JP3983772B2 - Charged particle beam application equipment - Google Patents

Description

  The present invention relates to a charged particle beam application apparatus including a charged particle beam exposure apparatus that directly patterns a substrate to be exposed such as a wafer using a plurality of charged particle beams.

  As an example of a charged particle beam application apparatus, conventionally, an electron beam exposure apparatus includes a point beam type using a spot-shaped beam, a variable rectangular beam type using a variable size rectangular beam, and a cell that collectively exposes a specific pattern. There are projection type devices. Since the electron beam has a short wavelength, it can be exposed with high resolution. However, there are many problems in terms of production volume (throughput) per unit time.

  As an apparatus for solving this problem, there has been proposed a multi-electron beam type exposure apparatus that individually controls a plurality of electron beams and exposes a desired pattern (see, for example, Non-Patent Document 1).

  This method has a feature that the throughput can be further improved because the area to be exposed at one time is wider than the conventional one.

"Journal of Vacuum Science and Technology": J. Vac. Sci. Technol. B 18 (6), Nov / Dec 2000, 3061-3066

  However, in the multi-electron beam type exposure apparatus, in order to form a multi-electron beam, a diaphragm plate having a plurality of openings, and an electrostatic lens group that converges each of the plurality of electron beams that have passed through the diaphragm plate, A deflector group is installed near the focal position of the electrostatic lens to deflect each of the plurality of electron beams. It is necessary to adjust the angle of the electron beam and the image rotation so that each electron beam passes through the diaphragm plate, the electrostatic lens group, and the deflector group.

  Such adjustment so that the beam can pass from upstream to downstream is called “beam alignment”. The diaphragm plate, the electrostatic lens group, and the deflector group that form a multi-electron beam are collectively referred to as a “multi-beam forming unit”. The “angle adjusting means” and “aligner” are both a mechanism for adjusting the angle of the beam and can be used as a deflector. However, what is installed in the multi-beam forming unit is an “angle adjustment”. Means ", those installed outside the multi-beam forming section are referred to herein as" aligners ".

  During beam alignment, the angle of the beam emitted from the multi-beam forming unit changes, and if the downstream projection optical system has a small aperture, the beam is likely to be interrupted midway, making alignment difficult while detecting the beam. It becomes. Therefore, normally, it is necessary to alternately perform the beam alignment in the multi-beam forming unit and the alignment in the projection optical system, which causes a problem that the alignment efficiency is low.

  Accordingly, an object of the present invention has been made in view of the above-described conventional problems, and to provide a charged particle beam application apparatus capable of efficiently performing beam alignment in a multi-beam forming unit. is there.

  In order to achieve the above object, the present invention has the following characteristics.

  (1) A multi-beam forming unit that forms a charged particle beam emitted from a charged particle source into a plurality of charged particle beams, and the plurality of multi-electron beams emitted from the multi-beam forming unit are simultaneously scanned in the vicinity of the emitting unit. In a charged particle beam application apparatus comprising: a deflecting unit; a projection optical system that projects the plurality of charged particle beams onto a substrate to be exposed with a one-stage or multi-stage lens; and a detector that detects the plurality of charged particle beams. The projection optical system includes a diaphragm installed at a rear focal position of the uppermost lens of the projection optical system, and a moving unit that moves an optical position of the diaphragm from the rear focal position of the uppermost lens in the optical axis direction. The plurality of charged particle beams are separated and detected by shifting the optical position of the diaphragm from the rear focal position of the uppermost lens by the moving means. The charged particle beam application device, characterized in that configured to obtain.

  (2) In the charged particle beam application apparatus having the above-described configuration, the multi-beam forming unit includes a plurality of aperture groups having one or a plurality of apertures and an angle of the charged particle beam between each of the plurality of aperture groups. And an angle adjusting means for adjusting image rotation of the charged particle beam between each of the plurality of aperture groups, and adjusting the angle adjusting means and the rotation adjusting means. The multi-beam forming unit is configured to allow the beam to pass therethrough.

  (3) In the charged particle beam application apparatus having the above-described configuration, the deflection unit is configured by an aligner that adjusts an angle of the charged particle beam emitted from the multi-beam forming unit, and is determined by the detector in the deflection by the aligner. By adjusting the aligner so that a deflection region capable of detecting a current value equal to or greater than a predetermined value is in the vicinity of the center of the deflection region, the beam can pass through the detector.

  (4) In the charged particle beam application apparatus having the above configuration, the detector is a detector having a detection surface that enables simultaneous detection of the plurality of charged particle beams.

