JP4699854B2 - Electron beam drawing apparatus and electron beam drawing method - Google Patents

Description

  The present invention relates to an electron beam drawing technique, and more particularly to an electron beam drawing apparatus and an electron beam drawing method for drawing an optical mask or the like.

  In an electron beam drawing apparatus using a variable shaped beam, the adjustment of the beam size is one of the most important techniques. Measuring the beam size with high accuracy becomes difficult as the size decreases.

  In view of this, Japanese Patent Application Laid-Open No. 11-149893 proposes a method of indirectly acquiring information on dimensions by measuring current amounts with a plurality of beam sizes and feeding it back to a variable shaping deflector.

JP-A-11-149893

  However, in recent years, the pattern of the optical mask has become very complicated for correcting the optical proximity effect, and an electron beam with a side of 10 nm to 100 nm is often used. Considering an electron beam with a maximum size of 2 μm, the dynamic range of current measurement becomes very wide, and current measurement using a conventional Faraday cup cannot guarantee the linearity of measurement. Here, linearity means that the output is linear with respect to the input. For example, the input is a beam current, and the output is an output current or output voltage of a detection system including a Faraday cup. When the linearity deteriorates, the position calibration accuracy of the drawing beam deteriorates, and it becomes difficult to draw the pattern as in the optical mask.

  Accordingly, an object of the present invention is to provide an electron beam drawing technique capable of drawing with high dimensional accuracy in a drawing apparatus using a variable shaped electron beam.

  To achieve the above object, according to the present invention, a drawing apparatus using a variable shaped electron beam has a plurality of electron beam detectors, measures the amount of current at a plurality of beam sizes, and performs exposure time ( (Irradiation time).

In addition, having one or more of the following features in the electron beam drawing apparatus is more effective in achieving the above object.
1) It has a function to set the beam size to be measured for each electron beam detector.
2) The sensitivity of the detector is different, the current amount of a smaller beam size is measured with a highly sensitive detector, and the current amount of a larger beam size is measured with a less sensitive detector.
3) feeding back the measurement results of different electron beam detectors to different control conditions of the electron beam;
4) feedback to different main control conditions according to the measurement results of different electron beam detectors;
5) It has a display function capable of identifying measurement results in a plurality of electron beam detectors.

  Furthermore, since it has a plurality of electron beam detectors, it is preferable to perform sensitivity calibration between the plurality of electron beam detectors with a beam size in a current range measurable by the plurality of electron beam detectors. Further, in response to the wide dynamic range, more efficient current measurement can be performed by switching the sampling times of the plurality of electron beam detectors according to the measurement beam size. Here, the dimension in one direction, which serves as a guide for switching the detector to be used, is around the resolution dimension of the electron beam or more than 0.05 μm, which may cause PD saturation, and the beam size measurement by the knife edge method is possible. Difficult 1 μm or less is preferable.

This means is effective for calibrating not only the beam size but also other optical characteristics of the variable shaped beam. For example, it is proposed to have multiple electron beam detectors, measure the focal position at multiple beam sizes, feed back to the focus corrector, or use different detectors for measuring the focal position and beam size. In addition, since it is necessary to perform measurement with greatly changing the beam size, it is preferable to use an integration circuit electrically connected to the electron beam detector in order to measure particularly a minute current with high accuracy. A wide range of current measurements can be accommodated by changing the integration time.

  When the maximum beam size to be used is small, it is possible to feed back to a plurality of control conditions with one detector. That is, in an electron beam drawing apparatus using a variable shaped beam, the measurement result of the current value of an electron beam having a plurality of beam sizes is fed back to different control conditions between the result of a larger beam size and the result of a smaller beam size. Become. At this time, feedback to different control conditions before and after the resolution of the electron beam is one standard.

  Hereinafter, typical configuration examples of the present invention will be listed.

  (1) An electron beam drawing apparatus according to the present invention includes an electron optical system that forms an electron beam emitted from an electron gun through at least one mask having an aperture, and the variable shaped beam In an electron beam lithography apparatus that uses a sample to expose a desired pattern, a plurality of electron beam detectors for measuring the amount of current of the variable shaped beam, and measurement according to a plurality of beam sizes of the variable shaped beam Means for feeding back the measured current value to the exposure time of the electron beam.

