JP2013077778A - Charged particle beam lithography apparatus and charged particle beam lithography method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged particle beam lithography apparatus in which a shot shape of an electron beam can be suppressed from being distorted in accordance with a deflection position, and a charged particle beam lithography method.SOLUTION: In an electron beam lithography apparatus 100, a deflection voltage obtained by also correcting an XY difference together with main deflection astigmatism correction is applied to a main deflector 208 and a sub deflector 209, and a desired pattern is drawn on a sample 216. Therefore, the electron beam lithography apparatus 100 comprises a main deflection correction amount arithmetic section 122 which calculates a correction amount of a deflection signal to be applied to the main deflector 208, a sub deflection correction amount arithmetic section 123 which calculates a second correction amount correcting the correction amount of a deflection signal to be applied to the sub deflector 209, and a deflection signal generation section 124 which generates the deflection signal to be applied to the main deflector 208 using the first correction amount and generates the deflection signal to be applied to the sub deflector 209 using the second correction amount.

Description

  The present invention relates to a charged particle beam drawing apparatus and a charged particle beam drawing method.

  In recent years, the circuit line width required for a semiconductor element has become increasingly narrower as the large scale integrated circuit (LSI) is highly integrated and has a large capacity.

  The semiconductor element uses an original pattern pattern (a mask or a reticle, which will be collectively referred to as a mask hereinafter) on which a circuit pattern is formed, and the circuit is exposed and transferred onto a wafer by a reduction projection exposure apparatus called a stepper. Manufactured by forming. Here, a drawing apparatus using an electron beam is used for manufacturing a mask for transferring a fine circuit pattern to a wafer. This apparatus has an essentially excellent resolution, and a large depth of focus can be secured, so that it has an advantage that dimensional variation can be suppressed even on a high step.

  Patent Document 1 discloses a variable shaping type electron beam drawing apparatus used in an electron beam lithography technique. The drawing data in such an apparatus is created by performing processing such as correction and graphic pattern division on design data (CAD data) such as a semiconductor integrated circuit designed using a CAD system. For example, the graphic pattern division processing is performed in units of the maximum shot size defined by the size of the electron beam, and the coordinate position, size, and irradiation time of each divided shot are set. Then, drawing data is created so that a shot is formed according to the shape and size of the graphic pattern to be drawn. The drawing data is divided into strip-shaped frames (main deflection areas) and further divided into sub-deflection areas. That is, the drawing data of the entire chip has a data hierarchical structure including a plurality of strip-shaped frame data according to the size of the main deflection area and a plurality of sub deflection area units smaller than the main deflection area in the frame. .

  The sub-deflection area is an area where an electron beam is scanned by the sub-deflector at a speed higher than that of the main deflection area, and is generally a minimum drawing unit. When drawing in the sub-deflection area, a shot having a size and shape prepared according to the pattern figure is formed by the shaping deflector. Specifically, after the electron beam emitted from the electron gun is shaped into a rectangular shape by the first aperture, it is projected onto the second aperture by the shaping deflector to change the beam shape and dimensions. . Thereafter, the light is deflected by the sub-deflector and the main deflector, and is irradiated onto the mask placed on the stage.

  By the way, when drawing a pattern on a mask, astigmatism may occur on the mask surface with different image planes in two orthogonal directions. For this reason, the process which correct | amends astigmatism is performed. The correction is performed for the main deflection astigmatism and is not performed for the sub deflection astigmatism. This is because the sub-deflection area is smaller than the main deflection area, and the variation in pattern dimension due to deflection astigmatism is small. However, there is a possibility that the influence of deflection astigmatism in the sub-deflection region cannot be ignored due to the miniaturization of patterns accompanying the high integration of LSI. In view of these points, Patent Document 2 discloses a method for correcting both the main deflection astigmatism and the sub deflection astigmatism.

JP-A-9-293670 JP 2007-227700 A

  According to the method of Patent Document 2, it is possible to perform correction so that the focal positions of different electron beams differ depending on directions. That is, blurring of the electron beam irradiation spot can be improved. However, in this case, anisotropy occurs in the magnification due to astigmatism correction by the main deflector. That is, there is a problem that the magnification of the image plane varies depending on the direction, and the shot shape of the electron beam is distorted. Such a problem cannot be ignored in recent years when the demand for drawing accuracy is increasing.

