Charged particle beam writing method and charged particle beam writing apparatus

Abstract

To suppress fluctuations in beam position due to spatial retention of secondary electrons and charging of deflector electrodes.SOLUTION: A charged particle beam writing method includes the steps of deflecting a charged particle beam to a position to which a deflection offset is added such that a range of each deflection voltage applied to each of a plurality of electrodes of an electrostatic positioning deflector does not include a state in which any of the deflection voltages becomes zero, irradiating the charged particle beam onto a substrate, and changing, at a predetermined timing or based on the amount of drift of the charged particle beam, the quadrant of the deflection offset relative to the origin of the deflection voltage at which the total deflection voltage becomes zero.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present invention relates to a charged particle beam writing method and a charged particle beam writing apparatus. [Background technology]

[0002] As LSIs become more highly integrated, the circuit line width required for semiconductor devices is becoming finer every year. To form the desired circuit pattern on a semiconductor device, a method is adopted in which a high-precision original pattern (called a mask, or a reticle, especially when used in steppers and scanners) formed on quartz is reduced and transferred onto a wafer using a reduction projection exposure system. The high-precision original pattern is drawn using an electron beam drawing system, using so-called electron beam lithography technology.

[0003] One type of electron beam lithography system is a multi-beam electron beam lithography system that uses multiple beams. Compared to lithography systems that use a single electron beam, a multi-beam electron beam lithography system can irradiate many beams at once, thereby significantly improving throughput.

[0004] In a multi-electron beam lithography system, the beam for each shot is focused on the surface of the substrate to be lithographed using an objective lens, and an electrostatic lens is used to dynamically correct the focus (dynamic focus) during lithography to accommodate the unevenness of the substrate surface. If this electrostatic lens is operated in the negative voltage range, secondary electrons generated by electron beam lithography return to the substrate surface, causing the resist to become charged, which hinders improvement in the dimensional accuracy of the lithography pattern.

[0005] In order to suppress the influence of returning secondary electrons, etc., it is preferable to operate the electrostatic lens in a positive voltage range relative to the substrate surface and guide the secondary electrons upward from the substrate surface.

[0006] However, when the electrostatic lens is operated in the positive voltage range, secondary electrons from the substrate surface suddenly decelerate after passing through the electrostatic lens and remain densely on the beam trajectory, or they become charged by non-conductive dirt (contamination) on the inner surface of the deflector electrodes, which changes the electric field near the electron beam, altering the electron beam trajectory and degrading the beam position accuracy. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-071354 [Patent Document 2] Japanese Patent Application Publication No. 09-260256 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-138183 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a charged particle beam drawing method and a charged particle beam drawing apparatus that suppress fluctuations in beam position due to spatial retention of secondary electrons and charging of deflector electrodes. [Means for solving the problem]

[0009] A charged particle beam writing method according to one aspect of the present invention comprises the steps of: deflecting a charged particle beam to a position to which a deflection offset is added so that a range of each deflection voltage applied to each of a plurality of electrodes of an electrostatic positioning deflector does not include a state in which any of the deflection voltages becomes zero; irradiating the charged particle beam onto a substrate; and changing, at a predetermined timing or based on the amount of drift of the charged particle beam, the quadrant of the deflection offset relative to the origin of the deflection voltage at which the total deflection voltage becomes zero.

[0010] A charged particle beam writing apparatus according to one aspect of the present invention comprises: an electrostatic positioning deflector having a plurality of electrodes for deflecting a charged particle beam to be irradiated onto a substrate to be written; and a deflection control circuit for controlling the deflection of the charged particle beam to a position to which a deflection offset is added so that a state in which any deflection voltage becomes zero is not included in the range of each deflection voltage applied to each of the plurality of electrodes; and for changing the quadrant of the deflection offset based on the origin of the deflection voltage at which all deflection voltages become zero at a predetermined timing or based on the amount of drift of the charged particle beam. [Effects of the Invention]

