] A charged particle beam drawing method according to one aspect of the present invention comprises the steps of: outputting laser light of a first frequency and a second frequency from a laser source; detecting a first combined light obtained by combining the laser light of the first frequency that has traveled back and forth between the first laser interferometer and the stage, and the laser light of the second frequency reflected within the first laser interferometer, using a first laser interferometer provided on the wall of a drawing chamber in which a movable stage on which a sample is placed is installed, and outputting a first beat signal; detecting a second combined light obtained by combining the laser light of the first frequency that has traveled back and forth between the second laser interferometer and a fixed mirror fixed at a predetermined position in the drawing chamber, and the laser light of the second frequency reflected within the second laser interferometer, using a second laser interferometer provided on the wall of the drawing chamber, and outputting a second beat signal; calculating the position of the stage based on the difference between the first beat signal and the second beat signal; and controlling a drawing unit based on the calculated position of the stage to irradiate the sample with a charged particle beam and draw a pattern.

[0010] A method for adjusting a phase difference plate according to one aspect of the present invention involves controlling the position of a movable third phase difference plate provided between the first laser interferometer and the stage of the charged particle beam lithography apparatus, so that the laser light of the first frequency does not pass through the third phase difference plate during the lithography process, and adjusting the first phase difference plate provided between the branching section that branches the laser light and the first laser interferometer, so that the laser light of the first frequency does not pass through the third phase difference plate. board The laser light of the first frequency that passes through the third phase difference plate and travels back and forth between the first laser interferometer and the stage, and the laser light of the second frequency reflected within the first laser interferometer are separated and measured, and the first phase difference plate is adjusted based on the measurement results. [Effects of the Invention]

[0011] According to the present invention, the stage position can be measured with high accuracy, and a decrease in drawing accuracy can be prevented. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of an electron beam lithography apparatus according to an embodiment of the present invention. [Figure 2] This is a schematic diagram of the stage and laser interferometer according to the same embodiment. [Figure 3] Figures 3A and 3B show the optical paths of laser light. [Figure 4] Figures 4A and 4B show the optical paths of laser light. [Figure 5] Figures 5A, 5B, and 5C show the optical paths of laser light. [Figure 6] Figures 6A, 6B, and 6C show the optical paths of laser light. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0014] Figure 1 is a schematic diagram of an electron beam lithography apparatus according to an embodiment of the present invention. The lithography apparatus 1 shown in Figure 1 is a variable-shape type lithography apparatus comprising a lithography unit 2 that irradiates a substrate W to be lithographed with an electron beam to draw a desired pattern, and a control unit 3 that controls the operation of the lithography unit 2.

[0015] The drawing unit 2 includes a drawing chamber 2a for housing the sample W to be drawn, and an optical lens barrel 2b connected to the drawing chamber 2a. The optical lens barrel 2b is located on the upper surface of the drawing chamber 2a and shapes and deflects the electron beam, irradiating the sample W inside the drawing chamber 2a. The inside of the drawing chamber 2a and the optical lens barrel 2b are under reduced pressure to create a vacuum.

[0016] A stage 11 supporting the sample W is provided within the drawing chamber 2a. This stage 11 is movable in the horizontal plane in mutually orthogonal X-axis and Y-axis directions (hereinafter simply referred to as the X direction and Y direction). A sample W, such as a mask blank, is placed on the stage 11. A measuring unit 4 for measuring the position of the stage 11 is provided on the outer periphery of the drawing chamber 2a. The configuration of the measuring unit 4 will be described later.

[0017] Inside the optical lens barrel 2b, there are arranged an emission part 21 such as an electron gun that emits an electron beam B, an illumination lens 22 that condenses the electron beam B, a first shaping aperture 23 for beam shaping, a projection lens 24, a shaping deflector 25, a second shaping aperture 26 for beam shaping, an objective lens 27 that forms a beam focus on the sample W, and a sub-deflector 28 and a main deflector 29 for controlling the beam shot position with respect to the sample W.

