Charged particle beam drawing device, emission data correction method, and charged particle beam drawing method

Abstract

The invention provides a charged particle beam drawing apparatus, an emission data correction method, and a charged particle beam drawing method. A charged particle beam drawing device according to one embodiment of the present invention is provided with: an emission unit that emits a charged particle beam; a stage on which a substrate to be drawn is placed and which is movable; an emission data correction unit that corrects emission data generated from drawing data by using a relationship between the table speed obtained in advance and a positional shift amount caused by a change in the table speed; and a drawing unit that uses the corrected emission data to irradiate the substrate with the charged particle beam, and sequentially draws a pattern on each of a plurality of strip-shaped regions formed by dividing a drawing region of the substrate by a predetermined width.

Description

Technical Field

[0001] The present invention relates to a charged particle beam drawing apparatus, a method for correcting emission data, and a charged particle beam drawing method. Background Art

[0002] With the high integration of LSIs, the circuit line widths required for semiconductor devices have been miniaturized year by year. In order to form a desired circuit pattern on a semiconductor device, the following method is adopted: A reduction projection exposure apparatus is used to reduce and transfer a high-precision original pattern (a mask, or particularly an intermediate mask used in a stepper or a scanner) formed on quartz onto a wafer. The high-precision original pattern is drawn by an electron beam drawing apparatus using so-called electron beam lithography technology.

[0003] In an electron beam drawing apparatus, a pattern is drawn on a substrate on a moving stage while measuring the stage position. Vibration generated due to the movement of the stage deteriorates the drawing accuracy. Therefore, conventionally, vibration damping control based on a vibration isolation table has been performed, but there are restrictions on the mechanical vibration characteristics, and sometimes vibration cannot be effectively damped. For example, in a slender structure such as an optical column, if a vibration mode that excites the structure to bend is generated, it is hardly detected by the vibration isolation table.

[0004] Japanese Patent Laid-Open No. 9-246134 discloses that a sensor is installed on an optical column, the sensor signal is analyzed, the beam offset amount is calculated, and correction is performed. However, it is always affected by the noise of the sensor, and the beam offset amount cannot be sufficiently corrected. In addition, a system for processing the sensor signal and noise needs to be set according to the type and number of sensors, which poses a cost problem. Summary of the Invention

[0005] A charged particle beam drawing apparatus according to one aspect of the present invention includes: an emission unit that emits a charged particle beam; an emission data generation unit that generates emission data based on drawing data; a stage that mounts a substrate to be drawn and is movable; a storage device that stores position offset amount data indicating a position offset amount of a beam irradiation position in the substrate caused by mechanical vibration generated due to the movement of the stage; an emission data correction unit that corrects the emission data to correct the position offset amount based on the position offset amount data; and a drawing unit that irradiates a beam onto the substrate mounted on the stage moving in a predetermined direction using the corrected emission data to draw a pattern. The drawing unit sequentially draws a pattern on each of a plurality of strip-shaped regions obtained by dividing a drawing region of the substrate into a predetermined width. The emission data correction unit corrects at least the emission data corresponding to the beam irradiated to the leading portion of each strip-shaped region. Brief Description of the Drawings

[0006] Figure 1 It is a schematic diagram of an electron beam lithography apparatus according to an embodiment of the present invention.

[0007] Figure 2 It is a diagram for explaining an example of a lithography operation.

[0008] Figure 3A It is a graph showing an example of a change in stage speed, Figure 3B It is a graph showing an example of a change in beam irradiation position offset.

[0009] Figure 4 It is a flowchart for explaining a method of lithographing an evaluation pattern.

[0010] Figure 5 It is a flowchart for explaining a method of lithographing a reference pattern.

[0011] Figure 6 It is a flowchart for explaining an electron beam lithography method according to the above embodiment. Detailed Embodiment

[0012] Hereinafter, embodiments of the present invention will be described based on the drawings. In the embodiments, as an example of a charged particle beam, a configuration using an electron beam will be described. 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.