[0011] According to the present invention, fluctuations in beam position due to spatial retention of secondary electrons and charging of deflector electrodes can be suppressed, thereby improving drawing accuracy. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of a multi-charged particle beam writing apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram of a shaping aperture array substrate. [Figure 3] FIG. 3 is a cross-sectional view of a second objective lens. [Figure 4] 10(a) and 10(b) are diagrams illustrating the trajectories of secondary electrons according to a comparative example. [Figure 5] 10A and 10B are diagrams illustrating a deflectable range and a drawing deflection region. [Figure 6] 1(a) and 1(b) are diagrams illustrating the trajectories of secondary electrons. [Figure 7] 10(a) to 10(d) are diagrams illustrating the position of a writing deflection region where the polarity of the deflection voltage is constant. [Figure 8] FIG. 2 is a diagram illustrating an example of the configuration of a positioning deflector. [Figure 9] 1A and 1B are diagrams illustrating an example of the configuration of a positioning deflector. [Figure 10] 10(a) to 10(c) are diagrams illustrating the position of a writing deflection region where the polarity of the deflection voltage is constant. [Figure 11]10(a) and 10(b) are diagrams illustrating the position of a drawing deflection region where the polarity of the deflection voltage is constant. [Figure 12] 10A and 10B are diagrams illustrating examples of modifications of the offsettable region in which the imaging deflection region is located. [Figure 13] 10 is a flowchart illustrating a drawing method according to the embodiment. [Figure 14] 3A and 3B are diagrams illustrating the configuration of a positioning deflector and voltages applied to each electrode. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the embodiment, a configuration using an electron beam as an example of a charged particle beam will be described. However, the charged particle beam is not limited to an electron beam, and an ion beam or the like may also be used.

[0014] 1 includes a drawing unit 10 that draws a desired pattern on an object such as a mask or a wafer by irradiating it with an electron beam, and a control unit 60 that controls the operation of the drawing unit 10. The drawing unit 10 includes an electron optical lens barrel 12 and a drawing chamber 40. In this embodiment, a configuration using a multi-beam drawing device will be described as an example of a drawing device.

[0015] Arranged within the electron optical column 12 are an electron source 14, an illumination lens 16, a shaping aperture array substrate 18, a blanking aperture array substrate 20, a projection lens 22, a stopping aperture (limiting aperture member) 24, a first objective lens 26, a positioning deflector 28, a second objective lens 30, and a focus correction lens 32. An XY stage 42 is arranged within the writing chamber 40. A mask blank, which is a substrate 44 to be written, is placed on the XY stage 42.

[0016] Substrate 44 includes, for example, a wafer, or an exposure mask for transferring a pattern onto a wafer using a stepper, scanner, or other reduction projection exposure device that uses an excimer laser as a light source, or an extreme ultraviolet exposure device. Substrate 44 also includes a mask on which a pattern is already formed. For example, a Levenson mask requires two drawing operations, so a second pattern may be drawn on an object that has been drawn once and processed into a mask.

[0017] As shown in Fig. 2, the shaping aperture array substrate 18 has m columns x n rows (m, n ≥ 2) of apertures (first apertures) 18A formed at a predetermined arrangement pitch. Each aperture 18A is formed, for example, as a rectangle of the same dimensions. The shape of the apertures 18A may also be circular. Portions of the electron beams B pass through each of the plurality of apertures 18A, thereby forming multiple beams MB.

[0018] The blanking aperture array substrate 20 is provided below the shaping aperture array substrate 18, and has formed therein passage holes 20A (second openings) corresponding to the respective openings 18A of the shaping aperture array substrate 18. A blanker (not shown), consisting of a pair of two electrodes, is disposed in each passage hole 20A. One of the blankers is fixed at ground potential, and the other is switched to a potential different from ground potential. The electron beams passing through each passage hole 20A are deflected independently by the voltage applied to the blanker. In this manner, the multiple blankers perform blanking deflection on the corresponding beams among the multi-beams MB that have passed through the multiple openings 18A of the shaping aperture array substrate 18.

