ION ACCELERATOR AND ION SPECIES SELECTOR

• US 3,786,359 A
• Filed: 03/28/1969
• Issued: 01/15/1974
• Est. Priority Date: 03/28/1969
• Status: Expired due to Term

• Current Assignee: William J. King
• Original Assignee: William J. King
• Inventors: King, William J.
• Primary Examiner(s): Segal, Robert
• Application Number:
  US04/811,361
• Time in Patent Office: 1,754 Days
• Field of Search: 328/233 250/49.5T
• US Class Current: 315/500
• CPC Class Codes: G21K 1/14 using charge exchange devices, e.g. for neutralising or changing the sign of the electrical charges of beams producing or accelerating neutral particle beams H05H3/00
• CPC Class Codes: H01J 37/3171 for ion implantation
• CPC Class Codes: H01J 49/284 using electrostatic and magnetic sectors with simple focusing, e.g. with parallel fields such as Aston spectrometer

Abstract

The apparatus disclosed herein provides high energy positive ions, suitable for semiconductor doping, by projecting positive ions through an electron stripping gas at relatively low energy thereby to obtain positive ions which are multiply ionized or charged. Those ions which are raised to a preselected ionization level or state are segregated, and then accelerated by a relatively high accelerating voltage to achieve an energy suitable for ion implantation in a semiconductor matrix. Since the ions subjected to the relatively high accelerating voltage are multiply ionized, the energy imparted thereto, measured in electron volts, is substantially equal to an integer multiple of the accelerating voltage.

Claims

1. Apparatus for providing high energy positive ions to a given ion utilization means, said apparatus comprising:

an ion source for providing positive ions;

means for defining an electron stripping canal;

means for providing to said canal a gas adapted to strip additional electrons from positive ions projected through said canal;

means for applying a relatively low accelerating voltage to ions emitted from said source thereby to project ions from said source through said canal and to thereby increase the extent of ionization of at least a portion of said ions;

means associated with said canal defining means for selecting a particular multiply ionized species in the ions emerging from said canal, species at other ionization levels being blocked; and

means for applying a relatively high accelerating voltage to said ions of the selected species thereby to further accelerate said ions of the selected species toward said utilization means, the energy thusly imparted to said ions of the selected species being substantially related to the product of said relatively high accelerating voltage and the multiple charge on each such selected ion.

2. Apparatus as set forth in claim 1 wherein said utilization means is substantially at ground potential and said source is at a relatively high positive potential.

3. Apparatus as set forth in claim 2 including means for scanning a beam of ions provided by said apparatus.

4. Apparatus as set forth in claim 1 wherein said ion source is a duoplasmatron.

5. Apparatus as set forth in claim 1 wherein said relatively low accelerating voltage is generally in the range of from 10 to 150 kilovolts.

6. Apparatus as set forth in claim 1 wherein said relatively high accelerating voltage is generally in the range of from 100 to 600 kilovolts.

7. Apparatus as set forth in claim 1 wherein said selecting means comprise means for applying crossed magnetic and electric fields to ions emerging from said stripping canal.

8. Apparatus as set forth in claim 1 including means for selectively passing ions of said selected species after acceleration by said relatively high voltage.

9. Apparatus as set forth in claim 8 wherein said means for selectively passing ions comprises means for applying an analyzing magnetic field.

10. Apparatus for providing high energy positive ions to a given ion utilization means, said apparatus comprising:

an ion source for providing positive ions;

means for defining an electron stripping canal;

means for providing to said canal a gas adapted to strip additional electrons from positive ions projected through said canal;

means for focusing a beam of said ions on said canal;

means for selecting a particular multiply ionized species of said ions emerging from said canal, species at other ionization levels being blocked;

means for focusing a beam of the ions emerging from said canal on said selecting means; and

means for applying a relatively high accelerating voltage between said selecting means and said utilization means whereby ions of said selected species are accelerated to energies which are substantially proportional to the product of said relatively high accelerating voltage and the multiply charge on each such selected ion.