JP2014038945A - Method for setting correction interval pattern for beam drift, method for determining execution period of parts maintenance for charged particle beam drawing device, and charged particle beam drawing device - Google Patents

Abstract

[Objective] To provide a method for setting a correction interval so as to minimize the influence on throughput.
A beam drift correction interval pattern setting method according to an aspect of the present invention includes a step of referring to a correction interval pattern for correcting a beam drift when an event occurs, and a correction defined in the correction interval pattern. A step of measuring the beam drift amount at every interval and executing the beam drift correction, and a correction interval in which the change amount of the beam drift amount measured from the start of drawing to the end of drawing after drawing is defined in the correction interval pattern The step of determining whether the change amount is larger or smaller than the change amount that is a basis for determining the difference, and as a result of the determination, if the change amount of the beam drift amount is larger than the change amount that is the basis of the correction interval, the correction interval is set. And a step of resetting the correction interval pattern so as to lengthen the correction interval when it is short and small.
[Selection] Figure 4

Description

  The present invention relates to a charged particle beam drift correction interval pattern setting method, a charged particle beam drawing apparatus component maintenance timing determination method, and a charged particle beam drawing apparatus. For example, a predetermined sample is applied to a sample using an electron beam. The present invention relates to a technique for setting a correction interval pattern for position drift correction of an electron beam in a drawing apparatus that draws a pattern and determining a time for performing component maintenance.

  Lithography technology, which is responsible for the progress of miniaturization of semiconductor devices, is an extremely important process for generating a pattern among semiconductor manufacturing processes. In recent years, with the high integration of LSI, circuit line widths required for semiconductor devices have been reduced year by year. In order to form a desired circuit pattern on these semiconductor devices, a highly accurate original pattern (also referred to as a reticle or a mask) is required. Here, the electron beam (electron beam) drawing technique has an essentially excellent resolution, and is used for producing a high-precision original pattern.

FIG. 8 is a conceptual diagram for explaining the operation of the variable shaping type electron beam drawing apparatus.
The variable shaped electron beam (EB) drawing apparatus operates as follows. In the first aperture 410, a rectangular opening for forming the electron beam 330, for example, a rectangular opening 411 is formed. Further, the second aperture 420 is formed with a variable shaping opening 421 for shaping the electron beam 330 having passed through the opening 411 of the first aperture 410 into a desired rectangular shape. The electron beam 330 irradiated from the charged particle source 430 and passed through the opening 411 of the first aperture 410 is deflected by the deflector, passes through a part of the variable shaping opening 421 of the second aperture 420, and passes through a predetermined range. The sample is irradiated on a stage that moves continuously in one direction (for example, the X direction). That is, the drawing area of the sample 340 mounted on the stage in which the rectangular shape that can pass through both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is continuously moved in the X direction. Drawn on. A method of creating an arbitrary shape by passing both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is referred to as a variable shaping method (VSB method).

  Here, for example, reflected electrons are generated by irradiating the sample with the above-described electron beam irradiated at the start of drawing. The generated reflected electrons collide with the optical system and detector in the sample apparatus and are charged up, thereby generating a new electric field. Then, the trajectory of the electron beam deflected to the sample is changed by the generated new electric field. At the time of drawing, a change in the trajectory of the electron beam, i.e., a beam position drift occurs, taking this factor as an example. Such beam position drift is not constant and is difficult to predict and correct without measurement. Therefore, conventionally, a certain period is determined, and the beam position drift amount is measured and corrected for each period (see, for example, Patent Document 1).

  With the recent miniaturization / higher accuracy of patterns, it is necessary to frequently perform such beam position drift correction. However, the correction of the beam position drift is performed by stopping the drawing process, which causes a deterioration in throughput. However, if correction is not performed, the drawing accuracy is degraded.

JP2011-192666A

  As described above, if the beam position drift correction is frequently performed, the throughput is deteriorated. Therefore, how the correction interval is set greatly affects the throughput. Further, as the beam position drift progresses, it will eventually be necessary to replace the parts in the apparatus and to perform maintenance, but this action also causes the throughput to deteriorate. However, conventionally, there has not been a sufficient method for setting the correction interval so as to minimize the influence on the throughput.

  Accordingly, an object of the present invention is to provide a method and a drawing apparatus for overcoming such problems and setting a correction interval so as to minimize the influence on throughput.

