JP2006339405A - Electron beam drawing device - Google Patents

Abstract

The present invention relates to an electron beam lithography apparatus that detects an irradiation position of an electron beam on a sample in real time, thereby enabling detection of recorrection timing and abnormality, improving reliability, and throughput. It aims at obtaining the effect which raises.
The present invention provides a measuring element that induces an electromotive force by a magnetic field generated by an electron beam, an arithmetic unit that obtains the position of the electron beam from the electromotive force induced by the measuring element, and the obtained electron beam. And a control device for controlling the deflection of the electron beam based on the position.
[Selection] Figure 1

Description

  The present invention relates to a technique for indirectly detecting a position of an electron beam in real time in an electron beam drawing apparatus.

  An electron beam lithography system applies a predetermined voltage or current to a deflector, and irradiates a shot of an electron beam having a predetermined shape to a predetermined position on a sample surface such as a semiconductor wafer or a mask one after another to form a circuit pattern. A device for drawing.

  Among these, many electron beam lithography apparatuses used for manufacturing semiconductor integrated circuit devices, etc., scan and irradiate uneven marks with an electron beam, so that reflected electrons or secondary electrons generated from the irradiation site are reflected to the reflected electrons. It has the structure which measures the dimension and irradiation position of an electron beam by detecting using a detector and a secondary electron detector, and computer-processing the signal (for example, refer patent document 1).

  While drawing on the sample with the electron beam, the mark is periodically detected, and the size and irradiation position of the electron beam are measured. With respect to the timing of this measurement, a technique is known in which a tendency is mathematically expressed from a plurality of electron beam drift graphs measured in advance and remeasured at each time calculated from the trend (see, for example, Patent Document 2).

  However, with this response, the scope of prediction is unavoidable. For example, when the pattern shape drawn on the sample changes, the amount of charge-up varies depending on the pattern mounting density, so that the amount of change in electron beam drift changes.

  Then, when re-correction is performed at the timing determined from the graph prepared in advance, the drift amount exceeds the limit, and the drawing becomes poor. Alternatively, if the timing of re-correction is too early, the useless time is increased, and there is a possibility that the throughput is significantly impaired even if the drawing is normal.

  Alternatively, when formulating all drawing patterns in advance, it is extremely inefficient to consider the number of patterns. Alternatively, even if all of the drawing patterns are preliminarily formulated, it is not possible to deal with sudden electron beam position shifts, and drawing defects are detected in the inspection after the drawing is completed.

  Then, not only the drawing time so far is wasted, but also a lot of time must be taken for the cause estimation. Also, if this inspection is a sampling inspection rather than a total inspection, many defects will be produced.

Japanese Patent Laid-Open No. 2000-216076.

JP-A-11-008171.

  The following are the problems of the prior art.

  (1). Since real-time correction cannot be performed and correction is performed based on a certain prediction, a correction error occurs or a useless correction time occurs.

  (2). It is difficult to know the cause of a sudden abnormality.

  The present invention enables an electron beam lithography apparatus to detect the irradiation position of an electron beam on a sample in real time, thereby enabling detection of recorrection timing and abnormality, improving reliability and increasing throughput. The purpose is to obtain.

  In order to solve the above problems, an embodiment of the present invention includes a measuring element that induces an electromotive force by a magnetic field generated by an electron beam, and an arithmetic unit that obtains the position of the electron beam from the electromotive force induced by the measuring element. And a control device for controlling the deflection of the electron beam based on the obtained position of the electron beam.

  According to the electron beam drawing apparatus of the present invention, the irradiation position on the sample of the electron beam can be detected in real time, so that the timing of recorrection and abnormality can be detected, which improves the reliability and increases the throughput. be able to.

  First, the principle will be explained. By measuring the magnetic field generated when the electron beam is irradiated, the current amount of the electron beam and the center position of the electron beam can be obtained without directly touching the electron beam.

  FIG. 2 is a conceptual diagram showing the principle of measuring the magnetic field of an electron beam.

  A measuring element 210 is formed by forming a ring with a conductor so as to interlink with the magnetic field H generated by the electron beam at a position r away from the reference axis of the electron beam. Usually, the normal line of the conductor ring is made equal to the direction of the magnetic flux generated by the electron beam. The following relationship arises between the current amount I of the electron beam and the magnetic flux density B that crosses the conductor ring. Here, μ is the magnetic permeability.

