Source: http://www.google.com/patents/US6525328?dq=6322901
Timestamp: 2015-02-01 16:00:47
Document Index: 399587615

Matched Legal Cases: ['Art 1', 'Art 2', 'Art 3', 'Art 4', 'Art 5', 'Art 4', 'Art 6']

Patent US6525328 - Electron beam lithography system and pattern writing method - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsAn electron beam lithography system 10 comprises an electron gun including a rectangular cathode 1 having an emission surface having an aspect ratio of other than 1, an illumination optical system 3 of an asymmetric lens system including multipole lenses Qa1 and Qa2, a CP aperture 5, and a projection...http://www.google.com/patents/US6525328?utm_source=gb-gplus-sharePatent US6525328 - Electron beam lithography system and pattern writing methodAdvanced Patent SearchPublication numberUS6525328 B1Publication typeGrantApplication numberUS 09/624,355Publication dateFeb 25, 2003Filing dateJul 24, 2000Priority dateJul 23, 1999Fee statusPaidPublication number09624355, 624355, US 6525328 B1, US 6525328B1, US-B1-6525328, US6525328 B1, US6525328B1InventorsMotosuke Miyoshi, Yuichiro Yamazaki, Katsuya OkumuraOriginal AssigneeKabushiki Kaisha ToshibaExport CitationBiBTeX, EndNote, RefManPatent Citations (2), Non-Patent Citations (6), Referenced by (28), Classifications (10), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetElectron beam lithography system and pattern writing methodUS 6525328 B1Abstract An electron beam lithography system 10 comprises an electron gun including a rectangular cathode 1 having an emission surface having an aspect ratio of other than 1, an illumination optical system 3 of an asymmetric lens system including multipole lenses Qa1 and Qa2, a CP aperture 5, and a projection optical system 8 of a symmetric lens system including multipole lenses Qb1 through Qb4. This electron beam lithography system 10 is used for emitting an electron beam at a low acceleration of 5 kV or less from the rectangular cathode 1, for controlling the illumination optical system so as to form an image of a desired character of the CP aperture 5 on an isotropic plane of incidence at different demagnifications in minor-axis and major-axis directions in accordance with the aspect ratio of the rectangular cathode 1, and for controlling the projection optical system 8 so that the electron beam leaving the CP aperture 5 as an aperture image is incident on a substrate 21 at the same demagnification in the minor-axis and major-axis directions and at different incident angles in the minor-axis and major-axis directions while passing through the trajectory without establishing any crossovers.
What is claimed is: 1. An electron beam lithography system having an electron optical system comprising:
an electron beam emitting device for emitting an electron beam to a substrate on which a desired pattern is to be written, said electron beam emitting device having a cathode for emitting electrons, said electron beam having a cross section, which is asymmetric with respect to an optical axis, and, said cathode emitting at an acceleration voltage at which the quantity of back scattered electrons generated from said substrate by irradiation with said electron beam is lower than a quantity at which the light exposure of a close pattern to be written is affected; a character aperture including a hole having a shape corresponding to the shape of said desired pattern; an illumination optical system for controlling the emitted electron beam so as to irradiate said character aperture with the electron beam, said illumination optical system being set with demagnifications which are different in X-axis and Y-axis directions to each other when the direction of said optical axis is Z-axis direction so that said character aperture is irradiated with said electron beam which includes a cross section having a first aspect ratio of about 1, said electron beam being shaped so as to correspond to the shape of said shaping aperture, and a projection optical system for demagnifying said electron beam and for forming an image on said substrate, said projection optical system demagnifying said electron beam at the same demagnification in X-axis and Y-axis directions to each other and forming the image on said substrate through a trajectory which is asymmetric with respect to said Z-axis at different incident angles in said X-axis and Y-axis directions to each other. 2. An electron beam lithography system as set forth in claim 1, wherein said illumination optical system has a first multipole lens.