A method for setting a beam drift correction interval pattern according to an aspect of the present invention includes:
A step of referring to a correction interval pattern in which a correction interval for correcting a beam drift of a charged particle beam is defined when a preset state change related to the drawing process occurs;
Measuring the beam drift amount of the charged particle beam at each correction interval defined in the correction interval pattern, and executing beam drift correction; and
A step of determining whether the change amount of the beam drift amount measured from the start of drawing to the end of drawing after drawing is larger or smaller than the change amount based on which the correction interval defined in the correction interval pattern is determined When,
A step of resetting the correction interval pattern so that the correction interval is shortened if the change amount of the beam drift amount is larger than the change amount that is the basis of the correction interval as a result of the determination; ,
It is provided with.

In addition, the method for determining the timing of component maintenance of the charged particle beam drawing apparatus according to one aspect of the present invention includes:
Multiple levels of thresholds are set according to the beam drift correction interval pattern described above,
Depending on the threshold level that exceeds the measured beam drift variation, a corresponding level warning is generated,
The minimum level of warning prompts the user to prepare for equipment part maintenance,
It is characterized in that maintenance of equipment parts is carried out with the maximum level of warning.

The charged particle beam drawing apparatus of one embodiment of the present invention includes:
A drawing unit for drawing a pattern on a sample using a charged particle beam;
A storage unit that stores a correction interval pattern in which a correction interval for correcting a beam drift of a charged particle beam is defined when a preset state change related to the drawing process occurs;
A reference processing unit for referring to the correction interval pattern;
An execution processing unit that performs beam drift correction for each correction interval defined in the correction interval pattern;
Along with the beam drift correction, a measurement unit that measures the beam drift amount of the charged particle beam,
Judgment whether the change amount of the beam drift amount measured from the start of drawing to the end of drawing after drawing is larger or smaller than the change amount based on which the correction interval defined in the correction interval pattern is determined And
As a result of determination, a setting unit that resets the correction interval pattern so that the correction interval is shortened when the change amount of the beam drift amount is larger than the change amount that is the basis of the correction interval, and when the change amount is small, the correction interval pattern is lengthened. When,
It is provided with.

  According to one aspect of the present invention, the correction interval can be set so as to minimize the influence on the throughput. In addition, according to another aspect of the present invention, it is possible to accurately grasp the maintenance time of device parts. As a result, it is possible to improve the throughput of the drawing process while maintaining the drawing accuracy.

1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 1. FIG. It is a figure for demonstrating the mode of XY stage movement. It is a top surface conceptual diagram of the XY stage of FIG. FIG. 6 is a flowchart showing main steps of a method for setting a beam drift correction interval pattern in the first embodiment. It is a figure which shows an example of the relationship between the beam drift and time in Embodiment 1, and a correction | amendment space | interval pattern. 7 is a diagram for explaining how to measure the position of a mark in Embodiment 1. FIG. FIG. 6 is a diagram showing a relationship between a drift amount and time in the first embodiment. It is a conceptual diagram for demonstrating operation | movement of a variable shaping type | mold electron beam drawing apparatus.

  Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and a beam using charged particles such as an ion beam may be used. Further, a variable shaping type drawing apparatus will be described as an example of the charged particle beam apparatus.

Embodiment 1 FIG.
FIG. 1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the first embodiment. In FIG. 1, the drawing apparatus 100 includes a drawing unit 150 and a control unit 160. The drawing apparatus 100 is an example of a charged particle beam drawing apparatus. In particular, it is an example of a variable shaping type drawing apparatus. 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 first aperture 203, a projection lens 204, a deflector 205, a second aperture 206, an objective lens 207, a deflector 208, and a detector 209 are arranged. Has been. An XY stage 105 is disposed in the drawing chamber 103. On the XY stage 105, a sample 101 such as a mask to be drawn at the time of drawing is arranged. The sample 101 includes an exposure mask for manufacturing a semiconductor device. Further, the sample 101 includes mask blanks on which nothing has been drawn yet. On the XY stage 105, a mark 152 is disposed at a position different from the position where the sample 101 is disposed. On the XY stage 105, a mirror 104 is disposed at a position different from the position where the sample 101 is disposed.

