Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/02—Details
  • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
  • H01J37/10—Lenses
  • H01J37/12—Lenses electrostatic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y40/00—Manufacture or treatment of nanostructures
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
  • H01J37/317—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation
  • H01J37/3174—Particle-beam lithography, e.g. electron beam lithography
  • H01J37/3177—Multi-beam, e.g. fly's eye, comb probe
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/03—Mounting, supporting, spacing or insulating electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/10—Lenses
  • H01J2237/12—Lenses electrostatic
  • H01J2237/1205—Microlenses

Definitions

• the present invention relates to a technique in the
• Electron lenses include electromagnetic ones and electrostatic ones.
• an electro-optical element for controlling optical characteristics of an electron beam.
• Electron lenses include electromagnetic ones and electrostatic ones.
• electrostatic electron lens does not require a coil core, has a simpler configuration, and is more easily downsized, compared to an electromagnetic electron lens.
• a multi-beam system for simultaneously drawing patterns without using any mask by a plurality of electron beams has been proposed among electron beam exposure
• Electrodes are stacked with an insulator between the electrodes.
• a point where a surface of the insulator, a surface of the electrodes, and space are in contact with each other serves as a triple junction.
• electrons are emitted from the surface of the electrode serving as a cathode due to the electric field concentration effect.
• the emitted electrons directly collide with the
• the electric charge on the surface of the insulator results in generation of an electric field.
• the electric field may deflect the trajectory of an electron beam.
• PL 1 Osamu Yamamoto et al., "Insulation performance and flashover mechanism of bridged vacuum gaps," T. IEE Japan, Vol. 110-A, No. 12, 1990
• emitted electrons may vary widely in initial trajectory and in position of collision with an insulator.
• the variation may result in insufficient stability in the charged state of the surface of the insulator to affect the trajectory of an electron beam.
• charged particle beam lens includes a first electrode including a surface having at least one aperture and a second electrode including a surface having at least one aperture and also includes a support intervening between the first electrode and the second electrode to electrically insulate the first and second electrodes from each other and support the first and second electrodes.
• a side surface of the support intervening between the first electrode and the second electrode includes a non-flat portion having at least one of a projected portion and a depressed portion and includes a tapered portion of a tapered shape, and an angle formed by the tapered portion and the surface having the aperture of the second electrode is larger than 0 degree and smaller than 90 degree.
• formation of the non-flat portion enables inhibition of the amount of electric charge on the surface of the support. Additionally, formation of the tapered portion enables generation of an electric field where a charged particle emitted from a triple junction receives force in a direction away from the support around the tapered portion. Therefore, a charged particle emitted from the triple junction follows a trajectory leaving from the support, and the electrification-induced power to attract a charged particle is inhibited in the non-flat portion due to the reduced amount of electric charge.
• a flying charged particle tends to reach an electrode on the other side before colliding with the support or tends to collide with the support and stay there because the flying charged particle is unlikely to generate a secondary charged particle due to small energy of the collision. It is thus possible to inhibit the charged state of the support from
• Fig. 1A is a cross-sectional view for describing a
• Fig. IB is a cross-sectional view for describing a charged particle beam lens according to an embodiment of the present invention.
• Fig. 1C is a cross-sectional view for describing a charged particle beam lens according to an embodiment of the present invention.
• Fig. 2A is a cross-sectional view for describing the principle of inhibiting the charged state of a support of a charged particle beam lens according to the present invention from fluctuating.
• Fig. 2B is a cross-sectional view for describing the principle of inhibiting the charged state of a support of a charged particle beam lens according to the present invention from fluctuating.
• Fig. 2C is a cross-sectional view for describing the principle of inhibiting the charged state of a support of a charged particle beam lens according to the present invention from fluctuating.
• Fig. 3A is a cross-sectional view for describing the functions of a non-flat portion and a tapered portion of supports of the charged particle beam lens.
• Fig. 3B is a cross-sectional view for describing the functions of a non-flat portion and a tapered portion of supports of the charged particle beam lens.
• Fig. 4A is a graph for describing advantageous effects of the non-flat portion and tapered portion of the supports .
• Fig. 4B is a graph for describing advantageous effects of the non-flat portion and tapered portion of the supports .
• Fig. 5A is a diagram and a view for describing a charged particle beam exposure device according to an embodiment of the present invention.
• Fig. 5B is a diagram and a view for describing a charged particle beam exposure device according to an embodiment of the present invention.
• a charged particle beam lens according to the present invention is characterized in that a side surface of a support intervening between electrodes (a surface extending between the electrodes) includes a non-flat portion and a tapered portion and that a taper angle formed by the tapered portion and a surface having an aperture of the electrodes is larger than 0 degree and smaller than 90 degree.
