JP2013074130A - Electric charge particle beam drawing device and electric charge particle beam drawing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric charge particle beam drawing device and an electric charge particle beam drawing method for improving throughput in drawing processing by performing a shot to an internal area in which higher location accuracy is not required than in a contour area of the drawing object with settling time shorter than that in a shot to the contour area.SOLUTION: A control computer 31 includes: a division part 31b which divides a graphic pattern P to be a drawing object into a plurality of areas; a determination part 31c which divides the areas into a contour area Ps in which high location accuracy is required, and an internal area Pi which is located on the inside of the counter area Ps, in which low location accuracy is enough; a flag addition part 31d which adds a flag to the internal area Pi; and an operation part 31e which calculates settling time to be required when a shot to the internal area Pi is performed so as to become shorter than settling time to be required when a shot to the contour area Ps is performed.

Description

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

  Lithography technology is used to form a desired circuit pattern on a semiconductor device. In the lithography technique, a pattern is transferred using an original pattern called a mask (also referred to as a reticle; hereinafter referred to as “mask” or “sample”). At this time, in order to manufacture a highly accurate mask, an electron beam (electron beam) drawing technique having an excellent resolution is used.

  An example of a charged particle beam writing apparatus that performs electron beam writing on a mask includes the following variable forming method. That is, although not shown here, this variable forming method is performed on the sample placed on the movable stage by the electron beam formed by passing through the opening of the first forming aperture and the opening of the second forming aperture. A graphic pattern is drawn.

  When performing such a drawing process, the charged particle beam drawing apparatus uses a deflector controlled with an electric field to control the activation of the electron beam. In order to stabilize the electric field by the deflector, although it depends on the deflector, a time of about 50 nsec is required. In the drawing process, this stabilization is performed between the irradiation (shot) of the electron beam. Have time for. This time is called settling time. Normally, the same settling time is adopted for all shots in one drawing process within the same mask.

  Since the settling time is the time required to stabilize the electric field as described above, the electric field is still unstable when the settling time is short. Deviation occurs in position. On the other hand, if the settling time is set to be long in order to eliminate misalignment, the electric field is stabilized, but the settling time directly affects the drawing processing time, so that the drawing processing takes a long time. Therefore, it is not preferable to set the settling time longer than necessary from the viewpoint of throughput.

  Therefore, how to set the settling time to improve the throughput of the drawing process is very important.

  Regarding the setting of the settling time, the invention disclosed in Patent Document 1 shown below deals with the following. That is, when drawing a pattern with a shape larger than the maximum area of the electron beam, the pattern is virtually divided into a peripheral part and an internal part, and when the internal part of the pattern is drawn, the electron beam is deflected to irradiate the electron beam. By drawing while shifting the position, when shifting the irradiation position of this electron beam, the electron beam blanking is not performed, and the settling time of the circuit that creates the voltage supplied to the electron beam deflector is eliminated. The drawing time is shortened.

JP 2002-260982 A

  However, in the invention described in Patent Document 1, the internal figure in the area of the internal part is divided so as to be an integral multiple of the same size. The shot size is also set so that the area of the inner part is smaller than the maximum beam size and the number of shots is minimized.

  On the other hand, if it is set in this way, the possibility that the area of the inner part is divided by the maximum beam size will be reduced. Therefore, since the electron beam blanking is not performed during the shot of the inner part area, it seems that the throughput is surely improved, but the shot time in the inner part area is when the shot is performed with the maximum beam size. It may take more time than that.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to divide a graphic pattern to be drawn into an outline area and an internal area, and a position accuracy higher than that of the outline area is not required. Provided is a charged particle beam drawing apparatus and a charged particle beam drawing method capable of improving throughput in drawing processing by performing shots on an inner region with a settling time shorter than that in a shot on a contour region. There is.

