In the printing configuration,
the test station is referred to as the static exposure station (SES).
Static means that the scanning and stepping systems required to
print complete circuit patterns on all the chips on a silicon wafer
are not implemented. Instead, only small ("microfield")
test patterns are imaged. Key features of the SES are the ability
to control the coherence of the illuminating EUV light (partially
coherent is optimum for printing) and the illumination pattern (disk-shaped,
annular, dipolar pairs of disks, channel-shaped, etc.). The combined
PS/PDISES system remains extremely flexible in that switching
between the interferometry and printing modes can be accomplished
in approximately two weeks.
Two 4x reducing optical
systems have been developed as part of the EUV lithography program
in which Intel, Motorola, Advanced Micro Devices, IBM, Micron Technology,
and Infineon Technologies (the EUV Limited Liability Corporation)
partnered with the "Virtual National Laboratory," consisting
of groups from Lawrence Livermore National Laboratory, Sandia National
Laboratories, and Berkeley Lab. The second, much higher quality, Set-2
optic is destined for integration into the prototype printing machine
(the Engineering Test Stand or ETS) for full-field scanned imaging,
but the CXRO team has already obtained valuable information by using
the SES to lithographically characterize the static imaging performance
of the Set-2 optic.
up to specs. Designed for printing patterns with sub-100-nm
features, the Set-2 optic imaged elbow test patterns with a
line-to-spacing ratio of 1:1 with high fidelity down to line
widths of 70 nm.
to image features of 100 nm and below in patterns with a dense 1:1
ratio of line widths and line spacing, the ETS Set-2 optic easily
lived up to its specs, achieving line widths as narrow as 70 nm
in elbow patterns. By adjusting the illumination pattern and the
exposure dose, the team printed less densely spaced lines with widths
down to 39 nm. These results indicate that with the new optic set
expected to arrive at the ALS for testing in November 2002, it should
be possible to print features in the 16-nm to 18-nm range and thus
meet the production requirements set for chips with 1 billion transistors
and up in the years 2007 to 2010.
controlling the exposure, the CXRO team was able to print
line widths down to 39 nm with the Set-2 optic for an elbow
test pattern with a line-to-spacing ratio of 3:1
conducted by P.P. Naulleau, K.A. Goldberg, E.H. Anderson, D. Attwood,
P. Batson, P. Denham, E. Gullikson, B. Harteneck, B. Hoef, K. Jackson,
D. Olynick, S. Rekawa, and F. Salmassi (Berkeley Lab); J. Bokor (University
of California, Berkeley, and Berkeley Lab); K. Blaedel, H. Chapman,
L. Hale, R. Soufli, E. Spiller, D. Sweeney, J. Taylor, and C. Walton
(Lawrence Livermore National Laboratory); G. Cardinale, A. Ray-Chaudhuri,
A. Fisher, G. Kubiak, D. O'Connell, R. Stulen, and D. Tichenor (Sandia
National Laboratories); and C.W. Gwyn, P.-Y. Yan, and G. Zhang (Intel
Research funding: Extreme Ultraviolet Limited Liability Corporation
and U.S. Department of Energy, Office of Basic Energy Sciences (BES).
Operation of the ALS is supported by BES.
Publication about this research: P.P. Naulleau et al., "Static
Microfield Printing at the Advanced Light Source with the ETS Set-2
Optic," Proc. SPIE 4688-05 (2002, in press).
Vol. 202, July 3, 2002