  The control unit 160 includes a memory 51, a monitor 53, an interface circuit 55, a control computer 110, a deflection control circuit 120, a detection circuit 130, storage devices 140, 142, 144 such as a magnetic disk device, and a laser length measuring device 300. The memory 51, the monitor 53, the interface circuit 55, the control computer 110, the deflection control circuit 120, the detection circuit 130, the storage devices 140, 142, 144, and the laser length measuring device 300 are connected to each other via a bus (not shown). .

  In the control computer 110, a drawing data processing unit 50, an event determination unit 52, an execution processing unit 54, a beam drift amount measurement unit 56, a correction value calculation unit 58, a reference processing unit 60, determination units 61, 62, and 63, a setting. A unit 65, a warning generation unit 67, a job (JOB) control unit 66, and a drawing control unit 68 are arranged. Drawing data processing unit 50, event determination unit 52, execution processing unit 54, beam drift amount measurement unit 56, correction value calculation unit 58, reference processing unit 60, determination units 61, 62, 63, setting unit 65, warning generation unit 67 The functions such as the job (JOB) control unit 66 and the drawing control unit 68 may each be configured by hardware such as an electric circuit, or may be configured by software such as a program for executing these functions. . Alternatively, it may be configured by a combination of hardware and software. Drawing data processing unit 50, event determination unit 52, execution processing unit 54, beam drift amount measurement unit 56, correction value calculation unit 58, reference processing unit 60, determination units 61, 62, 63, setting unit 65, warning generation unit 67 Information input / output to / from the job (JOB) control unit 66 and the drawing control unit 68 and information being calculated are stored in the memory 51 each time.

  In the deflection control circuit 120, an adder 72, a position calculation unit 76, and a deflection amount calculation unit 78 are arranged. The adder 72, the position calculation unit 76, and the deflection amount calculation unit 78 may each be configured by hardware such as an electric circuit, or may be configured by software such as a program that executes these functions. Alternatively, it may be configured by a combination of hardware and software. Information input / output to / from the adder 72, the position calculation unit 76, and the deflection amount calculation unit 78 and information being calculated are stored in a memory (not shown) each time.

  In the storage device 140, drawing data serving as layout data is input from the outside of the device and stored. For example, chip data for chip A, chip data for chip B, chip data for chip C, and so on are stored. Each chip is patterned. Further, the storage device 144 stores a correction interval pattern (diagnostic pattern) in which a correction interval for correcting the beam drift of the electron beam 200 when a preset state change (event) occurs is stored.

  Here, FIG. 1 shows a configuration necessary for explaining the first embodiment. The drawing apparatus 100 may normally have other necessary configurations. For example, the deflector 208 is used for position deflection, but it is also possible to use a multistage deflector having two main and sub stages. Alternatively, it is preferable to use a multistage deflector having three or more stages.

  During the drawing process, the drawing data processing unit 50 reads the drawing data from the storage device 140, performs a plurality of stages of data conversion processing, and generates shot data in a format for the drawing apparatus 100. In order to draw a graphic pattern with the drawing apparatus 100, it is necessary to divide the graphic pattern defined in the pattern data of the chip 1 into a size that can be irradiated by one beam shot. Therefore, the drawing data processing unit 50 generates shot figures by dividing each figure pattern into a size that can be irradiated with one shot of a beam in order to actually draw. Then, shot data is generated for each shot figure. In the shot data, for example, graphic data such as a graphic type, a graphic size, and an irradiation position are defined. In addition, the irradiation time according to the dose is defined. The generated shot data is stored in the storage device 142. Then, drawing is performed using such shot data.

  An electron beam 200 emitted from an electron gun 201 controlled to a predetermined current density J by a control unit (not shown) illuminates the entire first aperture 203 having a rectangular hole by an illumination lens 202. Here, the electron beam 200 is first shaped into a rectangle. Then, the electron beam 200 of the first aperture image that has passed through the first aperture 203 is projected onto the second aperture 206 by the projection lens 204. The position of the first aperture image on the second aperture 206 is controlled by the deflector 205, and the beam shape and size can be changed. Then, the electron beam 200 of the second aperture image that has passed through the second aperture 206 is focused by the objective lens 207, is deflected by the deflector 208 controlled by the deflection control circuit 120, and is movably disposed. The desired position of the sample 101 on the XY stage 105 is irradiated. The position of the XY stage 105 is measured by irradiating the mirror 104 with a laser from the laser length measuring device 300 and receiving the reflected light from the mirror 104.