  A feature of an embodiment of the present invention is that in a charged particle beam writing apparatus, a charged particle beam is deflected using a main deflector and a sub deflector, and a pattern is drawn on a sample placed on a movable stage. A control unit comprising: a drawing unit that controls the deflection of the charged particle beam; a stage control unit that controls the movement of the stage; and a control computer that controls the deflection control unit and the stage control unit The control computer is configured to divide the graphic pattern to be drawn into a plurality of areas that can be shot with a charged particle beam, and to provide high positional accuracy for the area formed as a result of dividing the graphic pattern. A determination unit that divides into a contour region that forms a contour of a graphic pattern for which a search is required, and an internal region that is located inside a contour region that requires low positional accuracy, and based on the determination of the determination unit A flag adding unit for adding a flag to the internal region, and a settling time required for performing a shot to the internal region to which the flag is added, and a settling time required for performing a shot to the contour region And a calculation unit that calculates to be shorter.

  Further, in the charged particle beam drawing apparatus, it is desirable that the calculation unit sets the settling time of the inner region so that the positional deviation of the shot becomes smaller than the minimum resolution dimension of the charged particle beam.

  In the charged particle beam drawing apparatus, it is desirable that the dividing unit divides the graphic pattern so that the charged particle beam can be shot in the largest size.

  In the charged particle beam drawing apparatus, it is desirable that the dividing unit divides the graphic pattern so that at least the inner region becomes a region where a shot can be shot with the largest size.

  According to an embodiment of the present invention, in the charged particle beam drawing method, a step of dividing a figure pattern to be drawn into a plurality of areas that can be shot with a charged particle beam, and a figure pattern of the divided area Determining the position in the contour area of the graphic pattern, determining that high positional accuracy is required in the contour area of the graphic pattern, and determining that the internal area located inside the contour area is low in positional accuracy, and a charged particle beam for the contour area A settling time for the inner region, a step for adding a flag to the inner region, and a step for setting the settling time of the charged particle beam for the inner region to which the flag is added shorter than the settling time for the contour region. .

  According to the present invention, a graphic pattern to be drawn is divided into an outline area and an internal area, and shots to an internal area where the positional accuracy is not required to be higher than the outline area are less than the settling time in the shot to the outline area. In addition, it is possible to provide a charged particle beam drawing apparatus and a charged particle beam drawing method capable of improving throughput in drawing processing by performing with a short settling time.

1 is a block diagram illustrating an overall configuration of a charged particle beam drawing apparatus according to an embodiment of the present invention. It is a block diagram which shows the internal structure of the control computer in embodiment of this invention. It is a flowchart which shows the flow of the settling time setting by the drawing pre-process in embodiment of this invention. It is a conceptual diagram regarding the division | segmentation of a figure pattern. It is a conceptual diagram regarding the division | segmentation of a figure pattern. It is a schematic diagram which shows the position shift regarding the single shot in an internal area | region at the time of dividing and dividing a figure pattern. It is a schematic diagram which shows the position shift regarding the single shot in an internal area | region at the time of dividing and dividing a figure pattern. It is a flowchart which shows the flow of settling time setting in the drawing process in embodiment of this invention. It is a graph which shows the relationship between settling time and position shift.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing an overall configuration of a charged particle beam drawing apparatus 1 according to an embodiment of the present invention. In the following embodiments, 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 may be a beam using charged particles such as an ion beam.

  The charged particle beam drawing apparatus 1 is an apparatus that draws a predetermined pattern on a sample, and is particularly an example of a variable shaping type drawing apparatus. As shown in FIG. 1, the charged particle beam drawing apparatus 1 includes a drawing unit 2 and a control unit 3. The drawing unit 2 includes an electron column 4 and a drawing chamber 6.

  In the electron column 4, along an optical path of an electron gun 41 and a charged particle beam (electron beam) EB irradiated from the electron gun 41, an illumination lens 42, a blanking deflector 43, and a blanking aperture are provided. 44, a first shaping aperture 45, a projection lens 46, a shaping deflector 47, a second shaping aperture 48, an objective lens 49, a sub deflector 50, and a main deflector 51 are arranged in this order. ing.