  (2) The electron beam lithography apparatus having the above-described configuration has a function of setting the beam size to be measured for each electron beam detector.

  (3) In the electron beam lithography apparatus having the above-described configuration, the plurality of electron beam detectors have different sensitivities, and the first electron beam detector measures a current amount of a smaller beam size of the variable shaped beam. And a second electron beam detector for measuring a current amount of a larger beam size of the variable shaped beam.

  (4) The electron beam lithography apparatus having the above-described configuration has a function of feeding back a plurality of measurement results obtained by the electron beam detector to different electron beam control conditions according to the beam size of the electron beam.

  (5) The electron beam lithography apparatus having the above-described configuration has a display function capable of individually identifying a plurality of measurement results obtained by the electron beam detector.

  (6) In the electron beam drawing apparatus having the above-described configuration, sensitivity calibration between the plurality of electron beam detectors is performed with a beam size in a current range measurable by the plurality of electron beam detectors.

  (7) The electron beam lithography apparatus having the above-described configuration is characterized in that a dimension in one direction is set to be around the resolution dimension of the electron beam as a guide for switching the plurality of electron beam detectors to be used.

  (8) In the electron beam lithography apparatus having the above-described configuration, the current density non-uniformity at a plurality of beam sizes of the variable shaped beam is fed back to control conditions other than the exposure time, and the current density remaining after the feedback is non-uniform. When the beam size has a uniformity exceeding a specified value, the exposure time is fed back.

  (9) In the electron beam lithography apparatus having the above-described configuration, the first electron beam detector is a photodiode, and the second electron beam detector is a Faraday cup.

  (10) The electron beam lithography apparatus having the above-described configuration includes an integration circuit electrically connected to the first electron beam detector.

  (11) An electron beam drawing method of the present invention includes an electron optical system that forms an electron beam emitted from an electron gun through at least one mask having an aperture, and the variable beam An electron beam lithography apparatus for exposing a desired pattern on a sample using a plurality of electron beam detectors, measuring a current amount according to a plurality of beam sizes of the variable shaped beam, and obtaining the current value In addition, the current density with respect to an arbitrary beam size of the variable electron beam is made substantially constant by correcting the exposure time of the electron beam.

  (12) In the electron beam drawing method having the above-described configuration, the sensitivity of the plurality of electron beam detectors is different, and a current amount of a small beam size of the variable shaped beam is reduced with a high sensitivity among them. The detector is configured to measure a current amount of a larger beam size of the variable shaped beam.

  (13) In the electron beam writing method having the above configuration, sensitivity calibration between the plurality of electron beam detectors is performed with a beam size in a current range measurable by the plurality of electron beam detectors.

  (14) In the electron beam drawing method having the above-described configuration, as a guide for switching the plurality of electron beam detectors to be used, a dimension in one direction is set to be around a resolution dimension of the electron beam.

  (15) In the electron beam writing method having the above-described configuration, the high-sensitivity detector is a photodiode, and the low-sensitivity detector is a Faraday cup.

  ADVANTAGE OF THE INVENTION According to this invention, in the drawing apparatus using a variable shaping | molding electron beam, the electron beam drawing technique which can perform drawing with high dimensional accuracy can be provided.

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

(Example 1)
FIG. 1 shows the configuration of the electron optical system of the electron beam drawing apparatus according to this embodiment. The electrons emitted from the electron gun 101 are accelerated to 50 kV and directly irradiate the first mask 102 having the first rectangular opening 140. The rectangular electron beam transmitted through the first mask is imaged on the second mask 109 by the two first transfer lenses 103 and the second transfer lens 107. On the second mask, a second rectangular opening 141 for variable molding is arranged at the center, and a collective figure opening 108 for collective figure irradiation is arranged around the second rectangular opening 141. The irradiation position of the first mask image on the second mask is controlled by the variable shaping deflector 105, the two first graphic selection deflectors 104, and the second graphic selection deflector 106. The electron beam that has passed through the second mask forms an image on the sample (for example, an optical mask) 115 through the two first reduction lenses 110, the second reduction lens 111, the two first objective lenses 112, and the second objective lens 114. The