B = μI / 2πr Equation 1
Further, an electromotive force U is induced in the measuring element 210. Here, φ is a magnetic flux, and d / dt indicates time differentiation.

U = −dφ / dt Equation 2
From this relational expression, an electromotive force U proportional to the amount of current of the electron beam is obtained.

  The position of the electron beam is calculated by arranging the measuring element 210 at a plurality of locations concentrically with respect to the reference axis of the electron beam and at a plurality of locations having different distances r, and obtaining and comparing the electromotive forces. Is possible.

  In addition, since the shape of the electron beam is known in advance for a shaped electron beam, a more accurate electron beam position can be obtained. Furthermore, the accuracy of calculation can be increased by combining the measurement results of a detector that can measure the current value regardless of the shape of the electron beam, such as a Rogowski coil.

  Using these functions, a table is created by measuring each current value at the electron beam shape and position as a reference in advance. When the sample is actually drawn, the current measurement value for the electron beam irradiation condition is sequentially compared with the table data. If the drift amount exceeds a certain value, the amount of correction is added or absolute correction is performed. As a result, correction can be performed at the optimum timing, and useless correction time is unnecessary.

  When a sudden electron beam misalignment (so-called shot misalignment) occurs, an abnormal signal is generated, and the drawing defect of the sample can be clarified. Also, by keeping those histories, it can be used to investigate the cause of an electron beam problem or a stage problem when a drawing defect occurs.

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

  (First Embodiment) FIG. 1 shows a longitudinal section of an electron beam drawing apparatus.

  The electron beam drawing apparatus includes an electron optical column portion 100 that exposes a pattern to a sample, and a control portion 124 that controls the electron optical column.

  The electron optical column portion 100 includes an electron gun 101 that generates an electron beam that irradiates a sample, a blanking electrode 102 that deflects and blocks the generated electron beam, a molded lens 105, a reduction lens 111, a rotating lens 108, An electron lens group including an objective lens 115, a shaping deflector 107 for controlling the electron beam size, a transfer deflector 106 for controlling the electron beam shape, an aligner deflector 110 for adjusting the shaped electron beam axis, and exposure positioning. Objective deflector 112.

  Also, under the electron optical column portion 100, a sample stage 122 on which a sample is placed, a reflected electron measurement system 141 used for measuring the position of the alignment mark and the electron beam itself, observation of the shape of the electron beam and electron beam dimensions. And an electron beam current system 140 with a knife edge or cross wire for measuring the amount of blur of the electron beam, a sample surface height measurement system 143, and a laser interference length measurement system 142 for measuring the sample stage coordinates. Moreover, it has the loader 123 for conveying a sample to a sample stage.

  The electron beam irradiated from the electron gun 101 passes through the blanking electrode 102 and the blanking aperture 103. When a voltage is applied to the blanking electrode 102 to bend the trajectory of the electron beam, the electron beam cannot pass through the blanking aperture 103 and does not reach the sample.

  Therefore, the blanking electrode 102 can control the irradiation and non-irradiation of the electron beam to the sample.

  The electron beam that has passed through the blanking electrode 102 is imaged at a predetermined rotation angle at the second shaping opening 109 by the first shaping opening 104, the shaping lens 105, and the rotation lens 108.

  Further, an electron beam is formed by a 4-pole shaping deflector 107 and an 8-pole transfer deflector 106. The generated shaped electron beam is reduced by several tenths while adjusting the rotation angle by the reduction lens 111 and the rotation lens 108, and enters the objective lens 115.

  The shaped electron beam incident on the objective lens 115 can be adjusted by the aligner deflector 110 so that the axis of the shaped electron beam is parallel to the central axis of the electron optical column.

  The shaped electron beam whose axis has been adjusted forms an image of the shaped electron beam on the sample stage by the objective lens 115. The objective deflector 112 that performs exposure positioning includes an 8-pole main deflector 113 and an 8-pole sub-deflector 114.