[0013] Figure 1 It is a schematic configuration diagram of the lithography apparatus of the present embodiment. The lithography apparatus includes a control unit 1 and a lithography unit 2. The lithography apparatus is an example of a multi-charged particle beam lithography apparatus. The lithography unit 2 includes an electron optical column 20 and a lithography chamber 30. In the electron optical column 20, an electron source 21, an illumination lens 22, a shaping aperture array substrate 23, a blanking aperture array substrate 24, a reduction lens 25, a limiting aperture member 26, an objective lens 27, and a deflector 28 are arranged. Both the reduction lens 25 and the objective lens 27 are composed of electromagnetic lenses, and a reduction optical system is formed by the reduction lens 25 and the objective lens 27.

[0014] An XY stage 32 is arranged in the lithography chamber 30. A substrate 40 to be lithographed is placed on the XY stage 32. The substrate 40 is an exposure mask for manufacturing a semiconductor device, a semiconductor substrate (silicon wafer) for manufacturing a semiconductor device, a mask blank coated with a resist and not yet lithographed, or the like.

[0015] A mirror 34 for position measurement using a laser is arranged on the XY stage 32.

[0016] The control unit 1 includes storage devices 17 and 18 such as a disk device, a control computer 10, a lithography control circuit 14, a laser length measuring device 15, a stage control unit 16, and the like.

[0017] The control computer 10 includes a transmitted data generation unit 11, a position offset calculation unit 12, and a transmitted data correction unit 13. The transmitted data generation unit 11, the position offset calculation unit 12, and the transmitted data correction unit 13 may also be constituted by software such as a program executed by a computer. Alternatively, they may be constituted by hardware such as electrical equipment or electronic equipment. Alternatively, they may be constituted by a combination of software and hardware. Alternatively, they may be constituted by a combination of firmware and hardware.

[0018] The laser length measuring device 15 irradiates a laser beam onto the mirror 34, receives the reflected light thereof, measures the position of the XY stage 32, and outputs the stage position to the control computer 10.

[0019] The stage control unit 16 outputs a stage control signal to control the speed and acceleration of the XY stage 32.

[0020] The drawing control circuit 14 controls and drives the respective devices of the drawing unit 2.

[0021] In Figure 1 it describes the components necessary for explaining the embodiments. For the drawing device, other necessary components may generally be included.

[0022] In the shaping aperture array substrate 23 provided in the electro-optical lens barrel 20, openings of m rows and n columns (m, n ≥ 2) are formed in a matrix with a prescribed arrangement pitch. Each opening is formed in a rectangular or circular shape with the same size and shape.

[0023] The electron beam B emitted from the electron source 21 illuminates the entire shaping aperture array substrate 23 substantially perpendicularly by means of the illumination lens 22. The electron beam B passes through the plurality of openings of the shaping aperture array substrate 23, thereby forming a multi-beam MB composed of m rows and n columns of individual beams.

[0024] On the blanking aperture array substrate 24, through holes are formed in positions corresponding to the arrangement positions of the respective openings of the shaping aperture array substrate 23. In each through hole, a group of a pair of two electrodes (blanker: blanking deflector) is disposed. An amplifier for applying a voltage is disposed on one of the two electrodes for each beam, and the other is grounded. The individual beams passing through the respective through holes are deflected independently by the voltages applied to the pair of two electrodes. Through the deflection of the individual beams, blanking control of each beam is performed.

[0025] The multi-beam MB that has passed through the blanking aperture array substrate 24 is reduced by the reduction lens 25 and travels toward the opening formed in the center of the limiting aperture member 26. The position of the individual beams deflected by the blanker of the blanking aperture array substrate 24 is shifted from the opening in the center of the limiting aperture member 26 and is blocked by the limiting aperture member 26. On the other hand, the individual beams that have not been deflected by the blanker pass through the opening in the center of the limiting aperture member 26.

[0026] Thus, the limiting aperture member 26 blocks each beam deflected by the blanker to the beam-off state. Then, a beam formed from the beam-on state to the beam-off state and after passing through the limiting aperture member 26 forms a beam of one transmission.