  An XY stage 61 is disposed in the drawing chamber 6. On the XY stage 61, a sample M such as a mask that becomes a sample at the time of drawing is arranged. The sample M is not actually placed directly on the XY stage 61 but is held by a holding member provided between the XY stage 61 and the sample M, but the illustration is omitted in FIG.

  The blanking deflector 43 is constituted by a plurality of electrodes such as two poles or four poles. Further, the shaping deflector 47, the sub deflector 50, and the main deflector 51 are constituted by a plurality of electrodes such as four poles or eight poles, for example. In FIG. 1, only one deflection amplifier is shown for each of the shaping deflector 47, the sub deflector 50, the main deflector 51, and each deflector, but at least one deflection amplifier is connected to each electrode.

  The control unit 3 includes a control computer 31, a deflection control unit 32, a blanking amplifier 33, a shaping deflection amplifier 34, a sub deflection amplifier 35, a main deflection amplifier 36, and a stage control unit 37. Although not shown in FIG. 1, the control computer 31 has an external interface (I / I) for connecting a storage device such as a memory or a magnetic disk device or the charged particle beam drawing apparatus 1 to the outside. F) A circuit may be provided.

  The control computer 31 mainly controls a deflection control unit 32 and a stage control unit 37 which will be described later. In addition, the entire charged particle beam drawing apparatus 1 is also controlled. The control computer 31 generates shot data such as the division of the graphic pattern and the irradiation amount of the electron beam EB necessary for performing the electron beam EB shot on the graphic pattern, and transmits the shot data to the deflection control unit 32.

  FIG. 2 is a block diagram showing an internal configuration of the control computer 31 in the embodiment of the present invention. The control computer 31 includes a reception unit 31a, a division unit 31b, a determination unit 31c, a flag addition unit 31d, a calculation unit 31e, and a transmission unit 31f.

  However, FIG. 2 shows only the configuration necessary for explaining the embodiment of the present invention, and other configuration necessary for the role required for the control computer 31 in the charged particle beam drawing apparatus 1. Is omitted here.

  Each of these units may be configured by software such as a program or hardware, or may be configured by a combination of software and hardware. When these units are configured to include software as described above, the input data input to the control computer 31 or the calculated result is stored in a memory (not shown) each time.

  The operation of each part constituting the control computer 31 will be described together with the description of the settling time setting flow in the embodiment of the present invention.

  Based on the shot data generated by the control computer 31, the deflection control unit 32 performs deflection control on the shaping deflection amplifier 34, the sub deflection amplifier 35, and the main deflection amplifier 36 upon irradiation with the electron beam EB.

  The control computer 31, the deflection control unit 32, and the stage control unit 37 are connected to each other via a bus (not shown). The deflection control unit 32, the blanking amplifier 33, the shaping deflection amplifier 34, the sub deflection amplifier 35, and the main deflection amplifier 36 are connected to each other via a bus (not shown). In the following, the shaping deflection amplifier 34, the sub deflection amplifier 35, and the main deflection amplifier 36 are collectively referred to as a “DAC (Digital to Analog Converter) amplifier”.

  The blanking amplifier 33 is connected to the blanking deflector 43. The shaping deflection amplifier 34 is connected to a shaping deflector 47. The sub deflection amplifier 35 is connected to the sub deflector 50, and the main deflection amplifier 36 is connected to the main deflector 51. Independent control digital signals are output from the deflection control unit 32 to the blanking amplifier 33, the shaping deflection amplifier 34, the sub deflection amplifier 35, and the main deflection amplifier 36. The shaping deflection amplifier 34, the sub deflection amplifier 35, and the main deflection amplifier 36 to which the digital signal is inputted convert each digital signal into an analog voltage signal, amplify it, and output it to each deflector connected as a deflection voltage. In this way, a deflection voltage is applied to each deflector from the connected DAC amplifier. The electron beam is deflected by the deflection voltage.