  A plurality of (two in this example) detectors, a first detector 130 and a second detector 131 are arranged on the stage 116 positioned downstream of the objective lens, and the electron beam incident position is determined. Can be moved. Thereby, each detector can detect an electron beam directly. The output of the detector is sent to the data control system 135 through the detection signal processing system 121, and fed back to the electron optical system through the irradiation time control system 134, the figure selection / dimension control system 118, and the like. Further, a display device 136 is installed in the data control system 135, and a current amount measurement result, an electron beam calibration result, and the like are output. In the figure, a reduction rate / rotation control system 119 controls the reduction rate and rotation of the electron beam by the first reduction lens 110, the second reduction lens 111, and the rotation lens 112, and the focus / astigmatism / position. The control system 120 performs focus correction, astigmatism correction, and position control of the electron beam. The objective electrostatic deflector 113 is a deflector that determines the drawing position on the sample.

  FIG. 2 shows the vicinity of the detection unit of this embodiment. One of the outputs from the two detectors is sent to a detection signal processing unit through an integration circuit 204 that is electrically connected. The electron beam 201 measures the current value by any detector. In this case, the first detector 202 is a Faraday cup (FC), and the second detector 203 is a photodiode (PD). PD is highly sensitive to detect while amplifying current, and is suitable for detecting minute current. Conversely, it is not suitable for detecting a large current because it causes a saturation phenomenon. In addition, an integration circuit is connected to the PD, and a more accurate current value is measured by integrating a minute current. This is effective in the present embodiment in which a very small current is detected. Further, although FC has low sensitivity, it has an advantage that it can also serve as an absolute reference for current value measurement.

  FIG. 3 shows an example of the measurement algorithm. First, FC and PD are calibrated. This is to obtain compatibility between detectors with different sensitivities. Sensitivity calibration was performed by comparing the outputs of both beams using an electron beam with a beam size detectable by both detectors (here, 500 nm square). The sensitivity calibration can improve accuracy by using an electron beam having a plurality of beam sizes, that is, current values.

  Next, beam size calibration is performed by a knife edge method with an electron beam of 1 μm square to 2 μm square (step 301). This is to correct the beam size by obtaining the beam size from the edge position of the beam profile and feeding it back to the control voltage of the variable shaping deflector. In this method, an error increases when a beam size of 1 μm square or less is measured.

  Here, the feedback procedure is as follows. 1) The beam size is controlled by changing the control voltage of the variable shaping deflector. 2) Measure the beam size with the knife edge. 3) An error from the original beam size is obtained from the measured beam size. 4) A control voltage value corresponding to the error is obtained. 4) Change the setting of the control voltage of the deflector. This feedback is performed through the detection signal processing system 121, the data control system 135, and the figure selection / dimension control system 118.

  Next, by changing the XY direction of the rectangular beam, the current detected by the FC in increments of 0.1 μm between 0.1 μm × 1 μm and 1 μm × 1 μm, and between 1 μm × 0.1 μm and 1 μm × 1 μm. The size is calibrated by the value (step 302). In the algorithm of FIG. 3, the notation is shown only in one direction, but in actuality, the current was measured while reducing the size of the beam in each direction in the two directions of XY. In addition to the control voltage of the variable shaping deflector 105, the rotation of the second mask 109 and the excitation adjustment of the first transfer lens 103 and the second transfer lens 107 were performed so that the current density obtained from the measured current value was constant. (Step 303).

  These two feedbacks have been performed conventionally. However, in recent optical masks, the pattern on the optical mask is very complicated due to the correction of the optical proximity effect, and when the pattern is decomposed into a drawing figure, a pattern with a dimension between 1 nm and 100 nm also appears. With such dimensions, the influence of non-orthogonality and edge roughness of the mask for forming the variable shaped beam becomes large, and calibration cannot be completed by the conventional control voltage of the variable shaping deflector, mask rotation, and transfer lens excitation adjustment.