• the non-flat portion is formed on the side of one of the electrodes, and the tapered portion is formed on the side of the other electrode.
• the non-flat portion and tapered portion may be formed so as to be completely separate from each other or so as to overlap at least partially with each other.
• the non-flat portion inhibits the charged state of the support from fluctuating mainly by trapping a charged particle entering a depressed portion by a projected portion.
• the tapered portion inhibits the charged state of the support from fluctuating mainly by
• FIG. 1A is a cross-sectional view of a charged particle beam lens according to the present embodiment with the details omitted
• Fig. IB is an enlarged view
• the charged particle beam lens includes two electrodes, a first electrode 1 and a second electrode 2.
• the two electrodes are electrically insulated and separated from each other by a support 3 intervening between the electrodes and are supported in a predetermined positional relationship.
• An aperture 4 of the electrodes 1 and 2 lets a charged particle beam emitted from a light source (not shown) pass through.
• the aperture 4 in the electrodes 1 and 2 is arranged such that a central axis 5 is substantially common to the electrodes and define an optical axis of the lens. As illustrated in Fig.
• a side surface of the support 3 intervening between the electrodes 1 and 2 includes a non-flat portion 3a havir.g one of a projected port.ion ar.d a depressed portion on the first electrode side and includes a tapered portion 3b on the second electrode side.
• a taper angle 6 of the tapered portion 3b formed by the tapered portion and a surface having the aperture 4 of the second electrode 2 is larger than 0 degree and smaller than 90 degree.
• a surface of the tapered portion 3b can be curved or stepped, as needed.
• a tip position of the tapered portion 3b in contact with the second electrode 2 and a tip position (a top surface position) of a projected portion of the non-flat portion 3a can be set so as to be substantially
• the non-flat portion 3a can, of course, have projected portions with different top surface positions (heights) . In the present embodiment ,. the non-flat portion 3a and tapered portion 3b are completely separately formed. A projected portion of the non-flat portion 3a extends in
• substantially parallel refers not only to a case where two objects are completely parallel but also to a case where two objects are nonparallel to such a degree that the advantageous effects of the present invention can be achieved and a case where a plurality of projected portions projects in nonparallel to each other. Accordingly, even a case where two objects are deliberately designed to be nonparallel and a case where two objects are made nonparallel due to a
• Electrodes with the above-described configuration are used as an electrostatic charged particle beam lens.
• Fig. 1C is an Einzel electrostatic lens in which the electrodes 1 and
• the charged particle beam lens is made to function as an electrostatic lens by applying a ground potential to the two upper and lower electrodes 1 and a negative potential to the central electrode 2, for example.
• Fig. 2A illustrates one half of the charged particle beam lens in Fig. 1A which is symmetric with respect to the central axis 5 of the aperture 4.
• a ground potential is applied to the electrode 1 and a negative potential is applied to the electrode 2
• a junction of the support 3, the electrode 2, and a vacuum region 8 serves as a triple junction 7 to cause electric field concentration.
• an electron is emitted from the triple junction 7 on the cathode side into the vacuum region 8 due to the tunnel effect.
• the emitted electron flies, for example, as indicated by a trajectory 9 to collide with the support 3 or reaches the electrode 1 at the ground potential and is reflected from the electrode 1 with a certain proba illty to coll ide with the support 3
• the support 3 emits a secondary electron from the surface.
• the surface of the support 3 is positively charged.
• the positively charged support 3 is more likely to attract an electron.
• the flight distance of a secondary electron to be more easily attracted decreases gradually, and the energy of collision with the support 3 decreases gradually.
• junction 7 vary in emission angle and energy, the electrons vary widely in position, angle, and energy of collision with the support 3.
• the charged state of the support 3 fluctuates slightly.
• a secondary electron generated by collision of an electron with the support 3 repeats collision with the support 3 until the electron reaches an anode (the electrode 1), and variation in collision position causes wider
• Electrode 1 Electrode 1
• FIG. 2B is an
• Fig. 2B illustrates surfaces 3c and 3d of the projected portion, an electric field 10 to be applied, and an electron trajectory 9.
• the surface 3c if an electron collides with the surface 3c, the surface 3c .emits a secondary electron at a position of the collision.
• the secondary electron behaves as indicated by the electron trajectory 9, for example.
• the surface 3c is positively charged at the collision position, and the emitted secondary electron collides with the
• the depressed portion can be handled as having peak and valley positions shifted by a half cycle from peak and valley positions of the projected portion, and hence the same as in the case of the projected portion occurs.