[0027] After passing through the aperture limiting member 26, the multi-beam MB is focused by the objective lens 27 to form a pattern image of a desired reduction ratio, which is then deflected collectively by the deflector 28 and irradiated onto the substrate 40. For example, when the XY stage 32 is continuously moved, the deflector 28 is controlled so that the irradiation position of the beam follows the movement of the XY stage 32.

[0028] Ideally, the multiple beams MB emitted at a time are arranged at a pitch obtained by multiplying the pitch of the multiple openings of the molded aperture array substrate 23 by the desired reduction ratio. While the drawing device draws the desired pattern by raster scanning, continuously and sequentially emitting beams, it controls the necessary beams to be beam-on according to the pattern through blanking control.

[0029] like Figure 2 As shown, the drawing area 50 of the substrate 40 is virtually divided into a plurality of strip-shaped areas 52 with a predetermined width in the y-direction. Each strip-shaped area 52 constitutes a drawing unit area. For example, the XY stage 32 is moved and adjusted so that the irradiation area that can be irradiated by a single multi-beam MB irradiation is located at the left end of the first strip-shaped area 52, and then drawing is started. By moving the XY stage 32 in the -x direction, drawing can be performed relatively in the x-direction (FWD drawing).

[0030] After the first stripe 52 is drawn, the stage position is moved in the -y direction, adjusted so that the irradiation area is located at the right end of the second stripe 52, and drawing is started. Then, by moving the XY stage 32 in the x direction, for example, drawing is performed in the -x direction (BWD drawing).

[0031] By depicting in the x - direction in the third bar region 52 and in the - x - direction in the fourth bar region 52, while alternately changing the orientation, the drawing time can be shortened. However, it is not limited to the case of alternately changing the orientation while drawing, and it is also possible to draw in the same direction when drawing each bar region 52.

[0032] After accelerating the XY stage 32 to reach a specified speed, the stage speed is made constant and pattern drawing is started. For example, as Figure 3A shown, the acceleration of the XY stage 32 starts at time t0, stops accelerating at time t1 after reaching the specified speed V, and the pattern is drawn on the bar region 52 while keeping the stage speed constant.

[0033] In a drawing apparatus, it is known that mechanical vibration generated due to the movement of the XY stage 32 deteriorates the drawing accuracy. The inventor of the present invention conducted in - depth research to solve this problem and obtained the following insights: As Figure 3B shown, the deviation of the beam irradiation position immediately after the start of drawing of the bar region 52 (the leading part of the bar region 52) is large, and the position deviation gradually becomes smaller. The inventor found that by previously measuring the amount of position deviation of the beam irradiation position due to the movement of the stage, for example, the position deviation caused by mechanical vibration, and correcting the beam irradiation position based on the previously measured amount of position deviation during pattern drawing, the above - mentioned problem can be solved.

[0034] By drawing an evaluation pattern and a reference pattern, and based on the difference between the drawing positions of the evaluation pattern and the reference pattern, the amount of position deviation of the beam irradiation position due to the movement of the stage can be obtained.

[0035] Figure 4 is a flowchart showing a method of drawing an evaluation pattern. The acceleration of the XY stage 32 is started (step S11), the acceleration is stopped as the stage speed reaches the target speed, the stage speed is made constant, and an evaluation pattern is drawn on an evaluation substrate coated with a resist (steps S12, S13). The shape of the evaluation pattern is not particularly limited and can be a line - and - space pattern or a dot pattern. After drawing the evaluation pattern, the XY stage 32 is decelerated and stopped (step S14).

[0036] Figure 5It is a flowchart showing a method for drawing a reference pattern. The acceleration of the XY stage 32 is started (step S21). When the stage speed reaches the target speed, the stage speed is maintained for a certain period of time (step S22). After a certain period of time, the reference pattern is drawn on the evaluation substrate while maintaining the stage speed (step S23). The shape of the reference pattern is the same as that of the evaluation pattern. After drawing the reference pattern, the XY stage 32 is decelerated and stopped (step S24).