  The sub-deflector 114 positions an area (subfield) that can be exposed in one shot, and the main deflector 113 positions a large area (field) that is a group of a plurality of subfields. In order to increase the accuracy of exposure and the positioning speed, it is also possible to deflect a region in which a plurality of fields are collected using a third objective deflector.

  The control part 124 includes a main control system 125, an analog control system 127 that controls each lens and deflector, a data control system 126 that creates control data to be passed to the analog control system 127, and a mechanism unit such as a sample stage. A mechanism control system 129 for controlling and a signal processing system 128 are provided.

  The main control system 125 uses a workstation equipped with an arithmetic device such as a computer, for example, to control the entire control, and by connecting a large capacity disk, a large amount of data processing and signal processing can be performed. In addition, a large amount of data can be held by connecting a mass storage device.

  The analog control system 127 controls the analog blanking control unit 130 for applying a control voltage to the blanking electrode 220, the analog shaping deflection control unit 131 for applying a control voltage to the shaping deflector 107, and the transfer deflector 106. An analog transfer deflection control unit 132 for applying a voltage, an analog main deflection control unit 133 for applying a control voltage to the main deflector 113, and an analog sub deflection control unit 134 for applying a control voltage to the sub deflector 114 And an analog following deflection control unit 135.

  Further, the analog control system 127 is rotated by the influence of the surrounding electromagnetic field during the electron beam transportation, the analog shaping lens control unit 136 for controlling the current flowing in the shaping lens coil for adjusting the aperture state of the electron beam. An analog rotation lens control unit 137 for controlling the current flowing through the rotating lens coil for adjusting the rotation angle of the electron beam, and an analog for controlling the current flowing through the reducing lens coil for adjusting the reduction rate of the shaped electron beam. A reduction lens control unit 138 and an analog objective lens control unit 139 for controlling the current flowing in the objective lens coil for focusing the shaped electron beam on the sample are configured.

  These analog control systems 127 are controlled by digital data transfer from the data control system 126, and the data control system 126 is controlled based on commands from the main control system 125, so that the main control system 125 can freely control the electronic control system 127. It is possible to control the beam.

  The mechanism control system 129 includes a stage control unit 510 that controls movement and positioning of the sample stage 122, a loader control unit 145 that controls a loader for carrying the sample to the sample stage, a sample surface height measuring instrument 116, and a sample. And a laser interference length measuring device 117 for measuring stage coordinates.

  The signal processing system 128 includes a backscattered electron detector 118 disposed in the vicinity of the sample stage for measuring the position of the alignment mark and the electron beam itself, observation of the electron beam shape, and measurement of the electron beam size and the amount of electron beam blur. A knife edge detector 119 and a Faraday cup 120 for measuring a current value.

  Drawing follows the following procedure.

  First, pattern data of a figure drawn on the sample is transferred from the main control system 125 to the data control system 126. The data control system 126 converts the pattern data into electron beam control data and transfers it to the analog control system 127.

  In accordance with the control data, the analog control system 127 sends an analog shaping deflection control unit 131, an analog transfer deflection control unit 132 to the shaping deflector 107 and the transfer deflector 106, and an analog main deflection control unit 133 sends an analog signal to the main deflector 113. A voltage signal is sequentially applied to the sub deflector 114 based on the data obtained by adding the sub deflection control unit 134 and the analog following deflection control unit 135. At the same time, the stage controller 129 moves and positions the sample stage 122 to the drawing position.

  The sample stage 122 is corrected in advance in the height direction by the sample surface height measuring instrument 116 and corrected in position accuracy by the laser interference length measuring device 117 for measuring the sample stage coordinates.

  When the applied voltage of each deflector is settled and the sample stage reaches a target position, the electron beam passes through the blanking electrode 102 and the blanking aperture 103 controlled by the electric signal of the analog blanking control unit 130, Irradiate the sample.

  When the exposure is completed, the electron beam is turned off by the blanking electrode, and the applied voltage of each deflection is changed. In the meantime, the sample stage continuously moves. When the next target position is reached, the blanking electrode 102 is again controlled by the electric signal of the analog blanking control unit 130 to irradiate the sample with the electron beam. .