  The charged particle beam drawing apparatus 1 is provided with four or eight shaping deflectors 47, sub deflectors 50, and main deflectors 51 so as to surround the electron beam EB as described above. A pair (two pairs in the case of four poles, four pairs in the case of eight poles) is arranged with the beam EB interposed therebetween. A DAC amplifier is connected to each of the shaping deflector 47, the sub deflector 50, and the main deflector 51. However, in FIG. 1, only one DAC amplifier is connected to each of the shaping deflector 47, the sub deflector 50, and the main deflector 51, and the other DAC amplifiers are not shown.

  The stage control unit 37 is connected to the XY stage 61 and the control computer 31, detects the movement of the XY stage 61, and performs drawing processing so that the sample M placed on the XY stage 61 is at a desired position. The XY stage 61 is moved according to the above.

  Note that the charged particle beam drawing apparatus 1 in the embodiment of the present invention shown in FIG. 1 shows only the configuration necessary for describing the embodiment of the present invention. Accordingly, other configurations such as a control circuit for controlling each lens may be added.

  The charged particle beam drawing apparatus 1 operates as follows to perform drawing on a drawing target. When the electron beam EB emitted from the electron gun 41 (emission unit) passes through the blanking deflector 43, the electron beam EB is blanked when the blanking deflector 43 is turned on. Is controlled to pass through. On the other hand, in the OFF state, the entire electron beam EB is deflected so as to be shielded by the blanking aperture 44 (indicated by a broken line in FIG. 1). The electron beam EB that has passed through the blanking aperture 44 until the deflection voltage from the blanking amplifier 33 is turned from OFF to ON and then turned OFF again becomes one electron beam shot.

  A deflection voltage that alternately generates a state in which the electron beam EB passes through the blanking aperture 44 and a state in which the electron beam EB is blocked by the blanking aperture 44 is output from the blanking amplifier 33. The blanking deflector 43 controls the direction of the passing electron beam EB by the deflection voltage output from the blanking amplifier 33, and the electron beam EB passes through the blanking aperture 44. Alternately create shielded states.

  As described above, the electron beam EB of each shot generated by passing through the blanking deflector 43 and the blanking aperture 44 is rectangular by the illumination lens 42, for example, a first shaping aperture 45 having a rectangular hole. Illuminate the whole. Here, the electron beam EB is first shaped into a rectangle, for example, a rectangle. Then, the electron beam EB of the first aperture image that has passed through the first shaping aperture 45 is projected on the second shaping aperture 48 by the projection lens 46. The first aperture on the second shaping aperture 48 is formed by a shaping deflector 47 to which a deflection voltage for controlling the direction of the electron beam EB that has passed through the first shaping aperture 45 is applied from the shaping deflection amplifier 34. The image is deflection controlled and the beam shape and dimensions can be changed.

  A deflection voltage for controlling the irradiation position of the electron beam EB that has passed through the second shaping aperture 48 is output from the sub deflection amplifier 35 to the sub deflector 50, and from the main deflection amplifier 36 to the main deflector 51. Is done. The electron beam EB that has passed through the second shaping aperture 48 and formed into the second aperture image is focused by the objective lens 49 and is placed at a desired position on the sample M arranged on the XY stage 61 that moves continuously. Irradiated.

  Next, the settling time setting flow in the embodiment of the present invention will be described. FIG. 3 is a flowchart showing a settling time setting flow in the pre-drawing process according to the embodiment of the present invention, that is, when creating graphic pattern data. In the embodiment of the present invention, it is assumed that a graphic pattern to be drawn cannot be drawn once even with the maximum shot size of the electron beam EB. Further, it is assumed that the resist applied to the sample M is positive.

  First, a graphic pattern to be drawn is divided by the dividing unit 31b (ST1). When the division unit 31b determines that the drawing pattern cannot be drawn at once even with the maximum shot size of the electron beam EB with respect to the drawing pattern to be drawn, Divide into By dividing in this way, a plurality of areas can be formed, and a desired drawing process can be performed on all areas of the graphic pattern to be set.

  When the figure pattern is divided, basically, the entire area of the figure pattern is divided by the electron beam EB into a size that allows the largest shot. This is because if the electron beam EB can be irradiated with the maximum shot size, it contributes to the improvement of the throughput of the drawing process.