  The present invention has been made in view of the above problems. That is, an object of the present invention is to provide a charged particle beam drawing apparatus and a charged particle beam drawing method capable of suppressing distortion of the shot shape of an electron beam depending on a deflection position.

  Other objects and advantages of the present invention will become apparent from the following description.

A first aspect of the present invention comprises an electromagnetic lens that focuses a charged particle beam;
A main deflector for deflecting the charged particle beam;
One or more quadrupole field generating means for generating a quadrupole field different from the main deflector,
Charged particles characterized in that the main deflector and the quadrupole field generating means correct astigmatism caused by the deflection amount of the main deflector and anisotropy of the magnification of the image plane of the charged particle beam. The present invention relates to a beam drawing apparatus.

A first aspect of the present invention is a correction amount of a deflection signal applied to a main deflector, and anisotropy of magnification between an astigmatism and an image plane of a charged particle beam generated depending on the deflection amount of the main deflector. A first calculation unit that calculates a first correction amount for correcting
A correction amount of the deflection signal applied to the quadrupole field generating means, which corrects astigmatism caused by the deflection amount of the main deflector and anisotropy of the magnification of the image plane of the charged particle beam. A second calculation unit for calculating the correction amount of
A deflection signal generating unit configured to generate a deflection signal to be applied to the main deflector using the first correction amount, and to generate a deflection signal to be applied to the quadrupole field generating unit using the second correction amount; It is preferable.

  In the first aspect of the present invention, the quadrupole field generating means is preferably a sub-deflector that deflects a charged particle beam.

A second aspect of the present invention is a charged particle beam drawing method in which a charged particle beam is focused on a sample by an electromagnetic lens and the irradiation position of the charged particle beam on the sample is controlled by a main deflector.
The main deflector and the one or more quadrupole field generating means for generating a quadrupole field different from the main deflector, the astigmatism generated depending on the deflection amount of the main deflector, and the charged particle beam The anisotropy of the magnification of the image plane is corrected.

  In the second aspect of the present invention, the quadrupole field generating means is preferably a sub-deflector that deflects the charged particle beam.

  ADVANTAGE OF THE INVENTION According to this invention, the charged particle beam drawing apparatus and charged particle beam drawing method which can suppress that the shot shape of an electron beam is distorted by a deflection position are provided.

It is a block diagram of the electron beam drawing apparatus in this Embodiment. It is a figure which shows the DAC amplifier unit which applies a deflector which consists of an 8 poles electrostatic deflector, and analog data to each electrode. This is an example in which no XY difference occurs in the shot shape of the electron beam. This is an example in which an XY difference occurs in the shot shape of the electron beam. It is explanatory drawing of the drawing method by an electron beam. It is a conceptual diagram explaining XY difference. It is a figure which shows a mode that an electron beam is irradiated to a sample in this Embodiment.

  FIG. 1 is a conceptual diagram showing a configuration of an electron beam drawing apparatus according to the present embodiment.

  In FIG. 1, the electron beam drawing apparatus 100 is an example of a variable shaping type electron beam drawing apparatus, and includes a drawing unit 150 and a control unit 160.

  The drawing unit 150 includes an electron column 102 and a drawing chamber 103.

  In the electron column 102, an electron gun 201, an illumination lens 202, a blanking deflector 212, a blanking aperture 214, a first shaping aperture 203, a projection lens 204, a shaping deflector 205, a second shaping aperture 206, An objective lens 207, a main deflector 208, and a sub deflector 209 are arranged. The illumination lens 202, the projection lens 204, and the objective lens 207 are electromagnetic lenses that adjust the imaging position by changing excitation.

  An XY stage 105 is disposed inside the drawing chamber 103.

  A sample 216 such as a mask to be drawn is placed on the XY stage 105. When a mask is used as the sample 216, for example, a light shielding film such as a chromium (Cr) film or a molybdenum silicon (MoSi) film is formed on a mask substrate such as quartz, and a resist film is further formed thereon. Can be. Then, a predetermined pattern is drawn on the resist film using the electron beam drawing apparatus 100.

