Apparatus and techniques for generating bunched ion beam

Patent metadata

Field	Value
Publication number	US-10867773-B2
Application number	US-202016842464-A
Country	US
Kind code	B2
Filing date	Apr 7, 2020
Priority date	Aug 21, 2018
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

An apparatus may include a first grounded drift tube, arranged to accept a continuous ion beam, at least two AC drift tubes, arranged in series, downstream to the first grounded drift tube, and a second grounded drift tube, downstream to the at least two AC drift tubes. The apparatus may include an AC voltage assembly, electrically coupled to at least two AC drift tubes. The AC voltage assembly may include a first AC voltage source, coupled to deliver a first AC voltage signal at a first frequency to a first AC drift tube of at least two AC drift tubes. The AC voltage assembly may further include a second AC voltage source, coupled to deliver a second AC voltage signal at a second frequency to a second AC drift tube of the at least two AC drift tubes, wherein the second frequency comprises an integral multiple of the first frequency.

First claim

The invention claimed is:

1. An apparatus, comprising:
a buncher, the buncher comprising:
a multi-ring drift tube assembly, the multi-ring drift tube assembly comprising:
a first grounded drift tube, arranged to accept a continuous ion beam;
at least two AC drift tubes, arranged in series, downstream to the first grounded drift tube; and
a second grounded drift tube, downstream to the at least two AC drift tubes; and
an AC voltage assembly, electrically coupled to the at least two AC drift tubes, the AC voltage assembly comprising:
a first AC voltage source, coupled to deliver a first AC voltage signal at a first frequency to a first AC drift tube of at least two AC drift tubes; and
a second AC voltage source, coupled to deliver a second AC voltage signal at a second frequency to a second AC drift tube of the at least two AC drift tubes, wherein the second frequency comprises an integral multiple of the first frequency; and
a linear accelerator, disposed downstream of the buncher.

2. The apparatus of claim 1 , the multi-ring drift tube assembly comprising a third AC drift tube, arranged in series with the first AC drift tube and the second AC drift tube, the apparatus further comprising a third AC voltage source, coupled to deliver a third AC voltage signal at a third frequency to the third AC drift tube, wherein the third frequency comprises an integral multiple of the first frequency, different from the second frequency.

3. The apparatus of claim 2 , wherein the first frequency comprises a frequency of at least 20 MHz, wherein the second frequency comprises a multiple of two of the first frequency, and wherein the third frequency comprises a multiple of three of the first frequency.

4. The apparatus of claim 1 , wherein the multi-ring drift tube assembly comprises:
a first AC drift tube, coupled to the first AC voltage source, disposed downstream to the first grounded drift tube, and adjacent to the first grounded drift tube; and
a second AC drift tube, coupled to the second AC voltage source, disposed adjacent the first AC drift tube, upstream of the second grounded drift tube, and adjacent to the second grounded drift tube.

5. The apparatus of claim 1 , wherein the multi-ring drift tube assembly is arranged to output the continuous ion beam as a bunched ion beam, comprising a plurality of discrete packets, wherein a packet of the plurality of discrete packets comprises a first plurality of phase-lagging ions and a second plurality of phase-leading ions.

6. The apparatus of claim 1 , wherein the multi-ring drift tube assembly is arranged to generate an acceptance in an accelerator stage, downstream to the multi-ring drift tube assembly, of at least 50%, wherein less than 50% of ion of the ion beam is lost.

7. The apparatus of claim 1 , wherein an amplitude of the first AC voltage signal and the second AC voltage signal is less than 25 kV.

8. The apparatus of claim 1 , wherein a length of the multi-ring drift tube assembly is at least 100 mm and less than 400 mm.

