Electric lamp and discharge devices: systems – High energy particle accelerator tube – Magnetic field acceleration means
Reexamination Certificate
2000-05-30
2003-11-25
Wells, Nikita (Department: 2881)
Electric lamp and discharge devices: systems
High energy particle accelerator tube
Magnetic field acceleration means
C315S005410, C250S492210, C313S360100
Reexamination Certificate
active
06653803
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to ion implantation systems, and more specifically to an improved ion implanter linear accelerator energizing apparatus and system.
BACKGROUND OF THE INVENTION
In the manufacture of semiconductor devices, ion implantation is used to dope semiconductors with impurities. A high energy (HE) ion implanter is described in U.S. Pat. No. 4,667,111, assigned to the assignee of the present invention, Eaton Corporation, which is hereby incorporated by reference as if fully set forth herein. Such HE ion implanters are used for deep implants into a substrate in creating, for example, retrograde wells. Implant energies of 1.5 MeV (million electron volts), are typical for the deep implants. Although less energy can be used, the implanter still must be capable of performing implants at energies between 300 keV and 700 keV. Eaton GSD/HE and GSD/VHE ion implanters can provide ion beams at energy levels up to 5 MeV.
Referring to
FIG. 1
a
, a typical high energy ion implanter
10
is illustrated, having a in terminal
12
, a beamline assembly
14
, and an end station
16
. The terminal
12
includes an ion source
20
powered by a high voltage power supply
22
. The ion source
20
produces an ion beam
24
which is provided to the beamline assembly
14
. The ion beam
24
is then directed toward a target wafer
30
in the end station
16
. The ion beam
24
is conditioned by the beamline assembly
14
which comprises a mass analysis magnet
26
and a radio frequency (RF) linear accelerator (linac)
28
. The linac
28
includes a series of resonator modules
28
a
-
28
n
, each of which further accelerates ions beyond the energies they achieve from prior modules. The accelerator modules are individually energized by a high RF voltage which is typically generated by a resonance method to keep the required average power reasonable. The mass analysis magnet
26
passes only ions of appropriate charge-to-mass ration to the linac
28
.
The linear accelerator modules
28
a
-
28
n
in the high energy ion implanter
10
individually include an RF amplifier
50
, a resonator
52
, and an electrode
54
as schematically illustrated in
FIG. 1
b
. The resonators, for example, as described in U.S. Pat. No. 4,667,111 operate at a frequency in the range of about 3-30 Mhz, with a voltage of about 0 to 150 kV, in order to accelerate ions of the beam
24
to energies over one million electron volts per charge state. A conventional connection of power between an RF amplifier
50
and a resonator
52
includes a first impedance matching network
56
within the amplifier
50
to match the active devices
51
, which may be solid state or vacuum tube devices, to the transmission line
58
impedance, typically 50 OHMs. A second matching network
60
at the feed into the resonator
52
matches the transmission line impedance to the resonator load impedance. The power losses due to the matching networks
56
and
60
, as well as the cable
58
are typically 2-5% of the total RF power. In addition, such matching networks and transmission lines or cables are costly. Further, the length of the cable
58
is critical, and an optimal cable length for matching purposes may include several meters of cable which occupies valuable space a in a typical high energy ion implantation system.
SUMMARY OF THE INVENTION
The present invention is directed to an integrated resonator and radio frequency (RF) amplifier system and apparatus for use in an ion accelerator, which eliminates or minimizes various problems associated with the prior art. In particular, the invention combines the previous multiple matching networks into a single network, thereby reducing the complexity and cost of an integrated resonator and RF amplifier system. The invention further provides a method of coupling an RF amplifier with a resonator.
In accordance with one aspect of the invention, an integrated resonator and amplifier system is provided wherein an RF output associated with the amplifier is substantially directly coupled to the resonator, thereby eliminating the costs associated with one or more matching networks and cables associated with prior art systems and devices. The system may comprise an amplifier having an RF output, a tank circuit substantially directly coupled to the RF output of the amplifier, and an accelerating electrode connected to the tank circuit. In addition to cost advantages, the present invention reduces the space required for an accelerator module. The present invention, moreover, eliminates or reduces the power losses associated with the eliminated networks and cable, thereby improving overall system efficiency. The reduction in the number of RF components according to the invention also advantageously improves the system reliability.
In accordance with another aspect of the invention, an apparatus is provided for accelerating ions in an ion implanter. The apparatus may comprise an amplifier having an RF output, a tank circuit having a coil substantially directly coupled to the RF output of the amplifier, and an electrode connected to the coil for accelerating ions.
In accordance with yet another aspect of the invention, a method of coupling an RF amplifier with a resonator in an ion accelerator is provided. The method comprises connecting an RF output of an amplifier to a coupler, and locating the coupler near a resonator coil, thereby coupling the RF output of the amplifier with the resonator. In addition, the invention provides for capacitive or inductive coupling of an RF amplifier with an ion accelerator resonator.
REFERENCES:
patent: 4667111 (1987-05-01), Glavish et al.
patent: 5504341 (1996-04-01), Glavish
patent: 6262638 (2001-07-01), Scherer
patent: 0996316 (2000-04-01), None
DiVergilio William F.
Saadatmand Kourosh
Scherer Ernst F.
Axcelis Technologies Inc.
Eschweiler & Associates LLC
Wells Nikita
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