  According to the present invention, when a plurality of charged particle beams are formed, adjustment is performed for the charged particle beam to pass between a diaphragm plate having a plurality of apertures, an electrostatic lens, and a deflector group, thereby facilitating the passage of the beam. It becomes possible to confirm.

  In the embodiments described below, an electron beam exposure apparatus will be described as an example of a charged particle beam application apparatus. The present invention is not limited to the electron beam exposure apparatus, but can be similarly applied to an application apparatus using a charged particle beam such as an electron beam or an ion beam.

  FIG. 1 is a schematic view of an electron beam exposure apparatus according to an embodiment of the present invention.

  The electron beam emitted from the electron source 1 enters the multi-electron beam forming unit 3 through the irradiation optical system 2 including the light source reduction lens 20 and the collimator lens 21. The astigmatism corrector 22 is controlled by the astigmatism correction control circuit 154 and corrects astigmatism generated in the irradiation optical system. The irradiation aligner 23 adjusts the beam angle to the collimator lens 21 and the multi-beam forming unit 3. In the figure, 11 indicates an optical axis.

  The multi-electron beam forming unit 3 includes an aperture array 31, an electrostatic lens array 32, a blanker array 33, octupole electrostatic deflectors 100 and 110, and image rotation lenses 120 and 130. The electrostatic lens array 32 includes three electrodes, an upper electrode 32a, a middle electrode 32b, and a lower electrode 32c, and is controlled by a focus control circuit 151. The aperture array 31 is a diaphragm plate having a plurality of openings, and each electron beam divided here is converged by the electrostatic lens array 32 in the vicinity of the position of the blanker array 33. The blanker array 33 is a group of deflectors for independently deflecting each electron beam, and is controlled by the pattern generation circuit 152.

  The electrostatic deflector 100 deflects the electron beam that has passed through the aperture array 31 and adjusts the angle for the electron beam to pass through the electrostatic lens array 32. The electrostatic deflector 110 deflects the electron beam that has passed through the electrostatic lens array 32, and performs angle adjustment for the electron beam to pass through the blanker array 33. Each deflector has a larger electrode spacing than the multi-beam area in order to allow simultaneous multi-beam deflection. The image rotation lens 120 rotates the image of the electron beam that has passed through the aperture array 31, and the image rotation lens 130 rotates the image of the electron beam that has passed through the electrostatic lens array 32, and the electrostatic lens array 32 and the blanker array 33 respectively. Make adjustments for the beam to pass through. Note that these deflectors and aligners may be electromagnetic deflectors and aligners.

  The plurality of electron beams formed by the multi-electron beam forming unit 3 is reduced and projected onto the stage 5 by the projection optical system 4. In the projection optical system 4, a symmetric magnetic doublet is configured by the two-stage lens of the first reduction lens 41 and the second reduction lens 42. The reduction projection optical system aligner 300 is an aligner that deflects the multi electron beam emitted from the multi electron beam forming unit 3, and mainly adjusts the optical axis of the projection optical system 4. In the projection optical system 4, there is a blanking stop BA that blocks each electron beam deflected by the blanker array 33.

  Beam detection is performed by a transmission electron detector 6 installed on the stage 5, or a reflection / secondary electron reflected or emitted by a reflection / secondary electron detection mark 8 on the stage 5 / secondary electrons. It is detected by the detector 9 and visualized through the signal processing circuit 157. The detector has a detection surface larger than the multi-beam area in order to enable simultaneous measurement of multi-beams, and the reflection / secondary electron detection mark 8 is larger than the multi-beam area and has a uniform structure. Use things. Stage movement is controlled by a stage control circuit 158.

  The electron beam not shielded by the blanking stop BA is scanned on the stage 5 by the deflector 7. At this time, the deflector 7 is controlled by the deflection control circuit 156. By controlling the voltage of the blanker array 33 by the pattern generation circuit 152 in accordance with the drawing data 160, a desired pattern is exposed.

  The aligner control circuit 153 controls the irradiation aligner 23, the electrostatic deflectors 100 and 110, and the reduction projection optical system aligner 300. The lens control circuit 155 includes the light source reduction lens 20, the collimator lens 21, the image rotation lenses 120 and 130, The doublet lenses 41 and 42 are controlled. The data control circuit 150 controls each of the control / processing circuits 151 to 158, and the detection result from the detector 6 or the reflection / secondary electron detector 9 through the signal processing circuit 157 is sent to the aligner control circuit 153 or the deflection control circuit 156. The information is displayed on the display mechanism 159 in synchronization.

  Next, a beam angle adjusting method according to the present invention will be described.