[0037] The reference pattern is preferably drawn near the evaluation pattern. Therefore, when drawing the reference pattern, compared with when drawing the evaluation pattern, the acceleration of the XY stage 32 starts from a position farther from the multi-beam irradiable area of the evaluation substrate. When a certain period of time has passed after the stage speed reaches the target speed, the multi-beam is irradiated onto the evaluation substrate.

[0038] Since the drawing starts as the stage speed reaches the target speed, the evaluation pattern includes the position offset amount of the beam irradiation position caused by mechanical vibration generated by the stage movement. On the other hand, the reference pattern is drawn after a certain period of time has passed since the stage speed reached the target speed. Therefore, the position offset amount of the beam irradiation position caused by mechanical vibration generated by the stage movement becomes extremely small.

[0039] After drawing the evaluation pattern and the reference pattern, development and other processes are performed, and the position of the formed resist pattern (evaluation pattern and reference pattern) is measured using a position measuring device. By subtracting the difference between the drawing position and the design position of the reference pattern from the difference between the drawing position and the design position of the evaluation pattern, the position error component caused by reasons other than vibration can be removed, and the position offset amount data of the irradiation position of each beam caused by vibration can be obtained. This position offset amount data becomes mapping data in which the position offset amount is defined in a mapping form.

[0040] The position offset amount is large immediately after the start of the drawing of the bar region 52 (the leading part of the bar region 52) and gradually becomes smaller (refer to Figure 3B ). Therefore, the position offset amount data can also be mapping data of the leading part of the bar region, for example, having a size of about 1 / 4 of the length of the bar region from the leading end. The position offset amount data can also be used as mapping data of one bar region.

[0041] The target speed is changed, the evaluation pattern and the reference pattern are drawn for a plurality of target speeds, and the position offset amount data is obtained. In addition, the position offset amount data for each stage traveling direction (FWD drawing / BWD drawing) is obtained. The position offset amount data is obtained in advance and stored in the storage device 18 (refer to Figure 1 ).

[0042] Next, according to Figure 6The flowchart shown below explains the pattern drawing method according to this embodiment.

[0043] The control computer 10 reads out the position offset data from the storage device 18 (step S31). Since the stage speed during pattern drawing is determined in advance, the control computer 10 reads out the position offset data corresponding to the stage speed.

[0044] The emission data generation unit 11 reads out the drawing data from the storage device 17 (step S32). In the drawing data, for example, the configuration coordinates of the graphic pattern, the graphic type, and the graphic size are defined.

[0045] The emission data generation unit 11 performs multi-level data conversion on the drawing data to generate emission data (step S33). In the emission data, the presence or absence of irradiation, the irradiation amount (irradiation time), etc. are defined for each of a plurality of irradiation regions (pixels) obtained by dividing the drawing region 50 of the substrate 40 into a grid pattern with a beam size, for example.

[0046] The position offset calculation unit 12 calculates the position offset of each beam within the bar region with reference to the position offset data read out in step S31 (step S34). The position offset data to be referred to is switched according to the drawing travel direction of the bar region.

[0047] The emission data correction unit 13 corrects the emission data to correct the beam position offset calculated in step S34 (step S35). For example, by allocating an irradiation amount corresponding to the area ratio of the offset to the pixel adjacent to the side opposite to the position offset direction, the position offset can be corrected.

[0048] The multi-beam MB is irradiated onto the substrate 40 using the corrected emission data to draw a pattern (step S36). The drawing control circuit 14 uses the emission data to output a blanking control signal to the individual blanking control circuits formed on the blanking aperture array substrate 24. Based on the conversion into an analog signal within the control circuit, a deflection voltage is applied to the corresponding electrodes of the plurality of blankers. Thus, the drawing control circuit 14 controls the plurality of blankers using the emission data.