In the present embodiment, a current value measurement by PD is further performed as a new feedback method (step 304). In this embodiment, since the integrating circuit 204 is connected to the PD, the amount of incident charge in a predetermined time is actually obtained, but the current value of the drawing apparatus is stable in a short time. It is considered to be substantially equivalent to current value measurement. The beam ON time can be determined directly, but here it is controlled by the exposure time per shot and the number of shots in order to obtain compatibility with actual exposure. Measurements were performed in increments of 9 nm or 10 nm between each of 1 nm × 1 μm to 100 nm × 1 μm and 1 μm × 1 nm to 1 μm × 100 nm with two elongated rectangular beams. In order to target a beam smaller than the measurement by FC, the measurement is performed by changing the size step. As described above, this apparatus has a function of setting the beam size to be measured for each electron beam detector. In this example, since it was used at a current density of 20 A / cm ² , 200 μA at 1 μm × 1 μm and 200 pA at 1 nm × 1 μm. The range of the current value measurement is three digits, and it can be seen that the combined use of FC and PD is effective for maintaining the linearity of the measurement.

  The beam resolution of this apparatus (the range in which the dimensional linearity of the drawing pattern is guaranteed) is about 100 nm, and the switching dimension of both detectors is 100 nm. In the present invention, as a guideline for switching between a plurality of detectors to be used, the dimension in one direction is preferably around the resolution dimension of the electron beam, for example, 0.05 μm or more and 1 μm or less.

  The current density is obtained from the measured current value, and the beam time is calibrated by shortening the exposure time for a beam size with a small current density and shortening the exposure time for a beam size with a large current density. The exposure time control is performed by controlling the operation of the blanker 133 through the exposure time control system 134. Thus, feedback ends.

  The beam of 100 nm or less is generated when the pattern on the optical mask is divided into long and narrow patterns, and there is no pattern by itself, and the effect of the divided beam is not the size addition itself below the resolution of the beam. The effect of adding energy to the sample is great. For these reasons, it is possible to obtain the same effect as the correction of the beam size by feeding back to the exposure time instead of the beam size itself.

  In FIG. 4, the current density in each size measured by FC and PD is shown. In the figure, black lines are displayed. Actually, those measured by PD are displayed in green, and those measured by FC are displayed in red. After the exposure time correction, the current density is substantially constant because the beam ON time at the time of measuring the current value is corrected. Since the measurement accuracy of the current value is limited, it is easy to perform feedback to the exposure time at a small beam size where the current value is sensitive to the beam size. This is another reason for applying exposure time correction to smaller beam sizes. In the figure, the values measured by FC and PD are displayed in different colors so that they can be identified. This figure is displayed on the display device 136. In this specification, only a part of beam sizes are displayed for easy viewing of the figure.

  Finally, drawing was performed on the sample based on the exposure time correction table 137 (step 305) created as a result of these (step 306). In the present embodiment, since only the measurement in the one-dimensional direction is performed, the two-dimensional table is created by integrating the dependence in the one-dimensional direction. The exposure time of the beam size not on the table is obtained by interpolation. As a result, it has become possible to improve the dimensional accuracy, which has been limited to 5 nm, to 3 nm.

  FIG. 5 shows an example in which the optical mask pattern is divided into rectangles for reference. Since the optical proximity effect correction is applied to the L-shaped pattern, it can be seen that there are many elongated fine figures when divided into rectangles.

  In this embodiment, FC and PD are used as detectors. However, it is obvious that the same effect can be obtained by using a plurality of PDs having different sensitivities or a plurality of PDs having different bias voltages. Although the algorithm becomes complicated, the feedback method also feeds back the measurement results of some dimensions with a low-sensitivity detector to the exposure time, and deflects the measurement results with some dimensions of a high-sensitivity detector. It is also possible to feed back to the control system.

  The feedback procedure in this case is as follows. 1) Measure currents of multiple dimensions with a low sensitivity detector. 2) Find the error from the original amount of current. 3) Calculate a correction value for the exposure time corresponding to the error. 4) Change the exposure time setting. 5) Measure currents of multiple dimensions with a low sensitivity detector. 6) An error from the original beam size is obtained from the measured beam size. 7) A control voltage value corresponding to the error is obtained. 8) Change the setting of the control voltage of the deflector. This feedback is performed through the detection signal processing system 121, the data control system 135, the figure selection / dimension control system 118, and the exposure time control system 134.