[0018] In the drawing part 2, the electron beam B is emitted from the emission part 21 and irradiated onto the first shaping aperture 23 by the illumination lens 22. The first shaping aperture 23 has, for example, a rectangular opening. When the electron beam B passes through the first shaping aperture 23, the cross-sectional shape of the electron beam is shaped into a rectangular shape and projected onto the second shaping aperture 26 by the projection lens 24. The projection position can be deflected by the shaping deflector 25, and by deflecting the projection position, it is possible to control the shape and dimensions of the electron beam B. The electron beam B that has passed through the second shaping aperture 26 is irradiated with its focus being aligned with the sample W on the stage 11 by the objective lens 27. At this time, the shot position of the electron beam B with respect to the sample W on the stage 11 is deflected by the sub-deflector 28 and the main deflector 29.

[0019] The control unit 3 includes a storage unit 3a that stores drawing data, a shot data generation unit 3b that processes the drawing data to generate shot data, and a drawing control unit 3c that controls the drawing part 2. Note that the shot data generation unit 3b and the drawing control unit 3c may be constituted by hardware such as an electric circuit, or may be constituted by software such as a program that executes each function, or may be constituted by a combination of both of them.

[0020] The drawing data is data that has been converted into a format for the drawing device 1 so that it can be input into the drawing device 1 from design data (layout data) created by semiconductor integrated circuit designers, etc., and is input from an external device to the storage unit 3a and stored there. For example, a magnetic disk device or a semiconductor disk device (flash memory) can be used as the storage unit 3a.

[0021] Furthermore, the aforementioned design data typically contains numerous minute patterns (such as geometric shapes), resulting in a large data size. If this design data is directly converted to another format, the amount of data after conversion will increase even further. For this reason, drawing data is compressed through methods such as data hierarchicalization and pattern array display. Such drawing data defines the drawing pattern for a chip area, or the drawing pattern for a virtual chip area created by virtually merging multiple chip areas with the same drawing conditions to represent a single chip.

[0022] The shot data generation unit 3b divides the drawing pattern defined by the drawing data into multiple stripe-shaped (strip-shaped) stripe regions (with the long side being the X direction and the short side being the Y direction), and further divides each stripe region into numerous matrix-like sub-regions. The shot data generation unit 3b determines the shape, size, and position of the figures within each sub-region, and further divides the figures into multiple sub-regions that can be drawn in a single shot, thereby generating shot data. The length of the stripe region in the short direction (Y direction) is set to a length that allows the electron beam B to be deflected by the main deflection.

[0023] When drawing a pattern, the drawing control unit 3c moves the stage 11 in the longitudinal direction (X direction) of the stripe area, positions the electron beam B in each sub-area using the main deflector 29, and shoots the electron beam B at predetermined positions in the sub-area using the sub-deflector 28 to draw the figure. After the drawing of one stripe area is completed, the stage 11 is moved in the Y direction in steps, and the next stripe area is drawn. This is repeated to draw the entire drawing area of ​​the sample W with the electron beam B. During drawing, since the stage 11 is moving continuously in one direction, the main deflector 29 tracks the drawing origin of the sub-area so that the drawing origin follows the movement of the stage 11.

[0024] In this way, the electron beam B is deflected by the sub-deflector 28 and the main deflector 29, and its irradiation position is determined as it follows the continuously moving stage 11. By continuously moving the stage 11 in the X direction and making the shot position of the electron beam B follow the movement of the stage 11, the drawing time can be shortened.

[0025] The drawing control unit 3c uses the position information of the stage 11 measured by the measuring side unit 4 to control the sub-deflector 28 and the main deflector 29, that is, to control the beam irradiation position.

