X-ray lithography sources: A review Page: 2 of 4
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at the NSLS, IBM has 2 beamlines and at the KEK Photon Fac-
tory, Fujitsu. Hitachi, NEC and NTT, each have 1 beamline.
Machine
Energy [MeV]
K (Al
Beamlines
NSLS VUV
750
25
2
BESSY
800
19.4
1-5
TERAS
800
21.8
2
ALADDIN
800
22.7
2-4
KEK PF
2500
3.1
4
Table 2: Existing conventional magnet rings being used for x-
ray lithography.
5. New Conventional Magnet Rings
Since the number of beamlines on existing rings is limited
and the development of superconducting magnet based rings will
require additional work, new conventional magnet storage rings
have beeh built to fill the gap. Table 3 lists the new conven-
tional magnet storage rings that are being built for the purpose of
x-ray lithography. Diversity probably best describes the
numerous approaches as various lattice configurations and injec-
tors are being tried.
The first four machines listed in Table 3 are located in
Japan where to date the greatest effort to develop storage rings
for x-ray lithography is taking place. All four of the Japanese
machines will be fully assembled and begin commissioning by
the middle of 1989.
NIJI-II, a four dipole racetrack type ring at the Electro-
technical Lab (ETL) in Tsukuba, is the smallest of the rings, C *
17 m. but with a critical wavelength of \e * 37 A it is not
optimized as a lithography source.
LUNA, a four dipole four superperiod machine, is being
constructed by Ishikawajima-Harima Heavy Industries (IHI) in
Tsukuba. It achieves its small circumference of C = 23.3 m by
using only four dipoles but with so few dipoles it is difficult to
meet the specification of <7X < 1 mm in the dipole. LUNA has a
45 MeV linac built by IHI as an injector.
The four superperiod Chasman-Green ring at NTT in Atsugi
was built by Toshiba as part of the NTT lithography effort and is
already in the commissioning stage. This ring is accompanied
by a 13 MeV linac injector that was delivered by Mitsubishi
Electric. The NTT ring can operate as a stand alone storage ring
or as a booster for NTT’s superconducting ring, SUPER ALIS,
about which more will be said in the next section.
The SORTEC corporation, which was established by the
Ministry of International Trade and Industry in 1986, is a colla-
borative effort between thirteen Japanese companies to develop
sources, beamlines and applications for x-ray lithography. To
this end SORTEC has purchased a 40 MeV linac from Mitsu-
bishi Electric to inject into a full energy booster ring provided by
Toshiba which eventually stacks electrons in the 1 GeV storage
ring supplied by Mitsubishi Electric.
The LSU-CAMD ring5 is also a four superperiod
Chasman-Green machine to be constructed on the Louisiana
State University campus by Maxwell-Brobeck Inc. The project
began in December 1988 and the machine is scheduled for
operation in early 1992 with 1 LSU sponsored lithography beam-
line to start with and plans for more later on.
6. New Superconducting Magnet Kings
In parallel with the construction of conventional magnet
rings at least six SC magnet rings are currently under construc-
tion (see Table 4), with two of these already in the commission-
ing stage. For these machines the diversity of approaches
exceeds that in the conventional magnet machines. There are
one, two and four dipole machines with a broad range of magnet
types and injectors.
AURORA6, which is being built by Sumitomo Heavy
Industries (SHI), is in a class by itself as it is constructed as a
single 360° dipole weak focusing storage ring along the lines of
the existing SURF II machine at NIST and the previously pro-
posed KLEIN ERNA7 machine. This design gives the smallest
possible circumference, 2xp = 3.14 m, and there arc no fringe
field regions to worry about but the machine itself is a monolith
of iron weighing 120 tons (3 m OD and height of 2.2 m).
although the large mass of iron will reduce the amount of
required external shielding. The injection system for AURORA
is a 25 turn, 150 MeV racetrack microtron built by SHI.
AURORA will make use of a novel half integer resonance injec-
tion scheme*.
For a weak focusing machine of the AURORA type an ana-
lytic expression for the electron beam sizes can be given in terms
of the field index, n, the bending radius, p and the electron
energy,
Ox [mm ] = 2.1 E [GeV J
P \m 1
n (3-4n)
' 1/2
O)
For typical values of the field index, 0 < n < .75, this lends to
horizontal electron beam sizes in the range of 1-2 mm. To lower
the beam size the dipole magnets must be split into more pieces
and quadrupoles must be added to reduce both the emittancc and
the dispersion. Split the magnet into more pieces also makes it
easier to include the other necessary hardware such as the KF
cavity, injection kickers, etc. The next four machines in Table 4
are machines making use of two 180° dipole magnets.
The COSY ring at BESSY makes use of a 50 MeV
racetrack microtron as an injector. While the superconducting
magnets were being fabricated the machine was fitted with con-
ventional magnets to study low energy injection. During that
time up to 100 ma were stored. The SC magnets, constructed by
Interatom, have since been delivered and the machine is
currently undergoing commissioning.
NTT’s SUPER ALIS9 ring was designed and constructed in
collaboration with Hitachi Corporation. A unique feature of this
machine is that it has two injection septum magnets to accommo-
date very low energy injection (15 MeV) directly from a linac or
full energy injection (600 MeV) from their conventional magnet
booster/storage ring. It is also the only two dipole machine to
have a magnet with an iron yoke. So-called ‘wobbler’ magnets
Machine
C [m]
E [MeV]
K [X]
Location
H,-, [MeV]
B |T|
P |m]
NIJ1 11
17
600
37
ETL
200 L
1.4
1.4
LUNA
23.5
800
22
IHI
45 L
1.33
2.0
NTT
52
800
20
Atsugi
15 L
1.46
1.83
SORTEC
46
1000
15.5
Tsukuba
1000 LB
1.2
2.77
CAMD
52.8
1200
9.5
LSU
150 L
1.37
2.93
Table 3: New conventional magnet rings being built for x-ray lithography (L = linac & B = booster).
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Murphy, J.B. X-ray lithography sources: A review, article, January 1, 1989; Upton, New York. (https://digital.library.unt.edu/ark:/67531/metadc1093797/m1/2/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.