  In order to deflect the multi-electron beam emitted from the multi-electron beam forming unit 3, adjustment is performed by installing a deflector downstream of the blanker array 33 or using the reduction projection optical system aligner 300 as a deflecting unit. In this embodiment, it is assumed that the reduction projection optical system aligner 300 is used as a deflecting unit. In the following drawings, as in FIG. 1, an example in which the electrostatic lens array 32 is driven is shown. However, adjustment can be performed in the same manner even when no voltage is applied to the electrostatic lens array 32.

  The beam image scanned on the blanking stop BA by the reduction projection optical system aligner 300 has a pattern reflecting the opening shape of the blanking stop BA and the beam shape at the blanking stop BA position. Hereinafter, assuming that the opening shape of the blanking diaphragm BA is circular, when the blanking diaphragm BA is at the rear focal position BF of the first reduction lens 41 as shown in FIG. Since the beams (in this example, the number of beams is 9) substantially coincide with each other, the beam shape is substantially circular, and the beam image scanned on the blanking stop BA by the reduction projection optical system aligner 300 is shown in FIG. As shown in FIG.

  As shown in FIG. 2C, when the blanking stop BA is optically shifted from the rear focal position BF of the first reduction lens 41 in the optical axis direction, the multi-electron beam is separated at the blanking stop BA position. The beam image scanned on the blanking stop BA by the projection optical system aligner 300 has a pattern in which multiple electron beams (9 beams) are separated as shown in FIG. When the amount of optically shifting the blanking stop BA from the rear focal position BF is small, the multi-electron beam is not completely separated, but adjustment is possible even in a state where it is not completely separated. However, it may be easier to adjust if separated.

  As a method of optically shifting the blanking diaphragm BA from the rear focal position BF of the first reduction lens 41 in the optical axis direction, the blanking diaphragm BA may be moved up and down mechanically or the excitation of the first reduction lens 41 may be performed. May be changed.

  Since the multi-beam forming unit 3 is composed of a plurality of minute aperture groups (aperture array 31, electrostatic lens array 32, blanking array 33), a multi-beam is formed without normal adjustment due to the effects of assembly errors. It is difficult to do. Therefore, beam alignment is performed by using octupole electrostatic deflectors 100 and 110 as angle adjustment means and image rotation lenses 120 and 130 as rotation adjustment means.

  If the angle adjustment means (octupole electrostatic deflectors 100, 110) and rotation adjustment means (image rotation lenses 120, 130) are changed for beam alignment, the angle of the beam emitted from the blanker array 33 and the image rotation are also changed. Change. When beam alignment is performed while detecting with the detector 6 on the stage 5, the beam is blocked by the lens inner wall in the reduction optical system 4, the blanking stop BA, or the like as the emitted beam from the blanker array 33 changes. .

  Therefore, as shown in FIGS. 2A and 2B, by observing the scanning image of the blanking stop BA in the reduction projection optical system aligner 300, the lens inner wall and the blanking stop in the reduction optical system 4 are observed. The beam can be prevented from being blocked by BA or the like, and the beam alignment can be performed efficiently. In this case, either of the conditions shown in FIGS. 2A and 2C may be used. Further, since the position information in the scanned image is angle information in the vicinity of the blanking array 33, the scanned image is also effective for observing the emission angle distribution of the blanking array 33 and the like.

  FIG. 3 is an example in which the blanking array 33 has a significant installation error with respect to the arrangement of the aperture array 31 and the electrostatic lens array 32. Although the beam alignment is performed using the octupole electrostatic deflector 110, FIG. 3A shows the case where the beam alignment is performed on the blanking array 33 opening different from the opening to be originally passed (on the left side in the figure). FIG. 3 (b) shows a case where beam alignment can be performed with the original aperture. Such a difference in optical conditions between FIGS. 3A and 3B is determined by an image obtained by shifting the blanking stop BA from the rear focal position BF of the first reduction lens 41 as shown in FIG. 2C. can do. When the blanking stop BA is shifted from the rear focal position BF of the first reduction lens 41, the scanned images in FIGS. 3A and 3B are as shown in FIGS. 3C and 3D, respectively. Thus, it can be determined whether or not the number of beams to be observed is a desired number.

  As a result of the adjustment as described above, the emission angle from the multi-beam forming unit 3 changes compared with that before the adjustment, and the beam may not pass through the downstream lens or the like. In such a case, in the blanking stop BA scan image by the reduction projection optical system aligner 300, as shown in FIG. 4A, an image shift is observed from the center of the alignment area (field center) of the aligner. By adjusting the offset value of the aligner 300 about the center of the visual field as shown in FIG. 4B, shielding of the beam can be avoided. Alternatively, the shielding of the beam can be avoided by adjusting the offset value of the aligner 300 so that the image shift becomes small before and after the adjustment described above.