[0026] Next, the configuration of the measuring side section 4 will be described. As shown in Figure 2, there are two measuring side sections 4. The measuring side section 4 located on the lower side in Figure 2 (first measuring section) measures the position of the stage 11 in the Y direction. The measuring side section 4 located on the left side in Figure 2 (second measuring section) measures the position of the stage 11 in the X direction. Since these two measuring side sections 4 have the same structure, their common structure will be described below.

[0027] The measuring side section 4 includes a laser source 5, a branching section 6 that branches the laser light emitted from the laser source 5, phase difference plates 9 and 10, a length measuring section 7 that measures the distance to the stage 11 using the laser light, and a wall displacement measuring section 8 that measures the wall displacement of the drawing chamber 2a. For example, a helium-neon laser can be used for the laser light. For example, a half mirror can be used for the branching section 6.

[0028] The length measuring unit 7 includes a laser interferometer 70 and a light receiving unit 71. The light receiving unit 71 can be, for example, a photodiode. The laser interferometer 70 (first laser interferometer) is housed in a housing chamber R1 formed on the side wall surface of the drawing chamber 2a and is mounted on the side wall surface.

[0029] The wall displacement measuring unit 8 includes a laser interferometer 80, a fixed mirror 88, and a light receiving unit 81. The light receiving unit 81 is, for example, a photodiode. The laser interferometer 80 (second laser interferometer) is housed in a housing chamber R2 formed in the side wall surface of the drawing chamber 2a and is mounted on the side wall surface. The fixed mirror 88 is fixed at a predetermined position near the stage 11 inside the drawing chamber 2a.

[0030] The laser source 5, branching section 6, phase difference plates 9 and 10, light receiving section 71, light receiving section 81, etc., are located outside the housing of the drawing section 2.

[0031] Although the inside of the drawing chamber 2a is in a vacuum state, deformation occurs on the side wall surface due to environmental changes such as atmospheric pressure fluctuations and temperature fluctuations. Furthermore, if the actuator (not shown) that drives the stage 11 is fixed to the side wall surface of the drawing chamber 2a, deformation can also occur on the side wall surface due to the reaction force of the actuator driving the stage. As described above, the laser interferometer 70 of the length measuring unit 7, which measures the distance to the stage 11, is attached to the side wall surface of the drawing chamber 2a. Therefore, in order to accurately calculate the distance to the stage 11, it is necessary to consider the changes in the side wall surface of the drawing chamber 2a. The wall displacement measuring unit 8 in this embodiment measures the change (displacement) of the side wall surface of the drawing chamber 2a.

[0032] The laser source 5 emits laser light of different frequencies. For example, the laser source 5 emits laser light of frequency f1 and laser light of frequency f2.

[0033] Laser beams of frequencies f1 and f2 are split at the branching section 6 and proceed to laser interferometers 70 and 80, respectively. A phase difference plate 9 (first phase difference plate) is provided in the optical path between the branching section 6 and the laser interferometer 70. A phase difference plate 10 (second phase difference plate) is provided in the optical path between the branching section 6 and the laser interferometer 80. Phase difference plates 9 and 10 are, for example, a rotating λ / 2 phase difference plate, a rotating λ / 4 phase difference plate, a rotating compensating plate, etc.

[0034] The laser light emitted from the laser source 5 is reflected by mirrors (not shown) or the like to guide it to the laser interferometers 70 and 80. However, this reflection can cause a phase shift in polarization, potentially leading to a reversal of frequencies f1 and f2, or noise due to crosstalk components generated by the tilt and ellipticization of polarization. Phase difference plates 9 and 10 are installed to prevent such frequency reversals and to remove noise. As a result, the two laser frequencies f1 and f2 are identical in laser interferometers 70 and 80.

[0035] As shown in Figures 3A and 3B, the laser interferometer 70 includes a polarizing beam splitter (PBS) 72, and reflectors 73 and 74.

