System and method for magnetic scanning, accelerating, and implanting of an ion beam

• US 5,483,077 A
• Filed: 02/03/1995
• Issued: 01/09/1996
• Est. Priority Date: 08/29/1990
• Status: Expired due to Term

• Current Assignee: Nissin Ion Equipment Co., LTD. (Nissin Electric Company Limited)
• Original Assignee: Nissin Electric Company Limited
• Inventors: Glavish, Hilton F.
• Primary Examiner(s): BERMAN, JACK I
• Application Number:
  US08/383,422
• Time in Patent Office: 340 Days
• Field of Search: 250/492.21, 250/398, 250/396, 315/506
• US Class Current: 250/492.2
• CPC Class Codes: G21K 1/093 by magnetic means
• CPC Class Codes: H01F 3/02 made from sheets
• CPC Class Codes: H01F 7/202 Electromagnets for high magnetic field strength for superconducting electromagnets H01F6/00; for transformers or inductances without a magnetic core H01F30/08
• CPC Class Codes: H01J 2237/31701 Ion implantation
• CPC Class Codes: H01J 29/76 Deflecting by magnetic fields only
• CPC Class Codes: H01J 3/32 by magnetic fields only
• CPC Class Codes: H01J 37/147 Arrangements for directing or deflecting the discharge along a desired path H01J37/045 take precedence; lenses H01J37/10
• CPC Class Codes: H01J 37/1475 magnetic
• CPC Class Codes: H01J 37/3007 Electron or ion-optical systems electron or ion-optical details H01J37/06 - H01J37/153
• CPC Class Codes: H01J 37/3171 for ion implantation plasma immersion ion implantation H01J37/32412

Abstract

Deflection apparatus is shown for high perveance ion beams, operating at 20 Hz fundamental and substantially higher order harmonics, having a magnetic structure formed of laminations with thickness in range between 0.2 and 1 millimeter. Additionally, a compensator is shown with similar laminated structures with resonant excitation circuit, operating at 20 Hz or higher, in phase locked relationship with the frequency of the previously deflected beam. Furthermore, features are shown which have broader applicability to producing strong magnetic field in magnetic gap. Among the numerous important features shown are special laminated magnetic structures, including different sets of crosswise laminations in which the field in one lamination of one set is distributed into multiplicity of laminations of the other set of coil-form structures, field detection means and feedback control system, cooling plate attached in thermal contact with number of lamination layers. Surfaces on the entry and exit sides of the compensator magnetic structure have cooperatively selected shapes to increase the length of path exposed to the force field dependently with deflection angle to compensate for contribution to deflection angle caused by higher order components. The entry and exit surfaces of the magnetic scanner and compensator structures cooperating to produce desired beam profile and desired limit on angular deviation of ions within the beam. Also shown is an accelerator comprising a set of accelerator electrodes having slotted apertures, a suppressor electrode at the exit of the electrostatic accelerator, a post-accelerator analyzer magnet having means for adjusting the angle of incidence by laterally moving the post-accelerator analyzer magnet, and a magnet to eliminate aberration created by the post-accelerator analyzer magnet. In the case of use of a spinning substrate carrier for scanning in one dimension, the excitation wave form of the scanner relates changes in scan velocity in inverse dependence with changes in the radial distance of an implant point from the rotation axis. Also an oxygen implantation method is shown with 50 mA ion beam current, the ion beam energy above 100 KeV, and the angular velocity of a rotating carrier above 50 rpm.

Claims

1. An electrostatic system for accelerating and focusing a previously produced high perveance beam of atomic or molecular ions comprising

a set of acceleration electrodes of said electrostatic accelerating system having a slotted aperture, said electrodes adapted to supply electrostatic energy to accelerate said ion beam in the direction corresponding to the potential difference across said electrodes, and

a suppressor electrode for maintaining electrons within said beam, said electrode having a slotted aperture and being located at the exit port of the electrostatic accelerating system.

3. The system of claim 1 or 2 wherein said produced beam has a ribbon profile.

4. The system of claim 1 or 2 wherein said set of acceleration electrodes comprises two relatively movable electrodes with slotted apertures for electrostatic focusing said ion beam in the short direction of said slotted apertures.

5. The system of claim 1 or 2 wherein said set of acceleration electrodes comprises three fixed, slotted aperture electrodes adapted to electrostaticly focus said ion beam in the short direction of said slotted apertures by varying potential on the center electrode.

2. In a system for delivering a substantially uniform dose of ions of a high perveance atomic or molecular beam to a selected surface,

means for producing a high perveance beam,

an electrostatic system for accelerating and focusing said beam having a set of acceleration electrodes with slotted apertures, said electrodes adapted to focus said beam in the direction of the short dimension of said slot,

a focusing device positioned along the beam axis, for focusing said beam in the dimension of said beam not being focused by said slotted apertures, and

a scanning system for rapidly sweeping said ion beam in order to achieve uniform irradiation of said selected surface by said beam.

6. The system of claim 2 further comprising

a rotatably driven carrier for repeatedly carrying said selected surface mounted on said carrier under said beam to effect scanning in one dimension, wherein said beam sweeping action of said scanning system performs scanning in the other direction, rotation of said carrier in cooperation with said scanning of said scanning system is designed to achieve uniform irradiation of said selected surface by said beam.

7. The system of claim 2 wherein said produced beam has a ribbon profile.

8. The system of claim 2 wherein said set of acceleration electrodes comprises two relatively movable electrodes with slotted apertures for electrostatic focusing said ion beam in the short direction of said slotted apertures.

9. The system of claim 2 wherein said set of acceleration electrodes comprises three fixed, slotted aperture electrodes adapted to electrostaticly focus said ion beam in the short direction of said slotted apertures by varying potential on the center electrode.

10. An electrostatic-magnetostatic system for accelerating and focusing a high perveance beam of atomic or molecular ions comprising

a set of acceleration electrodes forming an electrostatic accelerating system charged by a power source, said electrodes adapted to electrostaticly focus said ion beam in one dimension, said electrodes adapted to supply electrostatic energy to accelerate said ion beam in the direction corresponding to the potential difference across said electrodes,

a suppressor electrode for maintaining electrons within said beam, said electrode having an aperture and being located at the exit port of the electrostatic accelerating system, and

a post-acceleration analyzer magnet arranged to focus said beam in the other direction, said magnet having means for adjusting the angle of incidence of said ion beam into the entrance region of said post-acceleration magnet by laterally moving said post-acceleration magnet relative to the beam path, thereby focusing said beam in the other direction while removing neutral particles and ions of unwanted momentum ions from said ion beam.

11. The electrostatic-magnetic system of claim 10 wherein the apertures of said electrode are slotted apertures.

12. The system of claim 10 wherein said set of acceleration electrodes comprises two relatively movable electrodes for electrostatic focusing said ion beam by changing the distance between said electrodes.

13. The system of claim 10 wherein said set of acceleration electrodes comprises three fixed electrodes for electrostaticly focusing said ion beam by varying the electric potential on the center electrode.

14. The magnetic scanning system of claim 10 further comprising a multipole magnet with magnetic field arranged to eliminate aberration of said ion beam created by said post-acceleration analyzer magnet.

15. The system of claim 14 wherein said magnet is a sextupole.

16. The accelerating system of claim 10 adapted to decelerate said ion beam and further comprising a second suppressor electrode for maintaining electrons within said beam and preventing back-streaming, said second suppressor electrode being located at the entrance port of said accelerating system.