WO1993023871A1 - Ensemble a fente de resolution et procede d'implantation d'ions - Google Patents

Ensemble a fente de resolution et procede d'implantation d'ions Download PDF

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Publication number
WO1993023871A1
WO1993023871A1 PCT/GB1993/001034 GB9301034W WO9323871A1 WO 1993023871 A1 WO1993023871 A1 WO 1993023871A1 GB 9301034 W GB9301034 W GB 9301034W WO 9323871 A1 WO9323871 A1 WO 9323871A1
Authority
WO
WIPO (PCT)
Prior art keywords
rotors
slit
resolving slit
opposed
target
Prior art date
Application number
PCT/GB1993/001034
Other languages
English (en)
Inventor
Derek Aitken
Original Assignee
Superion Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Superion Limited filed Critical Superion Limited
Publication of WO1993023871A1 publication Critical patent/WO1993023871A1/fr

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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
    • H01J37/30—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
    • H01J37/3171—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 for ion implantation
    • 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
    • H01J37/09—Diaphragms; Shields associated with electron or ion-optical arrangements; Compensation of disturbing fields

Definitions

  • the present invention relates to a resolving slit assembly for example for use in an ion implantation apparatus or a mass separator, and to a method of and apparatus for implanting ions.
  • the invention relates particularly to apparatus for and methods of implanting ions of a preselected species into a target element, for example the controlled introduction of a species into the surface layer of another material.
  • the technique is important in semi-conductor technology where it is used in the manufacture of integrated circuits or other devices, particularly by modifying the conductivity of semi-conductor material by introducing chemical impurities into the material.
  • Ion implantation is used particularly in the manufacture of large scale integrated circuit chips, and is likely to be used in the manufacture of flat panel display (FPD) ion implantation.
  • FPD flat panel display
  • the magnetic analysis of the ion beam requires that the analysing magnet should bend the required ion beam through a predetermined angle and focus the beam through a narrow resolving slit in order to get the maximum resolving power capability.
  • the distance between the resolving slit and the target is often desirable to make the distance between the resolving slit and the target as short as possible. This reduces the pumping speed (or decreases the pumpdown time for a given pumping speed) involved in evacuating the apparatus to reduce neutralisation (and other charge exchange reactions) to an acceptable level.
  • Neutralisation of the beam is produced by unwanted collision of the ions with stray gas atoms, which results in uncharged atoms of the implanting element reaching the target, some at reduced energy. Because such uncharged atoms are not measured during implantation, an error in the dosage results.
  • This neutralisation is affected by the slit to target distance and the pressure, because the reactions are a function of pressure multiplied by distance.
  • the pressure upstream of the resolving slit can be maintained at a relatively high vacuum because of the differential pumping made possible by the small size of the resolving slit aperture.
  • the pressure downstream of the resolving slit can be limited by outgassing of the target chamber a er exposure to air (for systems which are vented for target loading) and outgassing of the targets (water vapour, solvents, and polymerising photoresist).
  • a problem can arise as a result of the desired small distance between the resolving slit and the target.
  • some of the species being implanted is implanted into the edges of the resolving slit, and this can subsequently be sputtered off and deposited on the surface of the target.
  • the species being sputtered is a previous species and the implant is now being contaminated with an unwanted species.
  • a resolving slit assembly for example for use in an ion implantation apparatus or a mass separator, comprising two opposed rotors providing ; the resolving slit between opposed peripheral portions of the rotors, and means for rotating the rotors to present different selectable peripheral portions of the rotors to form the resolving slit.
  • each rotor has a plurality of vanes extending outwardly from- its axis, the slit being formed between opposed outer portions of opposed vanes.
  • the vanes extend outwardly from a central core arranged to provide a cooled region relative to the outer edges of the vanes.
  • the central core may be cooled by being composed of material suitable to act as a heat sink, or, preferably, the central core includes means for passing a coolant through the core.
  • means for producing controlled rotation of the rotors such as to allow variation of the slit width.
  • means for varying the separation of the axes of rotation of the rotors to allow variation in the slit width.
  • an ion implantation apparatus comprising an ion source for producing an ion beam; a target support for supporting a target to be implanted by the beam; and means for directing the ion beam onto the target through a resolving slit formed between opposed peripheral portions of two opposed rotors.
  • the method of implanting ions comprising directing an ion beam onto a target to be implanted, including passing the beam between two opposed rotors providing a resolving slit between opposed peripheral portions of the rotors, rotating the rotors to present different peripheral portions of the rotors to form the resolving slit, and repeating the ion implantation step by directing the ion beam onto a target through a resolving slit formed by the different peripheral portions of the rotors.
  • One use of the step of rotating the rotors to present different peripheral portions of the rotors to form the resolving slit is to provide a fresh slit surround, after a substantial period of use of the apparatus, for example to provide a fresh slit surround free of flake or build-up of implant material.
  • Another use of the invention is in providing a slit by different peripheral portions, where a new species is to be implanted.