  Further, a reflection mirror 106 for laser length measurement is arranged at a position different from the sample 216 on the XY stage 105. The laser light emitted from the laser length measuring device 145 is reflected by the reflection mirror 106, and the laser length measuring device 145 receives the laser light to determine the position of the XY stage 105. The obtained data is output to the drawing data processing unit 112 of the control computer 110.

  A Z sensor 107 that detects the position of the sample 216 in the height direction (Z direction) is disposed above the drawing chamber 103. The Z sensor 107 is composed of a combination of a projector and a light receiver. The Z sensor 107 reflects the light emitted from the projector on the surface of the sample 216, and the light receiver receives the reflected light to measure the height of the sample 216. be able to. The height data detected by the Z sensor 107 is sent to the detector 143, converted into digital data, and then output to the drawing data processing unit 112 of the control computer 110.

  The blanking deflector 212 is configured by a plurality of electrodes such as two or four poles. The shaping deflector 205, the main deflector 208, and the sub deflector 209 are configured by a plurality of electrodes such as 4 poles or 8 poles, for example. Each deflector is connected to at least one DAC (digital / analog converter) amplifier unit for each electrode.

  The control unit 160 includes a control computer 110, a deflection control circuit 120, DAC amplifier units 132 and 134, a memory 142, and a storage device 144 such as a magnetic disk device.

  The control computer 110, the deflection control circuit 120, the memory 142, and the storage device 144 are connected to each other via a bus (not shown). The deflection control circuit 120 and the DAC amplifier units 132 and 134 are also connected to each other via a bus (not shown).

  The DAC amplifier unit 132 is connected to the sub deflector 209. The DAC amplifier unit 134 is connected to the main deflector 208. Although not shown, a DAC amplifier unit is also connected to the blanking deflector 212 and the shaping deflector 205, respectively.

  The deflection control circuit 120 outputs independent control digital signals to the respective DAC amplifier units. In each DAC amplifier unit, each digital signal is converted into an analog signal and further amplified. Thereafter, this signal is output to a deflector connected as a deflection voltage.

  As described above, a deflection voltage is applied to each deflector from the DAC amplifier unit connected to each deflector. Thereby, an electron beam can be deflected.

  In the present embodiment, the main deflector 208 and the sub deflector 209 are each composed of eight electrodes. At least one DAC amplifier unit is connected to each electrode, and the deflection control circuit 120 transmits a plurality of digital data for controlling each deflector in synchronization with the DAC amplifier unit. The digital data here is an instruction voltage signal (digital signal) to a plurality of electrodes constituting each deflector. Each DAC amplifier unit provided corresponding to each electrode DA converts the digital data received from the deflection control circuit 120, amplifies the analog data after DA conversion, and further converts the amplified analog data to the corresponding deflection. To the electrode of the vessel.

  FIG. 2 is a diagram showing eight electrodes 130a to 130h in the main deflector 208 shown in FIG. 1 and eight DAC amplifier units 232a to 232h for applying analog data to each electrode. The eight electrodes 130a to 130h are composed of four pairs of electrodes facing each other, and analog voltages are applied from the corresponding DAC amplifier units 232a to 232h, respectively.

Specifically, the voltage “y” is applied to the electrode 130a from the DAC amplifier unit 232a, and the voltage “−y” is applied to the electrode 130e that is the counter electrode of the electrode 130a from the DAC amplifier unit 232e. Further, the voltage “(x + y) / 2 ^1/2 ” is applied to the electrode 130b from the DAC amplifier unit 232b, and the voltage “(−x−y” is applied to the electrode 130f that is the counter electrode of the electrode 130b from the DAC amplifier unit 232f. ) / 2 ^1/2 "is applied. Further, the voltage “x” is applied to the electrode 130c from the DAC amplifier unit 232c, and the voltage “−x” is applied to the electrode 130g which is the counter electrode of the electrode 130c from the DAC amplifier unit 232g. Further, the voltage “(xy) / 2 ^1/2 ” is applied to the electrode 130d from the DAC amplifier unit 232d, and the voltage “(−x + y) is applied to the electrode 130h that is the counter electrode of the electrode 130d. ) / 2 ^1/2 "is applied.