  FIG. 2 is a diagram for explaining the movement of the XY stage. When drawing on the sample 101, the drawing (exposure) surface is virtually moved to a plurality of strip-like stripe regions where the electron beam 200 can be deflected while continuously moving the XY stage 105 in the X direction by a driving unit (not shown). The electron beam 200 irradiates one stripe region of the divided sample 101. Simultaneously with the movement of the XY stage 105 in the X direction, the shot position of the electron beam 200 also follows the stage movement. The drawing time can be shortened by continuously moving. When drawing of one stripe area is completed, the XY stage 105 is stepped in the Y direction, and the drawing operation of the next stripe area is performed in the X direction (for example, the opposite direction this time). The moving time of the XY stage 105 can be shortened by making the drawing operation of each stripe region meander.

  FIG. 3 is a conceptual top view of the XY stage of FIG. As shown in FIG. 3, a mark 152 for inspecting the amount of beam drift of the electron beam 200 is provided on the XY stage 105 on which the sample 101 is placed. The mark 152 is formed, for example, in a cross shape so that the position can be easily detected by scanning with the electron beam 200.

  FIG. 4 is a flowchart showing main steps of the method for setting the beam drift correction interval pattern in the first embodiment. In FIG. 4, the beam drift correction interval pattern setting method in the first embodiment includes a correction execution step (S101), a drawing start / event generation step (S102), a diagnostic pattern reference step (S106), and a determination step. (S108), a correction execution step (S112), a determination step (S114), a drift change determination step (S116), a resetting step (S118), and a warning generation step (S120). carry out.

When irradiation with the electron beam 200 is started, the electron beam causes beam drift.
FIG. 5 is a diagram showing an example of the relationship between the beam drift and time and the correction interval pattern in the first embodiment. As shown in FIG. 5, immediately after the start of irradiation, a beam drift (initial drift) of the electron beam itself or due to electron beam irradiation occurs. In the initial drift period in which the initial drift occurs, the amount of change in the beam drift is large, and the amount of change tends to decrease with time. In FIG. 5, the region where the amount of change is small is described as the stable period.

  Therefore, in the first embodiment, immediately after the start of irradiation with a large amount of change in beam drift, in other words, immediately after the start of drawing, the interval of the timing for performing the beam position drift correction is shortened, and drift correction is performed as drawing progresses over time. A correction interval pattern (diagnostic pattern) is set so as to lengthen the interval of the timing to be performed. In the example of FIG. 5, the drift correction step (1) is corrected three times at the interval of the period t1, and then the drift correction step (2) is corrected four times at the interval of the period t2, which is a period longer than t1. Thereafter, as a drift correction step (3), correction is performed three times at an interval of a period t3 that is a period longer than t2, and then, as a drift correction step (4), correction is performed at an interval of a period t4 that is a period longer than t3. For example, in the drift correction step (1), since the initial beam drift is large, the correction interval period t1 is set to 5 minutes. In the drift correction step (2), since the beam drift is reduced to some extent, the correction interval period t2 is set to 10 minutes. In the drift correction step (3), since the beam drift further decreases, the correction interval period t3 is set to 30 minutes. In the drift correction step (4), since there is almost no beam drift, the correction interval period t4 is set to 60 minutes. Here, the number of steps of the drift correction step may be any number of steps that seems to be optimum. In addition, the length of the period t in each drift correction step may be an arbitrary length considered to be optimum. Similarly, the number of corrections in each drift correction step may be any desired number that seems to be optimal.

  5 is preferably set so that the amount of change in the beam position drift per unit time does not exceed the allowable amount. For example, the correction interval may be set with the time when the amount of change per unit time becomes 90% of the allowable amount as the next correction time. However, the present invention is not limited to this. The correction interval may be an interval at which the next correction can be performed within a range in which the change amount per unit time of the beam position drift does not exceed the allowable amount.