  For the beam size correction by the edge method, 1) knife edge provided on FC, 2) knife edge provided on PD, 3) slit provided on PD, 4) third detector (low sensitivity) A knife edge or the like provided on PD) can be used.

(Example 2)
In this example, an apparatus similar to that in Example 1 was used. Drawing was performed according to the measurement algorithm shown in FIG. The measurement method is basically the same as the method in FIG. 3, and FC and PD are calibrated.

  First, beam size calibration is performed by an edge method with an electron beam of 1 μm square to 2 μm square (step 601). Next, the XY direction of the rectangular beam is changed to (0.1, 0.4, 0.7, 1.0) μm × (0.1, 0.4, 0.7, 1.0) μm. A size calibration is performed using the current value detected by the FC with an electron beam having a dimension represented by a matrix (step 602). Thereafter, as in the case of FIG. 3, mask rotation and transfer lens excitation adjustment are performed as necessary (step 603).

  Next, the current value is measured by the PD (step 604). In this embodiment, the beam size for measuring the current value is two-dimensionally changed. The dimension to be measured is L-shaped on a two-dimensional plane, and is (1, 2, 5, 10, 20, 50, 100) nm × (1, 2, 5, 10, 20, 50, 100). , 200, 500, 1000, 2000) nm and (1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, 2000) nm × (1, 2, 5, 10, 20, It is represented by a matrix of 50,100) nm. In this, the matrix portion of (1, 2, 5, 10, 20, 50, 100) nm × (1, 2, 5, 10, 20, 50, 100) nm is overlapped. May be represented by a single measurement. Since the error in the current density is expected to increase as the beam size decreases, the measurement dimension interval is reduced as the beam size decreases. This makes it possible to improve both the correction accuracy and the measurement efficiency. Spline interpolation was used between each dimension, but function fitting is also possible.

  In this embodiment, the minute current measurement by the PD is performed 105 times. Since the minimum measurement time required to perform the measurement with the required accuracy depends on the beam current, the overall measurement efficiency can be improved by switching the measurement time according to the beam size. In particular, since the current amount in this embodiment is 200 nA at 1 μm × 1 μm and 0.2 pA at 1 nm × 1 nm, the range is 6 digits, and it is extremely effective to use the multiple detectors of the present invention and to switch the measurement time. Become.

  7 and 8 show current densities at respective beam sizes shown in the display device in this embodiment. FIG. 7 shows a screen before exposure time correction, and FIG. 8 shows a screen after exposure time correction. In the figure, the deviation from the reference current density is indicated by an arrow. An up arrow means over, and a down arrow means under. Note that the current density of all measurement beam sizes is not shown in the figure. Although the drawing is black and white, for example, the boundary line is drawn with the area measured by FC being red and the area measured by PD being green.

  7 and 8, it can be seen that the current density that was larger in the small beam size region before the correction is converged to the reference current density after the correction. If the exposure time correction amount is too large, drawing will be hindered.If the current density is higher than the specified amount before correction, exposure time correction may be performed after using another feedback system such as a variable shaping deflector. Good.

  Drawing was performed on the sample based on the exposure time correction table (step 605) created as a result of these (step 606). As a result, the dimensional accuracy can be improved to 2.5 nm.

(Example 3)
The electron beam has a Coulomb effect, and the focal position changes depending on the beam size. In order to know this amount, it is necessary to measure the focal position at different beam sizes. However, it is also effective to use a plurality of detectors in order to perform highly accurate measurement with greatly different currents.

  In this embodiment, the following procedure is fed back. 1) First, the focal position was obtained from the 1 μm square to the 2 μm square using the first detector (FC) and from the 0.1 μm square to the 1 μm square using the second detector (PD). FIG. 9 shows the result displayed on the display device. Here, the measurement result of the first detector is represented by a white square mark, the measurement result of the second detector is represented by a black circle mark, and the boundary is clearly shown. It can be clearly seen that the focal position changes according to the beam size. 2) Next, a relational expression between the dimension and the focus correction amount is obtained from the obtained focus change amount. 3) Draw while changing the control voltage of the focus corrector according to this relational expression. As described above, highly accurate drawing is possible.