• the function of a tapered portion in Fig. 2C will be described.
• the electrodes 1 and 2 are electrodes.
• the tapered portion 3b is inserted between the electrodes 1 and 2 to cause the electrodes 1 and 2 to have a
• FIG. 2C also illustrates the electric field component 10, which passes through only the vacuum region 8 between the electrodes 1 and 2, and an electric field component 11 which passes through the tapered portion 3b and vacuum region 8.
• a potential at a position indicated by a dotted line 12 which is equidistant from the electrodes 1 and 2.
• the dielectric constant of the tapered portion 3b is not 1ess than 1, the electric______fieid component 11 is different in electric field strength from the electric field component 10, which passes through only the vacuum region 8. Accordingly, a position where the electric field component 11 and dotted line 12 cross and a position where the electric field component 10 and dotted line 12 cross are different in potential to cause a potential difference. Especially if the dielectric constant is not less than 1, the potential at the position where the electric field component 11 and dotted line 12 cross is lower than the potential at the position where the electric field component 10 and dotted line 12 cross. The potential difference
• the taper angle 6 is one of 0 degree and 90 degree, the dielectric constant is uniform on a path of the electric field component 11, as in the electric field component 12, the potential difference as described above is not generated. If the taper angle 6 is 45 degree, and the path of the
• tapered portion is provided on the cathode side to keep an emitted electron away from the support 3, and one of a projected portion and a depressed portion is provided on the anode side to reduce the amount of electric charge and not to attract an electron. This reduces the number of collisions with the support 3 on the cathode side and on the anode side and stabilizes the charged state.
• electrodes 1 and 2 each are made of single crystal silicon and have a thicknesses of 100 micrometer.
• the diameter of an aperture 4 is 30 micrometer.
• a support 3 is made of glass that is an insulating material and has a thickness of 400
• the support 3 is sandwiched between the electrodes 1 and 2, and the electrodes 1 and 2 are installed in parallel to a plane a normal of which is a central axis 5 of the aperture 4.
• a surface of a non-flat portion on the electrode 1 side of the support 3 has three projected portions, and the level difference of each projected portion (the difference between a bottom surface of a depressed portion and a top surface of the projected portion) is 20 micrometer.
• the support 3 also includes a tapered portion on the electrode 2 side, which is in contact with the electrode 2 to form an angle of 75 degree. A ground potential was applied to the
• FIG. 3A illustrates a configuration in which the tapered portion 3b has been omitted from the support 3 in Fig. IB.
• Fig. 3A illustrates a level difference d [micrometer] between a projected portion and a
• the function of the projected portion or the depressed portion is to form a barrier in a
• Fig. 4A illustrates a result of the calculation.
• the abscissa of Fig. 4A represents the level difference d micrometer while the ordinate represents the rate of electrons flying over the level difference d.
• the result showed that when the level difference d was 20 micrometer, the rate of escape from the projected portion was substantially zero.
• the level difference d is thus desirably not less than 20 micrometer.
• Fig. 3B illustrates a configuration in which the non- flat portion 3a has been omitted from the support 3 in Fig. IB.
• Fig. 3B illustrates a taper angle ⁇ .
• a region h of a support 14 where a tapered portion is provided is set to be 80 micrometer long.
• the function of the tapered portion is to keep an electron away from the support and inhibit the charged state of the support from fluctuating
• a charge variation was calculated while the taper angle ⁇ degree illustrated in Fig. 3B was varied.
• Fig. 4B illustrates a result of the calculation.
• the abscissa of Fig. 4B represents the taper angle ⁇ degree while the ordinate represents a relative value when the charge variation in the case of a taper angle of 90 degree is taken as 1.
• the result shows that advantageous effects are stably obtained when the taper angle ⁇ is not less than 45 degree and not more than 75 degree.
• FIG. 5A and 5B A second embodiment of the present invention will be described with reference to Figs. 5A and 5B.
• the present embodiment relates to a charged particle beam exposure device using a plurality of charged particle beams. Portions having the same functions as in the first embodiment are denoted by the same reference signs, and a redundant description of the portions will be omitted.
• Fig. 5A is a diagram illustrating the configuration of a multi charged particle beam exposure device according to the present embodiment.
• the exposure device of the present embodiment is a so-called multi-column type one including individual projection systems.
• Electrodes 109 and 110 forms an irradiation optical system crossover 112 by a crossover control optical system 111.
• a so-called thermionic electron source such as a e or BaO/W
• the crossover control optical system 111 includes two stages of electrostatic lenses. Each of the electrostatic lenses in the first and second stages includes three electrodes.