  For example, it is assumed that the DAC amplifier unit 134 in FIG. 1 includes the DAC amplifier units 232a to 232h in FIG. In this case, when the digital data for controlling the electrodes 130a to 130h of the main deflector 208 is transmitted from the deflection control circuit 120 of FIG. 1 to the DAC amplifier units 232a to 232h, the DAC amplifier units 232a to 232h The analog voltage is applied to each of the electrodes 130a to 130h.

  In addition, the main deflector 208 and the sub deflector 209 are not limited to the case where each is composed of four pairs (eight poles) of electrodes. For example, each deflector may be composed of electrodes such as 2 pairs (4 poles), 6 pairs (12 poles), 8 pairs (16 poles), or 10 pairs (20 poles).

  FIG. 5 is an explanatory diagram of a drawing method using an electron beam. As shown in this figure, the pattern 51 drawn on the sample 216 is divided into strip-shaped frame regions 52. Drawing with the electron beam 200 is performed for each frame region 52 while the XY stage 105 continuously moves in one direction (for example, the X direction) in FIG. The frame region 52 is further divided into sub-deflection regions 53, and the electron beam 200 draws only necessary portions in the sub-deflection regions 53. The frame area 52 is a strip-shaped drawing area determined by the deflection width of the main deflector 208, and the sub-deflection area 53 is a unit drawing area determined by the deflection width of the sub-deflector 209.

  Positioning of the reference position of the sub deflection region 53 is performed by the main deflector 208, and drawing in the sub deflection region 53 is controlled by the sub deflector 209. That is, the main deflector 208 positions the electron beam 200 in a predetermined sub-deflection area 53, and the sub-deflector 209 determines the drawing position in the sub-deflection area 53. Further, the shape and size of the electron beam 200 are determined by the shaping deflector 205 and the beam shaping apertures 203 and 206. Then, the sub-deflection area 53 is drawn while continuously moving the XY stage 105 in one direction. When drawing of one sub-deflection area 53 is completed, the next sub-deflection area 53 is drawn. When drawing of all the sub-deflection areas 53 in the frame area 52 is completed, the XY stage 105 is moved stepwise in a direction (for example, Y direction) orthogonal to the direction in which the XY stage 105 is continuously moved. Thereafter, similar processing is repeated to sequentially draw the frame regions 52.

  The sub deflection region 53 is a region where the electron beam 200 is scanned and drawn by the sub deflector 209 at a speed higher than that of the main deflection region, and is generally a minimum drawing unit. When drawing the sub-deflection area, a shot having a size and shape prepared according to the pattern figure is formed by the shaping deflector 205. Specifically, the electron beam 200 emitted from the electron gun 201 shown in FIG. 1 is shaped into a rectangular shape by the first shaping aperture 203 and then projected onto the second shaping aperture 206 by the shaping deflector 205. The beam shape and dimensions are changed. Thereafter, as described above, the electron beam 200 is deflected by the main deflector 208 and the sub deflector 209 and irradiated onto the sample 216 placed on the XY stage 105.

  In the present embodiment, the main deflector 208 is applied with a deflection voltage by one DAC amplifier unit 134 and generates a magnetic field in accordance with the applied voltage to deflect the electron beam 200. At this time, the image of the optical system should ideally be a point image, but blur is caused by astigmatism with different imaging points in two orthogonal directions. Causes of astigmatism include physical factors (assembly errors) in the two deflectors constituting the main deflector and aberrations of the lens constituting the electron beam optical system. Therefore, a correction voltage is applied to the main deflector 208 and adjustment is performed so that the imaging positions in the X direction and the Y direction coincide with each other from the state where the imaging positions in the X direction and the Y direction are shifted.

  For example, in FIG. 2, a positive voltage having the same value and the same sign, for example, a positive voltage is applied to the electrodes 130a, 130b, 130e, and 130f. On the other hand, a reverse voltage obtained by inverting the sign of the voltage, for example, a negative voltage, is applied to the electrodes 130c, 130d, 130g, and 130h disposed at positions rotated by 90 degrees with respect to these electrodes. . Thereby, it can progress to the direction which correct | amends astigmatism.