  In this embodiment, the focus correction amount is proportional to the change in the area of the beam, and feedback is performed through the detection signal processing system 121, the data control system 135, and the focus / astigmatism / position control system 120. The focus correction in the electron optical system is realized by adding a uniform control voltage to the objective electrostatic corrector in the objective lens. In this example, the dimensional accuracy could be improved to 2 nm.

Example 4
In this embodiment, since the maximum beam size is as small as 1 μm square, FC was used only for sensitivity calibration. Therefore, when the sensitivity of PD is known to some extent, FC is not necessary. In this case, calibration is performed with one electron beam detector.

  FIG. 10 shows a measurement / exposure algorithm, that is, a feedback algorithm. The measurement method according to the present embodiment is basically the same as the method in FIG. 6, but calibration is performed with one electron beam detector PD.

  First, beam size calibration is performed by an edge method with an electron beam of 0.5 μm square to 1 μm square (step 1001). Next, the XY direction of the rectangular beam is changed to (0.1, 0.2, 0.3, 0.4, 0.5) μm × (0.1, 0.2, 0.3, 0.3. (4, 0.5) Size calibration is performed with an electron beam having a size represented by a matrix of μm based on the current value detected by the FC (step 1002). Thereafter, the control voltage of the variable shaping deflector and the excitation current of the transfer lens are changed. (Step 1003).

  Next, the current value of a smaller beam size is measured using the same PD as that used for the beam size calibration by the edge method (step 1004). In this embodiment, the dimension for measuring the current value is (1, 2, 5, 10, 20, 50, 100) nm × (1, 2, 5, 10, 20, 50, 100, 200, 500, 1000). ) Nm matrix and (1,2,5,10,20,50,100,200,500,1000) nm × (1,2,5,10,20,50,100) nm matrix .

  Based on the result in step 1004, an exposure time correction table is created (step 1005), and the exposure time is changed instead of changing the control voltage of the variable shaping deflector and the excitation current of the transfer lens. To expose. (Step 1006).

  Thus, if the linearity of the current value measurement is good, it is possible to selectively use the measurement results of one detector. In this case, the result of the larger beam size is divided from the result of the smaller beam size. As a detector using PD, the same one as in Example 1 was used.

  FIG. 11 shows a screen of the corrected current value result. Different data colors of control values (control voltage of the variable shaping deflector, excitation current of the transfer lens or exposure time) to be changed at the time of correction are displayed. The 100 nm dimension is located at the boundary, and the data is used for both feedbacks. When one detector is used in this way, it is not necessary to calibrate the sensitivity with different detectors and it is easy to share data. By this example, a dimensional accuracy of 2 nm was realized.

(Example 5)
In this embodiment, only the PD is used as the transmission electron beam detector. FIG. 12 shows a measurement / exposure algorithm in this embodiment, that is, a feedback algorithm. The measurement method is basically the same as the method in FIG. 10, and calibration is performed with one detector PD.

  First, after performing beam size calibration by the edge method with an electron beam of 0.5 μm square to 1 μm square (step 1201), (1, 2, 5, 10, 20, 50, 100, 200, 500, 1000) nm. A current value is measured by PD with an electron beam represented by a matrix of × (1, 2, 5, 10, 20, 50, 100, 200, 500, 1000) nm (step 1202). The control voltage of the shaping deflection control system is corrected using all or a larger size of the result (step 1203).

  Again, if the current value is measured by PD with the electron beam represented by the above matrix (step 1204), it is expected that the uniformity of the current density is improved. As a result of the re-measurement of PD, a correction value is entered in the exposure amount correction table only for the beam size whose current density non-uniformity exceeds a specified value (step 1205), and exposure is performed according to the correction table (step 1206). By doing so, it is possible to automatically determine a control condition for performing feedback depending on the beam size.

  FIG. 13 shows a current density distribution before exposure time correction. The figure is shown on the screen of the display device so that the data of the beam size that should be subjected to exposure time correction (or the exposure time correction) can be identified. In this example, it is indicated by a dotted line. Basically, an error in current density tends to occur at a small beam size, and exposure time correction is performed only for a beam size of 100 nm or less. As a result of drawing while correcting the exposure time, a high dimensional accuracy of 2.5 nm is also obtained in this embodiment.