  If the deflector and aligner are used together as in the present embodiment, the apparatus configuration can be simplified. In FIG. 4, when the deflector and aligner are not used together, the aligner value is adjusted so as to reduce the image shift at the approximate center of the deflector field of view or before and after the adjustment described above, instead of adjusting the offset value of the aligner 300.

  As described above, according to the charged particle beam application apparatus of the present invention, when forming a plurality of charged particle beams, the charged particle beam passes between the diaphragm plate having a plurality of openings, the electrostatic lens, and the deflector group. It is possible to easily confirm the passage of the beam by making adjustments for this purpose. In addition, a charged particle beam exposure apparatus using this apparatus can expose a desired pattern, and in device manufacturing, it is possible to manufacture with higher yield and higher throughput than before.

The figure explaining the principal part outline of the multi electron beam exposure apparatus which concerns on one Example of this invention. The figure explaining the beam angle adjustment method by this invention. The figure explaining the beam angle adjustment with respect to the case where there is an installation error in the blanking array. The figure explaining beam angle adjustment with respect to the case where the image shift | offset | difference from the visual field center of a deflector is observed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electron source, 2 ... Irradiation optical system, 11 ... Optical axis, 20 ... Light source reduction lens, 21 ... Collimator lens, 22 ... Astigmatism corrector, 23 ... Irradiation aligner, 3 ... Multi electron beam formation part, 31 ... Aperture array, 32 ... electrostatic lens array, 32a ... upper electrode, 32b ... middle electrode, 32c ... lower electrode, 33 ... blanker array, 4 ... reduction electron optical system, 41 ... first reduction lens, 42 ... second reduction lens DESCRIPTION OF SYMBOLS 5 ... Stage, 6 ... Transmission electron detector, 7 ... Deflector, 8 ... Reflection / secondary electron detection mark, 9 ... Reflection / secondary electron detector, 100 ... Eight-pole electrostatic deflector 1, 110 ... 8-pole electrostatic deflector 2, 120 ... image rotation lens 1, 130 ... image rotation lens 2, 150 ... data control circuit, 151 ... focus control circuit, 152 ... pattern generation circuit, 153 ... aligner control circuit, 154 ... astigmatism Correction control circuit, 55 ... Lens control circuit, 156 ... Deflection control circuit, 157 ... Signal control circuit, 158 ... Stage control circuit, 159 ... Display mechanism, 160 ... Drawing data, 300 ... Reduced projection optical system aligner, BA ... Blanking stop, BF ... The rear focal position of the first reduction lens 41.

Claims (5)

  A multi-beam forming unit that forms a charged particle beam emitted from a charged particle source into a plurality of charged particle beams; and a deflecting unit that simultaneously scans the plurality of multi-electron beams emitted from the multi-beam forming unit in the vicinity of the emitting unit. A charged particle beam application apparatus comprising: a projection optical system that projects the plurality of charged particle beams onto a substrate to be exposed with a single-stage or multi-stage lens; and a detector that detects the plurality of charged particle beams; Has a diaphragm installed at the rear focal position of the uppermost lens of the projection optical system, and moving means for moving the optical position of the diaphragm from the rear focal position of the uppermost lens in the optical axis direction. The plurality of charged particle beams can be detected separately by shifting the optical position of the diaphragm from the rear focal position of the uppermost lens by the moving means. The charged particle beam application device, characterized in that the cormorants configuration.   2. The charged particle beam application apparatus according to claim 1, wherein the multi-beam forming unit includes a plurality of aperture groups each having one or a plurality of apertures, and an angle of the charged particle beam between each of the plurality of aperture groups. And an angle adjusting means for adjusting image rotation of the charged particle beam between each of the plurality of aperture groups, and adjusting the angle adjusting means and the rotation adjusting means. A charged particle beam application apparatus characterized in that the beam can pass through the multi-beam forming unit.   2. The charged particle beam application apparatus according to claim 1, wherein the deflection unit includes an aligner that adjusts an angle of the charged particle beam emitted from the multi-beam forming unit, and is determined by the detector in the deflection by the aligner. The charge is characterized in that the beam is allowed to pass through the detector by adjusting the aligner so that a deflection region capable of detecting a current value equal to or greater than a predetermined value is near the center of the deflection region. Particle beam application equipment.   2. The charged particle beam application apparatus according to claim 1, wherein the detector is a detector having a detection surface that enables simultaneous detection of the plurality of charged particle beams. 3. The charged particle beam application apparatus according to claim 1, wherein the charged particle beam is an electron beam or an ion beam.

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