[0019] The stopping aperture 24 blocks the beam deflected by the blanker. The beam not deflected by the blanker passes through an opening 24A (third opening) formed in the center of the stopping aperture 24. The stopping aperture 24 is placed on the image plane of the crossover (light source image) where the beam divergence becomes smaller, in order to reduce beam leakage during individual blanking by the blanking aperture array substrate 20.

[0020] The control unit 60 has a control computer 62, a deflection control circuit 64, and a lens control circuit 66. The deflection control circuit 64 controls the voltages applied to the blanker provided on the blanking aperture array substrate 20 and the electrodes of the positioning deflector 28. The lens control circuit 66 controls the voltages applied to the illumination lens 16, the projection lens 22, the first objective lens 26, the second objective lens 30, and the focus correction lens 32. For example, the lens control circuit 66 controls the voltage applied to the focus correction lens 32 based on the surface height of the substrate 44 detected by a Z sensor (not shown), thereby performing focus correction (dynamic focus).

[0021] Electron beam B emitted from electron source 14 (emitting section) is illuminated almost perpendicularly onto the entire shaping aperture array substrate 18 by illumination lens 16. Electron beam B passes through multiple apertures 18A in shaping aperture array substrate 18, forming a multibeam MB consisting of multiple electron beams. The multibeam MB passes through the corresponding blankers of blanking aperture array 20.

[0022] The multi-beams MB that have passed through the blanking aperture array substrate 20 are reduced in size by the projection lens 22 and proceed toward the central opening 24A of the stopping aperture 24. Here, the electron beams deflected by the blanker of the blanking aperture array substrate 20 move out of position with respect to the opening 24A of the stopping aperture 24 and are blocked by the stopping aperture 24. On the other hand, the electron beams that have not been deflected by the blanker pass through the opening 24A of the stopping aperture 24. Blanking control is performed by turning the blanker on and off, and the on / off of the beam is controlled.

[0023] In this way, the stopping aperture 24 blocks each beam deflected by the blanker of the blanking aperture array substrate 20 to be in the beam OFF state.

[0024] The multi-beams MB that have passed through the stopping aperture 24 are focused by the first objective lens 26, the second objective lens 30, and the focus correction lens 32 to form a pattern image with a desired reduction ratio, which is then irradiated onto the substrate 44.

[0025] A positioning deflector 28, disposed between the first objective lens 26 and the second objective lens 30, deflects and irradiates the multibeam MB onto a desired position on a substrate 44 placed on a continuously moving XY stage 42. The positioning deflector 28 has a plurality of electrodes, and may be, for example, a quadrupole deflector with four electrodes or an octupole deflector with eight electrodes. The beam deflection position (the beam irradiation position on the substrate 44) can be changed by changing the voltage applied to each electrode of the positioning deflector 28.

[0026] Since the area of ​​the substrate 44 irradiated with the multi-beam MB is as wide as about 100 micrometers square, there is no problem with the writing throughput even if the area to be deflected by the positioning deflector 28 (writing deflection area) is narrower than the size of the beam array of the multi-beam MB. For example, the size of the writing deflection area is sufficient if it is several micrometers square to about 10 micrometers square.

[0027] The focus correction lens 32 is disposed downstream of the positioning deflector 28 in the traveling direction of the multi-beams MB.

[0028] Electromagnetic lenses (magnetic lenses) are used for the illumination lens 16, projection lens 22, first objective lens 26, and second objective lens 30, but some or all of them may be electrostatic lenses. The focus correction lens 32 performs dynamic focus adjustment in response to height variations of the surface of the substrate 44, and is an electrostatic lens, but an electromagnetic lens (including a coil that generates an axially symmetric magnetic field) may also be used. It may also be configured as a multi-stage lens system in which the applied voltages and excitation currents change in conjunction with each other in a fixed relationship. Alternatively, the second objective lens 30 may also have the function of the focus correction lens 32, or the second objective lens 30 and the focus correction lens 32 may be configured to perform focus adjustment by interlocking with each other in a fixed relationship.