a first step of emitting said electron beam having a cross section which is asymmetric with respect to an optical axis at an acceleration voltage at which the quantity of back scattered electrons generated from said substrate by irradiation with said electron beam is lower than a quantity at which the light exposure of a close pattern to be written is affected; a second step of setting demagnifications of said illumination optical system to be different in X-axis and Y-axis directions to each other when the direction of said optical axis is Z-axis direction, and of controlling said electron beam so that said electron beam is cast on said character aperture so as to have a substantially isotropic cross section; and a third step of controlling said projection optical system so as to demagnify said electron beam from said character aperture at the same demagnification in X-axis and Y-axis directions and so as to cause said electron beam to pass through a trajectory which is asymmetric with respect to said optical axis and to be cast on said substrate at different incident angles in said X-axis and Y-axis directions to each other to form an image on said substrate. 18. A pattern writing method as set forth in claim 17, wherein said second step includes a step of setting focal conditions so that said electron beam is incident on said shaping aperture at different incident angles in said X-axis and Y-axis directions to each other.
On the other hand, a cell projection type electron beam lithography system using electrostatic columns has been proposed by H. Sunaoshietal. (Jpn. J. Appl. Phys. Vol. 34 (1995), pp. 6679-6683 (which will be hereinafter referred to as �Background Art 1�)). Another cell projection type lithography system is disclosed by K. Hattori et. Al (J. Vac. Scl. Technol. B 11(6), November/December 1993, p2346 (which will be hereinafter referred to as �Background Art 2�)).
The influence of the space-charge effect on the surface of a substrate has been analyzed by Y. Yamazaki and M. Miyoshi (Optik 96, No. 4 (1994), pp. 184-186 (which will be hereinafter referred to as �Background Art 3�)). This has analyzed the relationship between the increasing ratio of the beam diameter and the aperture angle ratio due to the space-charge effect of an elliptical cross-section beam. More specifically, this has analyzed the influence of the space-charge effect appearing in an optical system when the image of an elliptical cross-section beam having a uniform current density is formed at a circular spot on the surface of a substrate on the anamorphic image-formation optical conditions.
It has been described in some papers that a multipole asymmetrical lens system represented by a quadrupole lens is used for forming a probe. Some applied examples of such multipole asymmetrical lens systems are described in Electron Microscope (Vol. 25, No. 3 (1990), pp. 159-166 (which will be hereinafter referred to as �Background Art 4�)) and Electron Microscope (Vol. 25, No. 1 (1991), pp. 58-65 (which will be hereinafter referred to as �Background Art 5�)). On page 159 of Background Art 4, there is shown a conceptual diagram of an electron optical system of a variable shaped type electron beam lithography system using three-stage electric-field quadrupole lenses. Referring to FIG. 2, the construction of this electron optical system will be described below. Furthermore, in the following figures, the same reference numbers are given to the same elements, and the descriptions thereof are suitably omitted.
An image forming optical system based on different incident angles is disclosed by Y. Yamazaki and M. Miyoshi (Nuclear Instruments and Methods In Physics Research A363 (1995), 67-72 (Background Art 6)). In this paper, there is described the image forming conditions of an electric-field quadrupole lens system for reducing and projecting an electron beam from a line cathode (exactly a rectangular cathode) to an isotropic circular beam. The electron optical system shown herein comprises a light source of 10 μm�100 μm, an LaB6 line cathode having an aspect ratio of 10, and an anamorphic image forming system of a three-stage quadrupole lens system (triplet). This electron optical system is designed to deform and reduce the rectangular beam into the circular beam by setting a demagnification of 1/1000 in the X-axis (minor axis) and a demagnification of 1/100 in the Y-axis (major axis).
SUMMARY OF THE INVENTION It is therefore a first object of the present invention to provide a low acceleration electron beam lithography system wherein the influence of the space-charge effect is reduced to provide excellent resolution and throughput.
DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of a column of a cell projection type system will be explained with reference to FIG. 4. FIG. 4 is a schematic diagram showing the construction of the lens system. The column shown in FIG. 4 is a premise of an electron beam lithography system according to the invention. The lenses hereinafter include deflecting systems and aberration correcting systems in the broad sense. Furthermore, explanation of beam scanning/deflecting systems and aberration correcting systems, such as an astigmatism correcting system, which have no relation directly to explanation of the present invention, is omitted.