  By doing as described above, the focal position of the electron beam that differs depending on the direction can be corrected in the main deflection region. That is, the blur of the electron beam irradiation spot can be improved in the main deflection region. However, this correction causes a problem that the magnification of the image plane varies depending on the direction, and the shot shape of the electron beam is distorted. In the following, image distortion caused by the difference in image plane magnification depending on the direction may be referred to as “XY difference”. This is a special case in which the “direction” when “the magnification varies depending on the direction” coincides with the X axis and the Y axis of the apparatus.

  The XY difference will be described with reference to FIGS. In these drawings, reference numerals 200a to 200e and reference numerals 200a 'to 200e' denote electron beam shots.

  FIG. 3 is an example in which no XY difference occurs. In FIG. 3, shots 200a to 200e are shot at different deflection positions. However, the shot 200a is not deflected. In FIG. 3, none of the shots is distorted in shape, and no XY difference occurs.

  FIG. 4 is an example in which an XY difference occurs. In FIG. 4, shots 200a 'to 200e' are shot at different deflection positions. The shape of the shot 200a 'that has not been deflected is not distorted. However, in the shot 200b 'and the shot 200d' deflected in the Y direction and -Y direction, respectively, the magnification in the Y direction is lower than the magnification in the X direction, so that the shape is distorted. Further, in the shot 200c 'and the shot 200e' deflected in the X direction and the -X direction, respectively, the magnification in the X direction is lower than the magnification in the Y direction. Therefore, these shots are also distorted in shape.

  FIG. 6 is a conceptual diagram illustrating the XY difference. The electron beam 200 subjected to astigmatism correction by the correction voltage applied to the main deflector 208 passes through the objective lens 207 and is then irradiated onto the sample 216. At this time, the deflection angle of the deflected electron beam 200 differs between the X direction and the Y direction due to the effect of correcting the deflection astigmatism. For example, if the opening angle in the X direction is θ1 and the opening angle in the Y direction is θ2, θ1 ≠ θ2, and therefore the angular magnification is different between the X direction and the Y direction, and the magnification of the image plane varies depending on the direction. Become.

  If there is an XY difference, a pattern having a desired shape cannot be drawn on the sample. In particular, when high drawing accuracy is required, the distortion of the shot shape due to the XY difference cannot be ignored. Therefore, in the present embodiment, in addition to correcting the main deflection astigmatism, the shape of the image distorted due to the fact that the magnification of the image plane varies depending on the direction (magnification anisotropy) is corrected. Specifically, one or more means for generating a quadrupole field are provided separately from the main deflector. That is, a means for generating a quadrupole field other than the quadrupole field generated by the deflector constituting the main deflector is provided, and the XY difference is determined by two or more quadrupole field generation regions combined with the main deflector. to correct.

  The quadrupole field generating means may be a quadrupole electrode or a deflector. In the present embodiment, the sub deflector is used as the quadrupole field generating means. Thereby, the space utilization efficiency of an electron beam drawing apparatus can be improved. On the other hand, when a quadrupole electrode is used as the quadrupole field generating means, this electrode can be used only as a correction electrode for correcting the main deflection astigmatism and the XY difference. That is, a function such as deflecting an electron beam is not necessary for this electrode, and the applied voltage is lower than the deflection voltage, so that there is an advantage that an electrode having a simple circuit configuration is sufficient.

  In the following description, in the electron beam lithography apparatus 100, the deflection voltage obtained by correcting the XY difference as well as the main deflection astigmatism is applied to the main deflector 208 and the sub deflector 209, and a desired voltage is applied to the sample 216. A method for drawing a pattern will be described.

  In FIG. 1, a storage device 144 is connected to the control computer 110. A drawing data processing unit 112 is arranged inside the control computer 110.

  CAD data created by a designer (user) is converted into design intermediate data in a hierarchical format such as OASIS. In the design intermediate data, design pattern data created for each layer and formed on the sample is stored. Here, generally, the electron beam drawing apparatus is not configured to directly read OASIS data. That is, unique format data is used for each manufacturer of the electron beam drawing apparatus. For this reason, the OASIS data is converted into format data unique to each electron beam drawing apparatus for each layer and then input to the apparatus.