[0029] The second objective lens 30 is an electromagnetic lens, and has a coil 30a and a yoke 30b that houses the coil 30a, as shown in Fig. 3. The yoke 30b is made of a material with high magnetic permeability, such as iron, and has a notch (pole piece 30c) formed in one part.

[0030] Magnetic lines of force created by passing a current through the coil 30a leak into space via the pole piece 30c, creating a magnetic field.

[0031] The focus correction lens 32 is disposed, for example, inside the second objective lens 30, at the same height as the pole piece 30c. The focus correction lens 32 is an electrostatic lens having a ring-shaped electrode. A positive voltage with respect to the substrate surface is applied to this electrode, and the focus correction lens 32 is operated in a positive voltage range with respect to the substrate surface.

[0032] When the multi-beams MB (primary beams) are irradiated onto the substrate 44, secondary electrons are emitted from the substrate surface. By operating the focus correction lens 32 in the positive voltage range, the secondary electrons are guided upward from the substrate surface and travel upward inside the electron optical lens barrel 12. This prevents the secondary electrons from returning to the substrate surface, thereby suppressing positional fluctuations due to resist charging.

[0033] During the writing process, the resist on the surface of the substrate 44 may evaporate due to beam irradiation, and contamination (dirt) may adhere to the surfaces of the multiple electrodes of the positioning deflector 28. Secondary electrons traveling upward inside the electron optical column 12 may reach and charge the contamination on the electrode surfaces of the positioning deflector 28, which may change the trajectory of the multi-beam MB.

[0034] In conventional lithography systems, when changing the beam deflection position (beam irradiation position on substrate 44), the polarity of the deflection voltage applied to each electrode of positioning deflector 28 is frequently changed, as shown in Figures 4(a) and 4(b). When the polarity of the deflection voltage changes, the strength and direction of the electric field in positioning deflector 28 change significantly, and the arrival position of secondary electrons, i.e., the charged position, changes significantly across the electrodes. This large change in the charged position causes a large change in the electric field near the beam, resulting in a large fluctuation (drift) in the beam irradiation position.

[0035] Therefore, in this embodiment, an offset (deflection offset) is added to the deflection position of the positioning deflector 28, i.e., the deflection position is shifted during operation, thereby removing the secondary electrons from the vicinity of the beam center and moving them in a substantially constant lateral direction, so that the secondary electrons reach a limited area on the deflector surface, etc.

[0036] For example, as shown in FIG. 5, the imaging deflection region R1 is shifted within the deflection-enabled range R0 so that the imaging deflection region R1 does not include the origin of the deflection voltage, i.e., a state where the deflection voltage of any electrode of the positioning deflector 28 is 0 (any deflection voltage is 0). Here, the deflection-enabled range R0 is the range in which the positioning deflector 28 can deflect at the maximum output of the deflection amplifier included in the deflection control circuit 64. The imaging deflection region R1 is a deflection region required for imaging processing. By not including the origin of the deflection voltage within the imaging deflection region R1, the arrival position of the secondary electrons, i.e., the change in the charging position relative to the change in the deflection position, is suppressed, as shown in FIGS. 6(a) and 6(b), and therefore fluctuation (drift) in the beam irradiation position is suppressed.

[0037] Furthermore, it is more effective to set the deflection offset so that the polarity of the deflection voltage of each electrode (individual electrode) of the positioning deflector 28 remains constant. To keep the polarity of the deflection voltage of each electrode constant, the quadrupole deflector can be configured so that the drawing deflection region R1 falls within one of the offsettable regions R11 to R14 shown in Figures 7(a) to 7(d). This further limits the area where secondary electrons strike the deflection electrodes, thereby further limiting the range of positions where charging occurs. As a result, changes in the strength and direction of the electric field within the positioning deflector 28 are suppressed, beam irradiation position fluctuations (drift) are suppressed, and beam position accuracy is improved.