  As described above, the cause of the beam position drift is not only due to the passage of the period, but also due to other state changes in which it is difficult to accurately know the time to be corrected in advance and it is difficult to set the timing for performing the beam position drift correction. For example, a state in which a drawing operation is temporarily stopped by an artificial operation by a user, a state in which a temporary drawing is stopped to transport another substrate during drawing, a state at the time of preprocessing performed before drawing, and a pattern density of a pattern If drawing is performed after the state has changed abruptly, the stage speed (drawing speed) has changed abruptly, or the like, a position error due to beam drift may occur. In addition, if drawing is performed after the temperature has changed more than the permissible amount per unit time, or the atmospheric pressure has changed more than the permissible amount per unit time, a position error due to beam drift occurs. obtain. Therefore, in the first embodiment, when these states are detected as events and changed from these states to other states, the correction interval pattern in FIG. 5 is controlled to advance from the beginning. Further, it is preferable that the correction interval pattern (diagnostic pattern) shown in FIG. 5 is set for each event type. Therefore, the storage device 144 stores information on correction interval patterns (diagnostic patterns) for performing beam position drift correction for each event type. Also, drawing start is one of the events.

  In the correction execution step (S101), when starting the drawing process, first, beam position drift correction is performed before drawing. The drawing control unit 68 performs control so as to execute beam position drift correction. Specifically, the execution processing unit 54 outputs an execution instruction (command) so as to execute (start) an operation for beam drift correction, and causes each control circuit to operate.

  In the drawing apparatus 100, in response to the execution instruction, the XY stage is set so that the beam calibration mark 152 placed on the XY stage 105 separately from the sample 101 matches the center position of the objective lens 207 before starting drawing. 105 is moved. Then, the cross of the mark 152 is scanned with the electron beam 200, the reflected electrons from the mark 152 are detected by the detector 209, amplified by the detection circuit 130, converted into digital data, and the measurement data is converted into a beam drift amount. It outputs to the measurement part 56. The beam drift amount measuring unit 56 measures the drift amount of the electron beam 200 from the input measurement data.

  FIG. 6 is a diagram for explaining how to measure the mark position in the first embodiment. As shown in FIG. 6, by moving the XY stage 105, the mark 152 is moved to each desired position in the deflection region 10. For example, an area that can be deflected by the deflector 208 may be set as the deflection area 10. Then, the deflector 208 deflects the electron beam 200 to each position in the deflection region 10 and scans the mark 152 to measure the mark position. The residual of the deflection position set at each position is determined as the electron beam 200. The position drift amount is obtained. Here, for example, the predetermined deflection region 10 is performed at a total of 25 points of 5 points × 5 points. When performing main / sub two-stage deflection, the deflection region 10 is further divided into sub-fields (SF) that can be deflected by the sub-deflector, and the position of the main deflector is set at the reference position (for example, the center) of each SF. After the adjustment, the electron beam 200 is deflected to each position in the SF by the sub deflector and scanned on the mark 152 to measure the mark position, and the residual from the deflection position set at each position is determined as the electron beam. What is necessary is just to obtain | require as a positional drift amount of 200.

  The correction value calculating unit 58 calculates a correction value for correcting the beam position drift based on the position drift amount measured by the beam drift amount measuring unit 56. And it outputs to the adder 72 which is an example of a correction | amendment part, and a correction value is updated. An adder 72 adds and synthesizes original design value data and correction value data obtained from shot data, which will be described later, and corrects the beam position drift by rewriting the design data. Then, using the corrected design data and the position data of the XY stage 105 measured by the laser length measuring device 300 and calculated by the position calculation unit 76, the deflection amount calculation unit 78 calculates a deflection amount corresponding to the deflection voltage. It calculates, outputs a deflection amount signal, changes to analog data by an amplifier (not shown), amplifies it, and applies it to the deflector 208 as a deflection voltage. Based on the voltage, the deflector 208 deflects the electron beam 200. As described above, the deflection amount for deflecting the electron beam is corrected using the measured beam drift amount of the electron beam.

  As a drawing start / event generation step (S102), drawing processing is started first. The drawing unit 150 draws a pattern on the sample 101 using an electron beam. At that time, the deflection amount signal in the deflection control circuit 120 is a value obtained by correcting the above-described beam position drift amount. Then, the deflection amount signal is converted into analog data by an amplifier (not shown) and amplified and then applied to the deflector 208 as a deflection voltage. Based on the voltage, the deflector 208 deflects the electron beam 200. As described above, the deflection amount for deflecting the electron beam is corrected using the measured beam position drift amount of the electron beam.