[0036] As shown in Figure 3A, the laser light (measuring light) with frequency f1 travels in a straight line across the polarization separation surface 72a of the polarization beam splitter 72, is reflected by the reflector 12 on the stage 11, and is reflected sequentially by the polarization separation surface 72a, reflector 73, reflector 74, reflector 73, and polarization separation surface 72a, and travels towards the reflector 12. The laser light reflected again by the reflector 12 travels in a straight line across the polarization separation surface 72a and proceeds to the light receiving unit 71.

[0037] On the other hand, as shown in Figure 3B, the laser light with frequency f2 (reference light) is reflected sequentially by the polarization separation surface 72a, the reflector 74, and the polarization separation surface 72a before proceeding to the light receiving unit 71.

[0038] The light receiving unit 71 detects the first combined light obtained by combining the measurement light and the reference light on the coaxial optical axis and outputs a first beat signal fm.

[0039] As shown in Figures 4A and 4B, the laser interferometer 80 includes a polarizing beam splitter (PBS) 82, and reflectors 83 and 84.

[0040] As shown in Figure 4A, the laser light (measuring light) with frequency f1 travels in a straight line across the polarization separation surface 82a of the polarization beam splitter 82, is reflected by the fixed mirror 88, and is reflected sequentially by the polarization separation surface 82a, reflecting mirror 83, reflecting mirror 84, reflecting mirror 83, and polarization separation surface 82a, before traveling towards the fixed mirror 88. The laser light reflected again by the fixed mirror 88 travels in a straight line across the polarization separation surface 82a and proceeds to the light receiving unit 81.

[0041] On the other hand, as shown in Figure 4B, the laser light with frequency f2 (reference light) is reflected sequentially by the polarization separation surface 82a, the reflector 84, and the polarization separation surface 82a before proceeding to the light receiving unit 81.

[0042] The light-receiving unit 81 detects a second combined light formed by combining the measuring light and the reference light on the coaxial optical axis, and outputs a second beat signal fr.

[0043] The first beat signal fm includes the stage movement component and the side wall displacement component of the drawing chamber 2a. The second beat signal fr corresponds to the side wall displacement component of the drawing chamber 2a. The beat signal difference (fm-fr), which is the difference between the first beat signal fm and the second beat signal fr, is determined as the stage position (stage movement amount). By determining the difference between the first beat signal fm and the second beat signal fr, the side wall displacement component of the drawing chamber 2a is canceled out, and the stage movement amount can be measured accurately.

[0044] The drawing control unit 3c acquires the measurement results from the light receiving units 71 and 81 and determines the stage position from the beat signal difference (fm-fr). Based on the determined stage position, the drawing control unit 3c controls the drawing unit 2 and performs the drawing process. In this way, according to this embodiment, the position of the stage 11 can be accurately determined by considering the displacement of the side wall surface of the drawing chamber 2a, and the beam can be irradiated to the desired position, thereby preventing a decrease in drawing accuracy.

[0045] Furthermore, the polarization direction is adjusted so that the frequency f1 (stage measurement frequency) of the laser beam traveling to stage 11 (reflector 12 on stage 11) and the frequency f1 (fixed mirror measurement frequency) of the laser beam traveling to fixed mirror 88 are the same. This makes it possible to match the shift direction of the beat signal associated with the displacement of the object being measured between the laser interferometer 70 and the laser interferometer 80.

[0046] As described above, in this embodiment, phase difference plates 9 and 10 are installed in front of the laser interferometers 70 and 80 so that the frequency f1 of the measurement light and the frequency f2 of the reference light are the same, respectively, thereby reducing the crosstalk component. Adjustment of the phase difference plates 9 and 10 is necessary to reduce the crosstalk component.

[0047] It is preferable to adjust the phase difference plates 9 and 10 without opening the drawing chamber 2a to the atmosphere. Therefore, as shown in Figures 5A, 5B, and 5C, a movable phase difference plate 30 (third phase difference plate), such as a flap type, is installed in the optical path of the laser light in the drawing chamber 2a, that is, between the polarizing beam splitter 72 and the reflector 12 on the stage 11. The phase difference plate 30 is, for example, a λ / 4 plate.