[0049] When the stage speed reaches the target speed, the acceleration is stopped, the XY stage 32 is fixed, and pattern drawing is started from the front of the bar region 52. In this embodiment, the position offset of the beam irradiation position caused by mechanical vibration generated due to the movement of the stage is corrected. Therefore, the influence of the vibration generated due to the movement of the stage on the drawing accuracy can be effectively reduced.

[0050] In the above-described embodiment, a multi-beam drawing apparatus has been described, but it can also be applied to a single-beam drawing apparatus. In the case of a single beam, the emission position defined in the emission data is corrected based on the beam position offset.

[0051] In the above-described embodiment, an example has been described in which the drawing process within the bar region is performed with a constant stage speed, but the stage speed can also be changed in the middle of the bar region. In this case, the position offset data corresponding to the changed stage speed is read from the storage device 18, and the emission data after the stage speed change is corrected.

[0052] In the case where there are many types of stage speeds and it is difficult to store the position offset data for all stage speeds in the storage device 18, the position offset can also be stored as a function of time, converted into a function of position according to the stage speed, and calculated. For example, the position offset is decomposed into a plurality of frequency components, and the parameters of each frequency component depend on the stage speed.

[0053] In the above-described embodiment, an example has been described in which the emission position in the emission data is corrected to correct the position offset, but it is also possible to obtain the average value of the position offsets of the respective beams of the multi-beam and correct the deflection amount of the deflector 28 based on the average value.

[0054] Furthermore, the present invention is not limited to the above-described embodiment itself, and the components can be deformed and embodied within the scope not departing from the gist thereof at the implementation stage. In addition, various inventions can be formed by appropriately combining the plurality of components disclosed in the above-described embodiment. For example, several components can also be deleted from all the components shown in the embodiment. Furthermore, the components belonging to different embodiments can be appropriately combined.

Claims

1. A charged particle beam drawing apparatus, comprising: An emission unit that emits a charged particle beam; A stage that mounts a substrate to be drawn and is movable; An emission data correction unit that corrects emission data generated from drawing data by using a relationship between a previously obtained stage speed and a position offset amount caused by a change in the stage speed; and A drawing unit that irradiates the charged particle beam onto the substrate by using the corrected emission data, and sequentially draws a pattern on each of a plurality of strip regions obtained by dividing a drawing region of the substrate into a predetermined width.

2. The charged particle beam drawing apparatus according to claim 1, wherein The charged particle beam drawing apparatus further includes a storage device that stores a plurality of position offset amount data corresponding to a plurality of stage speeds, The emission data correction unit reads out position offset amount data corresponding to the stage speed at the time of irradiating the beam onto the substrate from the storage device, and corrects the emission data.

3. The charged particle beam drawing apparatus according to claim 1, wherein The charged particle beam drawing apparatus further includes a storage device that stores a function with a plurality of stage speeds as variables, The emission data correction unit uses the function read out from the storage device to obtain position offset amount data corresponding to the stage speed at the time of irradiating the beam onto the substrate, and corrects the emission data.

4. A method for correcting emission data, the emission data being used to draw a pattern by irradiating a charged particle beam onto a substrate mounted on a movable stage, the correction method comprising: A step of generating the emission data from drawing data; and A step of correcting the emission data corresponding to the beam irradiated at the time of a change in the stage speed by using a relationship between a previously obtained stage speed and a position offset amount caused by a change in the stage speed.

5. The method for correcting emission data according to claim 4, wherein The emission data is corrected by using a plurality of position offset amount data corresponding to a plurality of stage speeds.

6. The method for correcting emission data according to claim 4, wherein The emission data is corrected by using a function with a plurality of stage speeds as variables.

7. A charged particle beam drawing method, wherein The charged particle beam is irradiated onto the substrate mounted on the stage moving in a predetermined direction by using the emission data corrected by the method for correcting emission data according to claim 4, and a pattern is sequentially drawn.

8. The charged particle beam drawing method according to claim 7, wherein The charged particle beam is a multi-beam including a plurality of individual beams.

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