  When drawing is started, the JOB control unit 66 outputs information on the state to the event determination unit 52 as one piece of event information (state information).

  Here, as described above, in addition to the start of drawing, the above-described events occur during the drawing process. The JOB control unit 66 controls the contents of a job given to the drawing apparatus 100, and controls, for example, the above-described preprocessing, conveyance processing, and artificial operation by the user. Therefore, the JOB control unit 66, for example, an operation for temporarily stopping the drawing operation by an artificial operation by the user, an operation for stopping the temporary drawing to transport another substrate during drawing, and before the drawing is performed. When an operation for performing the process or the like is performed, information indicating a state generated by each operation is output to the event determination unit 52 as one piece of event information (state information). For example, these pieces of information are output constantly or periodically. For example, it outputs at intervals of 0.1 to 1 s.

  Further, the drawing control unit 68 controls the drawing process itself by controlling the drawing data processing unit 50, the deflection control circuit 120, the drawing unit 150, and the like when drawing the sample 101. For this purpose, shot information such as the pattern density of the pattern drawn and the irradiation time of each shot is acquired from the drawing data. Therefore, for example, the drawing control unit 68 uses the event information (state information) as one of the event information (state information) when the pattern density of the pattern changes abruptly and when the stage speed (drawing speed) changes abruptly. As a result, it outputs to the event determination part 52. For example, these pieces of information are output constantly or periodically. For example, it outputs at intervals of 0.1 to 1 s. In addition, data such as temperature and pressure may be input to the event determination unit 52 as event information from a temperature sensor or a pressure sensor (not shown).

  As described above, the event determination unit 52 detects a state change in which it is difficult to predict other periods rather than the passage of a period. When the event information described above is input, the event determination unit 52 determines whether or not the deflection amount correction by the beam position drift is necessary based on the input event information. Specifically, the determination is made as follows. For example, with respect to temperature, atmospheric pressure, pattern density, and stage speed, respective threshold values are set in advance, and it is determined whether or not the amount of change within a predetermined period has exceeded the threshold value. On the other hand, an operation for starting drawing, an operation for temporarily stopping the drawing operation, an operation for stopping the temporary drawing to transport another substrate during drawing, and a pre-process performed before the drawing by an artificial operation by the user Regarding the operation to be performed, it is determined that beam correction is necessary when any event information is input. Then, event generation information (signal) indicating that an event has occurred is output from the event determination unit 52 to the reference processing unit 52.

  As the diagnostic pattern reference step (S106), the reference processing unit 60 corrects the beam drift of the electron beam when drawing starts or when a preset state change (event) occurs after drawing starts. A correction interval pattern (diagnosis pattern) in which a correction interval is defined is referred to. Specifically, when the event generation information from the event determination unit 52 is input, the reference processing unit 60 refers to the diagnostic pattern stored in the storage device 144. Since the diagnosis pattern is created for each event type and stored in the storage device 144, the diagnosis pattern corresponding to the event type indicated in the event occurrence information is referred to.

  As a determination step (S108), the determination unit 61 determines whether or not the correction interval defined in the diagnostic pattern has elapsed, starting from the time when the event occurred. If it has elapsed, the process proceeds to the correction execution step (S112). If not, the process returns to the determination step (S108) until it has elapsed.

  In the correction execution step (S112), the beam drift amount of the electron beam 200 is measured at each correction interval defined in the diagnostic pattern, starting from the time when the event occurs, and the beam drift correction is executed. Specifically, it operates as follows. First, the drawing control unit 68 controls the drawing unit 150 so as to temporarily stop the drawing operation. The execution processing unit 54 outputs an execution instruction (command) so as to execute (start) an operation for beam drift correction, and causes each control circuit to operate. Thereafter, the operation is the same as in the correction execution step (S101). Thereby, the drift amount of the electron beam 200 is measured by the beam drift amount measuring unit 56. Further, the correction value for correcting the beam position drift added by the adder 72 as an example of the correction unit is updated.

  As a determination step (S114), the determination unit 62 determines whether or not the drawing process has ended. If the drawing process has not ended, the drawing process is resumed and the process returns to the determination step (S108). Then, the determination process (S108) to the determination process (S114) are repeated until the drawing process is completed. Alternatively, when a new event occurs midway, the process returns to the drawing start / event generation step (S102), and the steps from the drawing start / event generation step (S102) to the determination step (S114) are repeated.