  In FIG. 1, format data is input to the electron beam drawing apparatus 100 through the storage device 144.

  Since the figure included in the design pattern is a basic figure of a rectangle or a triangle, for example, the coordinates (x, y) at the reference position of the figure, the length of the side, a rectangle, a triangle, etc. Information such as a graphic code serving as an identifier for distinguishing graphic types, and graphic data defining the shape, size, position, etc. of each pattern graphic is stored.

  Furthermore, a set of figures existing in a range of about several tens of μm is generally called a cluster or a cell, and data is hierarchized using this. In the cluster or cell, arrangement coordinates and repeated description when various figures are arranged alone or repeatedly at a certain interval are also defined. The cluster data or cell data is further arranged in a strip-shaped region called a frame or stripe, which has a width of several hundreds μm and a length of about 100 mm corresponding to the total length of the photomask in the X direction or Y direction. The

  The graphic pattern division processing is performed in units of the maximum shot size defined by the size of the electron beam, and the coordinate position, size, and irradiation time of each divided shot are also set. Then, drawing data is created so that a shot is formed according to the shape and size of the graphic pattern to be drawn. The drawing data is divided into strip-shaped frames (main deflection areas) and further divided into sub-deflection areas. That is, the drawing data of the entire chip has a data hierarchical structure including a plurality of strip-shaped frame data according to the size of the main deflection area and a plurality of sub deflection area units smaller than the main deflection area in the frame. .

  In FIG. 1, the drawing data read from the storage device 144 by the control computer 110 is subjected to a plurality of stages of data processing by the drawing data processing unit 112. Thereby, shot data is generated. The shot data is sent to the deflection amount calculation unit 121 of the deflection control circuit 120.

  The deflection amount calculation unit 121 receives the shot data, the position information of the XY stage 105, and the height information of the sample 216 from the drawing data processing unit 112, and calculates each deflection amount of the main deflector 208 and the sub deflector 209. To do. Each of the obtained deflection amounts is referred to as a main deflection correction amount calculation unit (also referred to as a first calculation unit in this specification) 122 and a sub deflection correction amount calculation unit (also referred to as a second calculation unit in this specification). .) 123.

  The memory 142 stores a table that simultaneously satisfies deflection astigmatism correction and XY difference correction.

  Acquisition of the deflection astigmatism table which does not produce an XY difference can be performed as follows, for example.

  In the electron beam drawing apparatus 100, the electron beam 200 is deflected to a plurality of positions by the main deflector 208 at the position where the electron beam 200 is focused on the sample 216 by the objective lens 207. Then, the astigmatism generated at each deflection position is measured, and a map of the deflection position and the astigmatism is created. Similarly, an XY difference generated at each deflection position is measured, and a map of the deflection position and the XY difference is created. These astigmatism and XY differences are corrected by the voltages applied to the main deflector 208 and the sub deflector 209. Specifically, the voltage applied to the main deflector 208 is adjusted so that the imaging position of the electron beam 200 in the X direction and the Y direction coincide with each other. Then, the voltage applied to the main deflector 208 and the sub deflector 209 is adjusted while maintaining the state in which the astigmatism is corrected. As a result, a table of combinations of correction voltages to the main deflector and sub-deflector that can simultaneously correct the main deflection astigmatism and the XY difference is obtained.

  The correction of the deflection astigmatism and the XY difference is not limited to the above-described method, and may be performed using a correction coefficient, for example. Specifically, in the electron beam drawing apparatus 100, the electron beam 200 is deflected to a plurality of positions by the main deflector 208 at a position where the electron beam 200 is focused on the sample 216 by the objective lens 207. Then, the deflection amount, the deflection astigmatism corresponding to the deflection amount, and the XY difference correction amount are plotted, and the correction amount is fitted to each deflector to obtain the coefficient of the approximate expression. The coefficient thus obtained is a correction coefficient for the correction amount of each deflector.

  When the XY difference is corrected by the main deflector and the quadrupole electrode, a deflection astigmatism table that does not cause the XY difference can be obtained as follows.