  FIG. 4 is a conceptual diagram regarding division of the graphic pattern P1. Here, one figure pattern P1 is divided so as to be divided into a total of 18 areas of 6 in length and 3 in width. Each block shown in FIG. 4 represents one area. In addition, the size of this region is the size (size) at which the electron beam EB can be shot the largest.

  FIG. 5 is a conceptual diagram regarding division of the graphic pattern P2. The graphic pattern P2 shown in FIG. 5 is different from the graphic pattern P1 shown in FIG. 4 in that the entire area cannot be divided into the maximum shot size of the electron beam EB. In such a case, the area is divided so that a maximum shot size area that can be set as much as possible is created in the figure pattern to be divided, and the areas other than these areas are divided as areas not larger than the maximum shot size. Is done. For example, a triangular area is set in the graphic pattern P2 of FIG. 5, but such an area is an area having a size equal to or smaller than the maximum shot size.

  Although not assumed in the embodiment of the present invention, if the drawing target area is an area smaller than the maximum shot size of the electron beam EB and the pattern is a rectangle, a rectangle, or a triangle, division is performed. Division by the unit 31b is not performed. Whether or not the division by the dividing unit 31b is necessary may be determined by the dividing unit 31b or may be determined by a configuration not shown in FIG. 2 in the control computer 31, for example.

  Next, in each region generated by being divided and generated by the dividing unit 31b, when the electron beam EB is irradiated for drawing, the determining unit 31c determines how much position accuracy is required by the shot (ST2). In the embodiment of the present invention, two types of regions, a region where high positional accuracy is required as a positional accuracy for all formed regions and a region where high positional accuracy is not required compared to such a region. Divide into

  Specifically, the region constituting the contour of the graphic pattern P is a region where high positional accuracy is required. The reason why high positional accuracy is required in the area constituting the contour of the graphic pattern P is that the contour of the graphic pattern P needs to be clearly (clearly) formed (formed).

  In addition, it can be said that the area | region which comprises the outline of the figure pattern P is an area | region which forms the circumference | surroundings outside the figure pattern P, so to speak. In the following, this region is referred to as “contour region”. In FIG. 4 or FIG. 5, it is an area | region comprised by the area | region which is not filled one by one surrounding the area | region shown with an oblique line, and is an area | region shown with the part number Ps. In FIG. 4 or FIG. 5, the symbol Ps is used in each case of representing the “contour region” and each region constituting the contour region.

  On the other hand, as for the region constituting the graphic pattern P and other than the contour region Ps, that is, the region generated inside the graphic pattern P, high positional accuracy like the contour region Ps is not required. This is due to the fact that the positional accuracy is poor and, for example, even if the shot of the electron beam EB is deviated, depending on the amount of deviation, the obtained pattern is not affected.

  In the embodiment of the present invention, on the premise of such an idea, in order to avoid a reduction in drawing processing throughput due to obtaining high positional accuracy for all regions of the figure pattern P to be drawn, the figure pattern The P region is divided into a region where high positional accuracy is required and a region where high positional accuracy is not required. In the latter region, the settling time is shortened so that the electron beam EB can be irradiated to an extent that the amount of displacement can be allowed due to the positional displacement.

  Further, in the embodiment of the present invention, it is assumed that the area of the graphic pattern P that is classified as the area included in the latter area is surrounded by another area that is divided into eight sides of the area. . Since the region is basically formed by being divided into sizes corresponding to the maximum shot size of the electron beam EB, the region formed by being divided is also rectangular. However, for example, when only four sides of the rectangular area are surrounded by other areas and the apex part is not in contact with the other area, the apex part constitutes the contour of the graphic pattern. Therefore, as described above, in the embodiment of the present invention, the area included in the latter area of the graphic pattern P is surrounded by another area obtained by dividing one side of the area.

  4 or FIG. 5 is a region where positional accuracy comparable to that of the contour region Ps of the graphic pattern P cannot be obtained in this way. Hereinafter, such a region is referred to as “inner region Pi”. Note that the symbol Pi is also used for each region constituting the “inner region Pi”.