  In this way, by moving the sample stage while adjusting the electron beam conditions, the throughput can be increased, and by repeating this, a predetermined position on the sample can be irradiated with an electron beam having a predetermined shape one after another. Can do.

  The signal processing system 128 is mainly used for calibration of the electron beam system.

  The reflected electron detector 118 detects reflected electrons generated when the calibration mark 121 on the sample stage 122 is irradiated with the electron beam. The sample stage is fixed at a predetermined position, the objective deflector 112 irradiates the plurality of calibration marks 121 with an electron beam, and the reflected electrons at that time are detected by the reflected electron detector 118, whereby the position of the electron beam is determined. Check.

  An electron beam current system 140 with a knife edge or cross wire scans an electron beam on the knife edge detection unit 119, observes the shape of the electron beam from the signal waveform of the Faraday cup when the knife edge is crossed, Check the amount of electron beam blur.

  Next, a detailed configuration of current detection will be described with reference to FIG.

  A ring is formed of a conductor so as to interlink with the magnetic field 201 generated by the electron beam at a position r away from the reference axis which is the current path 200 of the electron beam, and the measuring element 210 is formed. Usually, the normal line of the conductor ring is made equal to the direction of the magnetic flux generated by the electron beam. The relationship between the current amount I of the electron beam and the electromotive force U induced in the measuring element 210 is as follows, and the current amount I can be obtained from the measured value of the detector 211.

I = A∫Udt (3)
Proportional coefficient A = f (distance from electron beam, shape of electron beam, shape of measuring element) Equation 4
The cable between the probe 210 and the detector 211 may be a coaxial cable so as not to detect excess magnetic flux in the path.

  Proportional coefficient A is determined in advance by using a Rogowski coil that measures the current using the conditions and marks in the device, and the magnetic field generated by the electron beam. Record and create a table. If the entire area due to the main deflection and the sub deflection cannot be covered with the actual measurement data, the table is filled with values calculated by interpolation from the actual measurement data.

  In order to reflect the position of the electron beam finally incident on the sample, the position of the probe 210 is preferably arranged on the sample side from the objective deflector 112, but in order to reflect the relational expression precisely. Don't be too close to the sample.

  For example, if the purpose is to correct the aligner deflector 110 to detect the position of the electron beam, such as the position of the probe 210a shown in FIG. For example, if the purpose is to detect an electron beam misalignment between the shaping deflector 107 and the transfer deflector 106, such as the position of the probe 210b shown in FIG. It may be on the sample side. For example, like the position of the measuring element 210c shown in FIG. 1, the measuring element 210 is arranged at a plurality of positions concentrically with respect to the reference axis of the electron beam and at a plurality of positions having different distances r. It is possible to calculate the position more accurately.

  It is better to increase the number of the measuring elements 210 as much as the physical restrictions on the arrangement and the cost restrictions allow, in order to increase the accuracy of position detection.

  The position of the current detector 180 may be anywhere where the electron beam passes. Although the electron beam is turned on and off by the blanking electrode 220, a position where the measurement is not affected when the electron beam is turned off, for example, just above the objective deflector 112, is preferably closer to the sample side than the electron beam dump.

  Since the above-described detection method uses a magnetic field, a magnetic shield may be used together for the purpose of preventing detection of anything other than the magnetic field generated by the electron beam. Alternatively, a separate magnetic field generation source may be provided to cancel unnecessary magnetic fields.

  Alternatively, there is a method of processing data such as measuring the surrounding magnetic field and its variation in advance and offsetting the measured data. In an electron beam drawing apparatus configured to control the deflection position of an electron beam with an electromagnetic deflector, a method of shielding or canceling the magnetic field around the electromagnetic deflector or making it a part of data as an offset amount is necessary. Become.

  The shape of the electron beam is shaped by the shaping deflector 107 into a patterned geometric shape. In order to reflect this shape in electron beam position detection, the current density distribution in the radial direction is obtained from the electron beam shape and the electron beam center position or the center of gravity position before the electron beam is passed through the shaping deflector 107. .

  If the cross-sectional area of the electron beam is circular and the radius of the electron beam is sufficiently small with respect to the distance r to the probe 210, the shape of the electron beam shape formed by the shaping deflector 107 is the current density distribution. On the other hand, if it is sufficiently small, it is easy to obtain the electron beam position from the value detected by the probe 210.