9. The apparatus of claim 1 , wherein the continuous ion beam comprises an ion energy of at least 250 kV.

10. An apparatus, comprising:
a buncher, the buncher comprising:
a multi-ring drift tube assembly, the multi-ring drift tube assembly comprising:
a first grounded drift tube, arranged to accept a continuous ion beam;
an AC drift tube, arranged in series, downstream to the first grounded drift tube; and
a second grounded drift tube, downstream to the AC drift tube, arranged to output a bunched ion beam; and
an AC voltage assembly, electrically coupled to the AC drift tube, the AC voltage assembly comprising:
a first AC voltage source, coupled to deliver a first AC voltage signal at a first frequency to the AC drift tube; and
a second AC voltage source, coupled to deliver a second AC voltage signal at a second frequency to the AC drift tube, wherein the second frequency comprises an integral multiple of the first frequency; and
a linear accelerator, disposed downstream of the buncher, in a path of the continuous ion beam.

11. The apparatus of claim 10 comprising, the AC voltage assembly comprising:
a third AC voltage source, coupled to deliver a third AC voltage signal at a third frequency to the AC drift tube, wherein the third frequency comprises an integral multiple of the first frequency.

12. The apparatus of claim 10 wherein the AC drift tube is immediately adjacent the first grounded drift tube and the second grounded drift tube.

13. The apparatus of claim 10 , wherein the multi-ring drift tube assembly is arranged to output the bunched ion beam as a plurality of discrete packets, wherein a packet of the plurality of discrete packets comprises a first plurality of phase-lagging ions and a second plurality of phase-leading ions.

14. The apparatus of claim 11 , wherein the first frequency comprises a frequency of at least 20 MHz, wherein the second frequency comprises a multiple of two of the first frequency, and wherein the third frequency comprises a multiple of three of the first frequency.

15. An ion implantation system, comprising:
an ion source to generate a continuous ion beam;
a buncher, disposed downstream of the ion source, to receive the continuous ion beam and output a bunched ion beam; and
a linear accelerator, comprising a plurality of acceleration stages, disposed downstream of the buncher, to accelerate the bunched ion beam, wherein the buncher comprises:
a drift tube assembly, comprising:
a first grounded drift tube, arranged to accept the continuous ion beam;
a solo AC drift tube, disposed downstream of and immediately adjacent to the first grounded drift tube;
a second grounded drift tube, downstream to the solo AC drift tube, and immediately adjacent to the solo AC drift tube;
an AC voltage assembly, arranged to send to the AC drift tube assembly a first AC voltage signal at a first frequency, and a second AC voltage signal at a second frequency, and a third AC voltage signal at a third frequency, wherein the second frequency is twice the first frequency, and the third frequency is three times the first frequency; and
an adder, coupled to receive the first AC voltage signal, the second AC voltage signal, and the third AC voltage signal, and to output to the solo AC drift tube a composite AC voltage signal comprising a sum of the first AC voltage signal, the second AC voltage signal, and the third AC voltage signal.

16. The ion implantation system of claim 15 , wherein the first frequency comprises a frequency of at least 20 MHz, and wherein the third frequency comprises a frequency of 120 MHz or less.

17. The ion implantation system of claim 15 , wherein the buncher outputs the bunched ion beam as a plurality of discrete packets, wherein a packet of the plurality of discrete packets comprises a first plurality of phase-lagging ions and a second plurality of phase-leading ions.

18. An ion implantation system, comprising:
an ion source to generate a continuous ion beam;
a buncher, disposed downstream of the ion source, to receive the continuous ion beam and output a bunched ion beam, the buncher comprising:
a first AC drift tube to receive a first AC signal at a first frequency; and
a second AC drift tube, disposed downstream of the first AC drift tube, to receive a second AC signal at a second frequency being an integral multiple of the first frequency; and

a linear accelerator, disposed downstream of the buncher, to receive and accelerate the bunched ion beam.

19. The ion implantation system of claim 1

Assignees

• Varian Semiconductor Equipment Ass Inc

Inventors

• Sinclair Frank

Classifications

• H05H9/00

  Linear accelerators · CPC title

• H05H7/22

  Details of linear accelerators, e.g. drift tubes (H05H7/02 - H05H7/20 take precedence) · CPC title

• H01J49/062

  Ion guides (linear ion traps performing mass selection H01J49/4225, mass filters H01J49/421) · CPC title

• H01J49/004

  Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn · CPC title

• H01J37/3171 Primary

  for ion implantation · CPC title