The cell projection type column shown in FIG. 4 mainly comprises an electron gun 51, an illumination optical system 53, a character projection aperture (which will be hereinafter referred to simply as a �CP aperture�) 5, and a projection optical system 58. All lenses of the column are constructed with electrostatic lenses. Moreover, the lens for convergent comprises an electrostatic lens of a rotation symmetric system.
(1) First Preferred Embodiment FIG. 5 is a schematic diagram showing an electron optical system of the first preferred embodiment of an electron beam lithography system according to the present invention. As shown in this figure, a cell projection type electron optical system 10 in this preferred embodiment comprises an electron gun having a cathode 1, a first aperture angle diaphragm 2, an illumination optical system 3, a first shaping/deflecting system 4, a CP aperture (shaping aperture) 5, a second shaping/deflecting system 6, a second aperture angle diaphragm 7, and a projection optical system 8.
In this preferred embodiment, the LaB6 cathode 1 having a size of 10 μm�100 μm is used. Therefore, the incident angle α1 on the CP aperture 5 in the X-axis trajectory direction is α1=0.2 mrad, and the incident angle γ1 on the CP aperture 5 in the Y-axis trajectory direction is γ1=2 mrad. In addition, the incident angle α2 on the top surface of the substrate 21 in the X-axis trajectory direction is α2=2 mrad, and the incident angle γ2 on the top surface of the substrate 21 in the Y-axis trajectory direction is γ2=20 mrad. A control method for realizing such incident angles with respect to each of optical systems will be described in detail below.
Δx/Δα=Δy/Δγ=2/[(α/γ)�+(γ/α)�] In this preferred embodiment, the aspect ratio of the LaB6 rectangular cathode has been set to be 1:10 to obtain the above described results. However, since an aspect ratio of 1:100 can be already obtained in the manufacturing technology, the influence of the space-charge effect can be reduced to about 1/10 by further one order if such a rectangular cathode is used.
(2) Second Preferred Embodiment While the rectangular light source has been used in the above described first preferred embodiment, the above described object of the present invention can be accomplished even if a widely used circular light source is used.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4798959 *Jan 2, 1987Jan 17, 1989Marks Alvin MSuper submicron electron beam writerJP2000173529A Title not available* Cited by examinerNon-Patent CitationsReference1H. Sunaoshi et al., "Electron Beam Calibration Method for Character Projection Exposure System EX-8D", Jpn. J. Appl. Phys. vol. 34, pp. 6679-6683, 1995.2K. Hattori et al., "Electron-beam direct writing system EX-8D employing character projection exposure method", J. Vac. Sci. Technol. B11(6), pp. 2346-2351, Nov./Dec. 1993.3S. Okayama, "Multipoles; Principles and Their Applications (2)", Electron Microscope, vol. 25, No. 3, pp. 159-166, 1990.4S. Okayama, "Multipoles; Principles and Their Applications (3)", Electron Microscope, vol. 26, No. 1, pp. 58-65, 1991.5Y. Yamazaki et al, "Anamorphotic quadrupole lens system for highly demagnified round spot", Nuclear Instruments & Methods In Physics Research A 363, pp. 67-72, 1995.6Y. Yamazaki et al., "Spot growth of an electron beam with an elliptical cross section due to a space charge effect", Optik, 96, No. 4, pp. 184-186, 1994.Referenced byCiting PatentFiling datePublication dateApplicantTitleUS6723997 *Oct 25, 2002Apr 20, 2004Jeol Ltd.Aberration corrector for instrument utilizing charged-particle beamUS6815698 *Aug 3, 2001Nov 9, 2004Kabushiki Kaisha ToshibaCharged particle beam exposure systemUS6852983 *Nov 20, 2002Feb 8, 2005Jeol Ltd.Charged-particle beam apparatus equipped with aberration correctorUS6870172May 21, 2004Mar 22, 2005Kla-Tencor Technologies