  FIG. 6 is a schematic diagram showing a positional shift related to a single shot in the internal region Pi when the figure pattern P3 is divided and shot. In the figure pattern P3, when the internal region Pi is irradiated with the electron beam EB, the position is shifted in the direction of the arrow from the position where it should be irradiated. As a result, a shift occurs between the position of the internal region Pi that is actually irradiated and the position that should be irradiated, and the resist remains. In this way, the region where the positional deviation occurs due to the irradiation of the electron beam EB and the resist remains is hereinafter referred to as “defect region D” (the defect region of the graphic pattern P3 shown in FIG. 6 is represented as “D1”). .

  The defect area D may be recognized as a defect depending on its size, or there may be a case where the defect area D exists but is not recognized as a defect in the drawing process. This determination is made on the basis of the minimum resolution dimension, which is the minimum dimension capable of resolving the graphic pattern. If there is a defect region D having a dimension larger than the minimum resolution dimension, the pattern remains after the pattern is formed, so that the graphic pattern is recognized as a defect. On the other hand, in the case of the defect region D having a dimension smaller than the dimension with the minimum resolution dimension as a reference, the pattern is not formed, so that the defect is not recognized.

  Therefore, as will be described later, even if the defect area D is generated, if the dimension remains smaller than the minimum resolution dimension, a positional shift in the internal area Pi can be allowed. Therefore, it is conceivable to set the settling time for the shot in the internal region Pi in relation to the minimum resolution size.

  Here, the expression “single” shot represents the shot when the internal pattern Pi is shot once in the graphic pattern P. Therefore, before and after the single shot are shots for the contour region Ps. When the single shot is the last shot in the graphic pattern, the previous shot, and when the single shot is the first shot in the graphic pattern, the subsequent shots are shots for the contour region Ps. In some cases, it is a “single shot”.

  On the other hand, FIG. 7 is a schematic diagram showing a positional shift related to continuous shots in the internal region Pi when the figure pattern P4 is divided and shot. Here, the expression “continuous” shot indicates the shot when the shot of the internal region Pi is continuously performed a plurality of times in the graphic pattern P. For example, when the internal region Pi is composed of two regions as in the graphic pattern P4 shown in FIG. 7, when the two internal regions Pi are continuously irradiated with the electron beam EB, the irradiation (shot) is performed. It is a continuous shot. In general, when a shot is shot in a region where the electron beam EB is present, it has been confirmed that the history of the previously shot shot is dragged. Therefore, when continuous shots are performed, the size of the defect area D2 tends to be larger than that in the case of single shots.

  Returning to FIG. 3, a flag is added to information indicating each area corresponding to the internal area Pi, in which the positional accuracy is not required to be strict, among the divided areas (ST3). That is, the outline region Ps and the internal region Pi are distinguished from each other in the figure pattern P to be drawn depending on the presence or absence of the flag. For the area determined as the internal area Pi by the determination unit 31c, information related to the internal area Pi is sent from the determination unit 31c to the flag adding unit 31d, and the flag is added, and then transmitted to the determination unit 31c again.

  In addition to the method described above, for example, a method for obtaining a flag from the determination unit 31c to the flag addition unit 31d and adding the flag to the corresponding internal region Pi may be used as the method for adding the flag.

  The determination unit 31c determines whether the graphic pattern to be drawn corresponds to the contour region Ps or the internal region Pi, and further, in the state where the flag is added to the internal region Pi, these Information is transmitted to the calculation unit 31e. In this state, the drawing process is actually performed.

  FIG. 8 is a flowchart showing the flow of settling time setting during the drawing process according to the embodiment of the present invention.

  The calculation unit 31e sets the settling time of the electron beam EB based on the presence or absence of a flag in the information sent from the determination unit 31c. That is, when it is determined whether or not there is a flag for the information sent to the calculation unit 31e (ST11), it can be determined that the information of the region to which the flag is not added is information on the contour region Ps (ST11). NO). Therefore, the settling time of the electron beam EB is set for each region Ps constituting the contour region Ps (ST12).