[0048] Furthermore, as shown in Figures 6A, 6B, and 6C, a movable phase difference plate 32 (fourth phase difference plate), such as a flap type, is installed between the polarizing beam splitter 82 and the fixed mirror 88. The phase difference plate 32 is, for example, a λ / 4 plate. The positions of the phase difference plates 30 and 32 are controlled by the drawing control unit 3c.

[0049] As shown in Figures 5A and 6A, during the drawing process (pattern drawing), the measuring light with frequency f1 is prevented from passing through the phase difference plates 30 and 32.

[0050] As shown in Figures 5B, 5C, 6B, and 6C, when adjusting the phase difference plates 9 and 10, the phase difference plates 30 and 32 are positioned on the optical path of the measuring light of frequency f1.

[0051] As shown in Figure 5B, in the laser interferometer 70, the measurement light at frequency f1 travels in a straight line through the polarization separation surface 72a of the polarization beam splitter 72, passes through the phase difference plate 30, is reflected by the reflector 12 on the stage 11, passes through the phase difference plate 30 again, travels in a straight line through the polarization separation surface 72a, and proceeds to the light receiving unit 79. The measurement result in the light receiving unit 79 is input to a measuring device such as an oscilloscope. As shown in Figure 5C, the reference light at frequency f2 is reflected sequentially by the polarization separation surface 72a, the reflector 74, and the polarization separation surface 72a, and proceeds to the light receiving unit 71. The measurement result in the light receiving unit 71 is input to a measuring device. In this way, the measurement light at frequency f1 and the reference light at frequency f2 can be measured separately, and the measurement results can be input to a measuring device.

[0052] As shown in Figure 6B, in the laser interferometer 80, the measurement light at frequency f1 travels in a straight line through the polarization separation surface 82a of the polarization beam splitter 82, passes through the phase difference plate 32, is reflected by the fixed mirror 88, passes through the phase difference plate 32 again, travels in a straight line through the polarization separation surface 82a, and proceeds to the light receiving unit 89. The measurement result at the light receiving unit 89 is input to the measuring device. As shown in Figure 6C, the reference light at frequency f2 is reflected sequentially by the polarization separation surface 82a, the reflector 84, and the polarization separation surface 82a, and proceeds to the light receiving unit 81. The measurement result at the light receiving unit 81 is input to the measuring device. In this way, the measurement light at frequency f1 and the reference light at frequency f2 can be measured separately, and the measurement results can be input to the measuring device.

[0053] If the measurement result of the measurement light or reference light input to the measuring device contains a crosstalk component, a beat signal of frequency f1-f2 will be detected in addition to frequencies f1 and f2. While checking the detection result by the measuring device, the phase difference plates 9 and 10 are adjusted to reduce the beat signal intensity. For example, the beat signal intensity is reduced by rotating the phase difference plates 9 and 10 (rotating λ / 2 phase difference plate, rotating λ / 4 phase difference plate, rotating compensating plate, etc.) around the axis of rotation of the incident light.

[0054] In the above embodiment, it is preferable to place the laser interferometer 70 and the laser interferometer 80 close together so that the wall displacement of the drawing room 2a is approximately the same. Depending on the distance between the laser interferometer 70 and the laser interferometer 80, the difference in wall displacement between the installation location of the laser interferometer 70 and the installation location of the laser interferometer 80 may be calculated based on atmospheric pressure and temperature, and the stage position may be corrected accordingly.