  However, many of the shapes formed by the forming deflector 107 are polygonal shapes. In order to obtain the electron beam center position in this shape, the cross-sectional area shape is regarded as a combination of simplified shapes such as a triangle or a quadrangle, and is divided into meshes of that shape, and then the center of gravity position of each shape and the probe Calculate the distance to 210.

  Further, the simplified current density ratio of each part is determined based on the current density distribution measured in advance. If the size of the electron beam shape formed by the shaping deflector is sufficiently small relative to the current density distribution, the current density ratio of each part of the simplified combined shape in the electron beam cross-sectional shape is set to 1, and The magnetic flux linked to the probe due to the flowing current can be calculated depending only on the distance r between the current path and the probe.

  3 and 4 are plan views showing a planar cross-sectional shape after the electron beam is formed. In FIG. 3, since the cross-sectional shape of the shaped electron beam is a quadrangle, it is divided into quadrilateral meshes, which are meshes 311, 312, 313, and 314, respectively. Further, the distances from the measuring element 310 are distances r1, r2, r3, and r4, respectively. Assuming that the current density of each mesh is equal, the proportionality coefficient A in Equation (4) is proportional to the following equation.

(R1) ⁻¹ + (r2) ⁻¹ + (r3) ⁻¹ + (r4) ^−1.
When the current density ratio of each part cannot be ignored, the magnetic flux linked to the probe is calculated in consideration of the distance r between the current path and the probe and the current density ratio of the current path. An example is shown in FIG. Since the shaped electron beam cross-sectional shape is a triangle, it is divided into triangular meshes, which are designated as meshes 311, 312, 313, and 314, respectively. Further, the distances from the measuring element 310 are distances r1, r2, r3, and r4, respectively. Assuming that the ratio of the current density of each mesh is 2: 1: 1: 1, the proportionality coefficient A of the above-described Equation 4 is proportional to the following equation.

2 × (r1) ⁻¹ + (r2) ⁻¹ + (r3) ⁻¹ + (r4) ⁻¹ Equation 6
(Second embodiment)
In the apparatus described in the first embodiment, the position of the electron beam detected by the probe 210 regardless of the shape of the electron beam is controlled by the objective deflector 112. Data sent from the main control system 125 through the data control system 126 is converted into a specific amount of electricity by the analog control system 127, and positioning control is performed by the objective deflector 112. In order to control the electron beam based on the detected data, the detected data is sent to the main control system 125 or the data control system 126. Further, when the control delay is caused by a drawing defect, it is possible to send the detection data to the analog control system 127 for quick control.

(Third embodiment)
In the apparatus described in the first embodiment, a current value that changes over time even during drawing can be measured in real time by using a means that can measure the total current regardless of the current path, such as a Rogowski coil. Is also possible. The detected electron beam current value data is sent to the main control system 125 and reflected in the control of the electron gun 101.

(Fourth embodiment)
In the apparatus described in the first embodiment, the probe 210 also reflects the temporal change in the current value of the electron beam.

  For example, when the electron beam moves away from the probe, the magnetic field detected by the probe 210 decreases. Even if the position of the electron beam does not change, if the current value of the electron beam itself decreases, the magnetic field detected by the same probe 210 also decreases. By mutually confirming using means capable of measuring the total current regardless of the current path such as the Rogowski coil, it is possible to measure the position without being influenced by the electron beam current value itself.

  In order to control the electron beam with the detected data, the detected data is sent to the main control system 125. Based on this data, it is determined whether to adjust the position control or to adjust the current value of the electron beam in consideration of the exposure accuracy and the exposure amount, and this is appropriately reflected in the control of the objective deflector 112 and the electron gun 101.

(Fifth embodiment)
5 and 6 are flowcharts showing an outline of the control.

  In FIG. 5, when drawing is started (step 501), electron beam condition data when the electron beam pulsed by the blanking electrode 102 is irradiated is set in the data control system 126 (step 502). The sample is irradiated for drawing (step 503), the position of the electron beam is measured by the measuring element 210 during drawing (step 504), and if drawing is not completed (step 505), it is based on the electron beam condition data. The position of the electron beam is compared with the data measured by the probe 210, the position deviation of the electron beam is obtained, and the correction amount is calculated (step 506).