• the electrostatic lens is an Einzel electrostatic lens in which a negative voltage is applied to the middle ciecLrode, and_the_to.p__and conversio-ttom—ele.ctrxxde.s_a.r-e grounded.
• Electron beams 113 and 114 emitted from the irradiation optical system crossover 112 over a wide area are converted into parallel beams 116 by a collimator lens 115 and are applied to an aperture array 117.
• Multi electron beams 118 into which the beams are divided by the aperture array 117 are individually converged by a converging lens array 119 and are focused onto a
• the aperture array 117, converging lens array 119, and blanker array 122 are denoted by reference numeral 150.
• the converging lens array 119 is an electrostatic lens including three porous
• converging lens array 119 is an Einzel electrostatic lens in which a negative voltage is applied to only the middle electrode of the three electrodes, and the top and bottom electrodes are grounded.
• the aperture array 117 is placed at a pupil plane position of the
• the converging lens array 119 (a front focal plane position of the converging lens array) so as to be responsible for defining an NA (convergence semi-angle) .
• the blanker array 122 is a device including individual deflecting electrodes and individually turns on or off beams according to a drawing pattern, based on a
• a blanking signal which is generated by a drawing pattern generating circuit 102, a bitmap conversion circuit 103, and a blanking command circuit 106.
• the beam status When the beam status is on, no voltage is applied to the deflecting electrodes of the blanker array 122.
• a voltage is applied to the deflecting electrodes of the blanker array 122 to deflect a multi electron beam.
• a multi electron beam 125 deflected by the blanker array 122 is blocked by a stop aperture array 123 in a subsequent stage (on the downstream side) and is turned off.
• a plurality of aligners 120 are controlled by an aligner control circuit 107 to adjust the incidence angle and incidence position of an electron beam.
• a controller 101 controls the entire circuit.
• a blanker array has a two- stage configuration.
• a second blanker array 127 and a second stop aperture array 128 having the same
• a multi electron beam having passed through the blanker array 122 is focused onto the second blanker array 127 by a second converging lens array 126.
• the multi electron beam is further focused onto a wafer 133 by third and fourth converging lens arrays 130 and 132.
• the second converging lens array 126, third converging lens array 130, and fourth converging lens array 132 are Einzel electrostatic lens arrays, like the converging lens array 119.
• the fourth converging lens array 132 is an objective lens, and the demagnification factor of the fourth converging lens array 132 is set to about 100.
• an electron beam 121 (whose spot size is 2 micrometer in terms of FWHM) on an intermediate imaging plane of the blanker array 122 is reduced to one-hundredth on the surface of the wafer 133, and a multi electron beam whose spot size is about 20 nm in terms of FWHM is focused onto the wafer.
• a multi electron beam on the wafer 133 can be scanned by a deflector 131.
• the deflector 131 is formed of an opposing electrode and includes four stages of opposing electrodes for two-stage deflection in each of the x and y directions (a two-stage deflector is illustrated as one unit in Fig. 5A for simplicity).
• the deflector 131 is driven according to a signal from a deflection signal generating circuit 104.
• the wafer 133 is continuously moved in the X direction by a stage 134.
• An electron beam 135 on the wafer surface is deflected in the Y direction by the deflector 131 based on a result of real-time length measurement by a laser length measuring machine.
• the blanker array 122 and second blanker array 127 individually turn on or off beams according to a drawing pattern.
• a beam 124 is a beam which is on, while the beam 125 and a beam 129 are beams which are off.
• a charged particle beam exposure device includes a charged particle source, an irradiation charged particle optical system which applies a charged particle beam emitted from the charged particle source, and a substrate having at least one aperture which is irradiated with the charged particle beam from the irradiation charged particle optical system.
• the charged particle beam exposure device also includes at least one deflector which individually deflects a charged particle beam from a plurality of apertures of the substrate to control blanking and includes a charged particle beam lens according to the present invention which is provided at least one position on the downstream side of a charged particle beam on the substrate and is capable of high-precision drawing.
• Fig. 5B illustrates a charged particle beam lens which is the same as the charged particle beam lens described in the first embodiment with reference to Fig. 1C except that a plurality of apertures 4 are present.
• An exposure device with less drawing errors can be

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• Mathematical Physics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Electron Beam Exposure (AREA)
• Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

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• 2011
  • 2011-06-14 JP JP2011131963A patent/JP2013004216A/ja not_active Withdrawn
• 2012
  • 2012-05-10 WO PCT/JP2012/062572 patent/WO2012172913A1/en not_active Ceased
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