[0038] Furthermore, if "deflection offsets are set so that the polarity of the deflection voltage of each electrode is constant," then "a state in which any of the deflection voltages is 0 is not included" is automatically (always) satisfied. Therefore, "constant polarity" is a more restrictive condition than "a state in which any of the deflection voltages is not 0."

[0039] It should be noted that the conditions related to the voltage applied to the deflector contribute more directly to reducing drift. The result is that the beam deflection position and deflection area on the substrate surface shift, and it cannot be said that the beam deflection position and deflection area on the substrate surface themselves directly contribute to reducing drift.

[0040] Fig. 8 shows an example of the configuration of the positioning deflector 28. In the example shown in Fig. 8, the positioning deflector 28 is an electrostatic quadrupole deflector having four electrodes 28a to 28d. When the deflection offset is (X0, Y0), the deflection amount for pattern drawing based on the pattern position of the drawing data is (X, Y), and the deflection sensitivity coefficient is k, the deflection voltages V1 to V4 applied to the electrodes 28a to 28d are as follows: V1=k(X0+X) V2=k(Y0+Y) V3=k(-X0-X) V4=k(-Y0-Y)

[0041] The deflection range in the x direction is -X M From XM The deflection range in the y direction is -Y M From Y M -X W From X W Deflect the deflection area in the y direction up to -Y W From Y W 5, the deflection offset (X0, Y0) is required to satisfy the following conditional expression so that the origin of the deflection voltage is not included in the writing deflection region R1 and so that the polarity of the deflection voltage of each electrode of the positioning deflector 28 is constant. X W <|X0|≦X M -X W Y W <|Y0|≦Y M -Y W

[0042] The deflection offset (X0, Y0) that satisfies the above conditional expression is determined in advance and stored in the memory (not shown) of the control unit 60.

[0043] During the writing process, the control computer 62 reads the writing data from the storage device and performs multiple stages of data conversion to generate shot data specific to the device. The shot data defines the dose and irradiation position coordinates of each shot. The irradiation position coordinates are calculated using the deflection offset (X0, Y0) described above as the origin of the deflection.

[0044] The control computer 62 outputs the dose for each shot based on the shot data to a deflection control circuit 64. The deflection control circuit 64 calculates the exposure time t by dividing the input dose by the current density. Then, when performing the corresponding shot, the deflection control circuit 64 applies a deflection voltage to the corresponding blanker on the blanking aperture array substrate 20 so that the blanker turns on the beam for the exposure time t.

[0045] The deflection control circuit 64 also determines the amount of deflection for drawing (X, Y) so that the beam is irradiated onto the irradiation position indicated by the shot data, adds or subtracts a deflection offset (X0, Y0) to this, and applies the above-mentioned deflection voltages V1 to V4 multiplied by a deflection sensitivity coefficient k to the electrodes 28a to 28d of the positioning deflector 28. When determining the amount of deflection for drawing, position information of the XY stage 42 is acquired from a position measuring device (not shown) such as a laser length measuring device and used.

[0046] In this way, the polarity of the deflection voltage of each deflection electrode of the positioning deflector 28 is kept constant, and the secondary electrons are guided to a limited area of ​​the positioning deflector 28, thereby suppressing changes in deflector charging and stabilizing the beam.

[0047] The positioning deflector 28 may be an octupole deflector having eight electrodes 28a to 28h as shown in Figures 9(a) and 9(b). The deflectors shown in Figures 9(a) and 9(b) have an installation angle that differs by 22.5 degrees. In this specification, the deflector in which the deflection coordinate axis passes through the center of the gap between the deflection electrodes as shown in Figure 9(a) is referred to as a 22.5-degree rotated arrangement, and the deflector in which the deflection coordinate axis passes through the center of the deflection electrodes as shown in Figure 9(b) is referred to as a 0-degree rotated arrangement.