  As described above, since the diagnostic pattern differs for each event, when a new event occurs, the diagnostic pattern of the new event is referred to in the diagnostic pattern reference step (S106). In the determination step (S108), it is determined whether the correction interval defined in the diagnostic pattern for the new event has elapsed. When the drawing process is completed, the process proceeds to the drift change determination step (S116).

  As the drift change determination step (S116), the determination unit 63 determines a correction interval in which the change amount of the beam drift amount measured from the start of drawing to the end of drawing is defined as a correction interval pattern (diagnostic pattern) after drawing is completed. It is determined whether the amount of change is larger or smaller than the base change amount.

  FIG. 7 is a diagram showing the relationship between the drift amount and time in the first embodiment. In the diagnostic pattern stored in the storage device 144, as shown in FIG. 7, the relationship between time and the amount of beam drift is defined (expected value). In addition, a plurality of levels of threshold values (threshold values 1, 2, 3) are set. Further, as shown in FIG. 7, a diagnostic pattern is defined for each event type. A plurality of levels of threshold values are set for each event type according to the diagnostic pattern. The determination unit 63 determines, for each event type, whether the measured change amount of the beam drift amount is large or small with respect to the data (expected value) between the currently defined time and the beam drift amount. To do.

  As the resetting step (S118), for each event type, the setting unit 65 determines that the amount of change in the beam drift amount is larger than the amount of change that is the basis of the correction interval currently defined in the diagnostic pattern as a result of determination. The correction interval pattern (diagnostic pattern) is reset (updated) so that the correction interval is short, and when the correction interval is small, the correction interval is lengthened. Then, the reset diagnostic pattern is stored in the storage device 144. For example, when the change amount of the beam drift amount is less than 90% (expected value) of the allowable value, the correction interval is extended so that the change amount of the beam drift amount becomes 90% of the allowable value. For example, when the change amount of the beam drift amount exceeds 90% (expected value) of the allowable value, the correction interval is shortened so that the change amount of the beam drift amount becomes 90% of the allowable value. The calculation of the correction interval may be obtained in a linear proportion or may be obtained using an approximate function obtained from past results. The relationship between the reset time and the beam drift amount is the next expected value.

  By repeating the resetting as described above, it is possible to set the correction interval along the actual drift amount. Therefore, the correction interval can be set so as to minimize the influence on the throughput. As a result, it is possible to improve the throughput of the drawing process while maintaining the drawing accuracy.

  As the warning generation step (S120), the warning generation unit 67 generates a warning when the measured change amount of the beam drift amount is larger than the threshold value. Further, a warning of a corresponding level is generated according to a threshold level that exceeds the measured change amount of the beam drift amount. When the measured change amount of the beam drift exceeds the threshold value 1 (minimum threshold value), a minimum level warning is generated. Further, if the measured change amount of the beam drift exceeds the threshold value 2 (intermediate threshold value), an intermediate level warning is generated. When the measured change amount of the beam drift exceeds the threshold value 3 (maximum threshold value), a maximum level warning is generated.

  Each warning is displayed on the monitor 53. Alternatively, the data is output to the outside from the interface circuit 55 as data. As described above, in the method for determining the timing of component maintenance of the electron beam lithography apparatus in the first embodiment, a warning of a corresponding level is generated according to the threshold level that exceeds the measured change amount of the beam drift amount. The minimum level warning prompts the user to replace the device part or prepare for maintenance. Further, the intermediate level warning allows the user to check whether the device parts are ready for replacement or maintenance. Also, replacement or maintenance of the device parts is performed by the maximum level warning.

  As described above, according to the first embodiment, it is possible to accurately grasp the maintenance time of apparatus parts. Therefore, it is possible to avoid drawing stop due to sudden component failure. In addition, since the maintenance can be prepared, the apparatus stop time can be minimized. As a result, it is possible to improve the throughput of the drawing process while maintaining the drawing accuracy.

  The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

  In addition, although descriptions are omitted for parts and the like that are not directly required for the description of the present invention, such as a device configuration and a control method, a required device configuration and a control method can be appropriately selected and used. For example, although the description of the control unit configuration for controlling the drawing apparatus 100 is omitted, it goes without saying that the required control unit configuration is appropriately selected and used.