CorporationMaskless reflection electron beam projection lithographyUS6906305 *Jan 7, 2003Jun 14, 2005Brion Technologies, Inc.System and method for aerial image sensingUS6930308 *Oct 3, 2002Aug 16, 2005Kla-Tencor Technologies CorporationSEM profile and surface reconstruction using multiple data setsUS7301263May 28, 2004Nov 27, 2007Applied Materials, Inc.Multiple electron beam system with electron transmission gatesUS7342224 *Jul 26, 2006Mar 11, 2008Thermo Finnigan LlcObtaining tandem mass spectrometry data for multiple parent ions in an ion populationUS7358512Mar 28, 2006Apr 15, 2008Kla-Tencor Technologies CorporationDynamic pattern generator for controllably reflecting charged-particlesUS7391034 *Nov 8, 2005Jun 24, 2008Kla-Tencor Technologies CorporationElectron imaging beam with reduced space charge defocusingUS7427765Oct 3, 2005Sep 23, 2008Jeol, Ltd.Electron beam column for writing shaped electron beamsUS7566882Dec 14, 2006Jul 28, 2009Kla-Tencor Technologies CorporationReflection lithography using rotating platterUS7692167Oct 26, 2006Apr 6, 2010Kla-Tencor Technologies CorporationHigh-fidelity reflection electron beam lithographyUS7755061Nov 7, 2007Jul 13, 2010Kla-Tencor Technologies CorporationDynamic pattern generator with cup-shaped structureUS7800075Aug 19, 2008Sep 21, 2010Benyamin BullerMulti-function module for an electron beam columnUS7816655May 21, 2004Oct 19, 2010Kla-Tencor Technologies CorporationReflective electron patterning device and method of using sameUS8039176Nov 14, 2009Oct 18, 2011D2S, Inc.Method for fracturing and forming a pattern using curvilinear characters with charged particle beam lithographyUS8089051Feb 24, 2010Jan 3, 2012Kla-Tencor CorporationElectron reflector with multiple reflective modesUS8253119Jul 27, 2009Aug 28, 2012Kla-Tencor CorporationWell-based dynamic pattern generatorUS8283094Oct 16, 2011Oct 9, 2012D2S, Inc.Method for fracturing and forming a pattern using circular characters with charged particle beam lithographyUS8343695Oct 7, 2011Jan 1, 2013D2S, Inc.Method for fracturing and forming a pattern using curvilinear characters with charged particle beam lithographyUS8373144Aug 31, 2010Feb 12, 2013Kla-Tencor CorporationQuasi-annular reflective electron patterning deviceUS8431914Aug 24, 2010Apr 30, 2013D2S, Inc.Method and system for manufacturing a surface using charged particle beam lithography with variable beam blurUS8501374Dec 21, 2012Aug 6, 2013D2S, Inc.Method for fracturing and forming a pattern using shaped beam charged particle beam lithographyUS8669023Jun 21, 2013Mar 11, 2014D2S, Inc.Method for optical proximity correction of a reticle to be manufactured using shaped beam lithographyUS20120054697 *Aug 31, 2011Mar 1, 2012Kazuhiro TakahataLight source shape calculation methodWO2006037675A1 *Jul 29, 2005Apr 13, 2006Leica Microsys Lithography LtdLighting system for a corpuscular radiation device, and method for lighting by means of a corpuscular beamWO2007041444A2 *Oct 2, 2006Apr 12, 2007Applied Materials IncElectron beam column for writing shaped electron beams* Cited by examinerClassifications U.S. Classification250/492.22, 250/396.00R, 250/398International ClassificationH01J37/317Cooperative ClassificationB82Y40/00, B82Y10/00, H01J37/3174European ClassificationB82Y10/00, B82Y40/00, H01J37/317BLegal EventsDateCodeEventDescriptionJul 28, 2010FPAYFee paymentYear of fee payment: 8Jul 28, 2006FPAYFee paymentYear of fee payment: 4Jun 11, 2001ASAssignmentOwner name: KABUSHIKI KAISHA TOSHIBA, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MIYOSHI, MOTOSUKE;YAMAZAKI, YUICHIRO;OKUMURA, KATSUYA;REEL/FRAME:011884/0657Effective date: 20010307Owner name: KABUSHIKI KAISHA TOSHIBA 72, HORIKAWA-CHO, SAIWAI-Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MIYOSHI, MOTOSUKE /AR;REEL/FRAME:011884/0657RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services