[0048] In the 22.5-degree rotated arrangement shown in FIG. 9(a), the deflection voltages V1 to V8 applied to the electrodes 28a to 28h are expressed as follows using the deflection offset (X0, Y0), the drawing deflection amount (X, Y), and the deflection sensitivity coefficient k: V1=k{(X0+X)+a(Y0+Y)} V2=k{(Y0+Y)+a(X0+X)} V3=k{(Y0+Y)-a(X0+X)} V4=k{-(X0+X)+a(Y0+Y)} V5=k{-(X0+X)-a(Y0+Y)} V6=k{-(Y0+Y)-a(X0+X)} V7=k{-(Y0+Y)+a(X0+X)} V8=k{(X0+X)-a(Y0+Y)} a=√2-1≒0.414

[0049] In a 22.5 degree rotation arrangement, in order to ensure that the polarity of the deflection voltage of each electrode of the positioning deflector 28 is constant, the drawing deflection area should fall within either 22.5 degrees to 67.5 degrees and the offset possible areas Ra (Ra1 to Ra4) every 90 degrees therefrom as shown in Figure 10(a), -22.5 degrees to 22.5 degrees and the offset possible areas Rb (Rb1, Rb2) rotated 180 degrees therefrom as shown in Figure 10(b), or 67.5 degrees to 112.5 degrees and the offset possible areas Rc (Rc1, Rc2) rotated 180 degrees therefrom as shown in Figure 10(c).

[0050] In order to fit the drawing deflection area into any of the offset possible areas Ra1 to Ra4, the deflection offset (X0, Y0) should satisfy the following conditional expression. |Y0|+Y W <(√2+1)(|X0|-X W ) |Y0|-Y W >(√2-1)(|X0|+X W ) |X0|≦X M -X W |Y0|≦Y M -Y W

[0051] In order to fit the drawing deflection area into the offset possible area Rb1 or Rb2, the deflection offset (X0, Y0) should satisfy the following conditional expression. |Y0|+Y W <(√2-1)(|X0|-X W ) |Y0|-Y W >-(√2-1)(|X0|-X W ) |X0|≦X M -X W |Y0|≦Y M -Y W

[0052] In order to fit the drawing deflection area into the offset possible area Rc1 or Rc2, the deflection offset (X0, Y0) should satisfy the following conditional expression. |X0|+X W <(√2-1)(|Y0|-Y W ) |X0|-X W >-(√2-1)(|Y0|-Y W ) |X0|≦X M -X W |Y0|≦Y M -Y W

[0053] In the 0-degree rotated arrangement shown in FIG. 9(b), the deflection voltages V1 to V8 applied to the electrodes 28a to 28h are expressed as follows using the deflection offset (X0, Y0), the drawing deflection amount (X, Y), and the deflection sensitivity coefficient k': V1=k´(X0+X) V2=k´b{(X0+X)+(Y0+Y)} V3=k´(Y0+Y) V4=k´b{-(X0+X)+(Y0+Y)} V5=-k´(X0+X) V6=-k´b{(X0+X)+(Y0+Y)} V7=-k´(Y0+Y) V8=-k´b{-(X0+X)+(Y0+Y)} b=1 / √2≒0.707

[0054] In the 0-degree rotation arrangement, in order to ensure that the polarity of the deflection voltage of each electrode of the positioning deflector 28 is constant, the drawing deflection area should fall within either the offsettable area Rd (Rd1 to Rd4) shown in Figure 11(a) which is symmetrical with respect to 0 degrees to 45 degrees, the x-axis, the y-axis, and the origin, or the offsettable area Re (Re1 to Re4) shown in Figure 11(b) which is symmetrical with respect to 45 degrees to 90 degrees, the x-axis, the y-axis, and the origin.

[0055] In order to fit the drawing deflection area into any of the offset possible areas Rd1 to Rd4, the deflection offset (X0, Y0) should satisfy the following conditional expression. |Y0|+Y W <|X0|-X W |X0|≦X M -X W |Y0|≦Y M -Y W |Y0|>Y W

[0056] In order to fit the drawing deflection area into the offset possible areas Re1 to Re4, the deflection offset (X0, Y0) should satisfy the following conditional expression. |X0|+X W <|Y0|-Y W |X0|≦X M -X W |Y0|≦Y M -Y W |X0|>X W

[0057] Keeping the deflection offset constant during writing operations is effective in reducing drift, but if contamination is originally present in the direction of the deflection offset, keeping the deflection offset constant may cause the contamination to grow larger, changing the beam trajectory and resulting in large drift.