  As described above in detail, according to the present invention, an electron beam drawing apparatus capable of drawing with high dimensional accuracy can be realized in a drawing apparatus using a variable shaped electron beam, and high-precision drawing of minute figures can be realized. This contributes to improving the dimensional accuracy of the optical mask.

The figure explaining the structure of the electron beam drawing apparatus by this invention. The figure explaining the detection part in this invention. The figure explaining an example of the measurement and exposure algorithm by this invention. The figure which shows the measurement result of the current density measured with the two detectors by this invention. The figure which shows an example of the rectangular division of the pattern of the optical mask by this invention. The figure explaining another example of the measurement and exposure algorithm by this invention. The figure which shows the two-dimensional distribution of the current density before exposure time correction | amendment measured with the two detectors shown in FIG. The figure which shows the two-dimensional distribution of the current density after exposure time correction | amendment measured with the two detectors shown in FIG. The figure which shows the change of the focus position by this invention. The figure explaining an example of the measurement and exposure algorithm in the case of calibrating with one detector by this invention. The figure which shows the two-dimensional distribution of the current density after the exposure time correction | amendment measured with one detector shown in FIG. The figure explaining another example of the measurement algorithm in the case of calibrating with one detector by this invention. The figure which shows the two-dimensional distribution of the current density before the exposure time correction | amendment measured with one detector shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Electron gun, 102 ... 1st mask, 103 ... 1st transfer lens, 104 ... 1st figure selection deflector, 105 ... Variable shaping deflector, 106 ... 2nd figure selection deflector, 107 ... 2nd transfer lens, DESCRIPTION OF SYMBOLS 108 ... Collective figure opening, 109 ... 2nd mask, 110 ... 1st reduction lens, 111 ... 2nd reduction lens, 112 ... 1st objective lens, 113 ... Objective electrostatic deflector, 114 ... 2nd objective lens, 115 ... Optical mask 116 ... stage 118 ... graphic selection / dimension control system 119 ... reduction ratio / rotation control system 120 ... focus / astigmatism / position control system 120 ... detection signal processing system 122 ... rotation lens DESCRIPTION OF SYMBOLS 130 ... 1st detector, 131 ... 2nd detector, 133 ... Blanker ..., 134 ... Exposure time control system, 135 ... Data control system, 136 ... Display apparatus, 137 ... Exposure time correction table ... 140 ... 1st rectangle Opening, 141 ... second rectangular openings, 201 ... electron beam ... beam, 202 ... first detector (FC), 203 ... second detector (PD), 204 ... integrating circuit.

Claims (4)

An electron optical system that forms an electron beam emitted from an electron gun through a at least one mask having an aperture and forms a variable shaped beam, and an electron that exposes a desired pattern on a sample using the variable shaped beam In a beam drawing apparatus, an electron beam detector for measuring a large current for measuring a current amount of the variable shaped beam, an electron beam detector for measuring a minute current, and a plurality of beam sizes of the variable shaped beam In an electron beam drawing apparatus having means for feeding back the measured current value to the exposure time of the electron beam,
An electron beam drawing apparatus , wherein the electron beam detector for measuring a minute current is constituted by a photodiode, and the electron beam detector for measuring a large current is constituted by a Faraday cup . 2. The electron beam drawing apparatus according to claim 1, further comprising an integration circuit electrically connected to the electron beam detector for measuring a minute current . An electron optical system that forms an electron beam emitted from an electron gun through a at least one mask having an aperture and forms a variable shaped beam, and an electron that exposes a desired pattern on a sample using the variable shaped beam In the beam drawing apparatus, a plurality of the variable shaped beams are formed by a first electron beam detector for measuring a large current constituted by a Faraday cup and a second electron beam detector for measuring a minute current constituted by a photodiode. By measuring the amount of current in accordance with the beam size and correcting the exposure time of the electron beam based on the current value, the current density with respect to an arbitrary beam size of the variable electron beam is made substantially constant. An electron beam drawing method characterized by that. 4. The electron beam writing method according to claim 3 , wherein a dimension in one direction is set to be around a resolution dimension of the electron beam as a guide for switching between the first and second electron beam detectors to be used. Electron beam drawing method .

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