[0055] In the above embodiment, a configuration was described in which two phase difference plates 9 and 10 are provided between the laser source 5 and the laser interferometers 70 and 80. However, a configuration in which either one of the phase difference plates 9 or 10 is omitted is also possible. Alternatively, the phase difference plates 9 and 10 may be omitted, and one phase difference plate may be placed between the laser source 5 and the branching section 6. In this case, the laser light emitted from the laser source 5 passes through the phase difference plate, is branched at the branching section 6, and guided to the laser interferometers 70 and 80. The frequency of the laser light is adjusted by the phase difference plate.

[0056] In the above embodiment, a lithography apparatus that irradiates with an electron beam was described, but it may also irradiate with other charged particle beams such as ion beams. Furthermore, the lithography apparatus may be a multi-beam lithography apparatus.

[0057] It should be noted that the present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Moreover, components from different embodiments may be appropriately combined. [Explanation of Symbols]

[0058] 1 Drawing device 2. Drawing section 2a drawing room 2b Optical barrel 3. Control Unit 3a Storage section 3b Shot data generation unit 3c Drawing control unit 4. Side section 5. Laser source 6 Branching point 7. Measuring section 8. Wall surface displacement measurement section 11 stages 70, 80 Laser Interferometer

Claims

1. It has a drawing chamber with a movable stage for placing a sample installed inside, and a drawing unit that draws a pattern by irradiating the sample with a charged particle beam, A laser source that outputs laser light of a first frequency and a second frequency, A length measuring unit that measures the position of the stage using laser light of the first frequency and the second frequency, A wall displacement measuring unit that measures the wall displacement of the drawing room using laser light of the first frequency and the second frequency, A drawing control unit that controls the drawing unit, Equipped with, The length measuring unit has a first laser interferometer provided on the wall surface of the drawing chamber, detects a first combined light obtained by combining the first frequency laser light that travels back and forth between the first laser interferometer and the stage and the second frequency laser light reflected within the first laser interferometer, and outputs a first beat signal. The wall displacement measuring unit has a second laser interferometer provided on the wall of the drawing room, and detects a second combined light obtained by combining the first frequency laser light that travels back and forth between the second laser interferometer and a fixed mirror fixed at a predetermined position in the drawing room, and the second frequency laser light reflected within the second laser interferometer, and outputs a second beat signal. The charged particle beam lithography apparatus is characterized in that the drawing control unit calculates the position of the stage based on the difference between the first beat signal and the second beat signal.

2. The laser light of the first frequency and the second frequency output from the laser source is split by the branching unit and input to the first laser interferometer and the second laser interferometer, respectively. The charged particle beam lithography apparatus according to claim 1, further comprising at least one of a first phase difference plate provided between the branching portion and the first laser interferometer, and a second phase difference plate provided between the branching portion and the second laser interferometer.

3. The laser light of the first frequency and the second frequency output from the laser source is split by the branching unit and input to the first laser interferometer and the second laser interferometer, respectively. A first phase difference plate is provided between the branching section and the first laser interferometer, A second phase difference plate is provided between the branching section and the second laser interferometer, A movable third phase difference plate is provided between the first laser interferometer and the stage, A movable fourth phase difference plate is provided between the second laser interferometer and the fixed mirror, Furthermore, The charged particle beam lithography apparatus according to claim 1, wherein the drawing control unit prevents the laser light of the first frequency from passing through the third phase difference plate and the fourth phase difference plate during the drawing process, and controls the positions of the third phase difference plate and the fourth phase difference plate so that the laser light of the first frequency passes through the third phase difference plate and the fourth phase difference plate during the adjustment of the first phase difference plate and the second phase difference plate.