[0058] Therefore, in this embodiment, drift measurement is performed at predetermined time intervals during the writing process, and if the amount of drift exceeds a predetermined threshold, the quadrant (and size) of the deflection offset is changed, and the offset possible area in which the writing deflection area is located is changed to a different offset possible area. For example, as shown in FIG. 12, the offset possible area in which the writing deflection area R1 is located is changed from offset possible area Ra1 to offset possible area Ra4. This makes it possible to suppress the growth of contamination and reduce drift.

[0059] Here, changing the quadrant of the deflection offset means moving the center position of the drawing deflection area in a circumferential direction around the origin of the deflection voltage (see FIG. 5) to another quadrant (a position where at least one of the polarities of X and Y is changed). Also, changing the magnitude of the deflection offset means increasing or decreasing the distance between the center position of the drawing deflection area and the origin of the deflection voltage.

[0060] The writing method according to this embodiment will be described with reference to the flowchart shown in Fig. 13. A new positioning deflector 28 is mounted on the writing device, and the deflection offset is set (steps S1 and S2). For example, as shown in Fig. 9(a), an octupole deflector is rotated 22.5 degrees, and the deflection offset is set so that the writing deflection area falls within the offset possible area Ra1 shown in Fig. 10(a).

[0061] The beam is irradiated onto the substrate 44 to write a pattern (step S3). The irradiation position coordinates are calculated using the deflection offset set in step S2 as the origin of deflection, the deflection offset is added to or subtracted from the amount of deflection for writing, and a deflection voltage is applied to each electrode of the positioning deflector 28.

[0062] The positioning deflector 28 continues to be used until the usage time exceeds a predetermined value (step S4_No), and when it is time to replace it after using it for the predetermined time (step S4_Yes), it is replaced (step S5).

[0063] While the positioning deflector 28 is being used to perform the drawing process, the drawing process is interrupted at a predetermined timing, and drift measurement is performed (step S6_Yes, step S7). The drift measurement method is not limited, and a known method can be used. For example, a specific beam (or a beam group including multiple beams) of the multi-beam is turned on, a mark (not shown) on the XY stage 42 is scanned with the beam, and reflected electrons are detected with a detector (not shown). The control computer 62 calculates the beam position from the waveform of the detected reflected electron amount and the stage position, and obtains the drift amount from the difference between the calculated beam position and the ideal value. A transmission mark may be used instead of a reflection mark, the transmission mark may be scanned, the beam that has passed through the aperture of the transmission mark may be detected, and the beam position may be calculated from the waveform of the detected electron amount and the stage position.

[0064] If the amount of drift is less than the predetermined value (No in step S8), pattern writing continues without changing the deflection offset.

[0065] If the drift amount is equal to or greater than a predetermined value (step S8_Yes), it is considered that contamination has grown significantly in the quadrant of the current deflection offset, so the quadrant of the deflection offset is changed, and the offsettable region in which the drawing deflection region is located is changed to a different offsettable region (step S9). For example, as shown in Fig. 12, the offsettable region in which the drawing deflection region R1 is located (fits) is changed from offsettable region Ra1 to offsettable region Ra4. The changed deflection offset is set, and the drawing process is resumed (step S3).

[0066] As described above, according to this embodiment, the focus correction lens 32 is operated in a positive voltage range relative to the substrate surface, so that secondary electrons are guided upward from the substrate surface, and spatial retention of secondary electrons can be suppressed. Furthermore, the writing deflection area is shifted by setting the deflection offset so as not to include a state in which the deflection voltage of any electrode of the positioning deflector 28 becomes 0, and when the drift amount increases, the quadrant (and size) of the deflection offset is changed to change the offset possible area in which the writing deflection area is located, so that fluctuations in the beam position due to charging of the deflector electrodes can be suppressed, and writing accuracy can be improved.