  This correction amount calculation is performed for each shot of the electron beam condition data. Then, the result can be fed back to the main control system 125, the data control system 126, the analog control system 127, etc., and the deviation amount can be corrected in real time.

  Alternatively, instead of feedback control, feedforward control may be performed by obtaining a primary or secondary approximate curve from a deviation amount. Immediately before the approximate curve exceeds the allowable range, for example, one to several shots before, the correction is performed by detecting the mark, or a new correction value is obtained by calculation from the conventional correction value, and the correction amount is changed.

  From this correction amount calculation (step 506), the data set (step 502) is repeated until drawing is completed (step 507).

  In the future, if the interval between shots will be shortened due to miniaturization of drawing data and high precision of drawing technology, the amount of misregistration should be calculated every shot instead of every shot as described above. To do. In this case, the timing for performing the recorrection must be advanced.

  FIG. 6 is a flowchart of an embodiment in which a tendency of displacement is considered with respect to the embodiment of FIG.

  In FIG. 6, when drawing is started (step 601), the electron beam condition data when the electron beam pulsed by the blanking electrode 102 is irradiated is set in the data control system 126 (step 602). The sample is irradiated for drawing (step 603), and the position of the electron beam is measured by the probe 210 during drawing (step 604). If drawing is not completed (step 605), the electron beam condition data is used. The position of the electron beam is compared with the data measured by the probe 210, and the positional deviation of the electron beam is obtained.

  The first time, the positional deviation is stored, and from the second time, the tendency is calculated from the increase / decrease of the positional deviation (step 606). It is determined whether or not correction is necessary from the tendency of positional deviation (step 607). If unnecessary, the process returns to step 603, and if necessary, a correction amount is calculated from the obtained positional deviation (step 608).

  If the amount of displacement or the amount of correction is greater than a predetermined threshold value and the error is expected to be large only by correcting the electron beam control data, the calibration for positioning provided on the sample, sample holder, sample stage, etc. The calibration mark 121 is detected by irradiating the mark 121 with an electron beam and acquiring a signal, and the position data reference is reset again.

  If detection of the calibration mark 121 is not necessary, the process returns to step 602 (step 609). If necessary, a positioning mark is detected (step 610), and the process returns to step 602.

  The correction amount calculation is performed for each shot of the electron beam condition data. Then, the result can be fed back to the main control system 125, the data control system 126, the analog control system 127, etc., and the deviation amount can be corrected in real time.

  Alternatively, instead of feedback control, feedforward control may be performed by obtaining a primary or secondary approximate curve from a deviation amount. Immediately before the approximate curve exceeds the allowable range, for example, one to several shots before, the correction is performed by detecting the calibration mark 121, or a new correction value is obtained by calculation from the conventional correction value, and the correction amount is changed. Go.

  This correction amount calculation (step 608) or calibration mark detection (step 610) is repeated until the data set (step 602) is drawn (step 611).

  By measuring the positional deviation of the electron beam for each shot, it is possible to detect a shot deviation that occurs suddenly. For example, the deviation amount is shot every time and its tendency is graphed, and the next deviation amount is always predicted.

  When a deviation amount of a certain amount or more in consideration of the detection error and the calculation accuracy is detected with respect to the expected value, it is detected as an abnormal shot deviation, and drawing is stopped together with an abnormal display. By not performing unnecessary drawing after the occurrence of an abnormality, the time that wasted due to drawing defects is minimized, the inspection process after drawing is omitted, and defective samples are placed downstream of the process. Prevent flowing.

  Alternatively, by setting a deviation amount detection criterion for each drawing pattern, drawing may be continued as long as it is within the allowable range even if a sudden shot deviation occurs, and an abnormality may be caused if the deviation is outside the range. . That is, it is possible to operate the apparatus in consideration of variations as products.

  If the correction amount calculation history is stored as data and the same drawing pattern is drawn with the first correction amount, the deviation amount is within a certain range, for example, within the measurement error range, and is stable. Alternatively, it is possible to determine whether the correction amount tends to increase or decrease, and to know whether the state of the apparatus is stable or changing.