  First, in the electron beam drawing apparatus 100, the electron beam 200 is deflected to a plurality of positions by the main deflector 208 at the position where the electron beam 200 is focused on the sample 216 by the objective lens 207. Then, the astigmatism generated at each deflection position is measured, and a map of the deflection position and the astigmatism is created. Similarly, an XY difference generated at each deflection position is measured, and a map of the deflection position and the XY difference is created. These astigmatism and XY differences are corrected by the voltage applied to the main deflector 208 and the quadrupole electrode. Specifically, the voltage applied to the main deflector 208 is adjusted so that the imaging position of the electron beam 200 in the X direction and the Y direction coincide with each other. The voltage applied to the main deflector 208 and the quadrupole electrode is adjusted while maintaining the state in which the astigmatism is corrected. This provides a table of combinations of correction voltages to the main deflector and quadrupole electrodes that can correct the main deflection astigmatism and the XY difference simultaneously.

  When correction is performed using the main deflector and the quadrupole electrode, the correction coefficient can be obtained as follows. For example, in the electron beam drawing apparatus 100, the electron beam 200 is deflected to a plurality of positions by the main deflector 208 at a position where the electron beam 200 is focused on the sample 216 by the objective lens 207. Then, the deflection amount, the deflection astigmatism corresponding to the deflection amount, and the XY difference correction amount are plotted, and the correction amount is fitted to the main deflector 208 and the quadrupole electrode to obtain the coefficient of the approximate expression. The coefficient thus obtained is a correction coefficient for the correction amount of the main deflector 208 and the quadrupole electrode.

  In FIG. 1, the main deflection correction amount calculation unit 122 refers to a table stored in the memory 142 that simultaneously satisfies the deflection astigmatism correction and the XY difference correction, and corresponds to the deflection amount sent from the deflection amount calculation unit 121. A first correction amount is obtained. The first correction amount is a correction amount of the deflection signal applied to the main deflector, and corrects the astigmatism caused by the deflection amount of the main deflector and the anisotropy of the magnification of the image plane of the electron beam. The amount of correction to be made.

  On the other hand, the sub-deflection correction amount calculation unit 123 refers to a table stored in the memory 142 that satisfies both the deflection astigmatism correction and the XY difference correction at the same time, and performs the second correction according to the deflection amount sent from the deflection amount calculation unit 121. Determine the amount of correction. The second correction amount is a correction amount of the deflection signal applied to the sub deflector, and corrects the astigmatism caused by the deflection amount of the main deflector and the anisotropy of the magnification of the image plane of the electron beam. The amount of correction to be made.

  The first correction amount calculated by the main deflection correction amount calculation unit 122 is sent to the deflection signal generation unit 124. In addition, the second correction amount calculated by the sub deflection correction amount calculation unit 123 is also sent to the deflection signal generation unit 124.

  The deflection signal generation unit 124 generates a deflection signal to be applied to each electrode of the main deflector 208 using the first correction amount, and outputs this to the DAC amplifier unit 134.

  Also, the deflection signal generation unit 124 generates a deflection signal to be applied to each electrode of the sub deflector 209 using the second correction amount, and outputs this to the DAC amplifier unit 132.

  The DAC amplifier unit 134 converts the digital deflection signal output from the deflection signal generation unit 124 into an analog signal, and then amplifies it to generate a deflection voltage. Then, this deflection voltage is applied to the main deflector 208. In addition, the DAC amplifier unit 132 converts the digital deflection signal output from the deflection signal generation unit 124 into an analog signal, and then amplifies it to generate a deflection voltage. Then, this deflection voltage is applied to the sub deflector 209. Thereby, the sample 216 is irradiated with the electron beam 200 in which the main deflection astigmatism and the magnification anisotropy are corrected.

  FIG. 7 is a diagram showing a state in which an electron beam is irradiated on a sample according to the present embodiment. As shown in this figure, the objective lens 207 focuses the electron beam 200 on the sample 216. In addition, a deflection voltage generated from the correction amount and the deflection amount is applied to the sub-deflector 209 and the main deflector 208 to deflect the electron beam 200. At this time, the deflection voltage applied to the main deflector 208 is generated using the main deflection astigmatism correction amount, the XY difference correction amount, and the deflection amount. Similarly, the deflection voltage applied to the sub deflector 209 is also generated using the main deflection astigmatism correction amount, the XY difference correction amount, and the deflection amount.