[0067] In step S9 of Fig. 13, the destination of the offsettable area where the imaging deflection area is located may be selected randomly, or the amount of drift in each offsettable area may be measured and the optimal offsettable area where the amount of drift is minimized may be selected. For example, when the offsettable area where the imaging deflection area is located is changed from the offsettable area Ra1 in Fig. 10(a) to one of the other offsettable areas Ra2 to Ra4, drift measurement is performed with the imaging deflection area positioned in each of the offsettable areas Ra2 to Ra4, and the offsettable area where the amount of drift is minimized is selected.

[0068] The drift amount in each offset possible area may be stored in a memory (not shown), and from the next time onwards, when changing the deflection offset, the offset possible area may be selected in ascending order of the stored drift amount.

[0069] In the above embodiment, an example has been described in which the deflection offset is changed when the measured drift amount becomes equal to or exceeds a predetermined value. However, the deflection offset may also be changed when the writing time or the number of writings (number of substrates written) reaches a predetermined value.

[0070] In the above embodiment, an example has been described in which the deflection offset is changed to change the offsettable region in which the imaging deflection region is located, but the imaging deflection region may be moved within the same offsettable region.

[0071] 14, a common voltage Vc that is positive with respect to the substrate surface may be added to the voltages applied to the electrodes of the positioning deflector 28. This common voltage Vc is a positive voltage V applied to the focus correction lens 32. F It is preferable to set the value equal to or greater than the upper limit of . This allows the secondary electrons that have passed through the focus correction lens 32 to move to the positioning deflector 28 without decelerating, thereby preventing the secondary electrons from accumulating between the focus correction lens 32 and the positioning deflector 28 and improving the accuracy of the beam irradiation position.

[0072] In the above embodiment, a drawing apparatus using multiple beams has been described, but the above drawing method can also be applied to a drawing apparatus using a single beam.

[0073] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0074] 10 Drawing section 12 Electron Optical Tube 14 Electron gun 16 Lighting lens 18 Molded aperture array substrate 20 Blanking aperture array substrate 22 Projection lens 24 Stopping Aperture 26 First objective lens 28 Positioning deflector 29 Magnetic field deflector 30 Second objective lens 32 Focus correction lens 40 Drawing room 42 XY stage 44 PCB 60 Control Unit

Claims

1. deflecting the charged particle beam to a position to which a deflection offset is added so that a range of each deflection voltage applied to each of the plurality of electrodes of the electrostatic positioning deflector does not include a state in which any of the deflection voltages is zero; irradiating a substrate with the charged particle beam; changing the quadrant of the deflection offset relative to an origin of the deflection voltage where the total deflection voltage is zero at a predetermined timing or based on the drift amount of the charged particle beam; A charged particle beam writing method comprising:

2. 2. The charged particle beam writing method according to claim 1, wherein the charged particle beam is deflected to a position to which the deflection offset is added so that the polarity of the voltage of each electrode does not fluctuate within the range of each deflection voltage.

3. 2. The charged particle beam writing method according to claim 1, further comprising the steps of: measuring a drift amount of the charged particle beam; and changing the deflection offset when the drift amount is equal to or greater than a threshold value.

4. 2. The charged particle beam writing method according to claim 1, wherein a focus correction lens disposed downstream of the positioning deflector in the traveling direction of the multi-charged particle beam is operated in a positive voltage range.

5. an electrostatic positioning deflector having a plurality of electrodes and deflecting the charged particle beam to be irradiated onto a substrate to be written; a deflection control circuit that controls the deflection of the charged particle beam to a position to which a deflection offset is added so that a state in which any of the deflection voltages becomes zero is not included in the range of each deflection voltage applied to each of the plurality of electrodes, and that changes the quadrant of the deflection offset with respect to an origin of the deflection voltage at which all the deflection voltages become zero at a predetermined timing or based on the drift amount of the charged particle beam; A charged particle beam writing apparatus comprising:

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