  Here, each region corresponding to the contour region Ps needs to be irradiated with high positional accuracy. Therefore, it must be avoided that the position shifts in the irradiation of the electron beam EB. Therefore, in consideration of these points, the calculation unit 31e sets the settling time, the irradiation amount, and the like of the electron beam EB for each region constituting the contour region Ps. The settling time set here is a settling time set when normal drawing processing is performed, and is a time during which the electric field is sufficiently stabilized. Therefore, the irradiation of the electron beam EB after the settling time does not cause a positional shift and is reliably shot at the set position.

  In addition, conditions such as the irradiation amount of the electron beam EB irradiated to each region corresponding to the contour region Ps are also set.

  On the other hand, when the presence or absence of a flag is determined for the information sent to the calculation unit 31e (ST11), it can be determined that the information is related to the internal area Pi if a flag is added. Therefore, in this case, a settling time suitable for irradiating the internal region Pi with the electron beam EB is set (ST13).

  Specifically, the settling time in the electron beam EB irradiated to the internal region Pi is set to a time that is short with respect to the settling time in the electron beam EB irradiated to the contour region Ps and does not generate a defect. As described above, when the settling time is shortened, the electron beam EB is irradiated in a state where the electric field is not sufficiently stable. Therefore, the positional accuracy in the irradiated region is irradiated in a state where the electric field is sufficiently stable. It becomes sweeter than the case, and misalignment easily occurs.

  However, in the embodiment of the present invention, in the internal region Pi, the settling time is shortened to shorten the time required for the entire drawing process rather than the occurrence of positional deviation, and as a result, the drawing process throughput is improved. I am going to do that. Therefore, in other words, in the embodiment of the present invention, it can be said that it is premised that a position shift occurs in the internal region Pi to the extent that it is not determined that no defect occurs, and a defect region D occurs.

  However, if the size of the defect region D is too large, a defect may occur in the sample M to be drawn. Therefore, the settling time is set as follows for the irradiation to the inner region Pi.

  FIG. 9 is a graph showing the relationship between settling time and misalignment. In this graph, the horizontal axis represents settling time, and the vertical axis represents the amount of positional deviation (indicated as “position error” in the graph of FIG. 9). The settling time is displayed every 60 nsec, and the positional deviation is displayed every 20 nm.

  For example, when the minimum resolution dimension is 20 nm, the resist remains in the drawing result (pattern) showing a value larger than 20 nm, and the sample M is determined to be defective. Therefore, it is necessary to set the settling time so that the size of the defect area D is smaller than the minimum resolution dimension. Therefore, referring to the graph shown in FIG. 9, if approximately 50 nsec can be secured as the settling time, even if the resist remains in the defect region D, it remains only smaller than the minimum resolution dimension. There are no defects.

  Therefore, the settling time in the irradiation of the electron beam EB in the internal region Pi is set based on the minimum resolution dimension. Note that the settling time in the irradiation of the electron beam EB to the contour region Ps to which no flag is added is longer than that in the internal region Pi. That is, the displacement amount in the contour region Ps must be smaller than the displacement amount in the inner region Pi. With reference to the graph shown in FIG. 9, the settling time for the contour region Ps is longer than the settling time for the inner region Pi. It is obvious.

  When the settling time is set for either the contour region Ps or the inner region Pi, information related to the irradiation of the electron beam EB including the settling time is transmitted from the control computer 31 to the deflection control unit 32 (ST14). . The deflection control unit 32 that has received the information performs control calculation of each deflector (DAC amplifier) based on the information (ST15). Then, a control signal based on the calculation is transmitted to each of the target deflectors (ST16). Each deflector deflects the electron beam EB based on these transmitted control signals.

  As described above, the graphic pattern to be drawn is divided into an outline area and an internal area, and shots to the internal area where the position accuracy cannot be obtained higher than the outline area are longer than the settling time in the shot to the outline area. Provided are a charged particle beam writing apparatus and a charged particle beam writing method capable of improving throughput in writing processing by performing with a short settling time.