  • the method includes the steps of directing an ion beam of a first species through the resolving slit onto a target; terminating the implantation step; rotating the rotors to present different peripheral portions of the rotors to form the resolving slit; carrying out a second ion implantation step by directing an ion beam of a different species onto the target through the resolving slit formed by the different peripheral portions of the rotors.
  • the method may include the step of varying the width of the resolving slit by varying the rotary position of the rotors, and/or by varying the separation of the axes of rotation of the two rotors.
  • the invention provides, at least in preferred embodiments, a solution to the problem of reducing the slit to target distance, while avoiding sputtering of unwanted species onto the target.
  • the invention provides a compact arrangement for giving multiple slit facilities. In the arrangement in which vanes protrude from a central core, the cooling of the core region gives the advantage that migration of atoms or molecules of the various species from one vane to another can be avoided or reduced. Migration of ions which have struck the edges of the slit is only a significant problem in the region of the slit where the slit defining elements are hot.
  • slits may be needed for example because slits of different widths are needed, and because slits must be taken out of service after substantial use because of flake formation caused by deposited material, which can pose a particulate hazard for semiconductor targets. Particulate contamination from the resolving slit can be an important issue for semiconductor and flat panel display implant.
  • the large number of slits and in addition the slits can be of variable width (for control of resolving power and current transmission).
  • the slit sides can be individually cooled, and there is the possibility of automatic cleaning.
  • Figure 1 is a diagrammatic plan view of a known ion implantation apparatus
  • Figures 2a to 2c are diagrammatic plan views of three forms of resolving slit assembly embodying the invention.
  • Figure 3 is a diagrammatic plan view of an ion implantation apparatus embodying the invention.
  • an ion implantation apparatus comprises an ion source 11 aligned with extraction electrodes 12 within a vacuum chamber 13.
  • a beam of ions 14 for implantation passes to an analysing magnet 15 for selection of the required ions species for implantation.
  • the analysed ion beam 14 passes through a resolving slit 16 and impinges on a target 17 mounted on a target support 18.
  • the magnet focuses the beam at the resolving slit position so that masses slightly heavier than the required species are under-deflected and do not pass through the narrow slit; similarly, lighter ions are over-deflected and also do not pass through the slit.
  • Such a single slit could be replaced with a sliding or rotatable slit plate so that a number of slits were available, but there would always be a danger of diffusion of impurities from one slit to another, caused by beam heating.
  • Each slit would have a fixed geometry, and the number of slits would be limited by the inconvenient geometry which would result. In such an arrangement a long sliding plate with water cooling would be required.
  • Figures 2a, 2b and 2c show three forms of a resolving slit assembly embodying the invention.
  • the resolving slit assembly indicated generally as 19 comprises two opposed rotors 20 and 21 and the slit is formed by two opposed peripheral portions 22 and 23 of the rotors 20 and 21.
  • the rotors 20 and 21 are rotatable about respective shafts 24 and 25, and the rotors are rotatably mounted in screening surfaces 26 and 27.
  • the slit formed between the opposed portions 22 and 23 is indicated by reference numeral 28.
  • the slit 28 is formed between two cylinders forming the rotors 20 and 21.
  • the rotors 20 and 21 consists respectively of inner cooled cores 30 and 31 from which there extends outwardly a plurality of vanes 29.
  • the cores can be cooled by coolant passing through passages not shown. Conveniently the cooling can be effected by a water cooled shaft.
  • the separation between the rotors 20 and 21 can be varied by moving the positions of the shafts 24 and 25, so as to control the width of the slit.
  • the slit width can be varied by changing the rotary positions of the vanes.
  • the vanes can be of differing lengths, in order to give different slit widths.
  • the shafts 24 and 25 can be eccentrically positioned relative to the perimeter of the rotor, again to give the possibility of varying the slit width. If a fully closed position is required, then in the arrangements of Figures 2b and 2c the two sets of vanes can be made slightly out of phase to give an overlap in the closed position.
  • the screening material 26 is made of a structural material suitable to screen unused vanes from any stray beams.
  • the sloping entry surfaces 32 and 33 are set at an angle such that any material sputtered from these surfaces does not have a line of sight through the slit under normal operating conditions.
  • vanes in accordance with the invention is also important for maintaining a clean resolving slit, especially when protecting from particulates.
  • a build-up of implanted material on the slit slides is in inevitable after a period of use, and the facility to change to a clean slit is important if particulate conditions are to be maintained.
  • Figure 3 shows an ion implantation apparatus embodying the invention, and reference numerals are used corresponding to same elements that have been shown in Figure 1, and Figure 2c.
  • the paths of unwanted ions are shown at 38 and 39, relating respectively to lower mass ions and higher mass ions.
  • the number of vanes that can be used varies according to the requirements. If the vanes are used to control the transmitted beam current by rotary movement, then the number of vanes will be limited by the need to protect the unused vanes from contamination over the range of rotary positions.
  • the beam 14 may be a beam of ions of boron, phosphorus, or silicon, for implantation in a silicon wafer or a silicon coated flat glass panel.
  • the ion source 13 may for example be held at +50 KV relative to the housing which is at earth, and the first extraction electrode may be held at -2 KV.
  • the vacuum may be 10 "5 Torr.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physical Vapour Deposition (AREA)