  According to this embodiment, the opening angle of the electron beam 200 with respect to the sample 216 can always be the same in the X direction and the Y direction. For example, if the opening angle in the X direction is θ1 and the opening angle in the Y direction is θ2, θ1 = θ2, so the magnification of the image plane is the same in the X direction and the Y direction. Therefore, distortion of the shot shape of the electron beam 200 depending on the deflection position can be suppressed.

  In the present embodiment, the XY difference between the main deflection astigmatism and the XY difference is corrected by the quadrupole field generated by the main deflector 208 and the quadrupole field generated by the sub deflector 209. By performing these corrections in real time, the focal position and magnification of the electron beam 200 are corrected according to the deflection position. Therefore, according to the present embodiment, it is possible to always irradiate the sample 216 by deflecting the electron beam 200 having a desired shot shape and reduced blur to a desired position.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, although the electron beam is used in the above embodiment, the present invention is not limited to this, and the present invention can also be applied to the case where another charged particle beam such as an ion beam is used.

DESCRIPTION OF SYMBOLS 100 Electron beam drawing apparatus 102 Electron barrel 103 Drawing chamber 105 XY stage 106 Reflecting mirror 107 Z sensor 110 Control computer 112 Drawing data processing unit 120 Deflection control circuit 121 Deflection amount calculation unit 122 Main deflection correction amount calculation unit 123 Sub deflection correction amount Arithmetic unit 124 Deflection signal generation unit 132, 134, 232a to 232h DAC amplifier unit 142 Memory 143 Detector 144 Storage device 145 Laser length measuring device 130a to 130h Electrode 150 Drawing unit 160 Control unit 200 Electron beams 200a to 200e, 200a ′ to 200e 'electron beam shot 201 electron gun 202 illumination lens 203 first shaping aperture 204 projection lens 205 shaping deflector 206 second shaping aperture 207 objective lens 208 main deflector 209 sub deflector 212 Blankin Deflector 214 the blanking aperture 216 sample 51 drawn from the pattern 52 frame region 53 sub-deflection region

Claims (5)

An electromagnetic lens for focusing the charged particle beam;
A main deflector for deflecting the charged particle beam;
One or more quadrupole field generating means for generating a quadrupole field different from the main deflector,
The main deflector and the quadrupole field generating means correct astigmatism caused by the deflection amount of the main deflector and anisotropy of the magnification of the image plane of the charged particle beam. A charged particle beam drawing apparatus. A correction amount of a deflection signal applied to the main deflector, the first correcting the astigmatism caused by the deflection amount of the main deflector and the anisotropy of the magnification of the image plane of the charged particle beam. A first calculation unit for calculating the correction amount of
A correction amount of the deflection signal applied to the quadrupole field generating means, which corrects the astigmatism caused by the deflection amount of the main deflector and the anisotropy of the magnification of the image plane of the charged particle beam. A second calculation unit for calculating a second correction amount to be
Deflection signal generation for generating a deflection signal to be applied to the main deflector using the first correction amount and generating a deflection signal to be applied to the quadrupole field generating means using the second correction amount The charged particle beam drawing apparatus according to claim 1, further comprising:   The charged particle beam drawing apparatus according to claim 1, wherein the quadrupole field generating means is a sub deflector that deflects the charged particle beam. In a charged particle beam writing method in which a charged particle beam is focused on a sample by an electromagnetic lens and the irradiation position of the charged particle beam on the sample is controlled by a main deflector.
Astigmatism caused by the main deflector and one or more quadrupole field generating means for generating a quadrupole field different from the main deflector depending on the deflection amount of the main deflector, A charged particle beam drawing method comprising correcting anisotropy of magnification of an image plane of a charged particle beam. The charged particle beam drawing method according to claim 4, wherein the quadrupole field generating means is a sub-deflector that deflects the charged particle beam.

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