  However, with respect to the irradiation of the electron beam to the internal region, the settling time is set to be short, so that a positional shift occurs and a defective region occurs. In the case of a single shot, even if the history of the previous shot may be dragged with respect to the shot to the inner area, the previous shot is a shot to the so-called contour area, and the settling time is sufficiently secured. Therefore, the electron beam is irradiated with the electric field sufficiently stable. Therefore, although it is not necessary to consider the enlargement of the defect area by dragging the history, for example, in the case of continuous shots as shown in FIG. 7, the enlargement of the defect area by dragging the history of the previous shot is dealt with. There is a need.

  When continuously irradiating the electron beam, the defect area is enlarged. For example, the above problem can be solved by mixing the reset shot in the continuous shot. Here, the “reset shot” is a shot of an electron beam irradiated with a settling time sufficiently secured and a stable electric field. When a reset shot is performed, no position shift occurs. Therefore, by including such a reset shot in the continuous shot, the history of the previous shot can be once canceled. The elimination of the history makes it possible to continue drawing again from a state in which no defective area occurs, which is an effective means.

  In addition, the settling time of the electron beam applied to the inner area is set shorter than the settling time for the shot to the contour area, but the defect area size is smaller than the minimum resolution size even if all scheduled shots are performed. Set the settling time so that it becomes smaller. By adopting such a method, it is possible to eliminate the adverse effects caused by continuous shots.

  Although an embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Charged particle beam drawing apparatus 2 Drawing part 3 Control part 31 Control computer 31a Receiving part 31b Dividing part 31c Judgment part 31d Flag addition part 31e Calculation part 31f Transmission part 32 Deflection control part 33 Blanking amplifier 34 Shaping deflection amplifier 35 Sub deflection amplifier 36 Main deflection amplifier Ps Contour area Pi Internal area

Claims (5)

A drawing unit that deflects a charged particle beam using a main deflector and a sub deflector and draws a pattern on a sample placed on a movable stage; and
A control unit configured by a deflection control unit that controls deflection of the charged particle beam, a stage control unit that controls movement of the stage, and a control computer that controls the deflection control unit and the stage control unit; With
The control computer is
A dividing unit that divides a figure pattern to be drawn into a plurality of regions that can be shot with the charged particle beam;
The region formed as a result of the division of the graphic pattern is divided into a contour region that forms the contour of the graphic pattern that requires high positional accuracy, and an internal region that is located inside the contour region that requires low positional accuracy. A judgment part to divide,
A flag adding unit for adding a flag to the internal region based on the determination of the determination unit;
A calculation unit that calculates a settling time required when performing a shot to the internal region to which the flag is added so as to be shorter than a settling time required when performing a shot to the contour region;
A charged particle beam drawing apparatus comprising:   2. The charged particle according to claim 1, wherein the calculation unit sets the settling time of the inner region so that the positional deviation of the shot is smaller than a minimum resolution dimension of the charged particle beam. Beam drawing device.   3. The charged particle beam drawing apparatus according to claim 1, wherein the dividing unit divides the figure pattern so that the charged particle beam is an area in which the charged particle beam can be shot with the largest size. 4.   The division unit according to any one of claims 1 to 3, wherein the division unit divides the figure pattern so that at least the inner area is an area where the shot can be shot with the largest size. Charged particle beam lithography system. Dividing a figure pattern to be drawn into a plurality of regions that can be shot with a charged particle beam;
The position of the divided area in the graphic pattern is confirmed, it is determined that high positional accuracy is required in the contour area of the graphic pattern, and low positional accuracy is sufficient in the internal area located inside the contour area. A step of judging;
Setting a settling time of the charged particle beam with respect to the contour region;
Adding a flag to the internal region;
Setting the settling time of the charged particle beam for the internal region to which the flag is added to be shorter than the settling time for the contour region;
A charged particle beam writing method comprising:

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