Abstract

Dispositif d'implantation d'ions comprenant une source d'ions (11) produisant un faisceau d'ions (14) analysé par un aimant (15) et dirigé sur une cible (17). Le faisceau d'ions (14) passe à travers une fente de résolution (28) définie entre deux rotors opposés (20 et 21). Les rotors comprennent des ailettes (29) montées sur des noyaux refroidis (30 et 31) et la fente (28) est définie par des parties opposées périphériques des ailettes. Après utilisation, on peut faire tourner les rotors, de façon à présenter différentes ailettes opposées pour définir la fente de résolution. On peut modifier l'espacement de la fente par rotation des ailettes ou par modification de l'écartement des axes des rotors.
PCT/GB1993/001034 1992-05-21 1993-05-20 Ensemble a fente de resolution et procede d'implantation d'ions WO1993023871A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB929210887A GB9210887D0 (en) 1992-05-21 1992-05-21 Resolving slit assembly and method of ion implantation
US9210887.7 1992-05-21

Publications (1)

Publication Number Publication Date
WO1993023871A1 true WO1993023871A1 (fr) 1993-11-25

Family

ID=10715867

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1993/001034 WO1993023871A1 (fr) 1992-05-21 1993-05-20 Ensemble a fente de resolution et procede d'implantation d'ions

Country Status (2)

Country Link
GB (1) GB9210887D0 (fr)
WO (1) WO1993023871A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0785567A3 (fr) * 1996-01-16 1998-07-29 Varian Associates, Inc. Dispositif de fente pour faisceau de particules chargées
EP3483915A4 (fr) * 2017-06-22 2020-03-18 Boe Technology Group Co. Ltd. Appareil et procédé de réglage de quantité d'implantation ionique, dispositif d'implantation ionique et procédé de détermination

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2851610A (en) * 1954-09-08 1958-09-09 Akashi Kazuhiko Variable aperture for electron microscope
EP0145120A1 (fr) * 1983-08-15 1985-06-19 Applied Materials, Inc. Dispositif pour l'implantation d'ions
EP0398335A2 (fr) * 1989-05-17 1990-11-22 KABUSHIKI KAISHA KOBE SEIKO SHO also known as Kobe Steel Ltd. Dispositif pour focaliser un faisceau d'ions

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2851610A (en) * 1954-09-08 1958-09-09 Akashi Kazuhiko Variable aperture for electron microscope
EP0145120A1 (fr) * 1983-08-15 1985-06-19 Applied Materials, Inc. Dispositif pour l'implantation d'ions
EP0398335A2 (fr) * 1989-05-17 1990-11-22 KABUSHIKI KAISHA KOBE SEIKO SHO also known as Kobe Steel Ltd. Dispositif pour focaliser un faisceau d'ions

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 13, no. 173 (E-748)24 April 1989 *
PATENT ABSTRACTS OF JAPAN vol. 6, no. 123 (E-117)(1001) 8 July 1982 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0785567A3 (fr) * 1996-01-16 1998-07-29 Varian Associates, Inc. Dispositif de fente pour faisceau de particules chargées
KR100483725B1 (ko) * 1996-01-16 2005-08-24 배리언 어소시에이츠 인코포레이티드 회전실린더에의해형성된빔제한슬릿을구비한대전입자빔시스템
EP3483915A4 (fr) * 2017-06-22 2020-03-18 Boe Technology Group Co. Ltd. Appareil et procédé de réglage de quantité d'implantation ionique, dispositif d'implantation ionique et procédé de détermination
US10734189B2 (en) 2017-06-22 2020-08-04 Chengdu Boe Optoelectronics Technology Co., Ltd. Ion implantation amount adjustment device and method, ion implantation apparatus and determination method

Also Published As

Publication number Publication date
GB9210887D0 (en) 1992-07-08

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