  For example, if a drawing pattern number is input at the time of data setting before drawing, the history for the same drawing pattern number is saved based on the drawing pattern number, and it becomes easy to separately analyze the data.

(Sixth embodiment)
According to the change in the current value measured by the current measuring mechanism described in the third embodiment, it is fed back to the control voltage setting of the electron gun 101 and continuously adjusted to a desired current value, or the change in current It is also possible to grasp the decreasing trend of the current from the amount, and to adjust the current amount intermittently before affecting the exposure amount.

  In addition, data can be accumulated as the usage history of the electron gun 101 from the change in the current value. By constantly monitoring the difference between the current value data and the management value of the use limit set separately, it is possible to predict the life of a chip that is a consumable part in the electron gun 101.

  By predicting the service life and replacing consumable parts at the optimal timing, it is possible to prevent the occurrence of defects due to the life of the chip being drawn.

  Alternatively, it is possible to graph the numerical value itself and detect a chip abnormality from the tendency of a straight line or a curve. Drawing defects due to abnormal chip consumption due to the chip itself, the chip installation method, or the drawing conditions can also be prevented in advance.

(Seventh embodiment)
Data measured by the current measurement mechanism described in the third and fourth embodiments can be used for calibration of the measuring element 210.

  The change with time in the current value of the electron beam is reflected in the probe 210. For example, in the same drawing pattern, the value detected by the probe 210 when drawing based on the same data should be the same.

  When they are different, it is possible to comprehensively determine whether or not the current is due to the positional deviation by simultaneously measuring all the current values, and the calculation accuracy can be improved.

(Eighth embodiment)
In the fourth, fifth and sixth embodiments, the means for obtaining the center position and shape of the electron beam in real time and feeding back to the control has been described, but the detection means provides the operator with the current position and cross section of the electron beam. It is also possible to give shape information.

  7 and 8 show examples of screen display. The shape and position of the electron beam can be displayed as image data with reference to the initial electron beam position not subjected to shaping and deflection in the visual field range of the sample surface.

  Alternatively, the electron beam shape can be cut into a mesh and the current density ratio of each part can be displayed together.

  In the display unit 500 of FIG. 7, which is an image of the inside of the electron optical column portion 100 of the electron beam drawing apparatus shown in FIG. 1, the display unit is finely cut with a mesh, and the electron beam-free portion 510 and the electron beam are divided in each section. The electron beam portion 521 with a relative intensity of 1 with a low current density ratio, the electron beam portion 522 with a relative intensity of 2 with an intermediate current density ratio of the electron beam, and an electron with a relative intensity of 3 with a high current density ratio of the electron beam. Different display is made as in the portion 520 with the beam.

  This display may be expressed by a black and white density ratio or pattern in a black and white image, and may be expressed by a color ratio or the combination of different colors in a color image.

  Alternatively, for each mesh, the position where there is no electron beam may be 0, the position where the electron beam exists may be 1 or more, and the relative intensity of the electron beam may be displayed numerically.

  An example of this is shown in FIG. In a square display unit 600 that looks like a window on a monitor, the display unit is finely cut with a mesh. In each section, the portion without an electron beam 610 is 0, the portion with an electron beam, and the relative intensity 1 of the electron beam. The portion 621 of the electron beam is displayed as 1, the portion of the relative intensity 2 of the electron beam 622 as distinguished from the portion 620 of the relative intensity 3 of the electron beam as 3 and displayed.

  It is also possible to display the current density ratio in the absolute value as well as the density of the current density ratio in the place by taking the measurement result of the current value into consideration.

  These displays are not displayed on the screen for each shot, but are displayed on the screen at a fixed period of drawing, or after drawing, the drawing time and the position on the sample are set as parameters, so that for one shot The electron beam cross-sectional area may be displayed.

  This can be important data for investigating the cause when an event such as missing shot needs to be confirmed in the inspection process after drawing.

  It is also possible to predict the life of the chip from the change in the measured current value and to give a warning display to the operator. Alternatively, the numerical value itself can always be displayed on the monitor screen or displayed as a graph. The numerical value to be displayed may be the current value itself, the life that can be predicted from it, or the remaining usable time.