4. A process of outputting laser light of a first frequency and a second frequency from a laser source, A first laser interferometer is installed on the wall of a drawing chamber in which a movable stage for placing a sample is located. The first laser interferometer is used to detect a first combined beam of light obtained by combining the first laser beam of a first frequency that travels back and forth between the first laser interferometer and the stage, and the second laser beam of a second frequency that is reflected within the first laser interferometer, and a first beat signal is output. A step of using a second laser interferometer provided on the wall of the drawing room to detect a second combined light obtained by combining the first frequency laser light that travels back and forth between the second laser interferometer and a fixed mirror fixed at a predetermined position in the drawing room, and the second frequency laser light reflected within the second laser interferometer, and outputting a second beat signal; A step of calculating the position of the stage based on the difference between the first beat signal and the second beat signal, The process involves controlling the drawing unit based on the calculated position of the stage, and irradiating the sample with a charged particle beam to draw a pattern, A charged particle beam lithography method comprising the following features.

5. The laser light of the first frequency and the laser light of the second frequency output from the laser source is branched at the branching section. The charged particle beam lithography method according to claim 4, further comprising at least one of the following steps: passing one of the branched laser beams through a first phase difference plate provided between the branching portion and the first laser interferometer; and passing the other of the branched laser beams through a second phase difference plate provided between the branching portion and the second laser interferometer.

6. The process of splitting the first frequency and second frequency laser light output from the laser source at a branching section, The process involves one of the branched laser beams passing through a first phase difference plate provided between the branching section and the first laser interferometer, The process involves the other branch of the laser beam passing through a second phase difference plate provided between the branching section and the second laser interferometer, A step of controlling the position of a movable third phase difference plate provided between the first laser interferometer and the stage, and the position of a movable fourth phase difference plate provided between the second laser interferometer and the fixed mirror, Furthermore, During the drawing process, the positions of the third phase difference plate and the fourth phase difference plate are controlled so that the laser light of the first frequency does not pass through the third phase difference plate and the fourth phase difference plate. The charged particle beam writing method according to claim 5, wherein when adjusting the first phase difference plate and the second phase difference plate, the positions of the third phase difference plate and the fourth phase difference plate are controlled so that the laser light of the first frequency passes through the third phase difference plate and the fourth phase difference plate.

7. A method for adjusting the first phase difference plate of the charged particle beam lithography apparatus according to claim 2, The position of a movable third phase difference plate, provided between the first laser interferometer and the stage, is controlled so that the laser light of the first frequency does not pass through the third phase difference plate during drawing processing, and so that the laser light of the first frequency passes through the third phase difference plate when the first phase difference plate is being adjusted. A method for adjusting a phase difference plate, comprising separating and measuring the laser light of a first frequency that has passed through the third phase difference plate and traveled back and forth between the first laser interferometer and the stage, and the laser light of a second frequency that has been reflected within the first laser interferometer, and adjusting the first phase difference plate based on the measurement results.

8. A method for adjusting the second phase difference plate of the charged particle beam lithography apparatus according to claim 2, The position of the movable fourth phase difference plate, which is provided between the second laser interferometer and the fixed mirror, is controlled so that the laser light of the first frequency does not pass through the fourth phase difference plate during drawing processing, and so that the laser light of the first frequency passes through the fourth phase difference plate when the second phase difference plate is adjusted. A method for adjusting a phase difference plate, comprising separating and measuring the laser light of the first frequency that has passed through the fourth phase difference plate and traveled back and forth between the second laser interferometer and the fixed mirror, and the laser light of the second frequency that has been reflected within the second laser interferometer, and adjusting the second phase difference plate based on the measurement results.

9. The charged particle beam lithography apparatus is provided with the first phase difference plate and the second phase difference plate, The position of a movable third phase difference plate, provided between the first laser interferometer and the stage, is controlled so that the laser light of the first frequency does not pass through the third phase difference plate during drawing processing, and so that the laser light of the first frequency passes through the third phase difference plate when the first phase difference plate is being adjusted. A method for adjusting a phase difference plate according to claim 8, comprising separating and measuring the laser light of the first frequency that has passed through the third phase difference plate and traveled back and forth between the first laser interferometer and the stage, and the laser light of the second frequency that has been reflected within the first laser interferometer, and adjusting the first phase difference plate based on the measurement results.

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