  In addition, a method for setting all beam drift correction interval patterns that include elements of the present invention and can be appropriately modified by those skilled in the art, a method for determining the timing of component maintenance of a charged particle beam drawing apparatus, and a charged particle beam drawing apparatus Are included within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Deflection area | region 50 Drawing data process part 51 Memory 52 Event determination part 53 Monitor 54 Execution process part 55 Interface circuit 56 Beam drift amount measurement part 58 Correction value calculation part 60 Reference process part 61,62,63 Determination part 65 Setting part 66 JOB Control unit 67 Warning generation unit 68 Drawing control unit 72 Adder 76 Position calculation unit 78 Deflection amount calculation unit 100 Drawing apparatus 101, 340 Sample 102 Electron barrel 103 Drawing chamber 104 Mirror 105 XY stage 110 Control computer 120 Deflection control circuit 130 Detection Circuits 140, 142, 144 Storage device 150 Drawing unit 152 Mark 160 Control unit 200 Electron beam 201 Electron gun 202 Illumination lens 203, 410 First aperture 204 Projection lens 205, 208 Deflector 206, 420 Second aperture 207 Objective lens 2 9 detector 300 laser length 330 electron beam 411 opening 421 variable-shaped opening 430 a charged particle source

Claims (5)

A step of referring to a correction interval pattern in which a correction interval for correcting a beam drift of a charged particle beam is defined when a preset state change related to the drawing process occurs;
Measuring a beam drift amount of the charged particle beam at each correction interval defined in the correction interval pattern, and executing beam drift correction;
After completion of drawing, it is determined whether the change amount of the beam drift amount measured from the start of drawing to the end of drawing is larger or smaller than the change amount based on which the correction interval defined in the correction interval pattern is determined. Process,
As a result of the determination, if the change amount of the beam drift amount is larger than the change amount that is the basis of the correction interval, the correction interval pattern is regenerated so that the correction interval is shortened, and when the change amount is smaller, the correction interval is lengthened. A setting process;
A method for setting a correction interval pattern for beam drift, comprising:   2. The beam drift correction interval pattern setting method according to claim 1, further comprising a step of generating a warning when the measured change amount of the beam drift amount is larger than a threshold value. The correction interval pattern is set for each state change with respect to a plurality of preset state changes,
For each state change, it is determined whether the amount of change in the measured beam drift amount is larger or smaller than the amount of change based on which the correction interval defined in the corresponding correction interval pattern is determined,
As a result of determination for each state change, the correction interval is shortened when the change amount of the beam drift amount is larger than the change amount serving as the basis of the correction interval of the corresponding correction interval pattern, and when the change amount is small, the correction interval is shortened. 3. The beam drift correction interval pattern setting method according to claim 1, wherein the correction interval pattern is reset so as to lengthen the length of the beam drift. Multiple levels of thresholds are set according to the beam drift correction interval pattern of the charged particle beam according to any one of claims 1 to 3,
Depending on the threshold level that exceeds the measured beam drift variation, a corresponding level warning is generated,
The minimum level of warning prompts the user to prepare for equipment part maintenance,
A method for determining the timing of component maintenance of a charged particle beam lithography system, wherein the maintenance of the device component is performed by a maximum level warning. A drawing unit for drawing a pattern on a sample using a charged particle beam;
A storage unit that stores a correction interval pattern in which a correction interval for correcting a beam drift of a charged particle beam is defined when a preset state change related to the drawing process occurs;
A reference processing unit for referring to the correction interval pattern;
An execution processing unit that performs beam drift correction for each correction interval defined in the correction interval pattern;
Along with the beam drift correction, a measurement unit that measures the beam drift amount of the charged particle beam,
After completion of drawing, it is determined whether the change amount of the beam drift amount measured from the start of drawing to the end of drawing is larger or smaller than the change amount based on which the correction interval defined in the correction interval pattern is determined. A determination unit;
As a result of the determination, if the change amount of the beam drift amount is larger than the change amount that is the basis of the correction interval, the correction interval pattern is regenerated so that the correction interval is shortened, and when the change amount is smaller, the correction interval is lengthened. A setting section to be set;
A charged particle beam drawing apparatus comprising:

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