(Ninth embodiment)
The correction amount will be described in detail with reference to FIG.

  A drawing result 902 based on the drawing data 901 is compared with the data in the table 903. If there is no difference between the current value data in the table 903 and the measured current value based on the drawing data 901, or if the difference value drift amount does not exceed a predetermined threshold value, the correction amount zero 904 is corrected. Done. That is, no correction is performed.

  When the drift amount of the difference value exceeds the threshold value, correction 905 with correction amount is added to the drawing data 901. The correction amount corresponds to the drift amount.

  In the correction when the correction amount is 905, the data in the table 903 is not corrected. However, when the correction continues in subsequent drawing, the data in the table 903 is regarded as an absolute correction, and the correction 906 from the table 903 is added to the drawing data 901.

  As a result, since the correction is performed sequentially while drawing is continued, useless correction time is eliminated and the throughput is increased.

The longitudinal cross-sectional view which concerns on the Example of this invention, and shows the structure of an electron beam drawing apparatus. The conceptual diagram which shows the principle which concerns on the Example of this invention and measures the magnetic field of an electron beam. The top view which concerns on the Example of this invention and shows the planar shape after an electron beam is shape | molded. The top view which concerns on the Example of this invention and shows the planar shape after an electron beam is shape | molded. The flowchart which concerns on the Example of this invention and shows the flow of electron beam position detection and correction amount calculation. The flowchart which concerns on the Example of this invention and shows the flow of electron beam position detection and correction amount calculation. The screen figure which displays the current density ratio thru | or relative intensity | strength of the electric current of an electron beam concerning the Example of this invention. The screen figure which concerns on the Example of this invention and displays the current density ratio thru | or relative intensity | strength of the electric current of an electron beam numerically. FIG. 3 is a block circuit diagram of correction according to the embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Electro-optical column part, 121 ... Calibration mark, 122 ... Sample stage, 124 ... Control part, 125 ... Main control system, 126 ... Data control system, 127 ... Analog control system, 128 ... Signal processing system, 129 ... Mechanism Control system, 180 ... current detector, 200 ... current path, 201 ... magnetic field, 210 ... measuring element, 211 ... detector, 310 ... measuring element, 500 ... display unit, 510 ... no electron beam part, 520 ... with electron beam 521: Electron beam present part, 522 ... Electron beam present part, 600 ... Display screen, 610 ... Electron beam absent part, 620 ... Electron beam present part, 621 ... Electron beam present part, 622 ... Electron beam present part.

Claims (6)

  A measuring element for inducing an electromotive force by a magnetic field generated by the electron beam; an arithmetic unit for determining the position of the electron beam from the electromotive force induced by the measuring element; and the electron beam based on the determined position of the electron beam. An electron beam drawing apparatus comprising: a control device that controls deflection. The electron beam drawing apparatus according to claim 1.
An electron beam drawing apparatus comprising a display device for displaying the position of the electron beam. The electron beam drawing apparatus according to claim 1.
A plurality of concentric circles with respect to a reference axis, which is an optical axis before deflection of the electron beam, and a plurality of positions apart from the reference axis by a certain distance and at different positions;
The said arithmetic unit calculates the position of the said electron beam by comparing the electromotive force induced by each said measuring element, The electron beam drawing apparatus characterized by the above-mentioned. The electron beam drawing apparatus according to claim 1.
An opening member that shapes the cross-sectional shape of the electron beam, and a table of current values based on electromotive forces at a plurality of positions of the electron beam based on one of the shapes of the electron beam formed by the opening member. A storage device,
The arithmetic device compares the current value based on the electromotive force induced in the probe while irradiating the sample with an electron beam, and compares the current value of the table with a difference value exceeding a predetermined threshold value. In the case of the electron beam drawing apparatus, the correction amount of the positional deviation corresponding to the current value exceeding the threshold value is calculated. The electron beam drawing apparatus according to claim 2.
The arithmetic device compares the position of the electron beam controlled by the control device and the actually measured position of the electron beam, and obtains a positional deviation between them. The electron beam drawing apparatus according to claim 5.
The display device displays occurrence of misalignment when the misalignment occurs, and the arithmetic unit includes a storage device for storing the misalignment.

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